Questions Flashcards
In which cell are the sickle red blood cells most likely to be hemolyzed??
Spleen:: one fxn of spleen is to remove old or deformed red blood cells red blood cells from circulation
A female heterozygous for sickle cell anemia marries a normal homozygous male. What is the probability that their first son is a normal homozygote?
50%:: the disease is autosomal so make so female is irrelevant. The child has 50% chance of getting a normal allele from the mother and 100% chance of getting a normal allele from the father, so overal probability is 50%.
Aldosterone's mechanism of action on its target cell is most similar to which of the following hormones? A. Testosterone B. glucagon C. Insulin D. ACTH
A:: both are steroid hormones so act in similar manner
All if the following will result in increased renin secretion except: A. Low blood pressure B. Low distal tubule [Na+] C. High levels of aldosterone D. A lack of angiotensinogen
C:: high lvls of aldosterone will increase Na+ and water reabsorption, blood volume, and arterial pressure REDUCING renin secretion
Activated aldosterone receptor most directly regulates activity of which of the following enzymes? A. DNA Polymerase B. RNA Polymerase II C. Na+/K+ ATPase D. Renin
B:: aldosterone binds to aldosterone receptors to regulate transcription of a specific set of genes. The enzyme that synthesizes mRNA is RNA polymerase II so it is this enzyme that would be most directly affected
A large dose of aldosterone is administered intravenously. The effect of this on the renin-angiotensin-aldosterone system is to
A. Increase the circulating lvls of angiotensin II
B. Decrease Na+ reabsorption in the nephron
C. Increase aldosterone secretion by the adrenal cortex
D. Decrease renin secretion by the juxtaglomeruler apparatus
D:: aldosterone will increase water and sodium reabsorption, increasing blood pressure. The increased blood pressure will reduce renin secretion however, since renin is no longer required to increase blood pressure
A drug is discovered that reduces smooth muscle contraction by inhibiting the muscle’s response to acetylcholine. This is likely to:
A. Reduce the transcription of Na+/K+ ATPase
B. Reduce the hypertensive effect of angiotensin II
C. Increase the strength of cardiac muscle contractions
D. Decrease renal blood flow
B:: in the absence of acetylcholine signaling, the overall tone of smooth muscle in artery walls will be reduced, reducing blood pressure.
The function of the chain group of the dienophile can be characterized as:
A. Electron-withdrawing, through the inductive effect to create a partial-positive carbon
B. electron-withdrawing, which stabilizes the free-radical intermediate
C. Electron-donating, which enriches the double bond for electrophilic attack
D. Electron-donating, which stabilizes the free-radical intermediate
A:: -CN is a strongly electronegative group by the inductive effect
The enzymes of the lysosomes require an acidic environment to be activated. This requirement for activity probably serves to…
Protect the organelles of the cytosol
All of the following statements regarding the synthesis and packaging of lysosomal enzymes are true except..
A. The lysosomal enzymes are synthesized in the rough endoplasmic reticulum
B. In healthy cells, all secreted enzymes pass through the endolysosome
C. The M6P is attached to the peptide in the cis-Golgi
D. I-cell disease results from a phosphorylation defect
B:: secreted proteins normally go from the Golgi to secretory vesicles which to directly to the plasma membrane, not to any other organelle
PKU is a rare autosomal recessive disorder, occurring in approximately 1 in 10000 births. What is the approximate percentage of parents who are heterozygous for the abnormal enzyme gene?
Remember the genotype frequency***
If the disease is recessive and if 1 in 10000 are affected then q^2= 1/10000
So q= 1/100= 0.01
And since p+q=1 p=0.99
Then now we could plug it in to find the heterozygous 2pq
Which is 0.02 or 2%
During spermatogenesis, spermatids…
A. Are frozen in meiosis II until after fertilization
B. Have already undergone neurotic recombination
C. Have four copies f the genome per cell
D. Have No nucleus
B:: sperm has a nucleus so D is wrong. The spermatids has passed through two reductive divisions in meiosis to end up with only one copy of the genome, so C is also wrong. Recombination occurs in both oogenesis and spermatogenesis during meiotic prophase 1 which the spermatids already completed so B is correct.
The alpha helix of the ras protein maintains secondary structure integrity primarily through: A. Peptide bonds B. Covalent bonds C. Disulfide bonds D. Hydrogen bonds
D:: the alpha helix is a form of secondary protein structure, with hydrogen bonding between groups along the peptide bond backbone.
The conversion of 2-phosphoenol-pyruvate is best characterized as... A. Reduction B. Oxidation C. Alkylation D. Elimination
D:: since an alkene is formed, the conversion is an elimination
Fructose 6 phosphate and glucose 6 phosphate are best characterized as... A. Epimers B. Enantiomers C. Stereoisomers D. Structural isomers
D:: these have the same molecular formula but different connectivity end. Choices A, B, and C could be eliminated since they all imply identical atom connectivity
