FL 4 B/BC-done Flashcards
Most cytochrome P450 enzymes alter the activity of drugs by:
A.phosphorylating them.
B.dephosphorylating them.
C.oxidizing them.
D.reducing them.
C) Cytochrome P450 acts as monooxygenases, where an oxygen atom is inserted into a substrate (the drug of interest), thereby resulting in the oxidation of the substrate.
During phosphorylation of STAT5b proteins, phosphate groups are exchanged for what atoms on tyrosine residues?
A.Hydrogen atoms of hydroxyl groups
B.Hydrogen atoms of methyl groups
C.Oxygen atoms of hydroxyl groups
D.Carbon atoms of methyl groups
A) The passage notes that JAK2 is a tyrosine kinase. Tyrosine has a nucleophilic hydroxyl group that attacks the terminal phosphate group (γ-PO32–) on ATP, resulting in the exchange of the hydrogen atom of a hydroxyl group for a phosphate group of ATP.
A defining characteristic of proteins that act as transcription factors (such as STAT5b) is that they:
A.can dimerize.
B.can phosphorylate other proteins.
C.contain a DNA binding domain.
D.are present within the nucleus of the cell.
C) The defining characteristic of a transcription factor is that it has a DNA-binding domain that allows it to bind to regulatory nucleic acid sequences in a gene to alter transcription.
Fatty acid oxidation in the ____ and synthesis in the ____.
mitochondria…..cytosol
As blood passes through actively contracting skeletal muscle tissue, the affinity of hemoglobin for oxygen in the muscle tissue:
A.increases as a result of an increase in plasma temperature.
B.increases as a result of an increase in plasma PO2.
C.decreases as a result of a decrease in plasma pH.
D.decreases as a result of a decrease in plasma PCO2.
C) Affinity would decrease with an increase in plasma temperature.
Affinity would increase when PO2 increases. However, PO2 in muscle cells decreases with exercise.
Affinity would decrease with a decrease in plasma pH, and during prolonged exercise, anaerobic respiration would decrease the plasma pH.
Affinity would increase with a decrease in plasma PCO2.
A researcher measures the concentration of CO2(aq) in a solution at equilibrium. Which additional quantity must be measured in order to calculate the Henry’s Law constant kH for the gas?
A.Atmospheric pressure
B.Volume of the solvent
C.Partial pressure of the gas
D.Vapor pressure of water
C) The Henry’s Law constant kH relates the solubility of a gas S to the pressure of that gas Pg above the solution and is written as S = kH•Pg. Therefore, in addition to the concentration of CO2(aq) in a solution at equilibrium, the partial pressure of the gas Pg must be measured.
Question
Hormone replacement therapy is often given to children who have Prader–Willi syndrome once they have reached the hyperphagic stage. Based on the passage, the most likely reason for this therapy would be to prevent:
A.giantism.
B.weight loss.
C.short stature.
D.muscle rigidity.
Prader–Willi syndrome is characterized by growth hormone deficiency. Thus, hormone replacement therapy will prevent short stature.
Eating suppresses ghrelin secretion. However, this suppression does not appear to be caused by the presence of food in the stomach or duodenum, nor by stomach distension. Given this, which of the following physiological conditions is likely to suppress ghrelin secretion following a meal?
A.Increased levels of circulating glucagon
B.Decreased osmolarity in the ileum
C.Increased levels of circulating insulin
D.Decreased levels of circulating insulin
C) The levels of circulating insulin will increase after a meal due to an increase in blood glucose levels.
Erythromycin interferes with protein synthesis by binding to which ribosomal subunit?
A.50S
B.60S
C.70S
D.80S
A) Based on the passage, erythromycin inhibits bacterial protein synthesis by binding to the 23S rRNA component of the large subunit of the bacterial ribosome. The large subunit of the bacterial ribosome has a sedimentation coefficient of 50 Svedberg (S).
60S corresponds to the sedimentation coefficient of the large ribosomal subunit of eukaryotic cells.
70S corresponds to the sedimentation coefficient of intact prokaryotic ribosomes.
80S corresponds to the sedimentation coefficient of intact eukaryotic ribosomes.
Which technique separates proteins independently of their charge?
A.Native PAGE
B.Gel filtration chromatography
C.Ion exchange chromatography
D.Isoelectric focusing
B) Gel filtration chromatography separates protein only on the basis of their size.
Which of the following statements best applies to the inactive X chromosome in mammalian females?
A.It does not replicate.
B.Its chromatin structure is less condensed than that of an active X chromosome.
C.It is one of the last chromosomes to replicate.
D.It is highly transcribed.
C) The inactivate X chromosome is one of the last chromosomes to replicate.
Which of the following events does the release of CCK likely trigger?
A.Relaxation of muscle in wall of gallbladder and relaxation of hepatopancreatic sphincter
B.Contraction of muscle in wall of gallbladder and relaxation of hepatopancreatic sphincter
C.Relaxation of muscle in wall of gallbladder and contraction of hepatopancreatic sphincter
D.Contraction of muscle in wall of gallbladder and contraction of hepatopancreatic sphincter
B) The passage states that in the presence of CCK, more bile is released. For this to happen, the smooth muscles around the gall bladder will have to contract, and the hepatopancreatic sphincter will have to relax.
Fats are digested by _____.
______ are enzymes that digest proteins.
Nucleotides are digested by ______.
Carbohydrates are digested by _____.
lipases
Peptidases
nucleases
carbohydrases
On the day of the experiment, the subjects drank about 1 L of water on average and excreted about 400 mL of urine. The most likely explanation for the difference between water intake and urine excretion is that:
A.the extra water was stored as blood.
B.water was consumed with the food that was eaten.
C.the extra water was excreted by the intestine.
D.water was excreted via the skin and the lungs.
D) Extra water is normally excreted through skin and lungs. The skin excretes water through the process of transpiration, and the lungs use water to humidify the air that enters the body.
The osmolarity of urine in these subjects was 958 milliosmoles/L, compared with an average blood osmolarity of 284 milliosmoles/L. The higher osmolarity of urine suggests that:
A.the kidneys are secreting very little Na+.
B.the kidneys are acting to conserve water.
C.the subjects are on a low-protein diet.
D.the subjects are dehydrated.
B) An increase in water conservation would result in higher urine osmolarity and lower blood osmolarity.
When your body is trying to conserve water, the concentration of salt in your urine increases. Your body is using less water to remove same amount of salt.
