What is the job of the Circulatory System?

The Circulatory System is responsible for transporting materials throughout the entire body. It transports nutrients, water, and oxygen to your billions of body cells and carries away wastes such as carbon dioxide that body cells produce. It is an amazing highway that travels through your entire body connecting all your body cells.

Parts of the Circulatory System
The circulatory System is divided into three major parts:

1. The Heart
2. The Blood
3. The Blood Vessels

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The Heart

The Heart is an amazing organ. The heart beats about 3 BILLION times during an average lifetime. It is a muscle about the size of your fist. The heart is located in the center of your chest slightly to the left. It's job is to pump your blood and keep the blood moving throughout your body.

It is your job to keep your heart healthy and there are three main things you need to remember in order to keep your heart healthy.

1. Exercise on a regular basis. Get outside and play. Keep that body moving (walk, jog, run, bike, skate, jump, swim).
2. Eat Healthy. Remember the Food Pyramid and make sure your eating your food from the bottom to top.
3. Don't Smoke! Don't Smoke! Don't Smoke! Don't Smoke! Don't Smoke!

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The Blood

The blood is an amazing substance that is constantly flowing through our bodies.

• Your blood is pumped by your heart.
• Your blood travels through thousands of miles of blood vessels right within your own body.
• Your blood carries nutrients, water, oxygen and waste products to and from your body cells.
• A young person has about a gallon of blood. An adult has about 5 quarts.
• Your blood is not just a red liquid but rather is made up of liquids, solids and small amounts of oxygen and carbon dioxide.

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Blood Cells

Red Blood Cells

Red Blood Cells are responsible for carrying oxygen and carbon dioxide. Red Blood Cells pick up oxygen in the lungs and transport it to all the body cells. After delivering the oxygen to the cells it gathers up the carbon dioxide(a waste gas produced as our cells are working) and transports carbon dioxide back to the lungs where it is removed from the body when we exhale(breath out). There are about 5,000,000 Red Blood Cells in ONE drop of blood.

White Blood Cells (Germinators)

White Blood Cells help the body fight off germs. White Blood Cells attack and destroy germs when they enter the body. When you have an infection your body will produce more White Blood Cells to help fight an infection. Sometimes our White Blood Cells need a little help and the Doctor will prescribe an antibiotic to help our White Blood Cells fight a large scale infection.

Platelets

Platelets are blood cells that help stop bleeding. When we cut ourselves we have broken a blood vessel and the blood leaks out. In order to plug up the holes where the blood is leaking from the platelets start to stick to the opening of the damaged blood vessels. As the platelets stick to the opening of the damaged vessel they attract more platelets, fibers and other blood cells to help form a plug to seal the broken blood vessel. When the platelet plug is completely formed the wound stops bleeding. We call our platelet plugs scabs.

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Plasma

Plasma is the liquid part of the blood. Approximately half of your blood is made of plasma. The plasma carries the blood cells and other components throughout the body. Plasma is made in the liver.

Where are the blood cells made?
The Red Blood Cells, White Blood Cells and Platelets are made by the bone marrow. Bone marrow is a soft tissue inside of our bones that produces blood cells.

The Blood Vessels

In class we talked about three types of blood vessels:

1. Arteries
2. Capillaries
3. Veins

Arteries

Arteries are blood vessels that carry oxygen rich blood AWAY from the heart. Remember, A A Arteries Away, A A Arteries Away, A A Arteries Away.

Capillaries

Capillaries are tiny blood vessels as thin or thinner than the hairs on your head. Capillaries connect arteries to veins. Food substances(nutrients), oxygen and wastes pass in and out of your blood through the capillary walls.

Veins

Veins carry blood back toward your heart.

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 AMAZING FACTS

• One drop of blood contains a half a drop of plasma, 5 MILLION Red Blood Cells, 10 Thousand White Blood Cells and 250 Thousand Platelets.
• You have thousands of miles of blood vessels in your body. "Bill Nye the Science Guy" claims that you could wrap your blood vessels around the equator TWICE!
• Keep your heart healthy...it's going to have to beat about 3 BILLION times during your lifetime!

Functions

Hemoglobin
green = heme groups
red & blue = protein subunits

Heme

Blood performs many important functions within the body including:

• Supply of oxygen to tissues (bound to hemoglobin, which is carried in red cells)
• Supply of nutrients such as glucose, amino acids, and fatty acids (dissolved in the blood or bound to plasma proteins (e.g., blood lipids))
• Removal of waste such as carbon dioxide, urea, and lactic acid
• Immunological functions, including circulation of white blood cells, and detection of foreign material by antibodies
• Coagulation, which is one part of the body's self-repair mechanism (blood clotting after an open wound in order to stop bleeding)
• Messenger functions, including the transport of hormones and the signaling of tissue damage
• Regulation of body pH
• Regulation of core body temperature
• Hydraulic functions

·         What blood does

·         Blood doesn't have "a" function, it has several. It carries food and oxygen to cells, it carries waste away from cells, and serves as a carrier for various disease-fighting cells such as the "white" blood cells. It also has a means of puncture-proofing the body: it clots, sealing up small holes quickly. Blood is also important in maintaining a constant temperature in your body.

Read more: http://wiki.answers.com/Q/What_is_the_function_of_the_blood#ixzz18rYT52fn

·          

Circulatory system consists of
Organ - heart; Connecting systems - arteries, veins and capillaries; cellular components - RBC - exchange of gases, WBC - immnuity against infection, platelets - blood coagulation during cuts.
Function of the circulatory system is

• Carry oxygen from lungs to tissues and carbondioxide from tissues to lungs therby aiding in the exchange of gases. Supply of oxygen is needed for proper functionaing of the cells. Removal of carbondioxide is also equally essential s it becomes toxic to cells when present in high amount.
• Help in fighting against infections by the defence cells- the granulocytes and agranulocytes
• Prevent overbleeding by forming blood clot by the platelets.
• Helps to maintain pH of the blood by buffering system present

Thus circulating blood performs varied functions.
To distribute oxygen to the cells of the body.

Read more: http://wiki.answers.com/Q/What_is_the_function_of_the_circulatory_system#ixzz18rYjuzI9

Circulatory System

Introduction

The circulatory system consists of blood, a heart, and blood vessels.

Functions of the Circulatory System

The circulatory system functions with other body systems to provide the following:
Transport of materials:
Gasses transported: Oxygen is transported from the lungs to the cells. CO₂ (a waste) is transported from the cells to the lungs.
Transport other nutrients to cells - For example, glucose, a simple sugar used to produce ATP, is transported throughout the body by the circulatory system. Immediately after digestion, glucose is transported to the liver. The liver maintains a constant level of glucose in the blood.
Transport other wastes from cells - For example, ammonia is produced as a result of protein digestion. It is transported to the liver where it is converted to less toxic urea. Urea is then transported to the kidneys for excretion in the urine.
Transport hormones - Numerous hormones that help maintain constant internal conditions are transported by the circulatory system.
Contains cells that fight infection
Helps stabilize the pH and ionic concentration of the body fluids.
It helps maintain body temperature by transporting heat. This is particularly important in homeothermic animals such as birds and mammals.

Circulatory System: Problems and Diseases

As we all know, the circulatory system or cardiovascular system comprises the blood, heart and blood vessels. The blood consists of the red blood cells (RBCs), white blood cells (WBCs), platelets and blood plasma. The blood vessels, on the other hand, comprise the veins, arteries, arterioles and capillaries. All of these parts contribute a lot to the proper functioning of the circulatory system. A disorder in any of the parts can cause certain health complications, which may vary from a mild disease to a life-threatening condition.

There are two types of circulatory system problems, viz. congenital (present at birth) and acquired (developed after birth). Common problems and diseases of the circulatory system include:

Aortic Aneurysm: Aortic aneurysm is bulging in the wall of the aorta, the largest artery of the body. Aortic aneurysm is caused due to aortic dissection (tear in the aortic wall) or defect in the aortic wall. A rupture of the bulging may cause heavy bleeding or hemorrhage. Aortic aneurysm can be developed as a complication of certain other diseases such as obesity, atherosclerosis and high blood pressure.

Angina: Angina is pain or discomfort in the chest area, due to blockage in the blood vessels leading to the heart. The symptoms of angina are observed when there is insufficient supply of oxygen and blood to the heart. Chest pain may lasts for about 10 minutes.

Arrhythmia: Arrhythmia is a heart problem, characterized by irregularity in the heart rhythm. Symptoms may vary from very slow to fast heart rhythm. Arrhythmia can be a congenital or an acquired problem. In case of acquired arrhythmia, it can occur at any stage of life.

Atherosclerosis: Atherosclerosis is hardening of the arterial wall (usually medium and large arteries) due to formation of plaque or atheroma. The plaque may be composed of cholesterol, calcium and fatty deposits. Atherosclerosis may hamper the blood circulation or at times, it can even stop the blood flow. A person suffering from this problem experiences sharp pain in the affected area.

High Blood Pressure: High blood pressure or hypertension is a condition, when the systolic pressure exceeds 140 mmHg and diastolic pressure exceeds 90 mmHg. It is mostly caused due to hereditary reasons or unhealthy lifestyle habits such as heavy drinking and smoking.

Peripheral Vascular Disease: Peripheral vascular disease is disorder in the blood vessels that are not part of the brain and heart. This disease is caused due to fatty acid deposits in the arteries of the leg portion. It can be hereditary or develop as a complication of obesity, high blood pressure and smoking.

In severe cases, heart disease can cause heart attack, heart failure and several other fatal health problems. One word of advice for those people who smoke cigarette and have circulatory problem would be to quit smoking, as it can worsen the existing condition, by constricting the blood vessels. Circulatory problems and diseases may also be caused due to intake of certain drugs like oral contraceptives and diuretics. It is always advisable to consult and seek advice from a qualified health practitioner before using any drugs and/or medications, in order to know the pros and cons of the same.

Domain Archaea

Domain Archaea is mostly composed of cells that live in extreme environments. While they are able to live elsewhere, they are usually not found there because outside of extreme environments they are competitively excluded by other organisms. Species of the domain Archaea are not inhibited by antibiotics, lack peptidoglycan in their cell wall (unlike bacteria, which have this sugar/polypeptide compound), and can have branched carbon chains in their membrane lipids of the phospholipid bilayer. It is believed that Archaea are very similar to prokaryotes that inhabited the earth billions of years ago. It is also believed that eukaryotes evolved from Archaea, because they share many mRNA sequences, have similar RNA polymerases, and have introns. Therefore, it is believed that the domains Archaea and Bacteria branched from each other very early in history, and membrane infolding produced eukaryotic cells in the archaean branch approximately 1.7 billion years ago.

The Archaea are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon (sometimes spelled "archeon"). They have no cell nucleus nor any other membrane-bound organelles within their cells. In the past they were viewed as an unusual group of bacteria and named archaebacteria, but the Archaea have an independent evolutionary history and show many differences in their biochemistry from other forms of life, and so they are now classified as a separate domain in the three-domain system. In this system the phylogenetically distinct branches of evolutionary descent are the Archaea, Bacteria and Eukaryota. Archaea are divided into four recognized phyla, but many more phyla may exist. Of these groups the Crenarchaeota and the Euryarchaeota are most intensively studied. Classification is still difficult, because the vast majority have never been studied in the laboratory and have only been detected by analysis of their nucleic acids in samples from the environment. Although archaea have, in the past, been classed with bacteria as prokaryotes (or Kingdom Monera), this classification is regarded by some as outdated.^[1]

Archaea and bacteria are quite similar in size and shape, although a few archaea have very unusual shapes, such as the flat and square-shaped cells of Haloquadratum walsbyi. Despite this visual similarity to bacteria, archaea possess genes and several metabolic pathways that are more closely related to those of eukaryotes: notably the enzymes involved in transcription and translation. Other aspects of archaean biochemistry are unique, such as their reliance on ether lipids in their cell membranes. Archaea use a much greater variety of sources of energy than eukaryotes: ranging from familiar organic compounds such as sugars, to ammonia, metal ions or even hydrogen gas. Salt-tolerant archaea (the Halobacteria) use sunlight as an energy source and other species of archaea fix carbon; however, unlike plants and cyanobacteria, no species of archaea is known to do both. Archaea reproduce asexually and divide by binary fission, fragmentation, or budding; in contrast to bacteria and eukaryotes, no known species form spores.

Initially, archaea were seen as extremophiles that lived in harsh environments, such as hot springs and salt lakes, but they have since been found in a broad range of habitats, including soils, oceans, and marshlands. Archaea are particularly numerous in the oceans, and the archaea in plankton may be one of the most abundant groups of organisms on the planet. Archaea are now recognized as a major part of Earth's life and may play roles in both the carbon cycle and the nitrogen cycle. No clear examples of archaeal pathogens or parasites are known, but they are often mutualists or commensals. One example is the methanogens that inhabit the gut of humans and ruminants, where their vast numbers aid digestion. Methanogens are used in biogas production and sewage treatment, and enzymes from extremophile archaea that can endure high temperatures and organic solvents are exploited in biotechnology.

Archaea recycle elements such as carbon, nitrogen and sulfur through their various habitats. Although these activities are vital for normal ecosystem function, archaea can also contribute to human-made changes, and even cause pollution.

Archaea carry out many steps in the nitrogen cycle. This includes both reactions that remove nitrogen from ecosystems, such as nitrate-based respiration and denitrification, as well as processes that introduce nitrogen, such as nitrate assimilation and nitrogen fixation.^[123][124] Archaean involvement in ammonia oxidation reactions was recently discovered. These reactions are particularly important in the oceans.^[125][126] The archaea also appear to be crucial for ammonia oxidation in soils. They produce nitrite, which other microbes then oxidize to nitrate. Plants and other organisms consume the latter.^[127]

In the sulfur cycle, archaea that grow by oxidizing sulfur compounds release this element from rocks, making it available to other organisms. However, the archaea that do this, such as Sulfolobus, produce sulfuric acid as a waste product, and the growth of these organisms in abandoned mines can contribute to acid mine drainage and other environmental damage.^[128]

In the carbon cycle, methanogen archaea remove hydrogen and are important in the decay of organic matter by the populations of microorganisms that act as decomposers in anaerobic ecosystems, such as sediments, marshes and sewage treatment works.^[129] However, methane is one of the most abundant greenhouse gases in Earth's atmosphere, constituting 18% of the global total.^[130] It is 25 times more potent as a greenhouse gas than carbon dioxide.^[131] Methanogens are the primary source of atmospheric methane, and are responsible for most of the world's yearly methane emissions.^[132] As a consequence, these archaea contribute to global greenhouse gas emissions and global warming.

Archaea form four major phyla, the

Euryarchaeota, the Crenarchaeota, the

Korarchaeota, and the Nanoarchaeota

Most archaea (but not Thermoplasma and Ferroplasma) possess a cell wall.^[47] In most archaea the wall is assembled from surface-layer proteins, which form an S-layer.^[62] An S-layer is a rigid array of protein molecules that cover the outside of the cell (like chain mail).^[63] This layer provides both chemical and physical protection, and can prevent macromolecules from contacting the cell membrane.^[64] Unlike bacteria, archaea lack peptidoglycan in their cell walls.^[65] Methanobacteriales do have cell walls containing pseudopeptidoglycan, which resembles eubacterial peptidoglycan in morphology, function, and physical structure, but pseudopeptidoglycan is distinct in chemical structure; it lacks D-amino acids and N-acetylmuramic acid.^[64]

Archaea flagella operate like bacterial flagella—their long stalks are driven by rotatory motors at the base. These motors are powered by the proton gradient across the membrane. However, archaeal flagella are notably different in composition and development.^[53] The two types of flagella evolved from different ancestors. The bacterial flagellum shares a common ancestor with the type III secretion system,^[66][67] while archaeal flagella appear to have evolved from bacterial type IV pili.^[68] In contrast to the bacterial flagellum, which is hollow and is assembled by subunits moving up the central pore to the tip of the flagella, archaeal flagella are synthesized by adding subunits at the base

Extremophile archaea, particularly those resistant either to heat or to extremes of acidity and alkalinity, are a source of enzymes that function under these harsh conditions.^[149][150] These enzymes have found many uses. For example, thermostable DNA polymerases, such as the Pfu DNA polymerase from Pyrococcus furiosus, revolutionized molecular biology by allowing the polymerase chain reaction to be used in research as a simple and rapid technique for cloning DNA. In industry, amylases, galactosidases and pullulanases in other species of Pyrococcus that function at over 100 °C (212 °F) allow food processing at high temperatures, such as the production of low lactose milk and whey.^[151] Enzymes from these thermophilic archaea also tend to be very stable in organic solvents, allowing their use in environmentally friendly processes in green chemistry that synthesize organic compounds.^[150] This stability makes them easier to use in structural biology. Consequently the counterparts of bacterial or eukaryotic enzymes from extremophile archaea are often used in structural studies.^[152]

In contrast to the range of applications of archaean enzymes, the use of the organisms themselves in biotechnology is less developed. Methanogenic archaea are a vital part of sewage treatment, since they are part of the community of microorganisms that carry out anaerobic digestion and produce biogas.^[153] In mineral processing, acidophilic archaea display promise for the extraction of metals from ores, including gold, cobalt and copper.^[154]

Archaea host a new class of potentially useful antibiotics. A few of these archaeocins have been characterized, but hundreds more are believed to exist, especially within Haloarchaea and Sulfolobus.^[155] These compounds differ in structure from bacterial antibiotics, so they may have novel modes of action. In addition, they may allow the creation of new selectable markers for use in archaeal molecular biology.^[156]

Thermophiles are microorganisms that live and grow in extremely hot environments that would kill most other microorganisms. Thermophiles are grouped into either prokaryotes or eukaryotes, and these two groups of extremophiles are classified in the group of archaea. They grow best in temperatures that are between 50C/120F- 70C/158F. They will not grow if the temperature reaches 20C/68F. Thermophiles are not easy to study because the extreme conditions that they need to survive are hard to provide in a laboratory.

Thermophiles either live in geothermal habitats, or they live in environments that create heat themselves. A pile of compost and garbage landfills are two examples of environments that produce heat on their own.

Some thermophiles like, Chaetomium thermophile, Humicola insolens, Humicola (Thermomyces) lanuginosus , Thermoascus aurantiacus, a Paecilomyces-like fungus and Aspergillus fumigatus are microorganisms called fungi.

A microorganism that produces methane as a byproduct of its metabolism. All known methanogens are both archaeans and obligate anaerobes, that is, they cannot live in the presence of oxygen. They are commonly found in wetlands, where they generate methane in the form of marsh gas, and in the guts of animals such as ruminants and humans, where they are responsible for flatulence.

Some methanogens, described as hydrotropic, use carbon dioxide as a source of carbon and hydrogen as a source of energy. Some of the carbon dioxide reacts with, and is reduced by, hydrogen to produce methane. The methane is turn gives rise to a proton motive force across a membrane, which is used to generate ATP – a key source of cellular energy. Other methanogens, called acetotrophic, use acetate (CH₃COO-) as a source of both carbon and energy. Still other methanogens exploit methylated compounds such as methylamines, methanol, and methanethiol as well.

More than 50 species of methanogens have been identified, including a number that are extremophiles. Live methanogens were recovered from a core sample taken from 3 kilometers under Greenland by researchers from the University of California, Berkeley. Another study discovered methanogens in soil and vapor samples from the vicinity of the Mars Desert Research Station in Utah. These findings add weigh to speculation by some scientists that methanogens may be responsible for the methane that has been in detected in the atmosphere of Mars.

Halophiles are aerobic microorganisms that live and grow in high saline/salty environments. The saline content in halophilic environments is usually 10 times the saline/salt content of normal ocean water.. Normal ocean water has a saline/salt level of 30 percent. Some environments that halophiles live in are the Great Salt Lake in Utah, Owens Lake in California, the Dead Sea, and saltines (crackers). These microorganisms use osmotic pressure and chemical substances like sugars, alcohols, amino acids to help control the amount of salt inside the cell. Osmotic pressure is relationship of fluids on the inside and outside of a cell. Healthy cells keep the pressure the same on the inside and outside of the cells. Halophiles are like other extremophiles because the proteins inside the microorganisms play the most important role of making it possible for them to survive in extreme saline/salty environments.

Genetics

GENETICS QUESTION - 1976 L. PETERSON/AP BIOLOGY

Each year a number of children are born with biological defects that impair normal function. For THREE of the following conditions, discuss such aspects as the biological cause, the methods of treatment and possible means of detection and/or prevention.
a. Phenylketonuria (PKU)
b. Sickle cell anemia
c. Down syndrome
d. Cretinism
e. Erythroblastosis fetalis
f. Blue-baby condition
g. Tay-Sachs


STANDARDS:
maximum of 5 points for each section discussed = 15

PHENYLKETONURIA (PKU)
Descriptive: mental retardation (1)
light-colored hair, etc. (1/2)
Cause: recessive (1/2)
mutation (1/2)
defect in amino acid metabolism (1)
phenylalanine not converted to tyrosine (1/2)
necessary enzyme lacking or ineffective (1/2)
high phenylalanine or derivatives in mother's blood affects fetus (1/2)
phenylalanine or derivatives excreted at high level (1)
Treatment: phenylalanine in diet restricted during childhood (1)
Detection: newborn's urine or blood tested (1/2)
Prevention for phenylalanine or derivatives (1/2)
heterozygotes in adults detected by phenylalanine tolerance test (1)

SICKLE CELL ANEMIA
Descriptive: common among sub-Sahara black populations & descendents (1/2)
heterozygotes resistant to malarial infections (1/2)
severe anemia (1/2)
intense pain (1/2)
shortened lifespan (1/2)
Cause: recessive (1/2)
mutation (1/2)
behaves as semidominant in heterozygotes (1/2)
substituted amino acid (1)
in beta chain of hemoglobin (1)
valine for glutamic acid at position 6 (1)
red blood cells have low efficiency in O2 transport (1)
red blood cells sickle, tend to clog smaller vessels (1)
red blood cells have shortened lifespan, resulting in anemia (1)
Treatment: transfusion of whole blood or packed cells (1)
treatment of pain by drugs (1)
Detection: red blood cells examined under microscope for sickling (1)
heterozygotes detected by simple blood test (1)


DOWN SYNDROME
Descriptive: mental retardation (1)
distinctive eyes (1/2)
abnormal dermatoglyphics (1/2)
thick tongue (1/2)
shortened lifespan (1/2)
low resistance to infection (1/2)
possible derangement of internal organs (1/2)
Cause: trisomy 21 (1)
extra chromosome (1/2)
nondisjunction as explanation of trisomy (1/2)
15/21 or other translocation (1/2)
incidence of trisomy increases with age of mother (1)
Treatment: no known cure (1)
custodial care (1/2)
special training (1/2)
surgery to correct internal derangements (1/2)
antibiotics to combat infections (1/2)
Detection: amniocentesis (1/2)
Prevention karyotype examination (1/2)
possible decision to abort if trisomy present (1/2)
pedigree & karyotype studies in young mothers of Down
syndrome children for translocation involvement (1/2)
counseling of older women about risks (1/2)

CRETINISM
Descriptive: mental retardation (1)
growth retardation (1/2)
low metabolic rate (1/2)
yellow thick skin (1/2)
distinctive eye structure (1/2)
Cause: mainly developmental (non-genetic) (1)
hypothyroidism (emphasis on gland) (1)
hypothyroidism (lack of sufficient thyroxin) (1)
low iodine in diet (1)
low TSH production by pituitary (1)
Treatment: thyroxin supplement (1)
Detection: metabolic rate measured (1)
Prevention protein-bound iodine test (PBI) (1)
presence of thyroxin in blood tested (1/2)
adequate iodine in diet assured (1/2)













ERYTHROBLASTOSIS FETALIS
Descriptive: lysis of red blood cells resulting in anemia (1/2)
jaundice (1/2)
physical malformation or edema (1/2)
Cause: depends on recessive homozygous genotype in mother (1)
mutation (1/2)
description of induction of antibodies in Rh- mother as a
result of carrying Rh+ fetus or previous transfusion (1)
description of interaction of maternal antibodies w/red blood
cells of (usually) second or later fetus (1)
Treatment: replacement of newborn's blood supply (transfusion) (1)
induction of early birth (1)
Detection: Rh+ antibody formation suppressed in mother after birth of Rh+
Prevention fetus with Rhogam (gamma-globulin) (1)
Rh+ antigen on red blood cells of parents tested (1)
Rh+ antibody level monitored during pregnancy of mother (1)
genetic counseling (1/2)

BLUE-BABY CONDITION
Descriptive: cyanosis (1/2)
resulting from lack of O2 to cells (1/2)
Cause: mainly developmental (non-genetic) (1)
failure of foramen ovale to close (1)
other circulatory defects (ductus arteriosus, restriction in
pulmonary artery) (1/2)
mixture of oxygenated & unoxygenated blood (1)
lungs bypassed (1/2)
Treatment: surgery to close foramen ovale (1)
to develop arterial shunt to pulmonary artery (1/2)
temporary: increase oxygen tension (1)
Detection: respiratory distress noted (1)
Prevention cyanosis noted (1/2)
abnormal heart sounds noted (1)
O2 level monitored with cardiac catheter (1)

TAY-SACHS DISEASE
Descriptive: neural deterioration, loss of response (1)
early death (4 years or younger) (1)
mainly in descendents of East European Jewish populations (1/2)
Cause: recessive (1/2)
mutation (1/2)
lack of essential enzyme (1)
hexosaminidase A (1/2)
accumulation of sphingolipids, etc. (1/2)
as intracellular nerve inclusions (1)
resulting in interference with normal nerve functions (1)
Treatment: none known (1)
Detection: enzyme level measured in potential parents to detect heterozygotes (1)
Prevention amniocentesis of mothers (1)
leading to enzyme assay (1/2)
genetic counseling (1/2)
possible decision to abort (1/2)

GENETICS QUESTION: 1983 L PETERSON/AP BIOLOGY

State the conclusions reached by Mendel in his work on the inheritance of
characteristics. Explain how each of the following deviates from these conclusions:
A. Autosomal linkage
B. Sex-linked (X-linked) inheritance
C. Polygenic (multiple-gene) inheritance


STANDARDS:
maximum = 15 points total

MENDEL (8 points maximum):
DISCRETE UNITS
2 FACTORS/TRAIT
DOMINANT/RECESSIVE

PUNNETT SQUARE:
GAMETES HAVE 1 FACTOR
EQUAL # GAMETES (EACH TYPE)
FACTORS SEGREGATE WHEN GAMETES FORM (SEGREGATION)
RANDOM DISTRIBUTION OF FACTORS (INDEPENDENT ASSORTMENT)
USE OF PROBABILITY

DEVIATIONS (12 points maximum):
AUTOSOMAL LINKAGE: DEFINITION (1)
EXAMPLE (1)
EXPECTED DEVIATION (1)
SEX-LINKED: DEFINITION (1)
EXAMPLE (1)
EXPECTED DEVIATION (1)
POLYGENIC: DEFINITION (1)
EXAMPLE (1)
EXPECTED DEVIATION (1)



















GENETICS QUESTION: 1988 L PETERSON/AP BIOLOGY

Discuss Mendel's laws of segregation and independent assortment.
Explain how the events of meiosis I account for the observations that
led Mendel to formulate these laws.


STANDARDS:
maximum = 10 points total (no more than 6 points for either part)

A. MENDEL'S LAWS

FACTORS (genes or alleles) in pairs / 2 alleles per trait (1)
FACTORS (alleles, genes)
dominant or recessive; or (1)
maternal + paternal origin; or (1)
heterozygote has 2 types. (1)
EXAMPLES (A, a; green, yellow, Punnett square) or monohybrid cross (1)
FIRST LAW EXPLAINED: segregation of alleles into gametes (1)
SECOND LAW EXPLAINED: independent assortment;
each pair assorts independently of other pairs (1)
EXAMPLE of dihybrid cross (or Punnett square) (1)
ONLY OCCURS WITH UNLINKED GENES; CROSSOVER EXCEPTIONS (1)
(max 6)
B. MEIOSIS I

GAMETES FORMATION (reduction division for purpose of maintaining chromosome #)
(1)
GENES (traits, alleles) are on chromosomes (1)
HOMOLOGOUS CHROMOSOMES PAIR (dyad, bivalent, tetrad used in context) (1)
PAIRING OCCURS DURING PROPHASE I (1)
SYNAPSIS (synaptonemal complex, chiasmata) (1)
may related chiasma to crossover
INDEPENDENT ASSORTMENT due to independent alignment at metaphase I (1)
PAIRS SEGREGATE AT ANAPHASE I (1)
DAUGHTER NUCLEI AFTER MEIOSIS I have one of each chromosome type
(each 2 chromatids) (1)
(may relate to Punnett square)
PHASES OF MEIOSIS I: prophase, metaphase, anaphase, telophase - in correct order
some description of each, for example:
prophase : organization
metaphase : line up at equator
anaphase : segregation
telophase : 2 "nuclei" (1)
(max 6)









GENETICS QUESTION: 1993 L PETERSON/AP BIOLOGY

Assume that a particular genetic condition in a mammalian species causes an
inability to digest starch. this disorder occurs with equal frequency in males
and females. In most cases, neither parent of affected offspring has the condition.

(a) Describe the most probable pattern of inheritance for this condition.
Explain your reasoning. Include in your discussion a sample cross(es)
sufficient to verify your proposed pattern.

(b) Explain how mutation could cause this inability to digest starch.

(c) Describe how modern techniques of molecular biology could be used to
determine whether the mutant allele is present in a given individual.


STANDARDS:
Students were expected to be able to describe the most likely pattern of inheritance based on an understanding of Mendelian genetics and the specific information given to them in the question. They needed to relate that understanding to molecular genetics in their explanation of mutations as the cause for the disorder. A variety of levels of understanding to molecular genetics in their explanation of mutation as the cause for disorder. A variety of levels of understanding of the effects of mutation were accepted as students could address the mutation as affecting DNA, transcription, translation, protein structure, or protein function. Students were also expected to demonstrate their understanding of modern techniques that could detect genetic disorders.

Part A (Maximum: 4 pts)

Most Plausible Pattern:
__ autosomal (non-sex chromosome), not on X (sex-linked) or Y (holandric)
__ recessive (allele is hidden, silent or masked)

Explanation of Genetic Pattern:
__ equal frequency of condition in females and males
__ parents might not show the trait (can be heterozygous, hidden trait possible)
__ most likely a single gene is involved (only two phenotypes observed)
eliminating a polygenic inheritance, etc.

Sample Cross:
__ Punnet Square, a sample cross or written explanation that substantiates their
genetic pattern










Part B (Maximum: 5 pts)

Mutations:
__ gene codes for polypeptide (amylase)
__ mutations are changes in DNA or a gene
__ types of mutations (nucleotide, point or chromosomal and/or example:
deletion, substitution, inversion, translocation, etc.)
__ mutations that affect transcription or RNA (RNA splicing, start signals, etc.)
__ mutations that affect translation (initiation, elongation, termination, frame shifts,
etc.)
__ mutations cause protein or enzyme structural changes:
missing or altered (amino acid sequence or shape, active site)
__ mutations cause protein or enzyme functional changes:
(production of a nonfunctional protein)
__ mutations cause structural changes that affect the release of the active enzyme
(in cell membrane or gland)

Part C (Maximum: 4 pts)

Modern Molecular Biology Techniques:
__ feasible techniques in context (one point for each technique)
DNA sequencing
RFLP (markers) - restriction fragment length polymorphisms
Monoclonal antibodies
Flourescent or radioactive probes
Hybridization (probe)
Assay of protein (amount or type)
PCR (Polymerase Chain Reaction) - to amplify the gene
__ explanation of technique (one point for each explanation)
__ measured as compared to standard (one point for each)

Enzymes

            ENZYME QUESTION - 1968                               L. PETERSON/AP BIOLOGY

            Suppose that you have isolated an extract from a tissue and you have found that

            the extract speeds up the rate of a particular reaction. What kind of information

            would you need to demonstrate that the substance responsible for increasing

            the rate of this reaction is an enzyme? Explain how this information would indicate

            that the catalytic effect is due to an enzyme.

STANDARDS:

  maxiumum points = 13

PROOF THAT IT IS ORGANIC (1/2 PT)

PROOF THAT IT IS PROTEIN (1 PT)

PROTEIN EVIDENCE:             (1 PT EACH/MAX, = 5)

  DENATURED under different pH or temperatures

  MACROMOLECULE

            will diffuse through DIALYSIS TUBING if acted on by protease

            centrifugation - large molecule - will be in precipitate

  NINHYDRIN

            will turn blue in presence of amino acids

            CHROMATOGRAPHY

RATE OF REACTION (1/2 PT)

  (2 PTS EACH/MAX. = 4)

            vary amount of substrate - determine changing rate of reaction;

            should level-off once maximum turnover rate is reached;

            vary pH & temperature - rate of reaction will be at maximum & drop off radically

            on either side;

INTERACTION BETWEEN ENZYME & SUBSTRATE (1/2 PT)

            X-ray Diffraction

            proof of changes in shape of "enzyme" (3/2 PTS)                      

 

            ENZYME QUESTION - 1969                               L. PETERSON/AP BIOLOGY

            Proteins functioning as enzymes exhibit precise specifications. Discuss the levels

            of structural organization within proteins which are responsible for specific molecular       interactions.

STANDARDS:

  maximum points = 20

PRIMARY STRUCTURE (1/2 PT)

(2)  amino acid sequence & number / determining other structures

        peptide bonds

SECONDARY STRUCTURE (1/2 PT) folding within polypeptide chain

(4)  H-bonds

        Disulfide bonds

            Alpha Helix - globular proteins

            Beta Configuration - fibrous proteins

TERTIARY STRUCTURE (1/2 PT)  further folding of alpha helix

(4)  H-bonds

        Disulfide bonds

        electrostatic forces (interactions)

        van der Waals forces

QUATERNARY STRUCTURE (1/2 PT)

(2)  Conjugated Proteins - many polypeptide chains

ENZYMES ARE SPECIFIC BECAUSE OF ACTIVE SITE

(6)  particular shape of molecule

        particular charge distribution

      Coenzymes or cofactors may be required

      Mention of Lock-Key Hypothesis

      Mention of Induced-Fit Hypothesis

      EXAMPLE

            ENZYME QUESTION - 1985                               L. PETERSON/AP BIOLOGY

            Describe the chemical compositions and configuration of enzymes and discuss

            the factors that modify enzyme structure and/or function.

STANDARDS:

  maximum points = 20

CHEMICAL COMPOSITION AND CONFIGURATION

  Proteins/Large Molecules/ Polypeptides/CHONS/CN Terminals (2 max)

  Prosthetic Groups/Metal Atoms/Apoenzyme/Coenzyme/Cofactor (2 max)

  Primary and Secondary with Discussion (2 max)

  Tertiary OR Quaternary with Discussion / Globular (2 max)

  Specificity or "Lock and Key" (1 pt)

  Peptide Bonds/Covalent Bonds for Primary

  Folding to Form a Groove, Active Site (1 pt)

  3D Configuration due to Van der Waal, R group, ionic, etc. (1 pt)

  Hydrophobic/Hydrophilic (1 pt)

                                                            Maximum = 8

FACTORS THAT MODIFY ENZYME ACTION AND/OR FUNCTION:

  Temperature = 1                      Discussion of Effect on Structure = 1

                                    Denatures Protein/3D shape altered = 1

                                    (reaction rate changes)

  pH               = 1          Discussion of Effect on Structure = 1

                                    Breakage of weak bonds changes enzyme's shape = 1

                                    Discussion of Effect on Function = 1

                        (altering of active site results in inability of substrate to bond at site)

  Allosteric Inhibition      Discussion of Effect on Structure = 1

                     = 1          (binding of an effector on an enzymes changes shape of enzyme)

                                    Discussion of Effect on Function = 1

                                    (results in activation or inactivation)

  Competitive Inhibition  Discussion of Effect on Function = 1

                     = 1          (competitive molecule binds to active site blocking it/NO rx)

                        May reverse action by increasing substrate/enzyme concentration = 1                

  Irreversible or Noncompetitive Inhibition

                      = 1             Discussion of Effect on Function (binding of molecule blocks

                                        functional groups at active site) = 1

  Activation of an Enzymatic Precursor on structure = 1

                                    (pepsinogen to pepsin)

                                    Effect on Functions = 1

                                    (nonfunctional to active)

  Genetic mistakes Modify Structure/Function of Enzymes = 1

  Feedback Inhibition relative to control = 1

  Induced Fit - binding of substrate to enzyme alters shape = 1

  Amount of substrate to Amount of enzyme - modifies function = 1

  Reversible/Irreversible denaturation = 1

  Factors may change energy of activation = 1

  Ionic Factors affect structure and/or function = 1

  Binding of Effector to speed activation/deactivation = 1

                                                            Maximum = 12

            ENZYME QUESTION - 1988                               L. PETERSON/AP BIOLOGY

            After an enzyme is mixed with its substrate, the amount of product formed is  

            determined at 10-second intervals for 1 minute. Data from this experiment

            are shown below.

            Time (sec)                     0          10         20         30         40         50         60

            Product formed (mg)     0.00       0.25        0.50        0.70       0.80       0.85        0.85

            Draw a graph of these data and answer the following questions.

            a. What is the initial rate of this enzymatic reaction?

            b. What is the rate after 50 seconds? Why is it different from the initial rate?

            c. What would be the effect on product formation if the enzyme were heated to a

                 temperature of 100 oC for 10 minutes before repeating the experiment? Why?

            d. How might altering the substrate concentration affect the rate of the reaction? Why?

            e. How might altering the pH affect the rate of reaction? Why?

STANDARDS:

  maximum points = 10

DATA RECORD AND CALCULATIONS

  GRAPH                       axis X = Time (ind); Y = Product (dep)    3 pts

                                    scale and label axis

                                    curve plotted - drawn curve necessary

  a.  initial rate               1 pt. setup (.25-.00)/(10-0)          2 pts

       0.025 mg/sec                   or    (.50-.00)/(20-0)

          .25  mg/10 sec           or    number 0.025

         1.5   mg/min         1 pt. units (mg/sec) or mg/min)

         1/40 mg/sec

  b.  rate after 50 sec                                                                             1 pt

            Zero                 1 pt. set up (.85-.85)/(60-50)

                    or             1 pt. units if not awarded in part a.

            net rate

            equilibrium

            Why?                                                                                        1 pt

              Substrate gone or reaction at equilibrium

              Other explanation - any are possible

                        Product inhibition

                        Product changes pH or temp optimum

                        Product release time varies                                Maximum = 7 pts

EXPLANATIONS:

c. Temperature variation

            Change: stops reaction; no product formation;               1 pt

                        rate near or at zero

            Explanation: Conformational shape change - denaturation           1 pt

                        (inactivation - "kills" in quotes)

d. Substrate concentration variation;

            Change:                                                                                    1 pt

                        (Increase) a) no change, initial slope same;

                                           longer to level off;

                                    or b) increase in reaction rate

                        and/or

                        (Decrease) more gentle slope; decrease rate or take less time to level off;

            Explanation:                                                                  1 pt

                        (Increase) a) Enzyme is working as fast as it can (Vmax)

                                      or b) It will approach Vmax

                        or

                        (Decrease) Enzyme no longer saturated; or further from saturation;

e. pH variation

            Change:                                                                                    1 pt

                        a) Slight change may affect the curve either way

                        b) Drastic change may stop the reaction

            Explanation:                                                                  1 pt

                        a) Enzyme has optimum pH

                        b) Enzyme can be denatured by extremes

                                                                                                Maximum = 6 pts

            ENZYME QUESTION - 1994                               L. PETERSON/AP BIOLOGY

  Enzymes are biological catalysts.

            a.  Relate the chemical structure of an enzyme to its specificity and catalytic activity.

            b.  Design a quantitative experiment to investigate the influence of pH or temperature

                  on the activity of an enzyme.

            c.  Describe what information concerning the structure of an enzyme could be inferred

                  from your experiment. 

Since the question asked students to respond with both specific facts about enzymes and broad conceptual statements about the design of an experiment, these standards reflect both approaches. In understanding how an enzyme could be affected by a quantitative experiment with temperature or pH, students not only had to state specific features such as the three dimensional shape of an enzyme, but they also had to describe how to control variables in an experiment. Finally, students were expected to apply the results of their experiment to changes in the structure of the enzyme.

Structure and catalytic activity of enzyme (maximum of 4 points)

__         protein or amino acids (and/or others, such as ribozyme)

__         3-D shape/levels of structure (primary, secondary, teritary, etc.)

__         bonding explanation of structure (alpha helix, hydrophobic interactions,

            van der Waals forces, etc.)

__         active site ("groove", "pocket") / special shape for substrate / "lock and key"

__         modifiers of enzyme shape (cofactors, activators, inhibitors)

__         induced fit theory (function of enzyme – substrate fit)

__         activation energy lowered

__         substrate altered

Experimental design (maximum of 5 points)

Experiment based on enzymatic activity / inital choice of temperature or pH is binding

__         eliminate other variables (conc., amounts, time, pH, temp in alternate experiment)

__         negative control (setup without enzyme or without substrate)

__         describe experimental variable (temperature or pH) values or range

__         uses correct enzyme-substrate pair

__         measure disappearance of substrate, appearance of product, heat production, etc.

__         report data

            (predicted results, such as loss of activity, reduced activity or no change in activity)

__         elaboration of experiment (exemplary set-up; indep, dep variables identified;

            rate calculation or explanation; replication of experiment, etc.)

Inference from experimental design (maximum of 2 points)

__         correct link of predicted results to changes in enzyme structure

            a.  range of activity implies slight change in shape OR

            b.  loss of activity implies denaturation OR

            c.  no loss in activity implies no change in structure

__         elaboration on changes in enzyme structure (conformation explanation,

            bonding shifts or an explanation of why no change in activity is predicted)