The nucleolus begins to fade from view – what is the term in cell biology Is this Prophase or Interphase?

The nucleolus begins to fade from view - what is the term in cell biology

Is this Prophase or Interphase?

Answer

• Prophase

Explanation:

During prophase, the nucleolus disappears and the chromosomes condense. The nuclear envelope that surrounds the nucleus, breaks down. Mitosis has four stages pr phases. During prophase which comes after interphase, the nucleolus disappears from view and this is followed by metaphase at which chromosomes align at the center of the cell. The next two phases are anaphase and lastly telophase.

 

 

If a P-wave was missing from an EKG tracing, which of the following would be true?

Group of answer choices

 

 

the SA node did not fire

 

the ventricles did not contract

 

the atria did not contract

 

the ventricles did not relax

 

two of the above are correct

Answer

• two of the above are correct

Explanation:

the SA node did not fire and the atria did not contract

 

 

The P wave in an electrocardiogram indicates the wave that results from depolarization as the blood leaves the atria. If the P wave is absent from the EEG, this indicates that there is a fine atrial fibrillation whereby the atria is unable to contract with each heartbeat to move blood into the ventricles or there is a sinoatrial arrest (its inability to fire).

 

 

 

What is a phospholipid?

Answer

• A phospholipid is a class of lipids which forms the major part of cell membranes and performs several other functions in the body. Phospholipids have hydrophilic phosphate heads which are water loving and the hydrophobic lipid tails which are water hating. They are composed of three parts; a glycerol molecule, one or two fatty acids and a polar phosphate group

Explanation:

The major types of lipids include fats and oils, waxes, phospholipids, and steroids.

Phospholipids are known as the major component of cell membranes. Our cell membrane has what is called a bilayer, and this bilayer forms because phospholipid has two parts, the part that is hydrophilic hence water loving, and the hydrophobic part which is water hating faces inside thus two layers of these phospholipids come together to make a cell membrane bilayer.

There are also several classes or types of phospholipids. The most common phospholipids are phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidylserine.

 

 

 

 

The existence of barriers that stop members of the two species from producing viable, fertile offpring is called？

1. Reproductive isolation
2. Morphological species concept

Answer

• Reproductive isolation

Explanation:

Reproductive isolation refers to the mechanism that results into separation and individuality of different gene pools which are not compatible and hence inability of two species not of the same pool to reproduce a viable offspring. Reproductive isolation can be caused by pre-zygotic barriers that prevent animals from mating such as ecological isolation, temporal isolation among others. post-zygotic barriers includes hybrid sterility and hybrid invariability.

 

 

Gene therapy has been used to treat which of these

 

A cystic fibrosis

1. familial hypercholesterolemia

c severe combined immunodeficiency

d all above

Answer

• d all above

Explanation:

Gene therapy involves an experimental technique that uses genes to treat a disease or disorder. For gene therapy to be applied, the disorder must be caused by a change in the normal gene or at least treatable by gene changes. All the above conditions are genetic disorders hence can be treated with gene therapy. For instance, Familial hypercholesterolemia is a genetic disorder. It is caused by a defect on chromosome 19. Severe combined immunodeficiency (SCID) is caused by mutations in different genes.

 

 

Compare and contrast photosynthesis vs. the complete breakdown of glucose( including glycolysis and cellular respiration). Choose ALL answers that are correct :

 

1. cellular respiration takes place in chloroplast while photosynthesis in mitochondrion.
2. as far as net energy change is concerned, the complete breakdown of glucose is exergonic and photosynthesis is endergonic.
3. ETC is used both in photosynthesis and in cellular respiration.
4. the reactants of photosynthesis are CO2 and H2O. The products of breaking down glucose are CO2 and H2O too
5. the electron carrier for photosynthesis is NADH and FADH2 for cellular respiration
6. most plants perform photosynthesis during the day when there is sun light. The break down glucose for energy occurs only during the night

Answer

• • as far as net energy change is concerned, the complete breakdown of glucose is exergonic and photosynthesis is endergonic.
  • the reactants of photosynthesis are CO2 and H2O. The products of breaking down glucose are CO2 and H2O too
  • most plants perform photosynthesis during the day when there is sun light. The break down glucose for energy occurs only during the night

Explanation:

During photosynthesis which occurs in the chloroplasts, energy from the sun is used which qualifies the process as endergonic while complete breakdown of glucose produces around 38 ATP molecules which qualifies this as exergonic reaction. Photosynthesis uses water and carbon dioxide as the main reactants forming glucose which undergoes cellular respiration forming carbon dioxide and water in the last steps of ETC. The energy storage molecule ATP and the reduced electron carrier NADPH. Since photosynthesis requires sun light, it takes place during the day while cellular respiration occurs mostly at night for plants.

 

 

When tryptophan is present,

 

1. The Repressor is able to bind to the operator.
2. The repressor is unable to bind to the operator
3. Transcription of structural genes occur
4. Transcription of the structural genes, operator, Promoter occurs.

e both b and c

Answer

• The Repressor is able to bind to the operator.

Explanation:

This entails the prokaryotic gene regulation. When tryptophan is present in the cell, two tryptophan molecules bind to the trp repressor which initiates a series of changes in its shape such that it can bind to the trp operator. When these two - both trp repressor and trp operator - bind, the operator is able to prevent the transcription and eventual expression of genes in the downstream region of the genome by preventing the binding of polymerase enzyme.

 

 

 

 

 

Which of the following is not part of the cardiovascular system
a) blood
b) blood vessels
c) heart
d) lungs
d) lungs

Explanation

The cardiovascular system refers to the heart, blood vessels and the blood. Blood contains oxygen and other nutrients which your body needs to survive. The body takes these essential nutrients from the blood.

 

What is the name of the membrane that surrounds the heart
a) peritoneum
b) synovium
c) pericardium
d) pleurae
c) pericardium

Explanation

A double-layered membrane called the pericardium surrounds your heart like a sac. The outer layer of the pericardium surrounds the roots of your heart’s major blood vessels and is attached by ligaments to your spinal column, diaphragm, and other parts of your body.

 

Which of the following initiates the heartbeat
a) SA node
b) AV bundle
c) AV node
d) Purkinje fibers
a) SA node

Explanation

SA node (sinoatrial node) – known as the heart’s natural pacemaker. The impulse starts in a small bundle of specialized cells located in the right atrium, called the SA node. The electrical activity spreads through the walls of the atria and causes them to contract. This forces blood into the ventricles.

 

How does Starlings law relate to the heart
a) our heart beats faster during extreme stress
b) blood pressure increases due to contraction of blood vessels
c) less oxygen is the blood will increase the heart rate
d) the heart beats with more force when there is an increase in blood volume returning to the heart
d) the heart beats with more force when there is an increase in blood volume returning to the heart

Explanation

The law states that the stroke volume of the heart increases in response to an increase in the volume of blood in the ventricles, before contraction (the end diastolic volume), when all other factors remain constant.

 

What is the name of the blood vessels that take blood away from the heart
a) veins
b) venules
c) capillaries
d) arteries
d) arteries

Explanation

There are five types of blood vessels: the arteries, which carry the blood away from the heart; the arterioles; the capillaries, where the exchange of water and chemicals between the blood and the tissues occurs; the venules; and the veins, which carry blood from the capillaries back towards the heart.

 

What is the purpose of precapillary sphincters
a) they regulate blood flow to the heart
b) they change the amount of blood flowing into capillary beds
c) they are muscles that pump blood back to the heart
d) they contract when the tissues need more oxygen and nutrients
b) they change the amount of blood flowing into capillary beds

Explanation

Precapillary sphincters are segments of smooth muscle that help direct blood flow into capillaries. Because there is a limited amount of blood in the body, these sphincters are important in directing blood to the tissues that need it the most, and reducing the flow to inactive tissues.

 

Which of the following is not a mechanism for assisting the veins in returning blood to the heart
a) valves
b) skeletal muscle contractions
c) gravity
d) all of these are ways of helping the veins return blood to the heart
d) all of these are ways of helping the veins return blood to the heart

Explanation

If gravity or muscle contractions try to pull the blood backward or if blood begins to back up in a vein, the cusps are pushed closed, preventing backward flow. Thus, valves help the return of blood to the heart—by opening when the blood flows toward the heart and closing when blood might flow backward because of gravity.

 

Which type of circulation extends from the right side of the heart through the lungs and back to the left atrium
a) portal
b) systemic
c) pulmonary
d) coronary
c) pulmonary

Explanation

The pulmonary artery carries  deoxygenated blood from the right ventricle into the lungs for oxygenation. The pulmonary veins carry oxygenated blood from the lungs into the left atrium where it is returned to systemic circulation.

 

Which is the most specific type of circulation that sends oxygen rich blood to the tissues of the heart
a) pulmonary
b) systemic
c) coronary
d) portal
c)coronary

Explanation

The aorta (the main blood supplier to the body) branches off into two main coronary blood vessels (also called arteries). These coronary arteries branch off into smaller arteries, which supply oxygen-rich blood to the entire heart muscle.

 

Which type of circulation sends nutrient rich blood from the gastrointestinal tract to the liver
a) pulmonary
b) systemic
c) coronary
d) portal
d) portal

Explanation

The hepatic artery carries blood from the aorta to the liver, whereas the portal vein carries blood containing the digested nutrients from the entire gastrointestinal tract, and also from the spleen and pancreas to the liver. These blood vessels subdivide into capillaries that then lead to a lobule.

 

In what way is the fetal circulation different
a) there is no pulmonary circulation
b) the umbilical arteries connect to the coronary circulation
c) the systemic circulation also goes to the lungs to pick up oxygen
d) the umbilical arteries bring oxygenated blood since the lungs of the fetus are not functioning
d) the umbilical arteries bring oxygenated blood since the lungs of the fetus are not functioning

Explanation

The prenatal circulation of blood is different than the postnatal circulation, mainly because the lungs are not in use. The fetus obtains oxygen and nutrients from the mother through the placenta and the umbilical cord. Blood from the placenta is carried to the fetus by the umbilical vein.

 

Hypertension is
a) a weak heart
b) pain in the heart
c) also known as a heart attack
d) high blood pressure
d) high blood pressure

Explanation

Hypertension is also known as high blood pressure. It is defined as transitory (short-lived) or chronic elevation of the blood pressure in the arteries. This elevation may lead to cardiovascular damage.

 

A weak spot in a blood vessel that could potentially burst in known as an
a) aneurysm
b) plaque
c) myocardial infarction
d) edema

1. aneurysm

Explanation

An aneurysm is an abnormal swelling or bulge in the wall of a blood vessel, such as an artery. It begins as a weak spot in the blood vessel wall, which balloons out of shape over time by the force of the pumping blood.

 

What condition usually develops as a result of congestive heart failure
a) aneurysm
b) hypertension
c) atherosclerosis
d) pulmonary edema

1. d) Pulmonary edema

Explanation

Cardiogenic pulmonary edema is a type of pulmonary edema caused by increased pressures in the heart. This condition usually occurs when the diseased or overworked left ventricle isn’t able to pump out enough of the blood it receives from your lungs (congestive heart failure).

 

Which of the following is not a formed element of the blood
a) plasma
b) white blood cells
c) platelets
d) red blood cells

1. plasma

Explanation

The formed elements are cells and cell fragments suspended in the plasma. The three classes of formed elements are the erythrocytes (red blood cells), leukocytes (white blood cells), and the thrombocytes (platelets).

 

Which of the following white blood cells is the largest
a) neutrophil
b) eosinophil
c) monocyte
d) lymphocyte

1. monocyte

Explanation

These are the largest type of white blood cells, and can be up to 20µm in diameter. They have a large eccentrically placed nucleus, which is kidney bean shaped. They have abundant cytoplasm, and some fine pink/purple granules in cytoplasm.

 

Which white blood cell attacks parasitic worms
a) eosinophil
b) basophil
c) lymphocyte
d) monocyte

1. eosinophil

Explanation

These parasites recruit eosinophils to the muscles at a very early stage of infection, then eosinophil’s are induced to produce IL-10, and this amplifies the immune response that prevents the parasite from being killed

 

What conditions exist during exercise that prompt hemoglobin to drop off its oxygen to the working muscle cells
a) low ph and low temp
b) high ph and high temp
c) high ph and low temp
d) low ph and high temp

1. low ph and high temp

Explanation

As a result, the body’s ability to dissipate heat will be decreased, and dehydration will result in a greater rise in core temperature during exercise-heat stress. In addition, the combination of an elevated core temperature and a reduced blood volume will increase the circulatory strain.

 

• The threads of a blood clot are formed by
  a) thrombin
  b) fibrin prothrombin activator
  c) platelet plug
• b) fibrin prothrombin activator

Explanation

Whenever there is rupture of blood vessels or damage is caused to blood, a complex of substances called prothrombin activator complex is formed

 

Which blood disorder is a cancer of the bone marrow
a) thrombin
b) leukemia
c) hepatitis
b) leukemia

Explanation

Leukemia, a type of cancer found in your blood and bone marrow, is caused by the rapid production of abnormal white blood cells. The high number of abnormal white blood cells are not able to fight infection, and they impair the ability of the bone marrow to produce red blood cells and platelets.

 

A lack of vitamin B12 can cause
a) HIV
b) anemia mononucleosis
c) carbon monoxide poisoning
b) anemia mononucleosis

Explanation

Vitamin B-12 is crucial to the normal function of the brain and the nervous system. It is also involved in the formation of red blood cells and helps to create and regulate DNA. The metabolism of every cell in the body depends on vitamin B-12, as it plays a part in the synthesis of fatty acids and energy production.

 

The ventricles are thicker than the atria because they must pump blood further
true

Explanation

Ventricles have thicker walls than atria because they must pump blood further. The atria only push blood into the ventricles, whereas the ventricles have to pump the blood either to the lungs or all the way around the body. The thicker muscle can contract with greater force, and so pump blood at higher pressure.

 

The mitral valve is most prone to prolapse, a condition that is more common in women
t

Explanation

MVP is the most common forms of valve disease, affecting 6 percent of all women. In this condition one or both of the valve leaflets is enlarged or floppy, preventing the valve from closing evenly. When the valve shuts, the leaflets bulge into the left atrium.

 

The tricuspid valve is located between the left ventricle and the aorta
false

Explanation

Tricuspid valve: located between the right atrium and the right ventricle. Pulmonary valve: located between the right ventricle and the pulmonary artery. Mitral valve: located between the left atrium and the left ventricle. Aortic valve: located between the left ventricle and the aorta.

 

Blood slows down in arterioles due to the large cross-sectional area
t

Explanation

As the total cross-sectional area of the vessels increases, the velocity of flow decreases.

 

The coronary circulation is actually part of the systemic circulation
t

Explanation

Coronary circulation, part of the systemic circulatory system that supplies blood to and provides drainage from the tissues of the heart.

 

Dietary restrictions moderate exercise reducing smoking and drinking and medication can all control hypertension
t

Explanation

A core component of hypertension treatment involves encouraging patients to adopt health-promoting lifestyle changes, including weight reduction for patients who are overweight or obese, dietary changes, reduction of salt intake, regular physical exercise, and moderation of alcohol consumption.

 

Congestive heart failure is a sudden onset of a weak heart, resulting in rapid deterioration
f

Explanation

Congestive heart failure (CHF) is a chronic progressive condition that affects the pumping power of your heart muscles which takes time to develop to this stage. While often referred to simply as “heart failure,” CHF specifically refers to the stage in which fluid builds up around the heart and causes it to pump inefficiently.

 

Hypertension is a risk factor for cardiovascular disease
t

Explanation

Hypertension is a major contributor to cardiovascular disease, which imparts a threefold increased risk over that of normotensive persons the same age.

 

A clot that blocks the flow to the brain can lead to stroke
t

Explanation

Thrombosis is the name given to the formation of blood clots. When the clot blocks the blood flow to the heart or the brain, a heart attack or stroke can follow. An embolism occurs when a blood clot travels around the body and lodges in an organ.

 

Hemoglobin is a protein in white blood cells that destroys pathogens like bacteria
t

Explanation

Hemoglobin: The protein inside red blood cells (a) that carries oxygen to cells and carbon dioxide to the lungs is hemoglobin (b). Hemoglobin is made up of four symmetrical subunits and four heme groups. Iron associated with the heme binds oxygen. It is the iron in hemoglobin that gives blood its red color.

 

Being type AB means you have both A and B antigens on your red blood cells
t

Explanation

Blood group antigens are found on the surface of red blood cells and are ignored by the immune system. But antigens of another blood type will be seen as foreign, and attacked by antibodies. Blood group A has A antigens on the red blood cells with anti-B antibodies in the plasma.

 

a menstuating woman could become anemic due to too much blood loss
t

Explanation

Blood loss is a common cause, and menstruating women are especially prone to anaemia.

 

Blood leaves the right side of the heart and enters the _____ which takes it into the lungs
pulmonary trunk

Explanation

Blood enters the right atrium and passes through the right ventricle. The right ventricle pumps the blood to the lungs where it becomes oxygenated. The oxygenated blood is brought back to the heart by the pulmonary veins which enter the left atrium.

 

___ the first number listed in blood pressure readings measures the force of the left ventricle contraction
systolic pressure

Explanation

The systolic pressure (the higher pressure and the first number recorded), which is the force that blood exerts on the artery walls as the heart contracts to pump the blood to the peripheral organs and tissues

 

An_____ is a graphic representaion of the electrical changes during a heartbeat
electrocardiogram

Explanation

The electrocardiogram is a graphic record of the direction and magnitude of the electrical activity generated by the depolarization and repolarization of the atria and ventricles of the heart.

 

If a person sits for a long time, blood may pool in the lower extremities causing____
edema

Explanation

Peripheral edema is swelling of your lower legs or hands. The cause may be simple, such as sitting for too long on a plane or standing for too long

 

The systemic circulation begins with the _____ side of the heart
left

Explanation

The heart pumps oxygenated blood out of the left ventricle and into the aorta to begin systemic circulation. After the blood has supplied cells throughout the body with oxygen and nutrients, it returns deoxygenated blood to the right atrium of the heart.

 

Death of the heart muscle due to lack of oxygen is known as_____
myocardial infarction

Explanation

Myocardial infarction (MI) (i.e., heart attack) is the irreversible death (necrosis) of heart muscle secondary to prolonged lack of oxygen supply (ischemia).

 

Unsightly and sometimes painful distensions of venous walls is a condition known as____
varicose veins

Explanation

Varicose veins and spider veins are unsightly and can be painful. Varicose veins are distensions of the venous walls near valves. Varicose veins occur when weak or defective valves allow blood to flow backward or stagnate within the vein, a condition known as venous insufficiency.

 

 

 

 

 

Which of the following techniques is NOT used to analyze gene function?

 

1. A) Southern blotting

 

1. B) Use of RNAi

 

1. C) Ribozyme technology

 

1. D) Functional Complementation

 

1. E) In situ Hybridization

Answer

• A) Southern blotting

Explanation:

In Situ Hybridization can be used to analyze gene function for instance through physical mapping, karyotyping and in developmental biology. Functional Complementation is an in vivo assay which is used to determine the function of a gene or enzyme. Ribozymes can be used to silence a certain gene in vivo or in vitro and by doing so, the technology is much useful in genetics and developmental biology. RNAi can be used to completely shut down a specific gene in the cell to identify its function. Southern blotting is used to identify specific DNA in a sample of tissue or DNA sample. This process rarely provides any useful information regarding the function of the sequence identified, but aids in the use of other methods above.

 

 

 

Elliott & Elliott: Biochemistry and Molecular Biology 4e Chapter 20

1. Which of the following statements about the nomenclature of nucleosides isnot correct?
2. Which of the following statements about the structure of nucleotides is correct?
3. Which of the following statements about the de novo synthesis of purine nucleotides is correct?
4. Which of the following statements about the salvage pathway for the synthesis of purine nucleotides is correct?
5. Which of the following statements about the formation of uric acid is correct?

 

Answer

Question 1
Which of the following statements about the nomenclature of nucleosides is not correct?

Your answer:
a) Cytosine is a nucleoside made up of the base cytidine attached to ribose.
Correct answer:
c) Thymine is a nucleoside made up of the base thymidine attached to ribose.
Feedback:
A nucleotide has the structure phosphate -sugar- base. The sugar is always a pentose, D-ribose in ribonucleotides (in RNA) or D-deoxyribose (in DNA). The bases in ribonucleotides of RNA are the purines, adenine (A), guanine (G), and the pyrimidines cytosine (C) and uracil (U). The nucleotides or monophosphate nucleosides are called AMP, GMP, CMP and UMP respectively. The bases in DNA are A, G, C and thymine (T). The deoxynucleotides or monophosphate deoxynucleosides are dAMP, dGMP, dCMP and TMP. Nucleosides lack the phosphate group and are called adenosine, guanosine, cytidine and uridine respectively or deoxy- adenosine, guanosine, cytidine and thymidine. The bases are attached to the pentose sugar by a β-glycosidic bond at the N-9 position for purines or the N-1 position for pyrimidines via (above the plane of the ring).
Hypoxanthine is an unusual ‘minor’ purine base. Its ribonucleoside is called inosine and its nucleotide is IMP.
Page reference: Page 299

 

Question 2
Which of the following statements about the structure of nucleotides is correct?

You did not answer the question.
Correct answer:
c) The bases in nucleotides are attached to the pentose sugar moieties by a glycosidic bond.
Feedback:
A nucleotide has the general structure phosphate-pentose sugar-base where the sugar component is always either ribose or 2′-deoxyribose, always in the D-configuration. The purine bases adenine and guanine can be found in nucleotides that make up DNA and RNA, whereas the pyrimidine bases cytosine and thymine are found in DNA, while uracil and not thymine is found in RNA.
The bases are attached to the pentose sugar moieties of nucleotides at the N-9 position for purines and the N-1 position for pyrimidines via a glycosidic bond in the β-configuration (above the plane of the ring).
Page reference: Page 299

 

Question 3
Which of the following statements about the de novo synthesis of purine nucleotides is correct?

You did not answer the question.
Correct answer:
b) The enzyme PRPP amidotransferase catalyses the committed step of the de novo synthesis pathway.
Feedback:
The de novo synthesis pathway of purine nucleotides involves the assembly of the purine ring, piece by piece, onto 5-phosphoribosylamine made from PRPP (5-phosphoribosyl-1-pyrophosphate) by PRPP amidotransferase. PRPP is made from ribose-5-phosphate and ATP by PRPP synthetase. Hypoxanthine is the first base assembled onto the ribose-5-phosphate to form the nucleotide IMP (inosinic acid). This is a branch point in the purine synthesis pathway since either adenine or guanine can be formed from it. This pathway is energetically expensive for a cell (six molecules of ATP are required) for each purine nucleotide molecule synthesised. The control of the de novo nucleotide synthesis pathway is a classical example of allosteric feedback control. The enzymes committed to each pathway are allosterically inhibited by the nucleotides AMP, ADP, GMP and GDP. This ensures a balanced production of ATP and GTP both of which are required for nucleotide synthesis.
Page reference: Page 300

 

Question 4
Which of the following statements about the salvage pathway for the synthesis of purine nucleotides is correct?

You did not answer the question.
Correct answer:
c) Increased PRPP levels in cells lead to the activation of hypoxanthine-guanine phosphoribosyl transferase (HGPRT).
Feedback:
Free purine bases released from the degradation of nucleotides are salvaged and utilized for nucleotide synthesis by reaction with 5-phosphoribosyl-1-pyrophoshate (PRPP). This pathway is known as the salvage pathway for the synthesis of purine nucleotides. The two enzymes which catalyse the reactions are either adenine phosphoribosyl transferase (APRT) or hypoxanthine-guanine phosphoribosyl transferase (HGPRT), the latter being more important. The synthesis of purines by the de novo pathway is energetically expensive. The salvage pathway is the only one that exists in some cells is less expensive energetically.
Page reference: Page 304

 

Question 5
Which of the following statements about the formation of uric acid is correct?

You did not answer the question.
Correct answer:
b) Uric acid levels are increased by a deficiency of hypoxanthine-guanine phosphoribosyl transferase (HGPRT).
Feedback:
Purine nucleotides not recycled by the salvage pathway are oxidised to uric acid by the enzyme xanthine oxidase. Uric acid is relatively insoluble and is deposited as crystals in tissues and joints causing pain. Deficiency of hypoxanthine-guanine phosphoribosyl transferase (HGPRT) reduces the utilization of 5-phosphoribosyl-1-pyrophoshate (PRPP) by the salvage pathway and hence a rise in the PRPP level. This leads to an increased de novo synthesis of purines and therefore increased uric acid production causing gout. The drug allopurinol is used in the treatment of gout. It is converted by xanthine oxidase to alloxanthine which is a potent inhibitor of the same enzyme. This is the phenomenon of suicide inhibition.
Page reference: Page 304