Biol 1001 Ch 9-13 Review
Humans have thousands of genes. How many alleles of each gene are present in your muscle cells, disregarding genes on the X and Y chromosomes? These alleles can be the same or different. one two 23 46
2 (b/c you inherited two alleles of each gene, one from your mother and one from your father)
Imagine that you are studying a newly discovered bacterium from a hot springs in Yellowstone National Park. When you examine the nucleotide composition of this organism, you find that 10% of the nucleotides in its DNA are adenine (A). What percentage of nucleotides are guanine? Explain. 10%, because A pairs with G 90%, because 100% minus 10% equals 90% 40%, because A pairs with T (accounting for 20% of the bases), leaving 80% of the nucleotides as G-C base pairs; half of 80% is 40% 80%, because 100% minus 20% equals 80%
40%, because A pairs with T (accounting for 20% of the bases), leaving 80% of the nucleotides as G-C base pairs; half of 80% is 40%
When Mendel crossbred plants that differed in two traits, he found that the phenotypic ratio was _____.
9:3:3:1 (Mendel's observation led to the law of independent assortment)
Anne Boleyn, King Henry VIII's second wife, was beheaded because she did not provide him with a son as an heir. Explain why King Henry should have blamed himself and not his wife.
All of the eggs that females produce contain an X chromosome, so their genetic contribution to the child does not determine its sex.
What are alleles?
Alleles are variations of the same gene—not exactly the same, but similar enough to be recognized as the same gene. (i.e., similar nucleotide sequences on homologous chromosomes)
What does Mendel's law of independent assortment tell us about the behavior of genes during meiosis?
Alleles of a particular gene will be distributed to gametes randomly, independent of other genes on different chromosomes.
Identify the research that first provided the basis for the following statement: DNA is the genetic material. Watson and Crick proposed a new model for DNA structure. Avery, MacLeod, and McCarty isolated the material that transformed R-strain bacteria into S-strain bacteria. Chargaff found that DNA contains equal amounts of adenine and thymine, as well as equal amounts of cytosine and guanine. Wilkins and Franklin used X-ray diffraction to study DNA structure.
Avery, MacLeod, and McCarty isolated the material that transformed R-strain bacteria into S-strain bacteria.
Which of the following is the first step in translation? Bases of the tRNA anticodon bind with the bases of the mRNA codon. A peptide bond forms between amino acids attached to the adjacent tRNAs on the ribosome. The ribosomal subunits are disassembled. Stop codons on the mRNA bind to special proteins rather than to tRNA molecules.
Bases of the tRNA anticodon bind with the bases of the mRNA codon.
Which of the following statements is false? DNA replication involves uncoiling of the parental DNA molecule. DNA replication produces a long, continuous strand and a series of short pieces. DNA ligase is required in the synthesis of one strand. Both parental strands end up in the same daughter strand after replication. DNA polymerase adds complementary nucleotides into the newly synthesized strand.
Both parental strands end up in the same daughter strand after replication. (this is a false statement b/c each daughter strand receives one of the original parental strands)
If you were to create a drug that recognized and bound irreversibly to the promoter region of a specific gene, thereby blocking it, what effect would you expect that drug to have? There would be no effect on the gene. Only transcription of that gene would halt. Only translation of the gene would halt. Both transcription and, eventually, translation of the gene would halt. Only replication of that specific gene would come to a halt. Both replication and translation of that specific gene would halt.
Both transcription and, eventually, translation of the gene would halt.
At the end of the mitotic (M) phase, the cytoplasm divides in a process called _________________.
Cytokinesis (the division of the cytoplasm that occurs in conjunction with telophase, the last phase in mitosis)
Which of the following events occurs within a DNA replication bubble? DNA polymerase helps to break hydrogen bonds between complementary base pairs. DNA helicase attaches the phosphate of a free nucleotide to the sugar of the previous nucleotide in the daughter strand. DNA helicase unwinds the double helix at each replication fork within a replication bubble. DNA ligase unwinds the double helix at each replication fork within a replication bubble.
DNA helicase unwinds the double helix at each replication fork within a replication bubble.
Before it was actually determined, many scientists had trouble believing that DNA was the genetic material. This is most likely because __________. it was known that proteins could be passed from generation to generation DNA is made up entirely by four nucleotides, a very small number destruction of proteins prevented genetic transformation it was known that RNA could be passed from generation to generation
DNA is made up entirely by four nucleotides, a very small number
Gene expression can not be regulated in eukaryotic cells by controlling the rate of _____. transcription translation DNA replication enzyme activity
DNA replication (b/c the rate of DNA replication determines how frequently a cell will divide, but it is not a mechanism cells use to regulate gene expression)
Which of the following is caused by an abnormal number of autosomes? Down syndrome Klinefelter syndrome Turner syndrome Marfan syndrome
Down syndrome
Which of the following lists the correct order of events in DNA replication? Enzymes unwind the DNA double helix; DNA polymerase makes two new DNA strands complementary to the old ones; the two DNA molecules wind up into a double helix with one new strand and one old strand. Two DNA molecules wind up into a double helix with one new strand and one old strand; DNA polymerase makes two new DNA strands complementary to the old ones; enzymes unwind the DNA double helix. DNA polymerase makes the new DNA strands complementary to the old ones; enzymes unwind the DNA double helix; the two DNA molecules wind up into a double helix with one new strand and one old strand. Enzymes unwind the DNA double helix; the two DNA molecules wind up into a double helix with one new strand and one old strand; DNA polymerase makes two new DNA strands complementary to the old ones.
Enzymes unwind the DNA double helix; DNA polymerase makes two new DNA strands complementary to the old ones; the two DNA molecules wind up into a double helix with one new strand and one old strand. (basically the original helix unwinds, two new strands are made, and two helices are produced)
Color blindness is a sex-linked recessive trait. A color-blind man marries a woman with normal vision whose father was color-blind. Which of the following statements is true about this situation? All of the male offspring will be color-blind. Half of the daughters will be color-blind. All of the male offspring will have normal vision. All of the children will be color-blind. All of the children will have normal vision.
Half of the daughters will be color-blind.
A couple brings home their new, nonidentical twin daughters, Joan and Jill. After several months, the father begins to suspect that there was a mix-up at the hospital, because Jill doesn't look much like either parent or like her sister. When the twins' blood tests come back, the father calls his lawyer to start a lawsuit against the hospital. The mother, father, and Joan have type A blood, but Jill has type O blood. Based on blood type, does the father have a case? Explain your answer. (The gene for blood type has three alleles: A, B, and O. The A and B alleles are codominant, and the O allele is recessive.) No, because parents with type A blood can have a child with type O blood. No, because parents with any blood type (A, B, AB, or O) can produce children with type O blood. Yes, because all of this couple's children will have type A blood. Yes, because only people with type O blood can have children with type O blood.
No, because parents with type A blood can have a child with type O blood.
Which of the following is an accurate statement concerning the differences between DNA and RNA? RNA is usually double-stranded, but DNA is usually single-stranded. RNA has the sugar deoxyribose, but DNA has the sugar ribose. RNA contains three different nucleotides, but DNA contains four different nucleotides. RNA lacks the base thymine (which is found in DNA), and DNA lacks the base uracil (which is found in RNA).
RNA lacks the base thymine (which is found in DNA), and DNA lacks the base uracil (which is found in RNA).
What would be an advantage of sexual reproduction?
Sexual reproduction promotes genetic variability, thereby increasing the probability that an individual with new combinations of favorable traits may arise.
Consider the backbone of the DNA double helix. Which statement is not true? The DNA backbone is composed of alternating sugar and phosphate groups. The backbone is not straight, but twisted. The DNA backbone forms the central core of the DNA molecule. The two backbones run in opposite directions.
The DNA backbone forms the central core of the DNA molecule. (b/c the sugar-phosphate backbones are on the outside of the DNA molecule)
what happens if a baby has only one X chromosome, and no Y?
The baby would be a female with Turner syndrome.
What must happen before a cell can begin mitosis?
The chromosomes must be duplicated. (b/c before mitosis can begin, the chromosomes, or genetic material, must be copied, which occurs during interphase. The nuclear envelope doesn't break up until mitosis is already underway)
Which of the following can account for a situation where Mendel's law of independent assortment fails to hold? The genes are close to each other on the same chromosome. pleiotropy self-fertilization The genes have undergone recombination. crossing over
The genes are close to each other on the same chromosome.
Some people are said to be "carriers" of genetic disorders. What does this mean?
The individual is heterozygous for the disorder, and the allele for the disorder is recessive.
In the results of a cross between plants heterozygous for two traits, an individual displays the recessive form for both traits. Which of the following statements describing the individual is true? This overall phenotype is the most abundant among the offspring. The individual must be heterozygous for both genes involved. The individual must be homozygous recessive for at least one of the two genes involved. The individual must have two recessive alleles for each of the genes in question. This individual will be weaker than the individual showing the dominant form for both traits.
The individual must have two recessive alleles for each of the genes in question. (b/c to display the recessive phenotype, the individual must be homozygous recessive. To display the recessive phenotype for two traits, it must be homozygous recessive for both genes)
Which of the following is true of a man with hemophilia? The man inherited the hemophilia gene from his mother. The man inherited the hemophilia gene from his father. The man could have inherited the hemophilia gene from either his mother or his father. The man has a dominant version of the gene.
The man inherited the hemophilia gene from his mother. (b/c the hemophilia gene is carried on the X chromosome, which all men inherit from their mothers)
What determines which of the two DNA strands will serve as the template? Only one of the strands can be transcribed at each gene. This is determined by the sequence of the bases in the RNA after transcription. The RNA polymerase can transcribe only one strand of the DNA. The entire other strand is unreadable. Only one strand will unwind. The orientation of the promoter and other regulatory sequences determines which strand is copied.
The orientation of the promoter and other regulatory sequences determines which strand is copied.
How can a cell, killed by heat in order to render it harmless, somehow still act to transform a second strain of bacteria from a noninfectious form into a disease carrier (i.e., a pathogen)? The second (noninfectious) strain of bacteria was changed into a disease carrier (i.e., pathogen) by something from the heat-killed cell. The heat-killed cell wasn't really dead. The second (noninfectious) strain spontaneously mutated into a deadly pathogen. The heat-killed cell is able to take in a key component from the living noninfectious strain.
The second (noninfectious) strain of bacteria was changed into a disease carrier (i.e., pathogen) by something from the heat-killed cell. (b/c even though cells of the heat-killed strain were dead, not everything was destroyed by the heat. Later, it was found that this still-viable substance was DNA)
Which one of the following statements is true of the sugar-phosphate backbone of DNA? The two sugar-phosphate strands are oriented in the same direction. The two sugar-phosphate strands are oriented in opposite directions from each other. The two sugar-phosphate strands can be oriented in either the same or the opposite direction. The sugar-phosphate backbone is in the center of the DNA molecule.
The two sugar-phosphate strands are oriented in opposite directions from each other.
When Mendel conducted his experiments with purple- and white-flowered pea plants, he found that the F1 generation did not contain any white-flowered plants. In the F2 generation, the white-flowered plants were seen. IS the white flower recessive or dominant to the purple flower allele?
The white-flower allele is recessive to the purple-flower allele. (b/c the entire F1 generation consists of heterozygous plants, all will be purple. In the F2 generation, the population will be a mix of homozygous purple, homozygous white, and heterozygous plants. The homozygous white will have white flowers.)
What is the relationship between codons and amino acids? Every amino acid has one unique codon. All codons code for amino acids. There are more amino acids than codons. There are more codons than amino acids.
There are more codons than amino acids. (b/c there are 64 codons, 61 of which code for the 20 amino acids)
Which of the following options would result from the actions of DNA polymerase during DNA replication? Two DNA polymerase molecules act to synthesize a long continuous daughter DNA strand from each parental strand; ligase is not needed. Two DNA polymerase molecules act to synthesize a short segment of daughter DNA from each parental strand; ligase is used to connect these short segments of both daughter strands. Two DNA polymerase molecules act to synthesize daughter DNA strands, one via a long continuous strand and a second via short segments of DNA that must be joined by ligase. Two DNA polymerase molecules act to synthesize daughter DNA strands, one via a long continuous strand and a second via short segments of DNA that must be joined by helicase.
Two DNA polymerase molecules act to synthesize daughter DNA strands, one via a long continuous strand and a second via short segments of DNA that must be joined by ligase.
Imagine that a codon in the template strand of a gene has the sequence TAC. What sequence of the anticodon would decode this codon? Explain your answer. ATG, because the anticodon is complementary to the template strand AUG, because the anticodon is complementary to the template strand UAC, because the anticodon has the same sequence as the template strand (but it has U instead of T) TAC, because the anticodon has the same sequence as the template strand
UAC, because the anticodon has the same sequence as the template strand (but it has U instead of T)
In a pedigree the symbol of a square that is colored in represents _____.
a male with the trait
The structure of DNA explained Chargaff's observations because ___________. the DNA molecule is a regular, repeating molecule the twisting of the DNA required certain amounts of bases adenines were found to pair with thymines and cytosines with guanines the sequence of bases is crucial to the storage of information there are only four different bases
adenines were found to pair with thymines and cytosines with guanines
Color blindness is a sex-linked recessive trait. A color-blind woman will pass the gene for color blindness on to __________.
all her children (b/c a color-blind mother has the genotype XcXc so she will pass the sex-linked recessive gene on to both her sons and her daughters)
Multiple replication bubbles on a single eukaryotic chromosome __________. allow for rapid replication of eukaryotic DNA do not occur lead to many DNA strands being synthesized from the same chromosome simultaneously occur to ensure that the DNA is replicated faithfully
allow for rapid replication of eukaryotic DNA (b/c eukaryotic chromosomes are so large, replication must take place at multiple sites on the chromosome to speed the process)
The sister chromatids separate and begin moving toward opposite poles of the cell during which phase of mitosis?
anaphase (third phase, sister chromatids separate and start their migration toward opposite poles during anaphase)
What is a clone?
any cell or organism that is genetically identical to another (b/c there are no exact duplicates of any organism. Even organisms that are genetically identical are not exact duplicates)
The two strands of DNA that make up a double helix _____. are identical to each other are held together by covalent bonds are oriented in the same direction are complementary to each other
are complementary to each other
The correct nucleotides to be added to the new DNA strand are determined by __________. DNA ligase base pairing between the free nucleotides and bases on the template strand DNA helicase base pairing between the free nucleotides and bases on the new DNA strand
base pairing between the free nucleotides and bases on the template strand
The next base to be added to the RNA strand is determined by __________. the previous base the order of the backbone in the RNA base pairing between the two DNA strands base pairing between the template strand and the RNA nucleotides
base pairing between the template strand and the RNA nucleotides (b/c base pairing is responsible for determining the sequence of the RNA)
The type of cell division carried out by prokaryotic cells is known as _____.
binary fission
If the inheritance pattern in a pedigree is due to an autosomal recessive gene, the genotype of which individual(s) would be aa? a male showing the trait a female showing the trait both the males and females showing the trait a female not showing the trait a male not showing the trait
both the males and females showing the trait
After translation is completed, the ribosome __________. stays intact and finds another AUG codon to begin translation moves back to the first AUG codon of the mRNA to begin again joins with other ribosomes to continue translation breaks into small and large ribosomal subunits will remain bound to the mRNA
breaks into small and large ribosomal subunits
DNA polymerase __________. can replicate both strands of DNA in a continuous manner can add nucleotides only to the free sugar end of a DNA molecule can bond short stretches of DNA together can move toward the other molecule of DNA polymerase in a replication bubble
can add nucleotides only to the free sugar end of a DNA molecule
The capacity for forming the peptide bond between two amino acids resides in the __________. catalytic site of the large subunit tRNA proteins involved in termination of translation amino acids themselves
catalytic site of the large subunit
Replication bubbles __________. consist of one moving replication fork and one fixed replication fork are always shrinking in size are present only once per chromosome consist of two replication forks moving in opposite directions
consist of two replication forks moving in opposite directions (...so that way each bubble will increase in size)
The sugars and phosphates in the "backbone" of a DNA strand are held together by _____. covalent bonds hydrogen bonds ionic bonds peptide bonds
covalent bonds (b/c the DNA backbone is held together by strong covalent bonds in which the phosphorus of the phosphate group and the oxygen of the sugar share electrons)
DNA ligase has all of the functions listed below except __________. repair of damaged DNA piecing together of small pieces of DNA during replication covalently bonding DNA strands made by adjoining replication forks covalently bonding small DNA pieces together during the synthesis of both strands of a double helix
covalently bonding small DNA pieces together during the synthesis of both strands of a double helix
Mendel was able to determine the dominant and recessive forms of seven traits in pea plants by __________. crossing plants that differed in two traits looking at the offspring resulting from self-fertilization of true-breeding plants simple examination of the plants expanding his research to include other plants doing several crosses using plants that differed in one trait
doing several crosses using plants that differed in one trait
Mendel's law of segregation concludes that __________. all the gametes formed by an organism will have the same allele each individual has two alleles for a particular gene genes are found at the same loci on homologous chromosomes dominant alleles may mask the expression of recessive alleles each gamete will contain only one allele from the parent's pair
each gamete will contain only one allele from the parent's pair
DNA replication is a semiconservative process because __________. each of the resulting DNA double helices will consist of one newly synthesized strand and one parental strand the resulting DNA molecules will consist of one with two newly synthesized strands, and the other containing the original parental strands the nucleotides from other nucleic acids are constantly being recycled to make new nucleic acids each resulting DNA molecule will contain short stretches of newly synthesized DNA interspersed with the original parental DNA
each of the resulting DNA double helices will consist of one newly synthesized strand and one parental strand (each of the parental strands will serve as a template for making a complementary strand. These will stay together to form a helix)
An interpretation of Griffith's experiments is that __________. fragments of DNA containing genes were taken up by the R-strain bacteria genetic material must have been transferred from the R-strain bacteria into the S-strain bacteria the genetic material must be protein base pairing accounts for the amounts of each base found
fragments of DNA containing genes were taken up by the R-strain bacteria
Which organism(s) spend(s) most of its/their life cycle in the haploid state?
fungi and unicellular algae
In peas, plants that are true-breeding for a particular trait must be __________ for that trait. heterozygous diploids homozygous either homozygous or heterozygous
homozygous (b/c in order for plants to be true-breeding, alleles for a particular trait must be identical)
In pea plants, tall plants are dominant over dwarf plants. A tall plant could be __________. heterozygous homozygous recessive homozygous dominant homozygous dominant or heterozygous homozygous recessive or heterozygous
homozygous dominant or heterozygous
In pea plants, yellow pods are recessive to green pods. If you see yellow pods, then the genotype of that plant must be __________ for pod color. heterozygous homozygous recessive homozygous dominant heterozygous or homozygous recessive heterozygous or homozygous dominant
homozygous recessive (b/c the only time that you see the recessive phenotype is from the homozygous recessive genotype. If an organism expresses at least one allele for the dominant trait, then the dominant trait will be expressed)
The two strands of a DNA double helix are held together by __________. covalent bonds between the sugars of one nucleotide and the phosphates of the adjacent nucleotide hydrogen bonds between bases on opposite DNA strands ionic bonds between the two DNA strands peptide bonds between the two DNA strands
hydrogen bonds between bases on opposite DNA strands
What does mRNA carry from the nucleus? ribosomes information amino acids tRNA
information
The longest phase of the eukaryotic cell cycle is _____.
interphase
After an RNA polymerase has completed transcription, the enzyme __________. is degraded joins with another RNA polymerase to carry on transcription begins transcribing the next gene on the chromosome is free to bind to another promoter and begin transcription will remain bound to the RNA
is free to bind to another promoter and begin transcription
All of the following are steps in transcription except __________. termination elongation initiation recognition of the promoter by RNA polymerase joining of short fragments of RNA by ligase
joining of short fragments of RNA by ligase
The information to synthesize proteins is carried to the ribosome by _____. tRNA mRNA rRNA template DNA double-stranded DNA
mRNA
The chromosomes line up in the center of the cell during which phase of mitosis?
metaphase (second phase, occurs in the middle of mitosis, when the chromosomes line up in the middle of the cell.)
Genetic recombination (crossing over) produces __________.
new combinations of alleles
If a gene has alleles that are incompletely dominant, an individual that is heterozygous at this locus will express a phenotype that is _________. the same as organisms that are homozygous for the recessive allele the same as organisms that are homozygous for the dominant allele intermediate between organisms that are homozygous for the recessive allele and organisms that are homozygous for the dominant allele either the same as organisms that are homozygous for the dominant allele or homozygous for the recessive allele, depending on the environment
ntermediate between organisms that are homozygous for the recessive allele and organisms that are homozygous for the dominant allele (EX: Snapdragons that are heterozygous for flower color, an incompletely dominant trait, will be pink, which is intermediate between the incompletely dominant red and recessive white phenotypes)
Meiosis comes from a Greek word that means "to decrease." What decreases during the process of meiosis?
number of chromosomes
What is the approximate error rate for DNA polymerase? one error for every 100 bases added one error for every 10,000 bases added one error for every billion bases added one error for every 1,000 bases added
one error for every 10,000 bases added
What is the approximate error rate for ALLLL of DNA replication? one error for every 1,000 nucleotides one error for every million nucleotides one error for every billion nucleotides one error for every 100 nucleotides
one error for every billion nucleotides
Information in DNA is carried in the__________. sugar-phosphate backbone of one DNA strand base pairs between nucleotides in the two DNA strands proteins that bind to the DNA double helix order of the nucleotide bases in one DNA strand
order of the nucleotide bases in one DNA strand (b/c the order of nucleotides in a gene corresponds to the order of amino acids in the protein it encodes. Note that each gene has two DNA strands, but only one strand is transcribed. (The non-transcribed strand is needed when DNA is replicated.))
The information to synthesize all of the following except _____ is directly coded by the DNA. organelles messenger RNA proteins ribosomal RNA transfer RNA
organelles
The appearance of an organism that results from its particular complement of genes is called its _____.
phenotype
A single gene capable of influencing multiple phenotypes within a single organism is said to be __________.
pleiotropic for that gene
During DNA replication, a mistake was made in which an A was changed to a G. This kind of mutation is called a(n) _____. point mutation insertion mutation deletion mutation neutral mutation
point mutation
Skin color in humans is determined by at least three genes, each with a pair of incompletely dominant alleles. This is an example of _____. incomplete dominance polygenic inheritance multiple alleles codominance
polygenic inheritance (b/c when two or more genes interact to form a trait, the trait is polygenic)
The centrosomes move away from each other and the nuclear envelope breaks up during which phase of mitosis?
prophase (the first phase of mitosis, when the centrosomes begin moving toward opposite poles and the nuclear envelope breaks up)
The cells in your skin have a different shape and different function than the cells in your liver because the two types of cells have different _____. DNA proteins lipids carbohydrates
proteins
Which of the following statements about the functions of RNA is correct? The information for protein synthesis is carried by tRNA. rRNA is an intermediate in the synthesis of mRNA. rRNA is an important component of ribosomes. Translation requires tRNA and mRNA, but not rRNA.
rRNA is an important component of ribosomes. (b/c without ribosomes, translation could't occur)
Imagine that a probe sent to Mars brings back a sample that contains a very primitive life-form, which appears similar to bacteria. Scientists are able to revive it and begin to grow it in culture. Much to their amazement, they discover that the organism has DNA and that the DNA encodes proteins. However, the DNA of these Martian microbes contains only two nucleotides. If the Martian microbe uses triplet codons, what is the maximum number of different amino acids that it can have in its proteins? Explain. nine, because 32 = 3 x 3 = 9 fifteen, because 42 = 4 x 4 = 16, but at least one of the codons must be for start eight, because 23 = 2 x 2 x 2 = 8 seven, because 23 = 2 x 2 x 2 = 8, but at least one of the codons must be a stop
seven, because 23 = 2 x 2 x 2 = 8, but at least one of the codons must be a stop (*Note that if an organism that had only two nucleotides needed to encode at least 20 amino acids plus a stop codon, its codons would need to be five nucleotides long (25 = 32).)
In pea plants, wrinkled seeds are recessive to smooth seeds, and green seeds are recessive to yellow seeds. Assume a plant produces wrinkled, green seeds. Using S to designate seed shape and Y to designate seed color, this plant must have the genotype _____. ssYy Ssyy SsYy ssYY ssyy
ssyy (b/c both wrinkled and green are recessive phenotypes. In order to produce such seeds, the plant's genotype must be homozygous recessive for both genes)
Cells that have the characteristics of self-renewal and the ability to differentiate into a variety of cell types are known as __________.
stem cells
The molecule responsible for bringing the correct amino acid to the ribosome at the correct time is _____. rRNA mRNA small subunit large subunit tRNA
tRNA (the molecule is responsible for bringing the genetic information to the ribosome)
The chromosomes arrive at the poles and nuclear envelopes form during which phase of mitosis?
telophase (the final phase of mitosis, when the chromosomes have arrived at the poles and the nuclear envelopes of the two new cells form)
Human chromosomes range in size dramatically, with the smallest (sex chromosome Y) being many times smaller than the largest (autosomal chromosome 1). What is responsible for determining the size of a chromosome? the length of the DNA molecule in it the amount of protein associated with it the number of DNA molecules in it the length of the RNA molecule in it.
the length of the DNA molecule in it (b/c the length of a chromosome is directly related to the length of the DNA molecule in it)
DNA structure can be described as a twisted ladder. Imagine you are climbing a model of DNA, just as if you were climbing a ladder. What parts of a nucleotide are your feet touching as you climb? the sugars the nitrogenous bases the phosphates
the nitrogenous bases (the bases form the "rungs" of the ladder)
In a DNA helix, all of the following are true except __________. the nitrogenous bases are covalently bonded to each other the nitrogenous bases are in the inner part of the helix the strands are in opposite orientation cytosine pairs with guanine adenine pairs with thymine
the nitrogenous bases are covalently bonded to each other (b/c nitrogen-containing bases are ACTUALLY hydrogen-bonded to each other)
In experiments done using pea plants, two purple-flowered plants are cross-fertilized. Some of the F1 generation plants have white flowers. In order for this to occur __________. the parental plants must both have been homozygous recessive the parental plants must both have been homozygous dominant the parental plants must both have been heterozygous one of the parents must be heterozygous, and the other homozygous dominant
the parental plants must both have been heterozygous
Alleles are alternate forms of a gene. The alleles for the gene that determines blood type in humans are found at __________. different loci on homologous chromosomes different loci on the same chromosome the same locus on homologous chromosomes the same locus on sex chromosomes
the same locus on homologous chromosomes (b/c alleles are alternate forms of the same gene, so they are found at the same locus on homologous chromosomes)
How many major checkpoints will occur in the eukaryotic cell cycle?
three
Unripe black walnuts contain a compound, juglone, which inhibits RNA polymerase. With which process would juglone directly interfere? mutation rate DNA replication transcription translation
transcription
RNA complementary to DNA is produced via _____. replication transcription translation protein synthesis
transcription (b/c the information encoded by DNA is written into an RNA molecule and transported to the cytoplasm)
One way transcription differs from DNA replication is that __________. only DNA replication involves base pairing to determine the next nucleotide in the chain transcription requires only one enzyme whereas DNA replication requires several transcription produces a newly synthesized strand whereas DNA replication produces a newly synthesized double helix transcription proceeds continuously whereas DNA replication only proceeds discontinuously there are no real differences
transcription requires only one enzyme whereas DNA replication requires several
The process that uses the genetic information carried by mRNA to specify the sequence of amino acids in a protein is called _____. replication translation transcription synthesis elongation
translation (mRNA is translated to produce a new protein molecule)
Which of the following is a type of mutation in which a section of DNA is cut out and inserted elsewhere? translocation nucleotide substitution insertion mutation deletion mutation inversion
translocation
If an organism reproduces sexually and has only three pairs of chromosomes, how many pairs of chromosomes are autosomes? one two three none
two
The purpose of DNA replication is to produce __________. two similar DNA double helices differing in a small number of specific sites two very different DNA double helices two identical DNA double helices one copy that is identical to the parental DNA molecule and one that is totally different a single-stranded DNA molecule from the double-stranded parent DNA
two identical DNA double helices
A duplicated eukaryotic chromosome contains __________.
two linear DNA double helices and two sister chromatids
Which of the following can cause errors to accumulate in DNA? metabolic activity ultraviolet light cold temperatures warm temperatures
ultraviolet light
