BIOL 1009 Midterm 2
Glucose-6-phosphate dehydrogenase deficiency (G6PD) is inherited as a recessive allele of an x-linked gene in humans. A woman whose father suffered from G6PD marries a normal man. -What proportion of their sons is expected to be G6PD? -If the husband was not normal but was G6PD deficient, would you change your previous answer?
-1/2 -no
Which of the following are needed for the initiation of transcription?
-A promoter sequence -RNA polymerase -transcription factors (All of these answers)
Which of the following statements regarding DNA polymerases is TRUE?
-DNA polymerases canNOT initiate synthesis of a new deoxyribonucleotide chain -DNA polymerases can only add nucleotides to the 3' end of a nucleotide chain -DNA polymerases can add nucleotides to the 3' end of an RNA molecule
Which of the following statements about pre-mRNAs (primary mRNAs) is correct?
-Introns are removed from primary mRNAs by splicing -PolyA tails are added to primary mRNAs -Primary mRNAs may contain both exons and introns (ALL THESE ANSWERS)
Which of the following statements is TRUE?
-Many eukaryotic genes have "intervening" sequences, or introns, that do not code for proteins -5' and 3' untranslated regions (UTRs) are parts of eons, but do not code for proteins -Many eukaryotic primary mRNA molecules have "intervening" sequences, or introns, that do not code for proteins (ALL THESE STATEMENTS)
When an electron moves from
-NADH to the first subunit of the electron transport chain, energy is RELEASED that can be used to do work -the first to the second subunit of the electron transport chain, energy is released that can be used to do work -the second to the third dubbing of the ETC, energy is released that can be used to do work (ALL OF THE ABOVE)
Which of the following statements regarding primases is TRUE?
-Primases can initiate synthesis of a new nucleotide chain -Primases add nucleotides to the 3' end of a nucleotide or nucleotide chain -Primases catalyze the formation of an RNA molecule (all of the above)
In a Drosophila experiment, a cross was made between homozygous wild-type females and yellow-bodied males. All of the resulting F1s were phenotypically wild type. However, adult flies of the F2 generation (resulting from matings of the F1s) had the following phenotypes: 123 wild-type males, 116 yellow-bodied males, and 240 wild-type females. Consider the following questions: -Is the mutant allele for yellow body recessive or dominant? -Is the yellow locus autosomal or X-linked?
-Recessive -X-linked
Why are chimpanzees and (most) humans so different?
-The nucleotide sequences of chimpanzee genes are slightly different than the nucleotide sequences of the corresponding human genes -Many genes are expressed at different levels in chimpanzees than in humans -The proteins encoded by chimpanzee genes have slightly different amino acid sequences than the corresponding proteins encoded by human genes (ALL OF THESE)
Transfer RNAs or tRNAs
-are NOT important components of ribosomes -do NOT for 3-dimensional shapes as a result of ionic bonds between different parts of the molecule -are NOT translated to form short polypeptides that are part of the ribosomes (NONE OF THESE ANSWERS IS CORRECT)
Which of the following is very important in regulating gene expression?
-controlling protein stability -controlling the rate at which primary mRNAs are modified -controlling the rate at which mRNAs leave the nucleus
Which of the following statements about how cytoplasmic determinants and induction help control which transcriptional activators are expressed by different cell types is TRUE?
-cytoplasmic determinants are unevenly distributed during cell division, causing the resulting daughter to express different combinations of transcriptional activators -induction causes the cells near the cell producing the inductive agent to express some of the same transcriptional activators -cytoplasmic determinants are unevenly distributed in egg cells (All of these statements are true)
Different cells may have different combinations of transcriptional activators because
-during cell division cytoplasmic determinants may not be evenly distributed to the two daughter cells -cytoplasmic determinants may not be equally distributed within egg cells -some cells may produce chemicals that turn off expression of transcriptional activators in nearby cells
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
When a DNA molecule is replicated,
-replication generally occurs by a "semi-conservative" mechanism -the DNA strands in the original molecule are known as the parental DNA strands -the DNA strands that are made by copying the parental DNA strands are known as the "daughter" strands
In the cross AaBbCc x AaBbCc, what is the probability of producing the genotype AABBCC?
1/64
Suppose two AaBbCc individuals are mated. Assuming that the genes are not linked, what fraction of the offspring are expected to be homozygous recessive for the three traits?
1/64
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%
A homozygous tomato plant with red fruit and yellow flowers was crossed with a homozygous tomato plant with golden fruit and white flowers. The F1 all had red fruit and yellow flowers. The F1 were testcrossed by crossing them to homozygous recessive individuals and the following offspring were obtained: Red fruit and yellow flowers—41 Red fruit and white flowers—7 Golden fruit and yellow flowers—8 Golden fruit and white flowers—44 How many map units separate these genes?
15
How many different amino acids could be specified if codons were two nucleotides in length?
16
A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. How many picograms would be found at the end of S? At the end of G2?
16; 16
How many different amino acids could be specified if codons were four nucleotides in length?
256
If the haploid number of a particular cell is x, the number of possible combinations of maternal and paternal chromosomes in gametes generated by meiosis (NOT accounting for variation due to crossing over) is:
2^x
If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be
2x
Given the locally unwound double strand below, in which direction does the RNA polymerase move? DNA template strand 5' _______ 3' DNA complementary strand 3' _______ 5'
3' --> 5' along the template strand
A possible sequence of nucleotides in the template strand of DNA that would code for the polypeptide sequence phe-leu-ile-val would be [visual missing]
3' AAA-GAA-TAA-CAA 5'
A particular triplet of bases in the template strand of DNA is 5' GGT 3'. The corresponding codon for the mRNA transcribed is
3' CCA 5'
A particular triplet of bases in the template strand of DNA is 5' GGT 3'. The corresponding codon for the mRNA transcribes is
3' CCA 5'
A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3' (mRNA). The anticodon loop of the first tRNA that will complement this mRNA is
3' GGC 5'
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'
A particular triplet of bases in the template strand of DNA is 5' AAT 3'. The corresponding codon for the mRNA transcribed is
3' UUA 5'
Given the parents AABBCc x AabbCc, assume simple dominance for each trait and independent assortment. What proportion of the progeny will be expected to phenotypically resemble the first parent with genotype AABBCc?
3/4
Given the parents AABBCc × AabbCc, assume simple dominance for each trait and independent assortment. What proportion of the progeny will be expected to phenotypically resemble the first parent with genotype AABBCc?
3/4
Phenylketonuria is an inherited disease caused by a recessive autosomal allele. If a woman and her husband are both carriers, what is the probability that their first child will be a phenotypically normal girl?
3/8!!
The diploid number of a roundworm species is 4. Assuming there is no crossover, and random segregation of homologues during meiosis, how many different possible combinations of maternal v. paternal chromosomes might there be in the offspring (NOT including variety generated by crossing over!!!)
4, 16
If a DNA sample were composed of 10% thymine, what would be the percentage of guanine?
40%
Of the following human aneuploidies, which is the one that generally has the most severe impact on the health of the individual?
47, trisomy 21
At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork: 3' C C T A G G C *T* G C A A T C C 5' An RNA primer is formed starting at the *T* of the template. Which of the following represents the primer sequence?
5' A C G U U A G G 3'
What will be the nucleotide sequence of the RNA molecule made from this segment of DNA? 5' AATTCGGG 3'
5' AAUUCGGG 3'
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' AATTCGGG 3'
5' CCCGAAUU 3'
An Okazaki fragment has which of the following arrangements?
5' RNA nucleotides, DNA nucleotides 3'
What would be the sequence of the DNA molecule made by replication of the DNA molecule shown below? 5' GCGAATA 3'
5' TATTCGC 3'
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' ATGCGTA 3'
5' UACGCAU 3'
The figure below represents a tRNA that recognizes and binds a particular amino acid (in this instance, phenylalanine). Which codon on the mRNA strand codes for this amino acid? [Anticodon is 5' GAA 3']
5' UUC 3'
Which of the following statements is TRUE? a. All of these statements are true. Incorrect b. 5' and 3' untranslated regions (UTRs) are parts of exons, but do not code for proteins. c. Many prokaryotic genes have "intervening" sequences, or introns, that do not code for proteins. d. Many prokaryotic primary mRNA molecules have "intervening" sequences, or introns, that do not code for proteins.
5' and 3' untranslated regions (UTRs) are parts of exons, but do not code for proteins
Imagine a species that is usually diploid, with a diploid number of 42 chromosomes per cell. If one cell in an individual of this species becomes triploid, this cell would be expected to have which of the following?
63 chromosomes in 21 sets of 3
The enzyme polynucleotide phosphorylase randomly assembles nucleotides into a polynucleotide polymer. You add polynucleotide phosphorylase to a solution of adenosine triphosphate and guanosine triphosphate. How many different artificial mRNA 3 nucleotide codons could possibly be made?
8
Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?
8%
In an analysis of the nucleotide composition of DNA, which of the following will be found?
A + C = G + T
In humans, ABO blood types refer to glycoproteins in the membranes of red blood cells. There are three alleles for this autosomal gene: IA, IB, and i. The IA allele codes for the A glycoprotein, The IB allele codes for the B glycoprotein, and the i allele doesn't code for any membrane glycoprotein. IA and IB are codominant, and i is recessive to both IA and IB. People with type A blood have the genotypes IAIA or IAi, people with type B blood are IBIB or IBi, people with type AB blood are IAIB, and people with type O blood are ii. If a woman with type AB blood marries a man with type O blood, which of the following blood types could their children possibly have?
A and B
What do we mean when we use the terms "monohybrid cross" and "dihybrid" cross?
A dihybrid cross involves organisms that are heterozygous for two characters that are being studied, and a monohybrid cross involves organisms that are heterozygous for only one character being studied.
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 these mutations would be LEAST likely to cause a cell to become cancerous?
A mutation that prevented the cell from passing through the restriction point in the G1 phase
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
A researcher has used in vitro mutagenesis to mutate a cloned gene and then has reinserted the mutated gene into a cell. To have the mutated sequence disable the function of the gene, what must occur?
A recombination resulting in replacement of the wild type with the mutated gene
During translation (polypeptide elongation), charged tRNAs enter the ribosome at the
A site
A human cell containing 22 autosomes and a Y chromosome is
A sperm
Which portion of the pathway shown in the figure below contains a phosphorylation reaction in which ATP is the phosphate source?
A. Glucose to Frustose-1, 6-biphosphate 2 ATP --> 2 ADP
A particular triplet of bases in the template strand of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is
AAA
Which of the following sequences is most likely to be cut by a restriction enzyme?
AATATT TTATAA
What are the products of linear phosphorylation?
ATP and NADPH
In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of
ATP, CO2, and ethanol (ethyl alcohol)
The nitrogenous base adenine is found in all members of which group?
ATP, RNA, and DNA
Which of the following problems with animal cloning might result in premature death of the clones?
Abnormal gene regulation due to variant methylation
The oxygen consumed during cellular respiration during cellular respiration is involved directly in which process or event?
Accepting electrons at the end of the electron transport chain
Which of the following is an INCORRECT prediction made by the "blending inheritance" hypothesis for how traits are passed from parents to offspring?
After many generations of mating, individuals within a breeding population will all come to have the same trait values because offspring are intermediate to their parents
Tumor-suppressor genes may encode polypeptides that
All of these answers are correct: -function in cell adhesion -function in DNA repair -decrease the rate of cell division
Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. A cross between a true-breeding sharp-spined cactus and a spineless cactus would produce_____.
All sharp-spined progeny!!!
Let us suppose that someone is successful at producing induced pluripotent stem cells (iPS) for replacement of pancreatic insulin-producing cells for people with type 1 diabetes. Which of the following could still be problems? I. the possibility that, once introduced into the patient, the iPS cells produce nonpancreatic cells II. the failure of the iPS cells to take up residence in the pancreas III. the inability of the iPS cells to respond to appropriate regulatory signals
All three
Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. Coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell?
Allolactose binds to the repressor protein
Which of the following are NOT components of a nucleotide?
An "R" group (nitrogenous base, sugar, phosphate group are present)
When the ribosome reaches a stop codon on the mRNA, no corresponding tRNA enters the A site. If the translation reaction were to be experimentally stopped at this point, which of the following would you be able to isolate?
An assembled ribosome with a polypeptide attached to the tRNA in the P site
Which of the following might result in a human zygote with 45 chromosomes?
An error in either egg or sperm meiotic anaphase
Mendel's observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division?
Anaphase I of meiosis
Flies with mutant bicoid genes develop posterior structures at both ends. The bicoid gene product is normally localized to the anterior end of the embryo. If large amounts of the product were injected into the posterior end of a normal (i.e. unmutated) fly embryo, which of the following would occur?
Anterior structures would form in both sides of the embryo
The beginning of anaphase is indicated by which of the following?
Attachments between sister chromatids are cleaved enzymatically
Plasmids are used as vectors in plant and bacterial genetic engineering. However, there is a major difference in the fate of genes introduced into bacteria on most bacterial plasmids and into plants on tumor-inducing (Ti) plasmids. What is this difference?
Bacterial plasmids and the genes they carry usually are NOT integrated into the chromosome; Ti plasmids and the genes they carry are integrated into the chromosome.
Why do our chromosomes become shorter as we age?
Because DNA polymerases can only add nucleotides to an existing nucleotide chain, an RNA primer is used to initiate DNA synthesis. Once that RNA primer is removed from the end of a linear chromosome, there is no mechanism to completely full in the missing nucleotides at the end of a linear chromosome.
Which of the following statements about repressor proteins is FALSE?
Binding of a corepressor stabilizes repressor proteins in their inactive shape
A plant has a unique photosynthetic pigment. The leaves of this plant appear to be reddish yellow. What wavelengths of visible light are being absorbed by this pigment?
Blue and violet
Why is aneuploidy of a sex chromosome less likely to cause serious disorders than aneuploidy of an autosome?
Both because the Y chromosome has only a small number of genes and because extra copies of the X chromosome are inactivated
Which of the following shows the correct base pairing of deoxyribonucleotides that occurs in nature?
C and G A and T
Which of the following statements describes the results of this reaction? C6H1206 + 6 O2 --> 6 CO2 + 6 H2O + Energy
C6H12O6 is OXIDIZED O2 is REDUCED
A particular triplet of bases in the coding strand of a gene is GGG. If an mRNA is made from this gene, the anticodon on the tRNA that will bind the codon on the mRNA is
CCC
The "building blocks" for the production of sugar molecules that occurs during photosynthesis are
CO2 and H2O
Which of the following calculations require that you utilize the addition rule?
Calculate the probability of a child having EITHER sickle-cell anemia OR cystic fibrosis if parents are each heterozygous at both loci
What is the term for metabolic pathways that release stored energy by breaking down complex molecules?
Catabolic pathways
In the cells of some organisms, mitosis occurs without cytokinesis. This will result in
Cells with more than one nucleus
The inheritance of variated color on the leaves of certain plants has been found to be determined only by the maternal parent. What phenomenon most likely explains this pattern?
Chloroplast inheritance
If a horticulturist breeding gardenias succeeds in growing a single plant with a particularly desirable set of traits, which of the following would be her most probable and efficient route to establishing a line of such plants?
Clone the plant
Which of the following statements regarding cytoplasmic determinants is FALSE?
Cytoplasmic determinants are evenly distributed within egg cells prior to fertilization, and then become unevenly distributed immediately after fertilization (NOT)
A biochemist isolates, purifies, and combines in a test tube a variety of molecules needed for DNA replication. When she adds some DNA to the mixture, replication occurs, but each DNA molecule consists of a normal strand paired with numerous segments of DNA a few hundred nucleotides long. What has she probably left out of the mixture?
DNA Ligase
In eukaryotic cells, chromosomes are composed of
DNA and proteins
Which of the following tools of DNA technology is INCORRECTLY paired with its use?
DNA ligase - cutting DNA and creating sticky ends of restriction fragments INCORRECT!!!
Which of the following enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of the DNA fragments resulting from DNA replication of one of the two DNA strands?
DNA polymerase I
What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?
DNA polymerase can join new nucleotides only to the 3' end of a growing strand
A new DNA strand elongates only in the 5' to 3' direction because
DNA polymerase can only add nucleotides to the free 3' end
Why are primases necessary in order for DNA replication to occur?
DNA polymerases can not initiate synthesis of new nucleotide chains
The process by which DNA molecules are copied so that when cells divide each cell can have a complete copy of the DNA is known as
DNA replication
Which of the following correctly shows the flow of information in a cell?
DNA to RNA to protein
A nonreciprocal crossover causes which of the following products?
Deletion and duplication
Why do neural cells have different characteristics than skin cells?
Different genes are expressed in neural cells than in skin cells
Which of the following can occur by the process of meiosis but not mitosis?
Diploid cells form haploid cells
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
Ther 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
When electrons move closer to a more electronegative atom, what happens?
Energy is RELEASED and the more electronegative atom is REDUCED
Hydrangea plants of identical genotypes are planted in a large flower garden. Some of the plants produce blue flowers and others pink flowers. Which of the following is the best explanation for why this might happen?
Environmental factors, such as soil pH, affect the plants' phenotype
Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. The relationship between genes S and Nis an example of _____.
Epistasis
What are the coding segments of a stretch of eukaryotic DNA called?
Exons
Which of the following statements about RNA processing is FALSE?
Exons are cut out before mRNA leaves the nucleus
If meiosis produces haploid cells, how is the diploid number restored for those organisms that spend most of their life cycle in the diploid state?
Fertilization
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
The only cells in the human body not produced by mitosis are
Gametes
One predicted aspect of climate change is that climates, including precipitation and temperature, over most of Earth will become more variable. Which of the following is a good crop genetic engineering strategy if this is true?
Genetically engineer several genotypes within single crop types
Genes located very far apart on the same chromosome may be ____, even though they are _____.
Genetically unlinked; physically linked
Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells?
Golgi-derived vesicles
A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Assuming normal meiosis, which of the following genotypes is possible in a gamete from this organism?
HT
A man who is an achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The man's father was six feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive. What proportion of their SONS would be color-blind and of normal height?
Half
In the thylakoid membranes, what is the main role of the antenna pigment molecules?
Harvest photons and transfer light energy to the reaction-center chlorophyll
Which of the following statements about bacterial repressor proteins is FALSE?
High levels of inducers stabilize repressor proteins in their active state
Which of the following pieces of information could NEVER help you predict a male child's phenotype for an X-linked trait?
His father's phenotype for the trait
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 happens at the conclusion of meiosis I?
Homologous chromosomes of a pair are separated from each other
What kind of chemical bond is found between paired bases of the DNA double helix?
Hydrogen
What type of bonding is responsible for maintaining the shape of a tRNA molecule?
Hydrogen bonding between base pairs
What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium? I. Transform bacteria with a recombinant DNA molecule. II. Cut the plasmid DNA using restriction enzymes (endonucleases). III. Extract plasmid DNA from bacterial cells. IV. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. V. Use ligase to seal plasmid DNA to nonplasmid DNA.
III. Extract plasmid DNA from bacterial cells II. Cut the plasmid DNA using restriction enzymes (endonuclease) IV. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments V. Use ligase to seal plasmid DNA to nonplasmid DNA I. Transform bacteria with a recombinant DNA molecule
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 out chromosomes shorten as we age might be decreased
Which of these statements about cell cycle regulation is FALSE?
If you fuse the cytoplasm of a cell in the M phase with the cytoplasm of a cell in the G1 phase, both cells will return to the G1 phase (FALSE!)
In eukaryotes, genetic information is passed to the next generation by processes that include mitosis or meiosis. Which of the explanations correctly describes one of these processes and supports the claim that heritable information is passed from one generation to another?
In asexual reproduction, a single individual is the sole parent and passes copies of its genes to its offspring without the fusion of gametes
Which of the following provides an example of epistasis?
In rabbits and many other mammals, one genotype (ee) prevents any fur color from developing, regardless of the individual's genotype at other loci affecting fur color
Which of the following is a true statement about sexual versus asexual reproduction
In sexual reproduction, individuals transmit half of their nuclear genes to each of their offspring
Which of the following statements comparing the chain termination method of DNA sequencing and next generation DNA sequencing is TRUE?
In the chain termination method, the order of bases is detected by fluorescently labeling each dideoxynucleotide in a different color, while next generation sequencing determines the order of bases by detecting the release of PPi during the formation of the phosphodiester bond.
Which of the following uses labeled probes to visualize the expression of genes in whole tissues and organisms?
In-Situ hybridization
Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The flower color trait in radishes is an example of which of the following?
Incomplete dominance
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
What is the function of the release factor?
It binds to the stop codon in the A site in place of a tRNA
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
Marfan syndrome in humans is caused by an abnormality of the connective tissue protein fibrillin. Patients are usually very tall and thin, with long spindly fingers, curvature of the spine, sometimes weakened arterial walls, and sometimes ocular problems, such as lens dislocation. Which of the following would you conclude about Marfan syndrome from this information?
It is PLEIOTROPIC
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 statements about the DNA in one of your brain cells is true?
It is the same as the DNA in one of your heart cells
Which of the following statements about the DNA in one of your brain cells is certainly TRUE?
It is the same as the DNA in one of your heart cells?
All female mammals have one active X chromosome per cell instead of two. What is the primary reason this inactivation appears to have evolved?
It prevents females from producing twice as much gene product as males do from genes located on the X chromosome
The final step in a Sanger DNA sequencing reaction is to run the DNA fragments on a gel. What purpose does this serve?
It separates DNA fragments generated during the sequencing reaction based on one-nucleotide differences in their size.
The cyclin component of MPF is destroyed toward the end of which phase?
M
A transcription unity that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of approximately 400 amino acids. This is best explained by the fact that
Many noncoding stretches of nucleotides are present in mRNA
Crossing over normally takes place during which of the following processes?
Meiosis I
What is a major difference between meiosis II and mitosis in a diploid animal?
Meiosis II occurs in a haploid cell, while mitosis occurs in diploid cells
Homologous pairs of chromosomes align opposite of each other at the equator of a cell during
Meiosis metaphase I
Scientists developed a set of guidelines to address the safety of DNA technology. Which of the following is one of the adopted safety measures?
Microorganisms used in recombinant DNA experiments are genetically crippled to ensure that they cannot survive outside of the laboratory.
When multicellular organisms reproduce asexually, the cells of their offspring arise solely through
Mitosis
Sister chromatids separate from each other during
Mitosis and Meiosis II
During aerobic respiration, H2O is formed. Where does the Oxygen atom for the formation of the water come from?
Molecular Oxygen (O2)
Which of the following is generally true of aneuploidies in newborns?
Monosomy X is the only viable monosomy known to occur in humans
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
In addition to ATP, what are the end products of glycolysis?
NADH and pyruvate
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 CO2 to form O2 and carbon compounds occurs during
NEITHER photosynthesis NOR respiration
In a plant leaf, the reactions that produce *NADH* occur in
NEITHER the light reactions NOR the Calvin cycle
In some parts of Africa, the frequency of heterozygosity for the sickle-cell anemia allele is unusually high, presumably because heterozygous individuals are less vulnerable to malaria than either homozygote. This phenomenon is related to which of the following?
Natural selection
A man who is an achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The man's father was six feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive. How many of their DAUGHTERS might be expected to be color-blind dwarfs?
None!
Which process is NOT a substantial contributor to the genetic variation that exists among offspring of the same two parents?
Novel mutations Independent assortment, crossing over, and random fertilization are substantial contributors to genetic variation
Why are there concerns about using increased telomerase activity to slow down the aging process?
One concern is that increasing telomerase activity could increase cancer rates
Duchenne muscular dystrophy is a serious condition caused by a recessive allele of a gene on the human X chromosome. The patients have muscles that weaken over time because they have absent or decreased dystrophin, a muscle protein. They rarely live past their twenties. How likely is it for a woman to have this condition?
One half of the daughters of an affected father and a carrier mother could have this condition
Which of the following statements most accurately describes the components of an operon?
Operons have promoters, which are DNA sequences where RNA polymerase binds; operators, which are DNA sequences where transcriptional repressors bind; and structural genes that typically code for proteins that function together in a particular process
A paleontologist has recovered a bit of tissue from the 400-year-old preserved skin of an extinct dodo (a bird). To compare a specific region of the DNA from the sample with DNA from living birds, which of the following would be most useful for increasing the amount of dodo DNA available for testing?
PCR
Pax-6 is a gene that is involved in eye formation in many invertebrates, such as Drosophila. Pax-6 is also found in vertebrates. A Pax-6 gene from a mouse can be expressed in a fly and the protein (PAX-6) leads to a compound fly eye. This information suggests which of the following?
Pax-6 is highly conserved and shows shared evolutionary ancestry across many species
Which of the following statements best describes the relationship between photosynthesis and respiration?
Photosynthesis stores energy in complex organic molecules, whereas respiration releases it
The primary reason why cytokinesis in plants happens differently from cytokinesis in animals is
Plant cells have cell walls, whereas animals do not
Which of these is NOT an outcome of mitosis?
Production of haploid gametes (NOT)
At which phase of mitosis are centrioles beginning to move apart in animal cells?
Prophase
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
Mendel crossed yellow-seeded and green-seeded pea plants and then allowed the offspring to self-pollinate to produce an F2 generation. The results were as follows: 6022 yellow and 2001 green (8023 total). The allele for green seeds has what relationship to the allele for yellow seeds?
Recessive
Pseudohypertrophic muscular dystrophy is a human disorder that causes gradual deterioration of the muscles. Only boys are affected, and they are always born to phenotypically normal parents. Due to the severity of the disease, the boys die in their teens. Is this disorder likely to be caused by a dominant or recessive allele? Is its inheritance sex-linked or autosomal?
Recessive, sex-linked
Anchorage dependence of animal cells in vitro or in vivo depends on which of the following?
Response of the cell cycle controls to signals from the plasma membrane
When the environment changes rapidly, most adaptations will probably arise through
Sexual reproduction
Genetic variation leads to genetic diversity in populations and is the raw material for evolution. Biological systems have multiple processes, such as reproduction, that affect genetic variation. They are evolutionarily conserved and shared by various organisms. Which statement best represents the connection between reproduction and evolution?
Sexual reproduction increases genetic variation because random mutations can be shuffled between parental and offspring generations.
How is natural selection related to sexual reproduction as opposed to asexual reproduction?
Sexual reproduction results in many new gene combinations, some of which will lead to differential reproduction
Where do the enzymatic reactions of the Calvin cycle take place?
Stroma of the chloroplast
Why do some scientists feel that telomerase might be used to slow the aging process?
Telomere extension in mice and worms has reversed some signs of aging
What information is critical to the success of PCR itself?
The DNA sequence of the ends of the DNA to be amplified must be known
Duplication of a cell's genome occurs during:
The S phase of the cell cycle
Which of the following statements is a correct explanation for the observation that all offspring exhibit a phenotype for a particular trait that appears to be a blend of the two parental varieties?
The alleles passed down by the parents exhibit incomplete dominance
Which pathways generate reduced electron carriers?
The citric acid cycle and glycolysis
Which of the following statements is true of linkage?
The close two genes are on a chromosome, the lower the probability that a crossover will occur between them
A flask containing photosynthetic green algae and a control flask containing water with no algae are both placed under a bank of lights, which are set between 12 hours of light and 12 hours of dark. The dissolved oxygen concentrations in both flasks are monitored. Predict what the relative dissolved oxygen concentrations will be in the flask with algae compared to the control flask.
The dissolved oxygen in the flask with algae will be higher in the light, but lower in the dark.
In comparing DNA replication with transcription, which of the following is true only of DNA replication?
The entire template molecule is represented in the product
What is proton-motive force?
The force exerted in 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
In the late 1950s, Meselson and Stahl grew bacteria in a medium containing "heavy" nitrogen and then transferred them to a medium containing lighter nitrogen. Which of the results in the figure would be expected after one round of DNA replication in the presence of the lighter nitrogen?
The hybrid DNA will be at an intermediate length on the DNA ladder. One strand. (D)
Suppose the interior of the thylakoids of isolated chloroplasts were made acidic and then transferred in the dark to a pH 8 solution. What would be likely to happen?
The isolated chloroplasts will make ATP
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
Which of the following statements about independent assortment and segregation is correct?
The law of independent assortment requires describing two or more genes relative to one another
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-protein complex can then degrade the mRNA
If you fuse the cytoplasm of a cell in the S phase with the cytoplasm of a cell in the G1 phase, what do you expect to happen?
The nucleus of the cell in the G1 phase will enter the S phase and start synthesizing new DNA
What characteristic of short tandem repeats (STRs) makes it useful for DNA fingerprinting?
The number of repeats varies widely from person to person or animal to animal
What does a frequency of recombination of 50% indicate?
The two genes are likely to be located on different chromosomes
In animals, what is the difference between reproductive cloning and therapeutic cloning?
Therapeutic cloning supplies cells for repair of diseased or injured organs
In an experiment, DNA is allowed to replicate in an environment with all necessary enzymes (dATP, dCTP, dGTP, and radioactively labeled dTTP) for several minutes and then switched to nonradioactive medium. It is then viewed by electron microscopy and autoradiography. The figure shown below represents the results. The grains in the figure (shown concentrated on either side of the replication fork) represent radioactive material within the replicating eye. Which of the following is the most likely interpretation?
There are two replication forks going in opposite directions
Which of the following statements describes proto-oncogenes?
They can code for proteins associated with cell growth and/or division
A balanced translocation mutation can still alter an individual's phenotype because
Translocated copies of a gene may be regulated differently than non-mutant copies of that gene
Sex determination in mammals is due to the SRY gene. Which of the following could allow a person with an XX karyotype to develop a male phenotype?
Translocation of SRY to an X chromosome
Somatic cells of roundworms have four individual chromosomes per cell. How many chromosomes would you expect to find in an ovum from a roundworm?
Two
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
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
The first cloned cat, Carbon Copy, was a calico, but she looked significantly different from her female parent because
X inactivation in the embryo is random and produces different patterns
A friend of yours is asked to conduct experiments to determine why a particular polypeptide is present in much higher levels in heart cells than in neural cells. She carefully measures the levels of mature mRNA from the gene that encodes the polypeptide and determines that heart and neural cells contain the same levels of the mature mRNA. She next measures the rate at which the mature mRNA that encodes the polypeptide is translated and finds that rates of translation of that mRNA are the same in heart and neural cells. Your friend now has no idea why the polypeptide is present at higher levels in heart versus neural cells and asks your advice on what to do next. What advice should you give her?
You should remind her that the levels of a polypeptide are determined not only by how frequently the mRNA encoding that polypeptide is translated, but also by the rate at which the polypeptide is degraded. So, she should consider conducting some experiments to determine whether the polypeptide is degraded more rapidly in neural cells than in heart cells.
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 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?
a deletion of three nucleotides
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 MOST serious effect on the polypeptide product?
a deletion of two nucleotides
Normally, only female cats have the tortoiseshell phenotype because
a male inherits only one allele of the X-linked gene controlling hair color
An oncogene is formed by
a mutation in a proto-oncogene that causes increased expression of the proto-oncogene
For a particular microarray assay (DNA chip), cDNA has been made from the mRNAs of a dozen patients' breast tumor biopsies. The researchers will be looking for
a pattern shared among some or all of the samples that indicates gene expression differing from control samples
In the process known as "substrate-level phosphorylation,"
a phosphate group is transferred from a substrate molecule to ADP
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
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
A chromosome is
a single long DNA molecule plus the proteins with which that DNA molecule is complexed
Plants are more readily manipulated by genetic engineering than animals because
a somatic plant cell can often give rise to a complete plant
How can a complex of polypeptides and a micro RNA (miRNA) or a small interfering RNA (siRNA) reduce expression of specific genes?
a. The nucleotides of the siRNA can base pair with complementary nucleotides on the mRNA. Polypeptide(s) in the siRNA-protein complex can then degrade the mRNA molecule. b. The nucleotides of the miRNA can base pair with complementary nucleotides on the mRNA. The miRNA-protein complex can then block translation of the mRNA molecule by ribosomes. Incorrect c. The nucleotides of the miRNA can base pair with complementary nucleotides on the mRNA. Polypeptide(s) in the miRNA-protein complex can then degrade the mRNA molecule. d. All of these answers are correct. <-----
The M-phase-promoting factor MPF promotes mitosis by
activating other proteins involved in mitosis by adding phosphate groups to them
In humans, clear gender differentiation occurs, not at fertilization, but after the second month of gestation. What is the first even of this differentiation?
activation of SRY in male embryos and masculinization of the gonads
If an organism uses the "conservative" model of DNA replication, rather than the normal "semi-conservative" model of DNA replication,
after DNA replication occurs, one of the two double-stranded DNA molecules will consist of two "daughter" DNA strands and the other will consist of two "parental" DNA strands
DNA microarrays have made a huge impact on genomic studies because they
allow the expression of many or even all of the genes in the genome to be compared at once
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 synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of
an endergonic reaction coupled to an exergonic reaction
A mutation that increases the expression of a gene that promotes cell division may cause that gene to become
an oncogene
Yeast cells are frequently used as hosts for cloning because they
are eukaryotic cells
Ribosomal RNAs, or rRNAs
are not translated to form proteins
The formation of Hydrogen bonds between complementary nucleotides is known as
base pairing
During translation, the role of release factors is to
bind the mRNA stop codon in the A site of the ribosome, causing release of the completed polypeptide
Plants photosynthesize only in the light. Plants respire
both in light and dark
Generation of protein gradients across membranes occurs during
both photosynthesis and respiration
Generation of proton gradients across membranes occurs during
both photosynthesis and respiration
Transgenic mice are useful to human researches because they
can be valuable animal models of human disease
Tumor-suppressor genes
can encode proteins that promote DNA repair or cell-cell adhesion
Altering expression of a single transcriptional activator
can have a huge effect on organismal development, even causing one body part to develop in place of another
Homologous chromosomes
carry information for the same traits
Aminoacyl tRNA synthetases
catalyze the formation of a covalent bond between an amino acid and an appropriate tRNA molecule
Epigenetic inheritance includes inheritance of
changes in both DNA and histone modifications
In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. The relationship between the alleles R and r at the phenotypic level can be described as
codominance
The group of three nucleotides that specifies an amino acid is known as a
codon
The "polyA" tail that is added to the 3' end of eukaryotic mRNA molecules
consists of a string of adenosine ribonucleotides
For the duration of meiosis I, each chromosome
consists of two sister chromatids joined by a centromere
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 regulatory (repressor) gene of a repressible operon in an E. coli cell would result in
continuous transcription of the structural gene controlled by that regulator
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
A lack of which molecule would result in the cell's inability to "turn off" genes?
corepressor
Kinetochore microtubules assist in the process of splitting centromeres by
creating tension by pulling toward opposite poles
Certain molecules (polypeptides, mRNAs, and other molecules) become unevenly distributed in egg cells and, consequently, in the two daughter cells formed by division of an egg cell. Some of these molecules then lead to expression of different sets of transcriptional activators in the daughter cells. These molecules are known as
cytoplasmic determinants
The elongation of the leading strand during DNA synthesis
depends on the action of DNA polymerase
The fact that plants can be cloned from many different types of cells demonstrates that
differentiated cells retain all the genes of the zygote
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
During photosynthesis, when a pigment molecule in a light-harvesting complex absorbs a photon of light,
energy from the photon causes an electron to move to a higher energy state
Inheritance of traits not directly involving nucleotide sequences is known as
epigenetic inheritance
Which of the following types of RNA molecules have polyA tails?
eukaryotic mRNA molecules
The transfer of electrons from the primary electron acceptor of photosystem II to the P700+ chlorophyll a molecules of photosystem I is
exergonic, as the P700+ chlorophyll a molecule is more electronegative than the primary electron acceptor
Muscle cells differ from nerve cells mainly because they
express different genes
During aerobic respiration, electrons travel downhill in which sequence?
food to NADH to electron transport chain to oxygen
During the light reactions of photosynthesis, electrons are transferred
from special chlorophyll a molecules to primary electron acceptors
A ____ is a sequence of DNA nucleotides that occurs at a particular ____ on a chromosome
gene; locus
In a nucleosome, the DNA is wrapped around
histones
Gene expression in eukaryotes is NOT regulated by
how efficiently trans-inducer molecules are transported to the correct part of the nucleus
The two strands of a double-stranded DNA molecule are held together by
hydrogen bonds between complementary nitrogenous bases
In a double-stranded DNA molecule, the two DNA strands base pair in such a way that the 5' end of one DNA strand base pairs with the 3' end of the other DNA strand. The two DNA strands are said to be
in an antiparallel arrangement
The reactions of the Calvin cycle can take place
in either the dark or the light
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
An enzyme, ribulose bisphosphate carboxylase oxygenase, or "Rubisco", attaches CO2 to a 5-carbon long sugar to form a 6-carbon long molecule, which
is unstable and splits to form two 3-carbon long molecules
The enzyme (ribulose bisphosphate carboxylase oxygenase, or "Rubisco") that attaches CO2 to a 5-Carbon sugar to form a 6-Carbon long molecule,
is very abundant on earth because it is very slow at its job (3 rxns per second)
The reason for using Taq polymerase for PCR is that
it is heat stable and can withstand the heating step of PCR
What is the role of DNA ligase during DNA replication?
it joins DNA fragments together
A single aminoacyl tRNA synthetase can typically recognize
just one amino acid, but several tRNAs
You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). These two classes of DNA probably represent
leading strands and Okazaki fragments
During the process of photosynthesis,
less than 100% of the energy captured from sunlight is transformed into potential energy in the form of a hydrogen ion gradient and then into potential energy in the form of covalent bonds
Changes in chromatin (the mixture of DNA and proteins) structure
may be inherited
The addition of methyl groups to a gene during genomic imprinting
may either activate or silence the gene
A particular small interfering RNA (siRNA)
may help target a specific mRNA for degradation
A particular micro RNA (miRNA)
may help target a specific mRNA for degradation may help block translation of specific mRNAs
Inheritance patterns cannot always be explained by Mendel's models of inheritance. If a pair of homologous chromosomes fails to separate during meiosis I, select the choice that shows the chromosome number of the four resulting gametes with respect to the normal haploid number, n
n+1, n+1, n-1, n-1
Absence of bicoid mRNA from a Drosophilia 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 head structures
DNA replication begins at special sites on the parental DNA molecule known as
origins of replication
CO2 is released during which of the following stages of cellular respiration?
oxidation and the oxidation of pyruvate to acetyl CoA
It is possible to prepare vesicles from portions of the inner mitochondrial membrane. Which one of the following processes could still be carried on by this isolated inner membrane?
oxidative phosphorylation
In mechanism, photophosphorylation is most similar to
oxidative phosphorylation in cellular respiration
One function of both alcohol fermentation and lactic acid fermentation is to
oxidize NADH to NAD+
When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes
oxidized
Which of the following is NOT a typical modification of a eukaryotic primary (or precursor) mRNA?
phosphorylation
Different alleles of a particular gene usually have slightly different
probabilities of being passed on to offspring
A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3' (mRNA). The charged transfer RNA molecules (with their anticodons shown in the 3' to 5' direction) shown in the table below are available. Two of them can correctly match the mRNA so that a dipeptide can form. The dipeptide that will form will be tRNA Anticodon Amino Acid GGC-----------------Proline CGU-----------------Alanine UGC-----------------Threonine CCG-----------------Glycine ACG-----------------Cysteine CGG-----------------Alanine
proline-threonine
Histones are
proteins around which the DNA in chromosomes wrap
In mitochondria, exergonic redox reactions
provide the energy that establishes the proton gradient
When a molecule of NAD+ gains a hydrogen atom (NOT a proton), the molecule becomes
reduced
Which of the following is required to make complementary DNA (cDNA) from RNA?
reverse transcriptase
A gene that contains introns can be made shorter (but remain functional) for genetic engineering purposes by using
reverse transcriptase to reconstruct the gene from its mRNA
Which of the following describes the sequence of events that occurs during DNA replication of a double-stranded DNA molecule?
separation of the DNA strands at DNA replication origins, unwinding of the DNA double helix, synthesis of RNA primers, synthesis of DNA, ligation of DNA fragments
A laboratory might use dideoxyribonucleotides to
sequence a DNA fragment
The DNA molecule is able to carry a vast amount of hereditary information in which of the following?
sequence of bases
In eukaryotic cells, transcription cannot begin until
several transcription factors have bound to the promoter
Movement of the chromosomes during anaphase would be most affected by a drug that prevents
shortening of microtubules
At the start of binary fission in prokaryotes, the ____ chromosome begins to replicate at the ____.
single, distal end
"Alternative splicing" refers to
slightly different sets of eons being present in different mature mRNA molecules made from a single gene
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
During translation, tRNAs leave the ribosome from
the E site
The three most important cell cycle checkpoints occur during
the G1 phase, the G2 phase, and metaphase of mitosis
If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then
the amino acid acts as a corepressor
If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then
the amino acid acts as a corepressor Remember that corepressors (and inducers) are NOT named because of how they affect the activity of the repressor protein. Instead, they are named because of how they affect the rate of transcription of the genes in the operon(s) they help regulate. Corepressors stabilize the active form of the repressor proteins with which they interact.
In human and many other eukaryotic species' cells, the nuclear membrane has to disappear to permit
the attachment of microtubules to kinetochores
FtsZ is a bacterial cytoskeletal protein that forms a contractile ring involved in bacterial cytokinesis. Its function is analogous to
the cleavage furrow of eukaryotic animal cells
The decline of MPF activity at the end of mitosis is due to
the degradation of cyclin
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
The reactions that produce NADPH occur in
the light reactions alone
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
How do the nucleotides used to make RNA molecules differ from those used to make DNA molecules?
the nucleotides used to make RNA molecules have ribose instead of deoxyribose as their sugar and uracil instead of thymine as one of their nitrogenous bases
When electrons flow along the electron transport chain in mitochondria, which of the following changes occurs?
the pH of the matrix increases
You are studying the polypeptides produced by a particular human gene, and notice that about half of the polypeptides have a molecular mass of 200 kDa and the other half have a molecular mass of 150 kDa. One of your hypotheses for why this gene might produce proteins of different molecular masses might be
the primary transcripts encoded by the gene undergo alternative splicing and the different mature mRNAs that result encode proteins with different numbers of exons and thus different molecular masses
Cell differentiation always involves
the production of tissue-specific proteins, such as muscle actin
To sustain high rates of glycolysis under anaerobic conditions, cells require
the regeneration of NAD+
Which of the following is an example of post-transcriptional control of gene expression?
the removal of introns and alternative splicing of exons
Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the storm. 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
What percentage of living organisms are dependent, directly or indirectly, on food molecules produced via photosynthesis?
the vast majority!
BRCA1 and BRCA2 are considered to be tumor-suppressor genes because
their normal products participate in repair of DNA damage
In a plant cell, where are the ATP synthase complexes located?
thylakoid membrane and inner mitochondrial membrane
RNAi methodology uses double-stranded pieces of RNA to trigger breakdown of a specific mRNA or inhibit its translation. For which of the following might this technique be useful?
to decrease the production from a harmful mutated gene
The purpose of fermentation reactions is
to regenerate NAD+ so glycolysis can continue
In vertebrate animals, brown fat tissue's color is due to abundant blood vessels and capillaries. White fat tissue, on the other hand, is specialized for fat storage and contains relatively few blood vessels or capillaries. Brown fat cells have a specialized protein that dissipates the proton-motive force across the mitochondrial membranes. Which of the following might be the function of the brown fat tissue?
to regulate temperature by converting most of the energy from NADH oxidation to heat
For the DNA molecule shown below, where would the promoter be located? DNA template strand 5'__________3' DNA complementary strand 3'__________5'
to the right of the template strand
The proteins that help RNA bind the DNA at the promoter site are known as
transcription factors
Some genes that encode polypeptides that function in DNA repair are known as
tumor suppressor genes
The tryptophan operon is a repressible operon that is
turned off whenever TRYPTOPHAN is added to the growth medium
Protein degradation may be mediated by
ubiquitin binding a protein and targeting it for degradation by a proteasome
The number of chromosomes in somatic cells
varies among species for reasons not fully understood
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)
If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of a descendent of the same cell at metaphase of meiosis II would be
x
