Upgrade to remove ads
B/BC AAMC MCAT PT #1
Terms in this set (44)
A man with a CRC mutation that results in the synthesis of HSP110ΔE9 and a woman that does not carry this mutation in any of her tissues have a child. What is the percent chance that the child will inherit the CRC mutation?
Given: "The larger HSP110 T17 deletions cause Exon 9 to be omitted from the final sequence during pre-mRNA processing....People with MSI CRC have HSP110ΔE9 transcripts in cancerous tissue only."
Since HSP110ΔE9 transcripts are not present in noncancerous tissue of people with MSI CRC.
-> deletion mutation in the HSP110 T17 microsatellite is a somatic, not germ line, mutation. Aka the mutation will not be inherited, and the percent chance that the child of a person with this mutation will inherit it is 0%.
Which nucleotide pairing(s) would be recognized by the MMR system during DNA replication?
I. dTMP and dCMP
II. dGMP and dAMP
III. dAMP and dTMP
Given: "About 15% of colorectal cancers (CRCs), or colon cancers, are caused by defects in the mismatch repair system (MMR) that corrects certain DNA replication errors."
The MMR system recognizes and repairs nucleotide mismatches during DNA replication. The nucleotide pairs dTMP and dCMP (I) and dGMP and dAMP (II) are mismatches. dAMP and dTMP (III) is a correct pairing.
________ is when exons, of a gene are brought together to make and messenger RNA (mRNA). The mRNA is then translated into A protein product.
_________ ___________ refers to the fact that different combinations of exons within the same gene can be brought together to make DIFFERENT/ MULTIPLE protein products.
________ are a type of protein folding that inhibits the formation of nonfunctional protein aggregates.
Transmembrane proteins enter the endomembrane system by docking at the rough ER facilitated by a ________ sequence
_______ is the process of ions (Na+,Cl-, H+) moved by diffusion across a semi-permeable membrane, generating energy inside the mitochondria.
-A process for synthesizing ATP using the energy of an electrochemical gradient and the ATP synthase enzyme.
If a man with a mutant copy of Ace2 has a child with a woman that is heterozygous for the mutant Ace2 allele, what is the probability that the child will be a female and homozygous for the mutant Ace2 allele?
-cross between an affected male and an unaffected female carrier will produce an affected female approximately 25% of the time.
During the initiation of muscle contraction, mysosin binds actin after troponin binds to which ion?
-during the initiation of muscle contraction, free Ca2+ in the cytosol binds to troponin, which pulls tropomyosin away from actin's myosin-binding site. This allows myosin to bind to actin. The other ions are not involved in actin-myosin binding.
What is the total number of fused rings present in a steroid?
- steroid is defined by its fused 4-ring structure.
Epilepsy may result in motor seizures due to massive synchronous firing of neurons in a small area of the cerebral cortex (the epileptic focus). Excitation spreads from the focus, involving an increasingly larger area of the cortex. A drug for the treatment of epilepsy would be most effective if it caused which of the following changes in the epileptic focus?
A.An increase in the neuron-firing threshold
B.An increase in extracellular Na+ concentration
C.A decrease in axon-membrane permeability to negative ions
D.A decrease in the length of the depolarization stage
Epilepsy drug reduces activity of the neurons in the epileptic focus, which are excitatory neurons based on their effect throughout the cortex.
-increasing the threshold required to generate an AP would decrease the chance that individual neurons would fire, thus reducing the overall amount of excitation that spreads from the epileptic focus throughout the cortex.
When concentrated urine is being produced, in which of the following regions of the kidney will the glomerular filtrate reach its highest concentration?
A.Proximal convoluted tubule
B.Distal convoluted tubule
C.Cortical portion of the collecting duct
D.Medullary portion of the collecting duct
D. Medullary portion of the collecting duct
-glomerular filtrate is most concentrated in the medullary portion of the collecting duct, compared to the other kidney structures listed.
Na+K+ ATPase measures the activity of:
I.Measuring the rate of ATP hydrolysis
II.Measuring the free energy of the ion transport
III.Measuring the rate of ADP production
IV. .Measuring the change in ion concentration within the liposome
I, III, IV.
Free energy is a thermodynamic quantity and is NOT a kinetic property. Activity is a kinetic property.
What is the function of the Na+K+ ATPase during a neuronal action potential?
A.Stimulation of the action potential
B.Depolarization of the membrane
C.Hyperpolarization of the membrane
D.Restoration of the resting potential
D. Restoration of the resting potential
- Na+K+ ATPase functions to restore the resting membrane potential by moving the ions against their concentration gradients.
In which direction does the Na+K+ ATPase transport ions across the cell membrane upon ATP hydrolysis?
A.Na+ is transported out of the cell; K+ is transported into the cell.
B.Na+ is transported into the cell; K+ is transported out of the cell.
C.Both Na+ and K+ are transported into the cell.
D.Both Na+ and K+ are transported out of the cell.
A. Na+ out, K+ in
-Na+K+ ATPase transports 3 Na+ out/ 2 K+ into the cell with each ATP hydrolyzed.
ABC transporter protein (specific for hydrophobic compounds), uses ATP to actively transport anti-tumor drugs out of the cell by serving as a:
-pump and uses active transport to move antitumor drugs outside the cell.
A cyclic oligosaccharide is composed of ______________.
Colchicine is a drug that prevents the formation of microtubules. Which of the following mitotic processes would NOT occur after exposure to this drug?
A.Formation of new cell plate
B.Replication of DNA during interphase
C.Breakdown of the nucleolus during prophase
D.Movement of the chromosomes toward opposite poles of the cell during anaphase
-microtubules function in chromosomal movements in cell division.
The initial filtration step in the glomerulus of the mammalian kidney occurs primarily by:
A.passive flow due to a pressure difference.
B.passive flow resulting from a countercurrent exchange system.
C.active transport of water, followed by movement of electrolytes along a resulting concentration gradient.
D.active transport of electrolytes, followed by passive flow of water along the resulting osmolarity gradient.
A. passive flow due to a pressure difference
- initial filtration in the glomerulus occurs as blood pressure forces the fluid from the glomerulus into the lumen of Bowman's capsule.
The half-life of urea is the time it takes for its concentration to fall by one-half. The graph illustrates the clearance of urea from an initial plasma concentration of 200 ng/mL. If it takes five half-lives for urea to be considered eliminated from the body, how long did it take to eliminate the urea?
Given: Takes 0.5 h for the plasma concentration of urea to fall by one-half (100 ng/mL to 50 ng/mL).
If it took five half-lives for urea to be considered eliminated from the body,
t1/2 = 0.5 h * 5 half-lives.
t1/2 = 2.5 hrs eliminate urea from the body.
Enzymes alter the rate of chemical reactions by all of the following methods EXCEPT:
B.altering local pH.
C.altering substrate shape.
D.altering substrate primary structure
-The primary structure of a protein substrate is the amino acid sequence of the protein.
Enzymes cannot alter primary structures of protein, but can colocalize substrates, alter local pH, and alter substrate shape.
Which of the following statements gives the most fundamental reason why ornithine is unlikely to be found in proteins synthesized in vivo?
A.There is no codon for it in the standard genetic code.
B.It cannot form a peptide bond.
C.It is not available in the diet.
D.It has a net positive charge in aqueous solution.
A. There is no codon for it in the std genetic code
-without a corresponding codon in the genetic code, an amino acid cannot take part in the process of protein translation from an mRNA transcript.
Which of the following terms best describes the role of ornithine decarboxylase in the reaction shown in Equation 1?
Equation 1) Ornithine + H2O → H2NCH2CH2CH2CH2NH2 + HCO3-
- ornithine decarboxylase is an enzyme and enzymes are catalysts.
In the example of the alcoholic in the passage, the presence of alcohol caused death because the alcohol:
A.denatured the cP-450.
B.inhibited the cP-450.
C.decreased the concentration of cP-450.
D.increased the concentration of cP-450.
Given: "cP-450 usually metabolizes barbiturates, alcohol acts as a competitive inhibitor of barbiturate metabolism."
B. .inhibited the cP-450.
- If alcohol acts as a competitive inhibitor of cP-450, thus preventing it from metabolizing barbiturate.
Ethanol may be metabolized to acetic acid, then condensed with a coenzyme to form acetyl coenzyme A. Acetyl coenzyme A may then participate in:
A.the Krebs (citric acid) cycle.
A. TCA cycle
-acetyl coenzyme A is the main input of the citric acid cycle.
The lung cells of heavy smokers would be expected to have greatly increased concentrations of cP-450 and:
A.DNA sequences that code for cP-450.
B.mRNA sequences that code for cP-450.
C.rRNA that process cP-450.
D.tRNA that are specific for cysteine.
B. mRNA sequences that code for cP-450.
-protein levels relate most directly to mRNA levels.
No drowsiness was initially felt by the alcoholic because the previous abuse of alcohol had:
A.denatured the cP-450.
B.inhibited the cP-450.
C.reduced the cP-450.
D.induced the cP-450.
D. induced the cP-450
- because the passage states that cP-450 is inducible and thus previous abuse of alcohol, a cellular toxin, results in an increased concentration of cP-450. This leads to rapid barbiturate metabolism by cP-450 and the absence of initial drowsiness.
The pericytes used in these experiments were probably in which phase of the cell cycle?
Given: "pericytes, smooth-muscle cells, and fibroblasts were growth-arrested—that is, treated so that they would not divide but other metabolic processes would function normally."
-Interphase (D) is the phase of the cell cycle between cell divisions and is the phase in which the cell obtains nutrients, grows, reads its DNA, and conducts other "normal" cell functions.
A student hypothesized that Endothelial cells growth might be affected by the DNA from circulating erythrocytes. Is this student's hypothesis reasonable?
A.No; the DNA in circulating erythrocytes is needed to help transport O2 through the capillaries.
B.No; circulating erythrocytes do not contain DNA.
C.Yes; DNA is responsible for cell division in most cells.
D.Yes; circulating erythrocytes carry DNA nutrients through the capillaries.
B. No; circulating erythrocytes do not contain DNA.
-mammalian erythrocytes (red blood cells) lose their nuclei during maturation. Therefore, circulating erythrocytes do not contain DNA that could affect endothelial cell growth.
Which of the following cells are most important in the exchange of O2 between the blood and the surrounding tissues?
B. Endothelial cells
-cells are most important in the exchange of oxygen between the blood and the surrounding tissues
The process of culturing bacteria often involves inoculation of cells on a noncellular, agar-based medium. Such a methodology would NOT result in growth of animal viruses because animal viruses:
A.are obligate parasites.
D.require essential vitamin supplements for growth.
A. are obligate parasites
-viruses can only reproduce in a host cell, and are therefore obligate intracellular parasites.
In general, telomeres are NOT important to bacterial cells because most bacterial chromosomes:
A.do not replicate.
C.replicate quickly and efficiently.
D.are composed of single-stranded DNA.
B. are circular
- most prokaryotes, DNA is circular and therefore does not have the repetitive, non-coding nucleotide sequences called telomeres that occur in eukaryotic DNA.
Best describes the bond that would form between the following 5' Thymine & and 3' Adenine. If they were located adjacent to each other as shown in a single strand of DNA?
A.A bond between the phosphate of the thymine and the phosphate of the adenine
B.A bond between an oxygen in the thymine base and a nitrogen in the adenine base
C.A bond between the phosphate of the thymine and the sugar of the adenine
D.A bond between the phosphate of the adenine and the sugar of the thymine
-nucleotides are linked to one another by phosphodiester bonds between the sugar base of one nucleotide and the phosphate group of the adjacent nucleotide in a way that the 5' end bears a phosphate, and the 3' end a hydroxyl group.
During an action potential, the movement of sodium ions into a neuron causes the neuronal membrane to do which of the following?
-movement of sodium ions into a neuron during an AP results in opening of more voltage-gated Na+ channels, causing further depolarization.
The aldosterone deficiency associated with Addison's disease will cause a decrease in the serum levels of all of the following ions EXCEPT:
Given: "Aldosterone, the primary mineralocorticoid, maintains ionic balance by causing conservation of Na+ and excretion of K+."
C. K+ ions
-passage states that aldosterone causes excretion of K+. Therefore, aldosterone deficiency will not lead to a decrease in serum levels of K+ ions.
The most rapid rate of gluconeogenesis will most likely occur in the body when:
A.blood glucose levels are high.
B.cortisol release is inhibited.
C.the body's stores of carbohydrates are low.
D.the body's stores of proteins are low.
C.the body's stores of carbohydrates are low.
-gluconeogenesis is the pathway for the synthesis of glucose from other metabolic compounds and thus it is activated when the body's stores of carbohydrates are low.
Glucose transporter proteins in the liver do not require the presence of insulin to facilitate the uptake of glucose. However, insulin does stimulate the first step in the glycolytic pathway within the liver. Therefore, in liver cells, insulin most likely:
A.hinders glucose uptake by increasing the cellular concentration of glucose.
B.aids glucose uptake by decreasing the cellular concentration of glucose.
C.hinders glucose uptake by using the ATP needed by the glucose transporter proteins.
D.aids glucose uptake by providing the ATP needed by the glucose transporter proteins.
B. aids glucose uptake by decreasing the cellular concentration of glucose.
-the stem states that insulin stimulates the first step in the glycolytic pathway in the liver, thus decreasing the cellular concentration of glucose.
--> This results in increased uptake of glucose to maintain the cellular concentration of glucose.
Exercise promotes the insulin-independent uptake of glucose in working skeletal muscles. Given this, regular exercise would most likely reduce blood glucose levels in patients with which type(s) of diabetes?
A.Type 1 only
B.Type 2 only
C.Both Type 1 and Type 2
D.Neither Type 1 nor Type 2
C. Both Type I and II
- stem states that exercise promotes the insulin-independent uptake of glucose and thus it will reduce blood glucose levels both in patients with impaired production of insulin (type 1 diabetes), and in patients who do not respond to insulin (type 2 diabetes).
During the production of insulin, the translated polypeptide is cleaved into the mature form and secreted from the cell. The cleavage most likely takes place in which of the following locations?
C. Endomembrane system
- secreted proteins such as insulin are cleaved into mature form within endomembrane system.
Despite the effects of diabetes, the brains of diabetic patients still receive adequate nourishment. This is most likely because the brain uses:
A.less glucose than do other body tissues.
B.insulin-independent transporters for the uptake of glucose.
C.fatty acids for energy instead of glucose.
D.insulin-dependent transporters for the uptake of glucose.
glucose is the main fuel for brain cells, and since the brains of diabetic patients receive an adequate amount of glucose, the brain must use an insulin-independent mechanism for glucose uptake
A certain bacterium was cultured for several generations in medium containing 15N, transferred to medium containing 14N, and allowed to complete two rounds of cell division. Given that the bacterium's genome mass is 5.4 fg when grown in 14N media and 5.5 fg when grown in 15N medium, individual bacteria with which of the following genome masses would most likely be isolated from this culture?
A.5.4 fg only
B.5.4 fg and 5.45 fg
C.5.4 fg and 5.5 fg
D.5.45 fg only
B because DNA replication is semi-conservative. Therefore, after the first round of cell division the genome mass in each bacterium will be 5.45 fg (one DNA strand will contain 15N and the other strand 14N). Following the second round of cell division, half of the bacteria will have a genome mass of 5.4 fg (14N exclusively) and the other half a mass genome of 5.45 fg (14N in one DNA strand and 15N in the other).
Assume that K and M are two unlinked genes that affect hearing. The dominant K allele is necessary for hearing, and the dominant M allele causes deafness regardless of the other genes present. Given this, what fraction of the offspring of parents with the genotypes KkMm and Kkmm will most likely be deaf?
D, because among the offspring of KkMm and Kkmm parents, the ones who lack a dominant K allele (necessary for hearing), or carry a dominant M allele (causes deafness) are deaf. Based on the Punnett square analysis, 10 out of 16 or 5/8 of all offspring are likely to be deaf.
An RNA molecule has 1500 bases. What is the maximum number of amino acids it can encode?
A because each amino acid is encoded by three bases, so 1500/3 is 500, which is the maximum of amino acids the RNA molecule can encode.
amino acid weight
THIS SET IS OFTEN IN FOLDERS WITH...
AAMC FL 1 Bio
C/P AAMC MCAT PT #1
AAMC FL 3
YOU MIGHT ALSO LIKE...
Practice Exam 1: Bio
MCAT Biology Systems Missed Question
AAMC MCAT FL#1: B/BC Review
OTHER SETS BY THIS CREATOR
Chp 15 exam review
MT - Chp 14 Exam Review
MT - Chp 13 Exam Review
MT - Chp 9 (Exam Review)