Biology topic 16/ midterm3
What is the probability that a male will inherit an X-linked recessive allele from his father?
0%
In a particular plant, leaf color is controlled by gene locus D. Plants with at least one allele D have dark green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-breeding dark-leaved plant is crossed with a light-leaved one, and the F1 offspring is allowed to self-pollinate. The predicted outcome of the F2 is diagrammed in the Punnett square shown in the figure below, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square. Which of the plants will be true-breeding?
1 and 4 only
The centimorgan (cM) is a unit named in honor of Thomas Hunt Morgan. To what is it equal?
1% frequency of recombination between two genes
Pea flowers may be purple (P) or white (p). Pea seeds may be round (R) or wrinkled (r). What proportion of the offspring from the cross PpRr x PpRr will have white flowers and wrinkled seeds?
1/16
Michelle and Keith are apparently normal, but their daughter was born with alkaptonuria, an inherited metabolic disorder. If alkaptonuria is like most other human hereditary disorders, the probability of their next child being born with alkaptonuria is _____.
1/4
In the cross AaBbCc × AaBbCc, what is the probability of producing the genotype AABBCC?
1/64
If each parent can produce 100 genetically distinct gametes, how many genetically distinct offspring can two parents produce?
10,000
Cinnabar eyes is a sex-linked recessive characteristic in fruit flies. If a female having cinnabar eyes is crossed with a wild-type male, what percentage of the F1 males will have cinnabar eyes?
100%
The pedigree below is for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. What is the probability that individual III-1 is Ww?
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
In a particular plant, leaf color is controlled by gene locus D. Plants with at least one allele D have dark green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-breeding dark-leaved plant is crossed with a light-leaved one, and the F1 offspring is allowed to self-pollinate. The predicted outcome of the F2 is diagrammed in the Punnett square shown in the figure below, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square. Which of the boxes marked 1-4 correspond to plants with a heterozygous genotype?
2 and 3
A possible sequence of nucleotides in the template strand of DNA that would code for the polypeptide sequence phe-leu-ile-val would be
3' AAA-GAA-TAA-CAA 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'
Drosophila (fruit flies) usually have long wings, but mutations in the BTgene can result in bent wings and mutations in the VG gene can result in vestigial wings. If flies that are heterozygous for both the bent wing gene and the vestigial wing gene are mated, what is the probability of offspring with bent wings only? Note that the mutant alleles of both genes are recessive.
3/16
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. Among the F2 offspring, what is the probability of plants with white axial flowers?
3/16
An individual with the genotype AABbCcDD can make how many different kinds of gametes?
4
If a DNA sample were composed of 10% thymine, what would be the percentage of guanine?
40%
They can transcribe a DNA copy from a RNA template.
40%
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 underlined T (T) of the template. Which of the following represents the primer sequence?
5' A C G U U A G G 3'
What would be the sequence of the DNA molecule made by replication of the DNA molecule shown below?
5' AAGCCTT 3'
What would be the sequence of the DNA molecule made by replication of the DNA molecule shown below? 5' AAGGCTT 3'
5' AAGCCTT 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'
What would be the sequence of the DNA molecule made by replication of the DNA molecule shown below? 5' GCGAATA 3'
5' TATTCGC 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'
What would be the sequence of the DNA molecule made by replication of the DNA molecule shown below? 5' TTCCGGA 3'
5' TCCGGAA 3'
A peptide has the sequence NH2-phe-pro-lys-gly-phe-pro-COOH. Which of the following sequences in the coding strand of the DNA would code for this peptide?
5' TTT-CCC-AAA-GGG-TTT-CCC 3'
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' TTTAAGG 3'
5' UUUAAGG 3'
Hemophilia is a sex-linked disorder. The daughter of a father with hemophilia and a carrier mother has a _____ probability of having hemophilia.
50%
When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype?
50%
In humans, male-pattern baldness is controlled by an autosomal gene (= a gene that is found on a chromosome other than an X or Y chromosome) that occurs in two allelic forms. Allele Hn determines nonbaldness, and allele Hb determines pattern baldness. In males, because of the presence of testosterone, allele Hb is dominant over Hn. If a man and woman both with genotype HnHb have a son, what is the chance that he will eventually be bald?
75%
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
During translation (polypeptide elongation), charged tRNAs enter the ribosome at the
A site
Which of the following shows the correct base pairing of deoxyribonucleotides that occurs in nature?
A with T
A = big apples;R = red apples; a = small apples; r = yellow apples. You have one tree that produces big yellow apples and another tree that produces small red apples. When the two are crossed, you find that half of the new trees produce big red apples and half produce big yellow apples. What are the genotypes of the parents?
AArr and aaRr
In the lysogenic cycle of phages, __________.
All of the listed responses are correct.
The symptoms of a viral infection in a person can be caused by __________.
All of the listed responses are correct.
Viruses are
All of these answers are correct.
When a DNA molecule is replicated,
All of these answers are correct.
Which of the following can protect a bacterium against infection by a bacteriophage?
All of these answers are correct.
Which of the following is true of viral genomes?
All of these answers are correct.
The chromosome theory of inheritance states that _____.
All these answers are correct.
A space probe returns with a culture of a microorganism found on a distant planet. Analysis shows that it is a carbon-based life-form that has DNA. You grow the cells in 15N medium for several generations and then transfer them to 14N medium and grown them for another generation. Which pattern in the figure shown below would you expect if the DNA was replicated in a conservative manner?
B
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 fill in the missing nucleotides at the end of a linear chromosome.
In the late 1950s, Meselson and Stahl grew bacteria in a medium containing "heavy" nitrogen (15N) and then transferred them to a medium containing 14N. Which of the results in the figure shown below would be expected after one round of DNA replication in the presence of 14N?
D
Which component is not directly involved in translation?
DNA
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 statements is TRUE?
DNA is transcribed and RNA is translated
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
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
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.
Which of the following statements regarding DNA polymerases is TRUE?
DNA polymerases can NOT initiate synthesis of a new deoxyribonucleotide chain
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
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
During translation, tRNAs leave the ribosome from
E site
E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two more generations (two rounds of DNA replication). DNA extracted from these cells is centrifuged. Which of the samples shown in the figure below shows the density distribution of DNA you would expect in this experiment?
EThe order in which chromatin packing occurs is as follows:
Queen Victoria was a carrier of a recessive sex-linked allele for hemophilia. Which of the following possibilities could explain the presence of the hemophilia allele in her genotype?
Either her mother was a carrier or her father had hemophilia.
Which of the following shows the correct base pairing of deoxyribonucleotides that occurs in nature?
G & C
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 of the following statements about bacterial repressor proteins is FALSE?
High levels of inducers stabilize repressor proteins in their active state.
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.
Which of the following statements about histones is FALSE?
Histones help transport mRNA molecules out of the nucleus
Will the chromosomes you pass onto your children be shorter than your chromosomes?
Hopefully not, because telomerase will restore the telomeres in your germline cells (the cells that produce egg or sperm cells) to approximately their original length.
What kind of chemical bond is found between paired bases of the DNA double helix?
Hydrogen
Why is it a bad idea to feed leftover scraps of meat, including brain and spinal cord tissue, from butchered cattle to other cattle?
If any of the butchered cattle had mad cow disease, a prion disease, the cattle eating the contaminated feed might become infected with mad cow disease.
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.
What happens to the short RNA "primers" that primase synthesizes and that are extended by DNA polymerase III during DNA replication?
In E. coli, DNA polymerase I removes the RNA primers and fills in the resulting gaps with deoxyribonucleotides
Which of the following statements describes the eukaryotic chromosome?
It consists of a single linear molecule of double-stranded DNA plus proteins.
What is the origin of the phospholipid membrane that envelops many animal viruses?
It is "stolen" from the host cell, but it contains some proteins encoded by the viral genome.
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.
What is the role of DNA ligase during DNA replication?
It joins DNA fragments together.
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.
How are prion diseases transmitted from cell to cell within an infected animal?
Mis-folded copies of the prion protein cause normally folded copies to become mis-folded.
Which of the following statements about the genetic code is TRUE?
Mitochondrial genes use a slightly different genetic code than nuclear genes.
Transfer RNAs, or tRNAs
None of these answers is correct.
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.
Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties?
One phenotype was completely dominant over another.
When a virus infects an E. coli cell, what part of the virus enters the bacterial cytoplasm?
Only the nucleic acid
Which of the following is TRUE of prion diseases?
Prion diseases are always fatal.
Reverse transcription, carried out by retroviruses, is the process by which __________.
RNA information is copied into DNA
Why do RNA viruses appear to have higher rates of mutation?
Replication of their genomes does not involve proofreading.
X-linked genes differ from Y-linked genes in which of the following ways?
Sons and daughters have equal probabilities in inheriting a recessive allele of an X-linked gene from their mother, but only sons can inherit rare Y-linked genetic disorders from their father.
A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have
T4 protein and T4 DNA.
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 is meant by the description "antiparallel" regarding the strands that make up DNA?
The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.
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.
The order in which chromatin packing occurs is as follows:
The DNA wraps around histones, forming nucleosomes; the histones within each nucleosome interact with adjacent nucleosomes and with the DNA between nucleosomes to form a 30-nm fiber; the chromatin forms loops by attaching to scaffold proteins, forming a 300-nm fiber
What is "chromatin"?
The combination of DNA and proteins that forms chromosomes
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 does a frequency of recombination of 50% indicate?
The genes are located on sex chromosomes.
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.
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.
Pea plants are tall if they have the genotype TT or Tt, and they are short if they have genotype tt. A tall plant is mated with a short plant. Which outcome below would indicate that the tall parent plant was heterozygous?
The ratio of tall offspring to short offspring is 1:1.
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.
What does a frequency of recombination of 50% indicate?
The two genes are likely to be located on different chromosomes.
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.
In an experiment, DNA is allowed to replicate in an environment with all necessary enzymes, dATP, dCTP, dGTP, and radioactively labeled dTTP (3H thymidine) 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 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.
How do retroviruses, such as HIV, differ from other viruses?
They can transcribe a DNA copy from a RNA template.
Duchenne muscular dystrophy is caused by a sex-linked recessive allele. Its victims are almost invariably boys, who usually die before the age of 20. Why is this disorder almost never seen in girls?
To express an X-linked recessive allele, a female must have two copies of the allele.
Which of the following shows the correct base pairing of ribonucleotides that occurs in nature?
U with A
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
Viruses are typically not classified as living, primarily because of which of the following?
Viruses do not have independent metabolism.
Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents?
XCXc and XCY
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.
Which of the following will happen to your chromosomes as you become older?
Your chromosomes will become shorter.
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
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
According to the "semi-conservative" model of DNA replication,
after DNA replication occurs, each of the two double-stranded DNA molecules will consist of one "daughter" and one "parental" DNA strand
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
If you cross a plant that is homozygous for the recessive allele of a trait with a plant that is homozygous for the dominant allele of the same trait, the F1 generation will differ from the F2 in that _____.
all of the F1 will show the dominant phenotype, but only three-fourths of the F2 will
Which of the following statements is TRUE? 5' UTRs are part of exons
all of these answers are correct
Which of the following would result in genetic variation by way of new combinations of alleles?
all of these answers are correct
Which of the following statements regarding DNA polymerases is TRUE?
all of these statements are true
Which of the following statements regarding primases is TRUE?
all of these statements are true
Which of the following are NOT components of a nucleotide?
an "R" group
Ribosomal RNAs, or rRNAs
are not translated to form proteins
A virus that infects bacteria is known as a
bacteriophage or phage
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
An individual who is heterozygous at a given genetic locus for a recessively inherited disorder is known as a
carrier
Epigenetic inheritance includes inheritance of
changes in both DNA and histone modifications
The pairs of nucleotides that interact to join together two DNA strands are known as
complementary nucleotides
Homologous pairs of chromosomes often _____.
contain different alleles
Operons
contain structural genes, promoters and an operator region.
The reaction used to join together nucleotides to form a nucleotide chain is known as a
dehydration reaction
The elongation of the leading strand during DNA synthesis
depends on the action of DNA polymerase.
Genotype
describes the genes (or alleles of genes) carried by a particular individual.
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
Inheritance of traits not directly involving nucleotide sequences is known as:
epigenetic inheritance
A "sex-linked" gene is a
gene found on either the X or Y chromosomes
The set of alleles carried by a particular organism are its
genotype
If an organism has two different alleles of a particular gene, the organism is
heterozygous for that gene
In a nucleosome, the DNA is wrapped around
histones.
RNA viruses require their own supply of certain enzymes because
host cells lack enzymes that can replicate the viral genome.
The limited number of species whose cells can be infected by a particular virus are known as the
host range for that virus
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
The two strands of a double-stranded DNA molecule are held together by
hydrogen bonds between complementary nitrogenous bases
If a plant variety is true-breeding for a dominant trait, then _____.
if the plant were allowed to self-pollinate, all of the progeny would have the dominant trait
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
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 part of the radish we eat may be oval or long, with long being the dominant characteristic. The flower color trait in radishes is an example of which of the following?
incomplete dominance
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.
Which of the following enzymes covalently connects segments of DNA?
ligase
A phage that inserts itself into the host DNA is called __________.
lysogenic
The phage reproductive cycle that kills the bacterial host cell is a __________ cycle, and a phage that always reproduces this way is a __________ phage.
lytic; virulent
Males are more often affected by sex-linked traits than females because
males only have one copy of the X chromosome.
A transcription unit 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.
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
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.
Aminoacyl tRNA synthetases
modification of the XIST gene so that it is active only on one X chromosome, which then becomes inactive
When new viruses are being assembled, what mediates the assembly?
nothing; they self-assemble
Which of the following represents the order of increasingly higher levels of organization of chromatin?
nucleosome, 30-nm chromatin fiber, looped domain
DNA polymerases can add deoxyribonucleotides to
only the 3' end of an existing nucleotide chain
A linkage map _____.
orders genes on a chromosome based on recombination frequencies
DNA replication begins are special sites on the parental DNA molecule known as
origins of replication
Histones are
part of nucleosomes
In considering the differences between lytic and lysogenic cycles of bacteriophages, which of the following is uniquely characteristic of the lytic cycle?
phage self-assembly
The observable physical and physiological traits of an organism, which are determined by its genetic makeup, are its
phenotype
The covalent linkages joining together nucleotides in a DNA molecule are known as
phosphodiester linkages
Which of the following enzymes initiates the synthesis of a new nucleotide chain during DNA replication?
primase
Which of the following enzymes synthesizes short segments of RNA?
primase
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
proline-threonine.
The "CRISPR-cas system" can
protect bacteria against infection by bacteriophages
Which of the following does NOT constitute any known type of virus particle?
protein plus lipid envelope
Histones are
proteins around which the DNA in chromosomes wrap
A viral genome that is permanently inserted into a host genome is known as a
provirus
An allele whose phenotypic effect is not observed in a heterozygote is a
recessive allele
Which viruses have single-stranded RNA that acts as a template for DNA synthesis?
retroviruses
An enzyme encoded by certain viruses (retroviruses) that uses RNA as a template for DNA synthesis is known as a
reverse transcriptase
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
The DNA molecule is able to carry a vast amount of hereditary information in which of the following?
sequence of bases
The final product of an expressed gene can be which of the following?
tRNA, rRNA or polypeptide
The ends of linear chromosomes are known as
telomeres
The DNA strand to which ribonucleotides hydrogen bond during transcription is known as the
template strand
The sequence of an RNA molecule will be complementary to the sequence of the
template strand from which that RNA molecule was made
Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. What does this suggest?
that the parents were both heterozygous for a single trait
Which of the following can protect a bacterium against infection by a bacteriophage?
the CRISPR-Cas system
Which of the following is a property of life shared by prokaryotic cells and eukaryotic cells, but not viruses?
the ability to process energy through metabolic reactions
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.
Telomeres are
the ends of linear chromosomes
The leading and the lagging strands differ in that
the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction
Wild type refers to _____.
the most common phenotype thought to be found in the natural population
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
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
Which of the following is an example of post-transcriptional control of gene expression?
the removal of introns and alternative splicing of exons
What is the function of DNA polymerase III?
to add nucleotides to the 3' end of a growing DNA strand
The proteins that help RNA polymerase bind the DNA at the promoter site are known as
transcription factors
The tryptophan operon is a repressible operon that is
turned off whenever tryptophan is added to the growth medium.
A prophage is a(n) __________.
viral genome that has been incorporated into a bacterial cell's chromosome
An infectious particle incapable of replicating outside of a cell, consisting of an RNA or DNA genome surrounded by a protein coat (capsid) is a
virus
Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of crosses BbTt× BBtt will be expected to have black fur and long tails?
½
