Biology 1009 Exam Two
An AABbccDdEeFF individual is crossed with an individual with the genotype AaBBCCDdEeff. What is the probability that their offspring will have the genotype AaBBCcddEEFf?
1/64
A plant is heterozygous for three genes, each on a different chromosome. If self-fertilized, what fraction of its progeny should be heterozygous for all three genes?
1/8
Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed directly by the reactions of glycolysis?
100%
Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?
12
Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F1 individuals have red, axial flowers. The genes for flower color and location assort independently. If 1,000 F2 offspring resulted from the cross, approximately how many of them would you expect to have red, terminal flowers?
190
The enzyme polynucleotide phosphorylase randomly assembles nucleotides into a polynucleotide polymer. You add polynucleotide phosphorylase to a solution of ATP, GTP, and UTP. How many artificial mRNA 3 nucleotide codons could possibly be made?
27: The 1st position of the artificial codon could be either A, U or G. Similarly, the 2nd position could be either A, U or G and the 3rd position could be either A, U or G. So, there are three possible nucleotides for each of the three positions, meaning a total of 3 x 3 x 3 = 27 different artificial codons could be formed in this experiment.
A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is:
3' UCA 5'
Given the locally unwound double strand below, in which direction does the RNA polymerase move?
3' → 5' along the template strand
The nucleotide sequence of the coding strand of a DNA molecule is shown below. What will be the nucleotide sequence of the RNA molecule made from this segment of DNA? 5' ATGCGTA 3'
5' AUGCGUA 3' (U substitutes T - keyword nucleotide sequence)
The nucleotide sequence of the template strand of a DNA molecule is shown below. What will be the nucleotide sequence of the RNA molecule made from this segment of DNA? 5' TTTAAGG 3'
5' CCUUAAA 3' (Normal) Template Strand
An Okazaki fragment has which of the following arrangements?
5' RNA nucleotides, DNA nucleotides 3'
Of the following, which is the most current description of a gene?
A DNA sequence that is expressed to form a functional product: either RNA or polypeptide
Which of the following cells are very likely to become cancerous?
A cell with a mutation that causes increased expression of a proto-oncogene and mutations in several tumor-suppressor genes that cause decreased expression of those genes.
Which of the following is the most immediate source of energy that drives the formation of all ATP during photosynthesis and almost all of the ATP formed during aerobic respiration?
A difference in the concentration of protons on opposite sides of a membrane
Which of the following is the best definition of a gene that is being "expressed"?
A gene that is producing its final product (protein or non-coding RNA) in a functional form is being expressed.
Which of the following would NOT be considered a gene that is being expressed?
A gene that is producing mRNA, but no protein.
Which of the following mutations would make it impossible for a bacterial cell to metabolize lactose?
A mutation in the promoter for the lac operon such that it can no longer bind RNA polymerase
Which of the following does not occur in prokaryotic gene expression, but does in eukaryotic gene expression?
A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end.
During the electron transport phase of oxidative phosphorylation, most of the energy that is captured for later use is in the form of:
A proton gradient
In cellular respiration, the energy for most ATP synthesis is supplied by
A proton gradient across a membrane.
Which of the following would you expect of a eukaryote lacking telomerase?
A reduction in chromosome length in gametes
Which of the following mutations would be most likely to have a harmful effect on an organism?
A single nucleotide insertion downstream of, and close to, the start of the coding sequence
A particular triplet of bases in the coding strand of a gene is TTT. If an mRNA is made from this gene, the anticodon on the tRNA that will bind the codon on the mRNA is
AAA
What are the products of linear photophosphorylation?
ATP and NADPH
Which of the following are products of the light reactions of photosynthesis that are subsequently utilized in the Calvin cycle?
ATP and NADPH
Which of the following is required for motor proteins to function in chromosome movement?
ATP as an energy source
Besides CO2 and H2O, to produce sugars through the reactions of the Calvin cycle cells also require
ATP as an energy source to "drive" the otherwise endergonic reaction and NADPH as a reducing agent.
The nitrogenous base adenine is found in all members of which group?
ATP, RNA, and DNA
The oxygen consumed during cellular respiration is involved directly in which process or event?
Accepting electrons at the end of the electron transport chain
High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location from the active site. This is an example of
Allosteric regulation.
Translation of mRNA
Almost always begins at an AUG codon, which specifies methionine
A single gene is known to code for three different, but related, proteins. This could be due to which of the following?
Alternative RNA splicing
The enzyme that catalyzes the formation of a covalent bond between a tRNA and a specific amino acid is
An aminoacyl tRNA synthetase
Which of the following might result in a human zygote with 45 chromosomes?
An error in either egg or sperm meiotic anaphase
Cells that have a number of chromosomes different from the normal number for their species are known as _____.
Aneuploid
Which of the following best describes the frequency of crossing over in mammals?
At least 1-2 per chromosome pair
Which of the following statements about repressor proteins is FALSE?
Binding of a corepressor stabilizes repressor proteins in their inactive shape
During the metabolic processes of cell respiration and photosynthesis, the complexes that are components of the electron transport chain
Both oxidize and reduce during electron transport
Synthesis of ATP by the chemiosmotic mechanism occurs during
Both photosynthesis and respiration
Which of the following shows the correct base pairing of deoxyribonucleotides that occurs in nature?
C and G
In the reaction shown below C6H12O6 + 6 O2 → 6 CO2 + energy + 6 H2O
C6H12O6 is oxidized and O2 is reduced
The particular tissue into which any portion of the embryo develops
Can be affected by neighboring cells, which can sometimes induce it to develop a certain way.
In Drosophila melanogaster there is a gene that affects eye color and a second gene that affects wing structure. Homozygous recessive individuals, for eye color and wing structure, have pink eyes and blistery wings. A cross between two true breeding strains (PPBB x ppbb) produces F1 progeny with normal (wild type) eyes and normal (wild type) wings. A cross between F1 individuals produces the following phenotypic frequencies in the F2 generation: 71% Normal (wild type) eyes and normal (wild type) wings 21% Pink eyed with blistery wings 4% Normal (wild type) eyes and blistery wings 4% Pink eyed with normal (wild type) wings In the above situation, the F2 phenotypic frequencies
Can best be explained by linkage and genetic recombination occurring during meiosis I.
During the dark reactions of photosynthesis
Carbon Dioxide is reduced to sugar
Which of the following describe(s) cyclin-dependent kinase (Cdk)?
Cdk is present throughout the cell cycle and is an enzyme that attaches phosphate groups to other proteins.
In the cells of some organisms, mitosis occurs without cytokinesis. This will result in
Cells with more than one nucleus.
Inside an active mitochondrion, most electrons follow which pathway?
Citric acid cycle → NADH → electron transport chain → oxygen
Experiments with cohesins have found that
Cohesins are protected from cleavage at the centromere during meiosis I.
Homologous pairs of chromosomes often _____.
Contain different alleles
Operons
Contain structural genes, promoters and an operator region.
What would occur if the repressor of an inducible operon were mutated so it could not bind the operator?
Continuous transcription of the operon's genes
A mutation that inactivates the function of a repressor protein involved in the regulation of a bacterial operon would result in
Continuous transcription of the structural genes in the operon.
Which of the following is NOT a common mechanism of gene regulation?
Control of gene duplication
A lack of which molecule would result in the cell's inability to "turn off" genes?
Corepressor
When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the direct result is the
Creation of a proton-motive force.
Recombination between linked genes comes about for what reason?
Crossovers between these genes result in chromosomal exchange.
In the G1 phase of the cell cycle, the Cdk protein (cyclin-dependent kinase) has kinase activity after binding to
Cyclin S.
Regulation of the cell cycle occurs at specific checkpoints that are controlled by synthesis and degradation of proteins called
Cyclins
Where does glycolysis take place in eukaryotic cells?
Cytosol
Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?
DNA in both daughter cells would be radioactive.
Which of the following enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of DNA fragments resulting from DNA replication of one of the two DNA strands?
DNA polymerase I
Which enzyme catalyzes the elongation of a DNA strand in the 5' → 3' direction?
DNA polymerase III
Tumor-suppressor genes may encode polypeptides that
Decrease the rate of cell division. Function in cell adhesion. Function in DNA repair.
The elongation of the leading strand during DNA synthesis
Depends on the action of DNA polymerase.
Different genes are expressed in different cells of our bodies because
Different combinations of activators
During translation, tRNAs leave the ribosome from
E Site
A transfer RNA (#1) attached to the amino acid lysine enters the ribosome. The lysine binds to the growing polypeptide on the other tRNA (#2) in the ribosome already. Where does tRNA #2 move to after this bonding of lysine to the polypeptide?
E site
According to the "semi-conservative" model of DNA replication, after a double-stranded DNA molecule is replicated
Each of the two resulting double-stranded DNA molecules will consist of one "daughter" and one "parental" DNA strand
Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy?
Electrons are being moved from atoms that have a lower affinity for electrons (such as C) to atoms with a higher affinity for electrons (such as O).
The typical beginning of the pathway of energy transfer that occurs during photosynthesis is
Energy from a photon of light → a pigment molecule → chlorophyll a → primary electron acceptor
The SIS8 gene is transcribed to form SIS8 mRNAs. The SIS8 mRNAs are then translated to form SIS8 polypeptides. The total number of SIS8 polypeptides present in a cell at a given moment is
Equally dependent on the rate at which the SIS8 polypeptides are made (translated) and the rate at which they are broken down
What does the chemiosmotic process in chloroplasts involve?
Establishment of a proton gradient across the thylakoid membrane
Which of the following types of RNA molecules have polyA tails?
Eukaryotic mRNA molecules
During which portion of the cell cycle does interphase occur?
G1, S, and G2
Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle did the nucleus contain 6 picograms of DNA?
G2
A particular triplet of bases in the template strand of DNA is GGG. The anticodon on the tRNA that binds the mRNA codon is
GGG
Which metabolic pathway is common to both cellular respiration and fermentation?
Glycolisis
Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?
Glycolysis
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the
H+ concentration across the membrane holding ATP synthase.
Which of the following sequences correctly represents the flow of electrons during photosynthesis?
H2O → NADPH → Calvin cycle
The final result of the process of meiosis is the
Halving of the amount of DNA in the cell.
A molecule that is phosphorylated
Has an increased chemical reactivity, it is primed to do cellular work.
A man who can roll his tongue and a woman who cannot roll her tongue have a son who can roll his tongue (R = can roll tongue; r = can't roll tongue). The son is curious about whether his father is homozygous or heterozygous for the tongue-rolling trait. Which of the following facts would allow him to know?
His father's mother cannot roll her tongue.
During certain types of cell division in Drosophila, studies have shown that there is phosphorylation of an amino acid in the tails of histones of gametes. A mutation in flies that interferes with this process results in sterility. Which of the following is the most likely hypothesis?
Histone tail phosphorylation prohibits chromosome condensation.
Which of the following statements about histones is FALSE?
Histones help transport mRNA molecules out of the nucleus
The "universal" genetic code is now known to have exceptions. Evidence for this can be found if which of the following is true?
If UGA, usually a stop codon, is found to code for an amino acid such as tryptophan (usually coded for by UGG only).
How do some scientists feel that telomerase might be used to slow the aging process?
If telomerase activity was increased in our cells, the rate at which our chromosomes shorten as we age might be decreased.
Okazaki fragments result from the
Inability of DNA polymerase to add nucleotides to the 5' end of a polynucleotide.
Transcriptional activators
Increase the affinity of RNA polymerase for the promoter
Increasing the affinity of RNA polymerase for the promoter of a particular gene will
Increase the rate at which that gene is transcribed.
Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its conformation?
Inducer
Which of the following, when taken up by the cell, binds to the repressor protein so that the repressor protein no longer binds to the operator?
Inducer
In an inducible operon, the regulator gene codes for a repressor protein that binds to the operator. When an inducer is present, the
Inducer combines with the repressor thus allowing the operon to be "turned on."
Some cells produce molecules that are transported either to the surface of the cell or are secreted by the cell. When some of these molecules come into contact with neighboring cells, they trigger expression of specific sets of transcriptional activators within those neighboring cells. This process is known as
Induction
Where is ATP synthase located in the mitochondrion?
Inner membrane
Which of the following statements about pre-mRNAs (primary mRNAs) is correct?
Introns are removed from primary mRNAs by splicing Primary mRNAs may contain both exons and introns PolyA tails are added to primary mRNAs
The direct product of the reaction catalyzed by ribulose bisphosphate carboxylase oxygenase, or "Rubisco"
Is not a sugar molecule and must be reduced using electrons from NADPH to form sugar molecules
There is a mutation in the lac repressor gene that results in production of an altered lac repressor protein known as a "super-repressor" because it represses the lac operon permanently. Which of these would characterize such a mutant?
It cannot bind to the inducer.
Which of the following statements about a codon is FALSE?
It extends from one end of a tRNA molecule. (Anticodons found at tRNA ends)
Which of the following is characteristic of the product of the p53 gene?
It is a transcriptional activator for other genes.
Which of the following enzymes covalently connects segments of DNA?
Ligase
The raw materials of the light reactions of photosynthesis are
Light, ADP, NADP+, and water.
Which of the following statements comparing mRNAs produced by prokaryotes versus eukaryotes is TRUE?
Mature prokaryotic mRNAs often code for multiple polypeptides whereas mature eukaryotic mRNAs typically code for only one polypeptide.
Changes in chromatin structure
May be inherited
In eukaryotes, transcriptional activators
May bind specific DNA sequences associated with genes and increase the affinity of RNA polymerase for the promoters for those genes.
A particular micro RNA (miRNA)
May help block translation of specific mRNAs
A particular small interfering RNA (siRNA)
May help target a specific mRNA for degradation
Which of the following is the meaning of the chromosome theory of inheritance as expressed in the early 20th century?
Mendelian genes are at specific loci on the chromosome and in turn segregate during meiosis.
Which of the following statements about the genetic code is TRUE?
Mitochondrial genes use a slightly different genetic code than nuclear genes.
What is meant by the statement that "the genetic code is redundant"?
Most amino acids are specified by more than one codon.
Which of the following statements regarding transcriptional activators is TRUE?
Most genes are regulated by several different transcriptional activators.
During photosynthesis, the carbon in CO2 is reduced, helping to form sugar molecules. Which of the following statements about this process is TRUE?
NADPH is the reducing agent for CO2
The splitting of carbon dioxide to form oxygen gas and carbon compounds occurs during
Neither photosynthesis nor respiration.
In a plant leaf, the reactions that produce NADH (NADH, not NADPH) occur in
Neither the light reactions nor the Calvin cycle.
Two alleles for flower color in snapdragons show incomplete dominance. Plants with pink flowers are the offspring of a cross between plants with white flowers and plants with red flowers. Which of the following crosses would produce a true-breeding line of plants with pink flowers?
No combo will accomplish this
During meiosis, homologous chromosomes sometimes "stick together" and do not separate properly. This phenomenon is known as _____.
Nondisjunction
Oncogenes are
Normal genes that have been transformed into cancer- causing genes.
Absence of bicoid mRNA from a Drosophila egg leads to the absence of anterior (e.g. head) larval body parts and mirror-image duplication of posterior parts. This is evidence that the product of the bicoid gene
Normally leads to formation of head structures
Which of the following is NOT one of the three major cell cycle checkpoints we discussed?
Nuclear envelope has fragmented
If photosynthesizing green algae are provided with CO2 synthesized with heavy oxygen (18O), later analysis will show that all but one of the following compounds produced by the algae contain the 18O label. That one is
O2.
DNA polymerases can add deoxyribonucleotides to
Only the 3' end of an existing nucleotide chain
The absorption spectrum for chlorophyll a and the action spectrum for photosynthesis are not identical to each other. Why are they not identical?
Other pigments absorb light in addition to chlorophyll a.
Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?
Oxidation of pyruvate to acetyl CoA and the citric acid cycle
In mechanism, photophosphorylation is most similar to
Oxidative phosphorylation in cellular respiration.
An important difference between oxidative phosphorylation and photophosphorylation is
Oxidative phosphorylation uses up NADH whereas photophosphorylation generates NADPH Oxidative phosphorylation uses energy from food to form a proton gradient whereas photophosphorylation uses energy from light to form a proton gradient
Most of the ATP produced during aerobic respiration is produced DIRECTLY from
Oxidative phosphorylation.
One function of both alcohol fermentation and lactic acid fermentation is to
Oxidize NADH to NAD+.
When comparing electronegativities,
Oxygen is more electronegative than NADH Oxygen is more electronegative than all of the components of the electron transport chain Oxygen is more electronegative than FADH2
Which of the following statements about the special chlorophyll a molecules that are part of reaction-center complexes is TRUE?
P680+ is part of photosystem II and is such a strong oxidizing agent it can strip an electron from water.
Histones are
Part of nucleosomes
The covalent linkages joining together nucleotides in a DNA molecule are known as
Phosphodiester linkages
Reduction of NADP+ occurs during
Photosynthesis.
Ribosomes are composed of
Polypeptides and RNAs
_____ is usually less severe than _____, and _____ species have been observed in plants, fish, amphibians, and even mammals.
Polyploidy ... aneuploidy ... polyploid
Movement of the chromosomes during anaphase would be most affected by a drug that
Prevents shortening of microtubules.
ATP, GTP, CTP, UTP are substrates for the enzyme
Primase
Which of the following enzymes synthesizes short segments of RNA?
Primase
The nucleotide sequence on a DNA molecule that is involved in the initiation of transcription is called the
Promoter
A mutant bacterial cell has a defective aminoacyl synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of the normal phenylalanine. The consequence of this for the cell will be that
Proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.
Proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells?
Proto-oncogenes normally help regulate cell division.
For a repressible operon to be transcribed, which of the following must occur?
RNA polymerase must bind to the promoter, and the repressor must be inactive.
Which of the following statements best describes the termination of transcription in prokaryotes?
RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.
Which of the following best describes the lac (lactose metabolism) operon in prokaryotes?
RNA polymerases transcribe the operon's three enzymes in the presence of lactose.
Which of the following does NOT occur during mitosis?
Replication of DNA
DNA replication (or chromosome duplication) in eukaryotes takes place during
S of interphase
Successful passage through the M phase checkpoint allows for what to occur?
Separase enzyme cleaves cohesins and allows chromatids to separate.
Transcription in eukaryotes requires which of the following in addition to RNA polymerase?
Several transcription factors (TFs)
"Alternative splicing" refers to
Slightly different sets of exons being present in different mature mRNA molecules made from a single gene.
As electrons are being transported down the electron transport chain from photosystem II to photosystem I
Some of the energy that is released is used to generate a proton gradient
When oxygen is released as a result of photosynthesis, it is a direct by-product of
Splitting water molecules.
Where do the enzymatic reactions of the Calvin cycle take place?
Stroma of the chloroplast
The ATP made during fermentation is generated by which of the following?
Substrate-level phosphorylation
The ATP made during glycolysis is generated by
Substrate-level phosphorylation.
What is the primary function of the Calvin cycle?
Synthesize simple sugars from carbon dioxide
One way scientists hope to use the recent knowledge gained about noncoding RNAs lies with the possibilities for their use in medicine. Of the following scenarios for future research, which would you expect to gain most from noncoding RNAs?
Targeting siRNAs to disable the expression of genes associated with disease
The DNA strand to which ribonucleotides hydrogen bond during transcription is known as the
Template Strand
When scientists analyzed the transcripts produced from a couple of human chromosomes, they found
That about 10x more DNA is transcribed than what would be predicted by the percentage of DNA sequences that code for polypeptides.
A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in which the transgene has integrated into the yeast genome. In four of the lines, the transgene is expressed strongly, but in the fifth there is no expression at all. Which of the following is a likely explanation for the lack of transgene expression in the fifth cell line?
The 5th transgene integrated into a region of the genome where the chromatin is relatively inaccessible.
Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the LEAST serious effect on the polypeptide product?
The WORST mutations that were listed are the insertion of 1, 2 or 4 nucleotides: Answer is 3
A particular cyclin called cyclin E forms a complex with Cdk 2 (cyclin-dependent kinase 2). This complex is important for the progression of the cell from G1 into the S phase of the cell cycle. Which of the following statements is correct?
The amount of free cyclin E is highest during G1.
Which of the following best describes how chromosomes move toward the poles of the spindle during mitosis?
The chromosomes are "reeled in" by the contraction of spindle microtubules, and motor proteins of the kinetochores move the chromosomes along the spindle microtubules.
Which pathways generate reduced electron carriers?
The citric acid cycle and glycolysis
Which statement describes the functioning of photosystem II?
The electron vacancies in P680+ are filled by electrons derived from water.
What is proton-motive force?
The force exerted on a proton by a transmembrane proton concentration gradient
Map units on a linkage map cannot be relied upon to calculate physical distances on a chromosome for which of the following reasons?
The frequency of crossing over varies along the length of the chromosome.
During translation,
The growing polypeptide chain is transferred from the tRNA in the P ribosome site to the amino acid attached to the tRNA in the A ribosome site.
In mitochondria, during chemiosmosis protons move from the intermembrane space to the matrix, whereas in chloroplasts, during chemiosmosis protons move from
The inter-thylakoid space to the stroma.
If a researcher moves the lac operator to a position upstream from the promoter for the lac operon, what would occur?
The lac operon will be expressed continuously.
If an experimenter moves the repressor gene (lac I) for the lac operon, along with its promoter, to a position some several thousand base pairs away from its normal position in the lac operon, which will you expect to occur?
The lac operon will function normally.
The reactions that produce molecular oxygen (O2) take place in
The light reactions alone.
The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that
The nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose.
Which of the following best describes how a micro RNA-protein complex can help cause degradation of an mRNA?
The nucleotides of the micro RNA (miRNA) can base pair with complementary nucleotides on an mRNA. Polypeptide(s) in the micro RNA (miRNA)-protein complex can then degrade the mRNA.
When electrons flow along the electron transport chain in mitochondria, which of the following changes occurs?
The pH of the matrix increases.
The pH of the inner thylakoid space and of the stroma have been measured. Which, if any, relationship would you expect to find?
The pH within the inner thylakoid space is less than that of the stroma.
During translation, after the ribosome breaks the bond between the growing polypeptide chain and the tRNA in the P site and then forms a covalent (peptide) bond between the growing polypeptide chain and the amino acid attached to the tRNA in the A site,
The position of the ribosome on the mRNA shifts and a new, charged tRNA enters the A site of the ribosome
When scientists analyzed the transcripts produced from a couple of human chromosomes, they found that about 10x more DNA is transcribed than what would be predicted by the percentage of DNA sequences that code for polypeptides. This finding may best be explained by
The presence of many transcripts that do not code for polypeptides.
Cell differentiation always involves
The production of tissue-specific proteins, such as muscle actin.
Within a cell, the amount of protein made using a given mature mRNA molecule depends partly on
The rate at which the mRNA is degraded.
Which of the following is an example of post-transcriptional control of gene expression?
The removal of introns and alternative splicing of exons
An experimenter moves the operator for the lactose operon to the far end of the operon (past all of the structural genes in the lactose operon). Which of the following would likely occur when the cell is exposed to lactose?
The structural genes will be transcribed continuously.
Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes?
The synthesis of ATP
During translation, after the ribosome breaks the bond between the growing polypeptide chain and the tRNA in the P site and then forms a covalent (peptide) bond between the growing polypeptide chain and the amino acid attached to the tRNA in the A site,
The tRNA that was in the P site is now in the E site and leaves the ribosome
How would one explain a testcross involving F1 dihybrid flies in which more parental-type offspring than recombinant-type offspring are produced?
The two genes are closely linked on the same chromosome.
BRCA1 and BRCA2 are considered to be tumor-suppressor genes because
Their normal products participate in repair of DNA damage.
When the genome of a particular species is said to include 20,000 protein-coding regions, what does this imply?
There are also genes for RNAs other than mRNA.
Graph with bars
Therefore, sample I represents a newly formed zygote, or somatic cells in G1, G0 or the last part of mitosis. Sample II represents somatic cells in G2 or the earlier part of mitosis. Sample III represents gametes.
Which of the following statements describes proto-oncogenes?
They can code for proteins associated with cell growth and/or division.
Whether during mitosis or meiosis, sister chromatids are held together by proteins referred to as cohesins. Such molecules must have which of the following properties?
They must be removed, at least along the chromosome arms, before anaphase can occur.
In a plant cell, where are the ATP synthase complexes located?
Thylakoid membrane and inner mitochondrial membrane
What is the function of DNA polymerase III?
To add nucleotides to the 3' end of a growing DNA strand
The purpose of fermentation reactions is
To regenerate NAD+ so glycolysis can continue
What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?
Traits are inherited in discrete units, and are not the results of "blending."
Which of the following help form a transcription complex at a promoter?
Transcription factors and RNA polymerase
The tryptophan operon is a repressible operon that is
Turned off whenever tryptophan is added to the growth medium.
A particular triplet of bases in the template strand of DNA is TTT. The anticodon on the tRNA that binds the mRNA codon is
UUU: The template strand of a DNA molecule is the strand that is hydrogen bonded to complementary ribonucleotides during the formation of an RNA molecule. So, the sequence of the RNA molecule will be complementary to the sequence of the DNA template strand. Also, remember that RNA molecules contain U in place of T. So, if the template strand is TTT, the mRNA will have the sequence AAA. The sequence of the anticodon that binds to AAA on the mRNA will thus be UUU.
Protein degradation may be mediated by
Ubiquitin binding a protein and targeting it for degradation by a proteasome.
Which of the following statements about the light reactions of photosynthesis is FALSE?
Upon absorbing the energy from a photon of light, pigment molecules in the light-harvesting complex may transfer an excited electron to a special chlorophyll a molecule in the reaction-center complex (Key word electron not just energy from an electron)
What percentage of living organisms are dependent, directly or indirectly, on food molecules produced via photosynthesis?
Vast majority
A particular triplet of bases in the coding strand of a gene is AAA. If an mRNA is made from this gene, the anticodon on the tRNA that will bind the codon on the mRNA is
What does this all mean? If the coding sequence is AAA, the sequence of the mRNA will also be AAA. The sequence of the anticodon that binds this codon on the mRNA will therefore be UUU.
Which of the following statements about the lac operon is TRUE?
When lac repressor protein binds allolactose, it is stabilized in its inactive shape, allowing transcription of the genes of the lac operon to proceed.
Which of the following statements about the trp operon is TRUE?
When trp repressor protein binds tryptophan, it is stabilized in its active shape, preventing transcription of the genes of the trp operon from occurring.
The transfer of an electron from a P680 chlorophyll a molecule to the primary electron acceptor of photosystem II
Will only occur if the P680 molecule has an electron that is sufficiently excited (i.e. of sufficiently high energy)
Which of the following is most likely to have a small protein called ubiquitin attached to it?
a protein involved in glycine biosynthesis in a cell with lots of glycine
Gene expression in eukaryotes is NOT regulated by
how efficiently trans-inducer molecules are transported to the correct part of the nucleus
Because the frequency of crossing over is not uniform along the length of a chromosome, _____.
map units do not necessarily correlate to physical distances along the chromosome
When comparing oxidative phosphorylation with photophosphorylation, you should notice that
oxidative phosphorylation uses up NADH whereas photophosphorylation generates NADPH
The anticodon sequence is found in
tRNA
The final product of an expressed gene can be which of the following?
tRNA, rRNA or polypeptide
Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." These little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. These inside-out membrane vesicles
will become acidic inside the vesicles when NADH is added.
