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Altius 5,6,7 BB
FLE Exams 5,6,7 Bio/Biochem
Terms in this set (87)
Why did the researchers use two controls?
because they wanted to compare different trials to
1. both the baseline expression level with no experimental manipulation whatsoever, and
2. the expression level when inactive molecules were added
How do antibodies bind and inhibit functional proteins in vivo?
Antibodies are water-soluble proteins that function outside of a cell by binding to surface antigens on the OUTSIDE of the cell membrane. Antibodies do not normally cross the lipid bilayer of eukaryotic membranes. In fact, given that they are hydrophilic, they could not without a specific protein channel or carrier.
H-ras participates in a signal transduction pathway in synovial cells that eventually results in secretion of IL-6. Because Protein A proved effective at inhibiting H-ras, investigators may consider which cellular component (protein) as a target for inhibiting other signal transduction pathways using Protein A?
Nearly all signal transduction pathways involve a cell receptor that is a transmembrane protein. The receptor protein usually binds to the signaling molecule and transduces the signal across the plasma membrane into the cell.
In order for plasmids to produce Protein A in synovial cells, the plasmid must be localized to the:
The plasmid DNA coding for the Protein A would have to be transcribed into mRNA in the nucleus. Therefore, the plasmid would have to be localized to the nucleus
If the plasmid was only in the cytosol, or only in the ER (and never in the nucleus) expression of the plasmid gene could not occur.
True or false: mitochondrial genes are primarily transcribed and translated using nuclear DNA and the regular cytosolic ribosomes
True or False: humans can digest β-linked saccharides
False, humans cannot digest β-linked saccharides. Vertebrates can only digest α-linked saccharides using their own enzymes
What happens to the ascending limb when ADH causes increased water reabsorption at the collecting ducts?
Aquaporin proteins are opened up in the collecting duct, allowing water to pass into the medulla. A more dilute medulla shifts the equilibrium between the filtrate in the ascending limb and the medulla, driving more ions out of the ascending limb (Note: recall that the ascending limb is impermeable to water, but highly permeable to ions). This increased removal of ions decreases the osmolarity of the filtrate in the ascending limb
True or False: Adults express lactase
False. Nearly all human babies produce the enzyme lactase. However, only a certain percentage of individuals continue to express lactase in adulthood. The presence, absence, or deficiency of lactase enzyme in adults is responsible for the various degrees of lactose intolerance.
Maltose v.s. Lactose
They both contain one galactose and one glucose
Maltose = α-linkage
Lactose = β-linkage
oxygen position on the anomeric carbon
α-linkages = oxygen on the anomeric carbon is in the ANTI- position relative to the -CH2OH group (OPPOSITE side of ring)
β-linkages = anomeric oxygen is on the SAME side of the ring as the -CH2OH group
How do you elute molecules bound to the column in ion exchange chromotography?
add a high concentration of an ion of the opposite charge (affinity for the resin) to out-compete the bound molecules and elute them off.
How to form a Haworth projection from a Fischer projection
All the groups on the RIGHT-hand side will be BELOW the plane of the ring structure in the Haworth projection, and all the groups on the left-hand side will be above the plane of the ring.
The next-to-last carbon doesn't "count" as far as determining what is above and below the plane of the ring because this hydroxyl group becomes part of the hexose ring.
The outer membrane of Gram negative bacteria features lipopolysaccharide molecules that illicit a strong host immune response. Given this information, the cell wall of Gram negative bacteria contains which of the following components?
II. Both an inner and an outer membrane
Bacteria are separated into Gram positive and Gram negative classes based on how they respond to Gram staining. Both Gram positive and Gram negative bacteria contain peptidoglycan in their cell wall (Statement I), but ONLY Gram NEGATIVE bacteria have both an inner and an outer membrane (Statement II). As indicated by the question stem, Gram negative bacteria are also the only class that contains lipopolysaccharides (Statement III).
Facilitated diffusion through the plasma membrane moves a substance:
down its concentration gradient and RELEASES ENERGY.
At physiological pH, the acetylation of K327 causes which change to the amino acid side chain?
When lysine is acetylated, an amide linkage forms between the amino group and the new acetyl group. Amide linkages are neutral. So, the charged amino nitrogen is neutralized.
Acetic anhydride v.s. Acetyl-CoA for acetylation
Acetic anhydride is an acetylating agent used in laboratory organic synthesis, but is not a natural biological molecule in vivo.
Acetyl-CoA is commonly used by enzymes in the body for acetylation reactions as the carbonyl carbon is easily attacked by the nucleophilic nitrogen of an amino acid residue.
What experimental finding provides the strongest support for the conclusion that acetylation of K327 regulates, but is not necessary for, Tip60 HAT activity?
Evidence to support this statement should indicate that wild-type Tip60 still shows HAT activity when Lys-327 is present but is NOT acetylated.
The K327Q mutant exhibited decreased HAT activity would not be the answer because this is a mutation where Lys has been replaced with Gln, which would provide information about the effect of the lysine residue being present.
Deacetylated Tip60 maintained substantial HAT activity is the correct answer bc deacetylated Tip60 contains all of its native lysine residues, but none of them are acetylated, including K327. If HAT activity is still observed in deacetylated Tip60, this suggests that acetylation of K327 is not necessary for HAT activity.
T-cells contain a membrane receptor, TIM-1, that binds proteins produced by Ebola virus. With what viral protein does TIM-1 most likely associate?
The host membrane receptor, TIM-1, must interact with a protein on the viral envelope (NOT within the virion)
The researchers used an adenoviral vector for delivery of Ebola virus proteins, with the intent to stimulate cytotoxic T lymphocytes. This approach could be problematic because the adenoviral vector may:
not infect the same cell types as EBOVs. Cytotoxic T lymphocytes (CTLs) are not stimulated through the internalization of a virus. Rather, they are activated when an antigen presenting cell is infected with a virus and that cell presents the antigen to the CTL. The adenovirus is simply a delivery system to carry an EBOV gene vector into the patient. If EBOV and the adenovirus infect different cell types, this method is unlikely to be effective.
The vaccine described in the passage was based on protein profiles from the Ebola-Zaire strain, the most virulent and deadly of all EBOVs. Will this vaccine provide protection against all future outbreaks of Ebola?
No, because some EBOV strains may have different proteins.
The passage study was designed to bypass the stomach in order to measure ileal digestion and absorption. What aspect of the study results might be modified if the proteins were ingested orally?
Some proteins may have been digested by stomach enzymes before reaching the ileum.
True or False: Bacteria could secrete chemicals or enzymes that alter the rate of digestion or absorption
True or False: Bacteria could cause a bacterial infection in the ileum, which is a naturally sterile environment.
False, the ileum is NOT a sterile environment under normal conditions. It is filled with natural bacterial flora.
After leaving the stomach, in which order does food travel through the regions of the small intestine?
Duodenum → jejunum → ileum
For an enzyme catalyzed reaction, initial reaction velocity is linearly related to which variable?
Enzyme concentration (not substrate concentration)
The relationship between product formation and initial enzyme concentration is proportional, while the relationship between product formation and initial substrate concentration is not.
In the Michaelis-Menten Equation, the numerator includes a product of [S] and the denominator includes a sum of [S], which means the relationship between velocity and [S] cannot be linear.
the graph of initial V vs [S] is hyperbolic, not linear.
During DNA replication, which enzyme removes RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments?
What is the function of primase?
used in DNA replication (not transcription) to polymerize the RNA primer so DNA polymerase can use the free 3'OH group to begin DNA synthesis.
In a certain species of mice, black skin (B) is dominant to albino skin (b) and a long tail (L) is dominant to a short tail (l). Given this information, which mating will produce only heterozygous offspring?
BBll x bbLL
If an EMG and FGT (force generation test) are performed on the working muscle of a healthy patient during a period of increasing muscle fatigue, these tests are expected to reveal:
sustained electrical voltage and reduced force generation
Muscles that rely exclusively on glycolysis fatigue more quickly than muscles that utilize aerobic respiration. Does this finding support lactic acid accumulation?
Yes, because glycolysis produces lactic acid. Muscles that rely exclusively on glycolysis are known as fast, glycolytic fibers. Per glucose metabolized, or per ATP produced, they will produce much more lactic acid than slow, oxidative fibers that preferentially rely on aerobic respiration.
How does lactic acid differ from a strong acid?
Lactic acid is a weak acid, so the same concentration of lactic acid will be less dissociated in solution resulting in a smaller Ka and larger pKa. Weak acids have less of an effect on pH at any given concentration than strong acids.
Which piece of evidence would most strongly support the conclusion that the ability of β-cells to produce a synchronized response when organized into pancreatic islets is dependent on gap junctions?
Mutant β-cells within pancreatic islets treated with a gap junction inhibitor exhibit a variable response to changes in blood glucose.
From which structure in a human cell do functional ribosomes originate?
Nucleolus (not ER)
True or False: Mitochondrial genetic information was contributed equally by the father and the mother.
False, the mitochondrial genome is inherited from the mother of the offspring only.
Where is Gastrointestinal epithelium derived embryologically?
Where is sensory epithelium derived embryologically?
A molecular biologist plans to amplify the human OPG gene using the polymerase chain reaction (PCR). What information will allow this biologist to establish the correct elongation time, and to design the correct forward and reverse primers?
The length and nucleotide sequence of the OPG gene. Length is important for the correct elongation time. Nucleotide sequence of the primer region is important to design forward and reverse primers. These primers must be complementary to the 3' ends of both strands for the region being targeted.
A cold ethanol wash could be used in the synthesis of another molecule for what?
To remove ethanol-SOLUBLE impurities. It is important to use cold solvent because most solid products are increasingly soluble in warmer solvents. Using warm solvent may accidentally dissolve some of the product and flush it through the funnel.
What is polymerization of tubulin?
assembly of globular proteins to form microtubules
True or False: T cells differentiate into plasma cells
False, B cells turn into plasma cells
Investigators examined the effect of DMSO on membrane transport because it is:
a solvent used to prepare the potential drugs for administration. DMSO is a polar, aprotic solvent that dissolves both polar and nonpolar compounds.
True or False: protozoans are unicellular eukaryotes
What effect does an decrease in the number of gas moles during a reaction have on entropy?
It decreases entropy, because there are less things on the right side than the left side
2H + O2 -> 2H2O
A drug that blocks ion channels will impede the normal function of which cellular structures?
II. Neuron cell membrane
III. Muscle cell sarcoplasmic reticulum
All of them.
The inner mitochondrial membrane contains the ATP synthase enzyme, a specialized ion channel that allows H+ ions to pass from the intermembrane space to the mitochondrial matrix while using the associated energy to produce ATP.
Before fatty acids can be oxidized, they must be activated via the following reaction:
Fatty acid + CoA + ATP ⇌ Fatty acyl-CoA + AMP + PPi
The equilibrium constant for this reaction is close to one, while the free energy change is nearly zero. The reaction proceeds spontaneously in vivo because it is coupled to the:
The reaction will be driven forward by a large negative ΔG° value from the highly exergonic (release of energy) hydrolysis of PPi. PPi contains a high energy phosphate bond that releases its energy upon hydrolysis. This provides the large ΔG° value needed to move the reaction in the forward direction.
A new chemotherapy drug is thought to disrupt the normal processing and delivery of proteins to the cell membrane. This drug is likely to have the most direct impact on which organelle?
Suppose a bacterium consumes lactose sugar, resulting in activation of the lac operon. This activation is the result of:
degradation of the lac repressor.
(not dissociation of the lacrepressor from the operon)
Effects of inhibitor binding - MM graph
Effects of inhibitor binding - lineweaver graph
Examples of positive feedback
Oxytocin release during childbirth.
Blood clotting following injury.
Spreading of an action potential in skeletal muscle.
Given that Rheumatoid arthritis (RA) is linked to chronic inflammation, which treatment would be most beneficial for patients suffering from RA? An antibody that binds to:
TNF-α, a pro-inflammatory cytokine that would be inhibited when bound by an antibody.
If Patient X, whose blood type is A+, donates blood to Patient Y, whose blood type is AB-, will Patient Y produce reactive antibodies to this transfusion?
Yes, Patient Y will produce anti-Rh antibodies.
Patient Y with AB blood types will express approximately equal amounts of antigen A and antigen B. The immune system develops self-tolerance to an individual's own blood antigens, meaning the immune system will not produce reactive antibodies against those same proteins in blood received via transfusion.
The plus and minus signs used in relation to blood typing denote the Rh factor, another antigen found on blood cells. The donor, Patient X, is positive for Rh and therefore has the antigen. The recipient, Patient Y, is negative for Rh and therefore does not possess the antigen. As a consequence, Patient Y will produce antibodies against the Rh protein, which it will recognize as a foreign antigen.
True or False: The 5' cap and poly-A tail moieties are found only in mature prokaryotic mRNA.
True or False: Introns must be spliced out of the pre-mRNA transcript in prokaryotes
False, splicing out of introns, and the alternate assembly of exons is unique to eukaryotes
The orientation of an mRNA codon relative to a tRNA anticodon is best described as:
An antimicrobial drug that disrupts transcription in prokaryotes, but not eukaryotes, could target which class of enzymes?
RNA polymerases, bc prokaryotes and eukaryotes use different RNA polymerase enzymes
The influenza virus must first create a template of its own RNA genome before the translation of viral proteins can occur because host:
ribosomes cannot translate negative-sense RNA
The Hardy-Weinberg equation is shown below. Assuming qrepresents the recessive allele in a hypothetical population, which quantity can be counted directly using a population survey?
p² + 2pq + q² = 1
q^2, because it represents the frequency of homozygous recessive individuals (aa), who will demonstrate the phenotype associated with the recessive allele (a).
Protein folding involves a transition from a more disordered state to a more ordered state. This entropic penalty does not prevents spontaneous folding because:
the net ΔS of the surroundings is positive, resulting in a negative ΔG for the overall process.
The reduction in the solvation layer is associated with a significant positive entropy which overcomes the entropic penalty associated with increased order in the folded state. This phenomenon is sometimes called the "hydrophobic effect." This allows the net Gibbs free energy change to be negative and therefore the process is still spontaneous. The entropy associated with protein folding is negative (more order). The entropy change of the surroundings must be positive for this effect to overcome the entropic penalty of increased order in the folded state.
Inhibition of Complex II of the electron transport chain will have what impact on oxidative phosphorylation?
The rate of ATP production will decrease. Complex II in the electron transport chain accepts electrons from succinate and passes them to CoQ (and then to Complex III). Without utilizing succinate, the process cannot utilize the electrons from FADH2, and therefore some products of the citric acid cycle will not be used to produce ATP.
Na+, K+, Ca2+, and Cl- are all ions whose extra- and intracellular concentration influence the excitation of a neuron. In equimolar amounts, which ion will occupy the most volume in the extracellular fluid?
Think ionic radius (not atomic radius)
What is the structure of I?
What is the structure of L?
extra carbon before valine look-alike
The excessive use of antibiotics may put evolutionary pressure on:
pathogens, increasing the natural selection of drug-resistant bacterial strains.
Antibiotics are not putting evolutionary pressure on humans. The evolutionary pressure is on the pathogens, resulting in mutations that convey antibiotic resistance becoming more frequent.
Natural selection is one of the foundational concepts of the theory of evolution. It can be simply expressed as the pressure for the gene frequency of a species to change from one generation to the next such that its fitness is increased. Natural selection is the "natural" outcome when RANDOMNESS creates so much variability that at least one random mutation coincidentally happens to lend a fitness advantage.
During inflammation, immune cells are able to translocate into inflamed tissue by:
exiting dilated capillaries through gaps in the epithelium.
True or False: immune cells are able to translocate into inflamed tissue by exiting dilated lymphatic vessels through gaps in the epithelium.
False, lymphatic vessels carry cells away from the tissues via lymphatic vessels
Levodopa is a dopamine precursor used to treat the symptoms of Parkinson's disease. If only 30% of an orally administered 100 mg dose of levodopa (MW = 197 g/mol) is absorbed from the GI tract, what is the initial concentration of levodopa in the bloodstream? (Note: Assume a total blood volume of 5.1 L)
The mass of levodopa that reaches the bloodstream is 30% of the original 100 mg dose, or exactly 30 mg. 30 mg is exactly 0.030 g. The levodopa concentration in the blood stream is therefore given by (moles levodopa)/(5.1 L) = (0.030 g)(1 mol/197 g)(1/5.1 L) = 0.00003 M or 0.030 mM
If the guanine moiety of a nucleotide is replaced with adenine, the IR spectrum of the new compound will be most easily distinguished by the:
lack of a sharp peak at 1700cm-1
Adenine contains a primary amine at the location where guanine contains a carbonyl. The peak corresponding to the carbonyl will disappear. Carbonyls typically appear around 1700 cm-1
rod shaped bacteria are called?
round shaped bacteria are called?
What effect does deamination have on cytosine?
it turns it into uracil
Bacteria do not undergo mitosis. The analogous bacterial process for cell division differs from mitosis in all of the following ways:
Cell division via binary fission is faster than cell division via mitosis.
Binary fission does not utilize the spindle apparatus used during mitosis.
Only binary fission involves attachment of the chromosome to the plasma membrane.
True or False: Binary fission occurs only in prokaryotes, while mitosis occurs only in eukaryotes.
False, although binary fission is the most common form of reproduction in prokaryotes, it also occurs in some single-celled eukaryotes like Amoeba
What is aneuploidy?
existence of an abnormal number of chromosomes in a cell
What is tetraploidy?
existence of two complete sets of chromosomes (four total)
The researchers used microarray analysis, which involved the binding of mRNA molecules to DNA sequences affixed to a microarray plate. Which type of intermolecular attraction binds the target mRNA molecules to the microarray?
Telomere length is considered a reliable biomarker for aging because telomeres become shorter with each cell division. Which biomolecule must be isolated to confirm the shortening of telomeres?
Telomeres are nucleotide sequences found at the ends of each strand of DNA that protect the structural integrity of the chromosome.
What is the most likely impact of a point mutation to the terminal guanine on a 5' exon?
The intron will not be spliced from the mRNA transcript. The first step in intron splicing is the nucleophilic attack of a 2' hydroxyl at the phosphate of the guanine located at the end of the 5' exon. This step forms the lariat structure. The proposed mutation would disrupt this process, preventing the excision of the intron from the transcript.
Which amino acid is most disruptive to normal secondary structure when integrated into an alpha helix?
type 1 v.s. type 2 error
type 1 = false positive
type 2 = false negative
Where in the cell cycle fo growth factors influence cell cycle progression?
G1 checkpoint is regulated by growth factors (not G2)
What is sexual selection?
preference of one mate over another based on phenotype, and thus on the genotype responsible for that phenotype.
What is adaptation?
Adaptation occurs when an allele increases or decreases and individual's fitness.
What is the founder effect?
founder effect occurs when individuals from a larger population settle in an isolated geographic location, a location that prevents mating with the source population. This would result in only a few alleles propagating in the population, thereby increasing the prevalence of the founder alleles relative to the source population.
What is acclimation
Acclimation occurs when an individual adapts to changes in their environment WITHOUT a change in genotype. (does not explain a change in genotypic allele frequency)
If the triplet codon on a coding DNA strand is CTG, the complementary tRNA codon must be which of the following?
Suppose an E. coli colony is transfected with an ampicillin-resistant, tetracycline-resistant plasmid. If the gene encoding for GFP (Green Fluorescent Protein) is ligated into this plasmid by endonuclease cleavage within the tetracycline-resistance segment, how could a biologist select for bacterial colonies that contain GFP?
Culture E. coli in ampicillin and isolate colonies that survive and exhibit fluorescence.
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