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AAMC tests BB
Sample, FLE1, FLE2, FLE3, FLE4
Terms in this set (98)
The passage describes the alpha-beta heterodimer as an "adhesion receptor". The adherence of neutrophils was facilitated by an adhesion receptor on the neutrophil membrane. Additionally, the inactivation of the beta subunit by the antibodies prevents tissue damage. What is the function of the beta subunit?
adhering neutrophils to the endothelium, bc inactivation of the beta subunit prevents neutrophil adhesion
The scientist claimed that antibody B offers a better means for preventing organ injury than agents such as free radical or protease inhibitors. Which of the following reasons offers the best support for this claim?
Antibody B can block the initiation of events that result in the release of harmful, biologically active molecules.
NOT Antibody B is a very specific antibody; therefore, it will not recognize anything other than the beta subunit.
The results of the experiment presented in the passage show that the presence of antibody B, which is directed at subunit B, significantly reduces tissue injury. The results also suggest that the function of subunit B is to adhere the neutrophil to vascular endothelium, which occurs before the release of toxic molecules by the neutrophil. Thus, the use of antibody B would be a proactive treatment that prevents neutrophil adherence and the subsequent release of free radicals and proteases, rather than a reactive treatment, such as free radical and protease inhibitors. This supports the claim that antibody B is a better treatment.
The scientist wanted to use antibody B clinically (to treat humans), but this proposal was rejected. Which of the following is the most logical reason for the rejection?
Because the antibody was generated in the mouse, repeated usage in the same patient would elicit the production of human anti-mouse antibodies.
Human immune system will recognize the mouse antibody as a foreign substance (antigen) and generate an immune response towards it, which may include a mild to severe allergic reaction. The immune response will generate antibodies against the mouse antibody, limiting its usefulness as a treatment
A neutrophil has point mutations in the genes coding for the alpha and the beta subunits of the adhesion receptor. However, this cell can still migrate through endothelium. Which of the following conclusions about the effect of this mutation can be drawn?
The cell can bind to endothelium.
The mutation isn't changing anything in the cell so its going to keep doing the same function
According to the passage, neutrophil migration into endothelium occurs after adhesion to endothelium. Thus, this cell must still be able to bind to endothelium, suggesting that the mutation either does not affect the cell's adherence ability or enhances it.
The symptoms of hemophilia can be at least partially alleviated by administration of functional Factor VIII. A scientist claimed that hemophilia is caused by a functional deficiency in Factor VIII. The evidence in the passage that would best support this claim is that Factor VIII is:
able to relieve hemophilia symptoms.
Answer choices that can be characteristics of both functional and nonfunctional proteins do not provide the best support for the claim
The synthesis of Factor VIII requires mRNA splicing. Recombinant DNA technology allows scientists to mass-produce some human proteins by transferring human genes into bacteria. The characteristic of bacteria that would most likely prevent Factor VIII from being produced in this way is that bacteria:
lack a mechanism for splicing out introns.
mRNA processing does not occur in prokaryotes. Because transcription in prokaryotes occurs in the cytoplasm, ribosomes are able to bind and begin translation even before transcription is complete; prokaryotic mRNA requires no additional processing after transcription.
In oxidative phosphorylation, cytochrome c acts as:
1 electron carrier
What is a heme protein that only cycles between a ferrous and ferric state during oxidative phosphorylation?
2 electron carriers
NADH and FADH2
What characteristic in a primer is most suitable for PCR?
suitable primers have a high GC content and have G or C base pairs at the 5 and 3 ends.
If the concentration of amino acid transport protein is increased, the transport affinity Kt of L-alanine will:
it will not change.
transport affinity for a given substrate (in this case, alanine) is a property of the amino acid transport protein itself, and thus, Kt will not change as a result of there being more transport protein. In other words, the Kt value is not dependent on the concentration of the amino acid transport protein.
Do D- or L- amino acids form proteins during ribosomal protein synthesis?
What enables an organism to determine how long the stored energy reserves will last?
average metabolic rate
LOWER metabolic rate = longer lasting energy reserves = best suited to withstand periods of long term nutrient deprivation
Why would a bacterial colony not grow immediately after a polysaccharide was added?
because digestive enzymes for the polysaccharides had to be transcribed and translated, which takes a bit of time
What do telomeres and centromeres have in common?
They are both types of heterochromatin
Which amino acids are neutral, but zwitterionic at pH 7, despite possessing two nitrogen atoms in its formula?
Of the amino acids that contain two nitrogen atoms, only asparagine, glutamine, and tryptophan carry an equal amount of positive and negative charge at neutral pH.
Note that arginine has 4 nitrogen atoms
Antigenic variation is a survival strategy used by the human malaria parasite Plasmodium falciparum to avoid destruction by the host's immune system. Switching of var gene expression probably most directly benefits P. falciparum by reducing the parasite's:
elimination by the human adaptive immune system.
as the specific var gene expressed switches, so does the antigenicity of the PfEMP1 expressed on the erythrocyte surface. Thus, it is most likely that the antibodies that bind a specific PfEMP1 variant will not bind the next variant that is expressed, so a new adaptive immune response will have to be mounted against the new variant.
Affinity chromatography identified actin as an essential component of the complex that interacts with the var intron. Perturbation of normal actin with jasplakinolide, an actin stabilizer, results in movement from the heterochromatin clusters and activation of previously silent var genes.
The information in the passage supports the hypothesis that which type of filament is involved in the transport of var genes from heterochromatin to the active var gene expression site?
the passage discusses the role of actin in var gene silencing, and actin filaments are microfilaments.
BAT is the primary site of nonshivering thermogenesis (heat production) in rodents. Which of the following organelles would be relatively more abundant in brown adipose tissue (BAT) than in typical white adipose tissue?
BAT is a specialized adipose tissue that contains large numbers of mitochondria that generate heat during thermogenesis
The individual cells making up a tissue differ from single-celled organisms such as Paramecium in that only the latter:
are capable of extended independent life.
only the Paramecium, and not tissue cells, can survive independently for an extended period of time. Both Paramicium and tissue cells divide by mitosis, have subcellular organelles, and can metabolize nutrients
When a striated muscle cell metabolizes glucose in the complete absence of O2, which of the following substances is NOT produced in a significant amount?
A. Pyruvic acid
C. Lactic acid
in the absence of oxygen, pyruvate is converted to lactate in the cytoplasm and is not transported to the mitochondria to be converted to acetyl-CoA
A fatty acid is comprised of a long hydrocarbon tail and a head consisting of:
fatty acids contain a carboxylic acid head group and a hydrocarbon tail.
The head group is NOT a phosphate group. But can be attached to a phosphate
Administration of a carbonic anhydrase inhibitor to the RBCs would most likely cause an increase in the concentration of:
Carbonic anhydrase works in the red blood cells to convert the substrates CO2 and H2O into their product carbonic acid (H2CO3). If the enzyme is inhibited, carbon dioxide would build up in the tissues because the normal method of carbon dioxide removal is inhibited.
Lung capillaries are so narrow that RBCs must pass through them in single file. This feature aids respiration by:
giving maximum exposure of each RBC to diffusing gases.
gases enter and exit the RBC through diffusion across the RBC plasma membrane. If RBCs pass through capillaries single file, more RBC surface area is exposed, increasing the efficiency of gas exchange.
If a protein moved directly from the early endosome to the golgi, then it would bypass which organelle?
The most likely result of various alanine to proline mutations in subunit A is:
loss of secondary structure.
proline disrupts α helices
Several strains of STx-producing E. coli are responsible for disease. Despite the availability of antibiotics that lyse E. coli cells, the reason this is NOT a recommended course of treatment is because:
the bacterial lysate will disrupt host translation.
Subunit A is a protein activated by cleavage. Which type of enzyme is responsible for activating subunit A?
Proteases cleave proteins
Introduction of which amino acid substitution would result in the largest decrease in the entropic penalty associated with a protein folding into its native conformation?
changing a surface-exposed hydrophobic residue for a more hydrophilic residue eliminates the entropic penalty associated with ordered water molecules around hydrophobic groups.
e.g. Leu to Thr substitution at a surface-exposed site
In humans, the lining of which structure is NOT primarily derived from the endoderm?
Mouth is derived from an invagination of ectoderm
Most of the epithelial tissues inside the body (B, C, D) are derived from endoderm.
People with microsatellite instability (MSI) colorectal cancers (CRCs) have HSP110ΔE9 transcripts in cancerous tissue only. 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?
HSP110ΔE9 transcripts are not present in noncancerous tissue of people with MSI CRC. This means that the deletion mutation in the HSP110 T17 microsatellite is a somatic, not germ line, mutation. Therefore, 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
I and II
Mismatch Repair (MMR) only recognizes non-Watson Crick pairs during DNA replication
Deletions in the T17 microsatellite located in Intron 8 of HSP110 cause Exon 9 to be omitted from the final mRNA sequence during pre-mRNA processing. This best supports the conclusion that Intron 8 of HSP110 most likely contains what?
Intron 8 contains a splice acceptor site.
Exon 9 would be omitted during alternative splicing, which strongly suggests that the microsatellite contains sequences that influence splicing.
HSP110 can bind structurally similar heat shock proteins and functions to facilitate proper protein folding and to reduce levels of nonfunctional protein aggregates. According to this information, HSP110 is most likely which type of protein?
Chaperone proteins assist in protein folding
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?
25% bc (XcXc, XcY, XcX, XY)
What is the total number of fused rings present in a steroid?
steroid is defined by its fused 4-ring structure
When concentrated urine is being produced, in which of the following regions of the kidney will the glomerular filtrate reach its highest concentration?
glomerular filtrate is most concentrated in the medullary portion of the collecting duct
What aspect of Experiment 1 does NOT address whether membrane composition has an effect on Na+K+ ATPase activity? The activity of the Na+K+ ATPase:
increased with temperature in both the 14:1 liposome and the 14:0 liposome.
the researchers were not trying to show that protein activity increases with temperature, which is an expected result of all kinetic studies assuming the protein does not thermally denature. They raised the temperature to see how fluidity plays a role in activity.
Which approach does NOT measure the activity of the Na+K+ ATPase?
A. Measuring the rate of ATP hydrolysis
B. Measuring the free energy of the ion transport
C. Measuring the rate of ADP production
D. Measuring the change in ion concentration within the liposome
Measuring the free energy of the ion transport.
bc free energy is a thermodynamic quantity and is NOT a kinetic property. Activity is a kinetic property.
STN is a planar and hydrophobic molecule with aromatic rings and heterocyclic molecules. Considering the structure of STN, what is the most likely mechanism for its entry into the cell?
because it is hydrophobic, it can pass through he membrane by simple diffusion
P-glycoprotein (P-gp) is a plasma membrane ABC transporter that has broad substrate specificity for hydrophobic compounds. P-gp is responsible for multidrug resistance (MDR) in tumor cells by preventing drugs from accumulating to cytotoxic levels. Which mechanism best describes how P-gp facilitates drug resistance?
P-gp serves as a pump and uses active transport to move antitumor drugs outside the cell.
P-gp is an ABC transporter protein, which uses ATP to actively transport antitumor drugs out of the cell.
What are ABC transporters?
carrier proteins that use energy from ATP to transport solutes
Colchicine is a drug that prevents the formation of microtubules. What mitotic process would NOT occur after exposure to this drug?
Movement of the chromosomes toward opposite poles of the cell during anaphase
True or False: Enzymes alter primary structures of protein
False, Enzymes cannot alter primary structures of protein, but can colocalize substrates, alter local pH, and alter substrate shape.
cP-450 does not metabolize all toxins at the same rate. For example, although cP-450 usually metabolizes barbiturates, alcohol acts as a competitive inhibitor of barbiturate metabolism. A chronic alcoholic died of a barbiturate overdose because of the role of cP-450 in the metabolism of toxins. The presence of alcohol caused death because the alcohol:
alcohol acts as a competitive inhibitor of cP-450, thus preventing it from metabolizing barbiturate. So alcohol inhibited the cP-450
A student hypothesized that EC growth might be affected by the DNA from circulating erythrocytes. Is this student's hypothesis reasonable?
No, bc circulating erythrocytes do not contain DNA. mammalian erythrocytes (red blood cells) lose their nuclei during maturation to make space for Hb
Pericytes were growth-arrested in Experiment 1 so that the:
pericyte growth would not interfere with the measurement of EC growth.
The question asks the examinee to identify the reason for using pericytes that were growth-arrested in Experiment 1. The results of the experiment were expressed in terms of the number of endothelial cells. Had the pericytes been allowed to divide, the observed increase in the number of cells in the culture would have been due to increases in the number of pericytes and in the number of endothelial cells. By inhibiting the division of pericytes, the observed change in cell number is attributable solely to the growth of endothelial cells. The reason for using growth-arrested cells is therefore to simplify the measurement of the number of endothelial cells in the culture.
what cells are important in the exchange of oxygen between the blood and the surrounding tissues?
Endothelial cells separate the blood fro the surrounding tissue
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:
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:
in most prokaryotes, DNA is circular and therefore does not have the repetitive, non-coding nucleotide sequences called telomeres that occur in eukaryotic DNA.
What describes the bond that would form between 5' Thymine and 3' Adenine nucleotides if they were located adjacent to each other in a single strand of DNA?
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.
Addison's disease occurs when cells of the adrenal cortex are destroyed, leaving the gland unable to secrete either glucocorticoids or mineralocorticoids. Normally, a hypothalamic factor stimulates the release of adrenocorticotropic hormone (ACTH) from the pituitary gland. In a patient with Addison's disease, the secretion of the hypothalamic factor will:
be higher than normal.
ACTH stimulates the adrenal cortex to secrete glucocorticoids. ACTH secretion is expected to be higher than normal in a patient with Addison's disease to attempt to stimulate the adrenal cortex.
A major function of cortisol, the body's primary glucocorticoid, is to stimulate gluconeogenesis (formation of glucose from noncarbohydrate sources) in the liver by activating DNA transcription to produce liver enzymes and by mobilizing amino acids from muscle tissue. Addison's disease occurs when cells of the adrenal cortex are destroyed, leaving the gland unable to secrete either glucocorticoids or mineralocorticoids. If a patient with Addison's disease is given too high a replacement dose of glucocorticoids, the effect over time will be an increase in:
glucocorticoids act on skeletal muscle causing the breakdown of muscle proteins. Therefore, if a patient is given too high a replacement dose of glucocorticoids, this will result in muscle weakness.
The most rapid rate of gluconeogenesis will most likely occur in the body 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:
aids glucose uptake by decreasing the cellular concentration of glucose.
Insulin does NOT provide ATP needed by the glucose transporter proteins
Which of the following is LEAST likely to be a symptom of diabetes mellitus?
A. Loss of appetite
B. Sweet-tasting urine
C. Unexplained weight loss
D. Feelings of fatigue
Loss of appetite
Symptoms of diabetes mellitus are frequent urination and catabolism of fatty acid as well as proteins as alternative energy sources. In diabetic patients, high blood glucose results in excretion of excess sugar into the urine, hence sweet-tasting urine. Similarly, the catabolism of fatty acids and proteins results in weight loss and feelings of fatigue respectively.
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?
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 15-N and the other strand 14-N). Following the second round of cell division, half of the bacteria will have a genome mass of 5.4 fg (14-N exclusively) and the other half a mass genome of 5.45 fg (14-N in one DNA strand and 15-N in the other).
Another way of thinking about this, is that the molar mass of Nitrogen is 14, but this is just an average of the isomers. So most isomers of nitrogen weight close to 14amu, but some weight more. Therefore, the genome will weight mostly 5.4fg due to many isomers but will also have isomers that increase the genome weight to less than 5.45fg
Assume that K and M are two unlinked genes that affect hearing. The dominant K allele is necessary for hearing, and the dominant Mallele causes deafness regardless of the other genes present. Given this, what fraction of the offspring of parents with the genotypes KkMmand Kkmm will most likely be deaf?
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?
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.
XPA is a rate-limiting factor in nucleotide excision repair system (NER). CRY1 and XPA have opposing actions. The information in the passage suggests that in mice CRY1 most likely affects XPA by:
repressing TRANSCRIPTION (NOT REPLICATION) of the XPA-encoding gene.
if you represses the expression of a gene, then you are repressing transcription.
It was found that AlP exposure resulted in a 65% decrease in ATP levels and a 48% decrease in the rate of ATP synthesis in the mitochondria. When researchers determined the total cellular concentration of ATP in AlP-exposed rat liver cells, they found the concentration to be equal to the control value. Which conclusion about the metabolic state of the cell is best supported by these data?
A. Glycolytic flux is increased after AlP treatment.
B. Glycolytic flux is decreased after AlP treatment.
C. Citric acid cycle flux is increased after AlP treatment.
D. Citric acid cycle flux is decreased after AlP treatment.
Mitochondrial ATP synthesis has been decreased, so most of the ATP that will be made will be in the cytosol outside of the mitochondria. This suggests that ATP is produced by glycolysis. So, Glycolytic flux is increased after AlP treatment
Remember that ATP is NOT directly produced by the citric acid cycle. TCA make electron carriers so that ETC can make ATP
Inhibition of phosphofructokinase-1 by ATP is an example of:
I. allosteric regulation
II. feedback inhibition
III. competitive inhibition
Allosteric regulation and feedback inhibition
ATP does NOT bind to the active site, so it is not a competitive inhibitor. It binds to a spot other than the active site when is known as the allosteric site.
What is required to activate transcription factors?
Nuclear localization sequence
Addition of Protein X to the liposomes caused a gradual release of the fluorescent dye from the liposomes. What event will most likely occur if Protein X is inserted into the inner membrane of mitochondria?
A.The citric acid cycle will cease to function.
B.The electron transport chain will cease to function.
C.The proton gradient across the inner membrane will dissipate.
D.The pH of the intermembrane space will decrease.
Protein X causes a leak from the membrane (as shown by the fluorescent dye). So the proton gradient would disappear. Answer is C.
What is the best experimental method to analyze the effect of tdh2 gene deletion on the rate of histone acetylation? Comparing histone acetylation in wild-type and Δtdh2 cells by:
Histone acetylation is a type of post-translational modification of proteins. So western blot for proteins would be the best method
S. typhi is the causative agent of typhoid fever. Researchers have noted that chloramphenicol (a commonly used antibiotic) is becoming less effective in treating typhoid fever. The best explanation for this observation would be selection:
for chloramphenicol resistance in populations of S. typhi.
As S. typhibecomes resistant to chloramphenicol, this antibiotic will become less effective in treating typhoid fever.
Individuals homozygous for the ΔF508 allele have CF. Human epithelial cells expressing ΔF508 ingest significantly fewer S. typhi than do epithelial cells that express wild-type CFTR. What is the phenotype of an individual who is heterozygous with one ΔF508 and one wild-type CFTR allele?
More resistant to typhoid fever than wild-type homozygotes and does not have CF
The entry of an EboV nucleocapsid into the host cell cytoplasm starts with the fusion of the viral membrane with a host cell membrane, a process facilitated by EGP. Recognizing the similarities between how EGP and the glycoproteins of related viruses are processed during viral infection, as well as how inhibitors of endosomal acidification block EboV infection, researchers hypothesized that acid-dependent proteases trigger the conformational changes in EGP that are necessary for fusion.
Based on the passage, proteases CatB and CatL most likely act on EGP in which of the following cellular compartments to facilitate membrane fusion?
the entry of the virus into the host cell requires CatB and CatL proteases and involves endocytosis through the fusion of the viral membrane with the host cell membrane. Internalization of viral particles through endocytosis is mediated by endosomes.
Based on the passage, does optimal VSV-EGP infection in vitro require CatB, CatL, or both? Optimal infection:
requires both CatB and CatL.
the data presented in Figure 1 indicate that CatB-/-, CatL−/− mouse cells expressing either CatB or CatL have low levels of viral infection. In contrast CatB−/−, CatL−/− mouse cells expressing both CatB and CatL exhibit several folds higher viral infection levels.
The precursor of EGP is translated from a transcript that has had one nontemplated nucleotide added to the open reading frame. This change does not create or eliminate a stop codon. Compared with the protein sGP, which is produced from the unedited transcript, EGP most likely has the same primary:
amino-terminal sequence as sGP, but a different primary carboxy-terminal sequence.
the addition of one nucleotide to the open reading frame of EGP results in a frameshift mutation and an aberrant carboxy-terminal domain
Under anaerobic conditions, how many net molecules of ATP are produced by the consumption of 5 moles of glucose?
Under anaerobic conditions, 2 moles of ATP are produced from each mole of glucose. Thus, 10 moles of ATP would be generated from 5 moles of glucose. Since there are 6 × 10^23 molecules per mole, 10 moles of ATP is equal to 6 × 10^24 molecules.
In humans, eggs and sperm are most similar with respect to:
A. cell size.
B. genome size.
C. the time required for development.
D. the numbers produced by a single individual.
both eggs and sperm contain a haploid number of chromosomes and therefore they are most similar with respect to their genome size
Where in the human male reproductive system do the gametes become motile and capable of fertilization?
sperm, produced in the seminiferous tubules of the testes, completes maturation and becomes motile in the epididymis.
According to the cross-bridge model of muscle contraction, the muscles stiffen after death because ATP is unavailable to bind and directly release:
the myosin head from the actin filament
What are the relative potentials for force and power generation by a slow-twitch muscle fiber and a fast-twitch muscle fiber of the same diameter?
The fast-twitch fiber is capable of generating more power than the slow-twitch fiber, while the potential for force generation is the same.
similarly sized fibers would generate similar force, regardless of fiber type. However, since the fast-twitch fiber would generate the same force with greater velocity, the fast-twitch fiber would generate more power.
force generation would be equal due to similar cross-sectional areas, while power would be dissimilar.
It has been proposed that the protein cFLIP is a structurally similar homolog of caspase-8 that lacks catalytic activity. Caspase-8 is a protease that triggers apoptotic cell death. Which type of catalytic activity is most likely missing from cFLIP?
How do proteases work?
they cleave peptide bonds by hydrolyzing them
Figure 3A indicate that compared to NDU-KO cells, in WT cells which possess NDU, oxygen consumption is reduced under hypoxia. If the NDU gene is amplified inside cells leading to overexpression of the protein, what event is likely to occur under hypoxic conditions?
Oxygen consumption within the mitochondria will decrease further.
What is an imprinted gene?
A gene where only one allele is transcriptionally active. Imprinted genes are expressed in a parent-specific manner.
Assuming that protein synthesis was under way when the radioactive amino acids were added, which of the following best describes how the radioactivity was distributed in one of the first molecules of Protein X that was completely translated?
Radioactive amino acids were located only at one end of the molecule.
the stem assumes that protein synthesis was under way when the radioactive amino acids were added, inferring that the N-terminal end and probably the middle part of the protein were already synthesized before the addition of the radioactive amino acids.
Certain viruses contain RNA as their genetic material. One of the ways these RNA viruses replicate themselves is to:
code for or carry a transcriptase that copies viral RNA.
Large amounts of protein are found in the urine of a patient. Based on this information, which portion of the nephron is most likely malfunctioning?
Glomerulus bc the glomerular capillaries prevents the entry of large molecules, such as proteins, into the filtrate
Within the intestines, unabsorbed fats are broken down into fatty acids by intestinal bacteria. Given this, excess unabsorbed fats most likely have which of the following effects within the intestines?
They increase the osmotic pressure within the intestines, leading to diarrhea.
an excess of unabsorbed fats in the intestines inhibits normal water and electrolyte absorption, resulting in increased osmotic pressure and diarrhea. (water flows towards proteins)
Glutamate gets converted to glutamine via glutamine synthetase. Glutamine can then be converted into tryptophan. The activity of glutamine synthetase decreases as the concentration of tryptophan increases.
The number of glutamine synthetase molecules in the cell remains constant regardless of the tryptophan concentration. These observations are consistent with a mechanism of:
the level of glutamine synthetase molecules in the cell remains constant regardless of the tryptophan concentration, thus excluding transcriptional or translational controls. In absence of other types of control, an increase in tryptophan concentration that is accompanied by decreased activity of glutamine synthetase is consistent with feedback inhibition.
A defining characteristic of proteins that act as transcription factors is that they:
contain a DNA binding domain that allows it to bind to regulatory nucleic acid sequences in a gene to alter transcription.
Where does fatty acid oxidation occur?
Where does fatty acid synthesis occur?
As blood passes through actively contracting skeletal muscle tissue, the affinity of hemoglobin for oxygen in the muscle tissue:
Affinity would decrease with a decrease in plasma pH, and during prolonged exercise, anaerobic respiration would decrease the plasma pH.
When choosing an antigen for vaccine production, there are two aspects to consider:
immunogenicity (Ability of pathogens to induce an immune response) and toxicity
What amino acids can be phosphorylated?
serine (S), threonine (T), and tyrosine (Y)
Which technique separates proteins independently of their charge?
Gel filtration chromatography separates protein only on the basis of their size.
Native PAGE is used to separate molecules based on their electrophoretic mobility, relying on length, conformation, and charge.
A peptide consisting of nine amino acids was partially hydrolysed. Three different tripeptides were isolated. None of the tripeptides share a common amino acid. Based on the data, what is the total number of possible structures possible for the full-length peptide?
If the sequences were ABC, DEF, and GHI, they can only be joined in 6 different possible ways to make a nonapeptide. Each of the tripeptides can appear in the first position and can combine in two possible ways with the other two tripeptides: 3 × 2 = 6.
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.
Both the active and inactive X chromosomes replicate. However, the inactivate X chromosome is one of the last chromosomes to replicate (answer c)
True or False: water doesn't appear in Keq
True, Water, as liquid and solvent, does not appear in the equilibrium constant expression.
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:
water was excreted via the skin and the lungs
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.
Which immune cells would mount the initial immune response to N. meningitidis that results in meningitis?
Microglia are phagocytotic innate immune cells specific to the brain. Other adaptive immune cells (B cells, Cytotoxic T cells, Helper T cells) require activation by microglia to mount an immune response
UAG stop codon
The three STOP codons have been named as amber (UAG), opal or umber (UGA) and ochre (UAA)
In Drosophila, white eyes are recessive to red eyes, and yellow bodies are recessive to dark bodies; both genes are on the X chromosome. The genotype of a red-eyed, dark-bodied female (XX) could be determined by mating it with a male (XY) that has which of the following phenotypes?
White eyes, yellow body
This is a method to identify if an organism that shows a dominant phenotype is a homozygous or heterozygous. The female is red-eyed and dark bodied, which means she has a dominant phenotype. However, the female could also be homozygous or heterozygous for one or both traits. Mating this type of female with a male with a recessive phenotype for both traits (white eyes and yellow body) would determine the genotype of the female.
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