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98 Cards in this Set
- Front
- Back
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After replication is completely, the new DNAs, called ________, are identical to each other.
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daughter DNA
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During DNA replication, an open section of DNA, in which a DNA polymerase can replicate DNA, is called a ______.
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Replication fork.
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The new DNA strand that grows continuously in the 5' to 3' direction is called the _______.
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Leading strand.
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What are the short sections of DNA that are synthesized on the lagging strand of the replicating DNA?
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Okazaki fragments.
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What's the enzyme that can replicate DNA?
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DNA polymerase.
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What would you expect to happen of a eukaryote lacking telomerase?
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A reduction in chromosome length in gametes.
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In an analysis of the nucleotide composition of DNA, which of the following will be found?
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A+C = G+T
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What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?
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It joins the Okazaki fragments together.
Hint: think of the Spanish verb "ligar" which means "to bind." It binds together the two fragmented strands. |
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What is the function of topoisomerase?
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Relieving strain in the DNA ahead of the replication fork.
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A new DNA strand elongates only in the 5' to 3' direction because
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DNA polymerase can only add nucleotides to the free 3' end.
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What is the abbreviation for the start codon?
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AUG
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What is the name of the start codon?
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Methionine
-> Nearly every mRNA gene that codes for a protein begins with the start codon, AUG, and thus begins with a methionine. |
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What are the stop codons?
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UGA, UAA, UAG
nemonic device: U GO AWAY A ARE WAY U ARE GONE |
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An amino acid sequence is determined by what?
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Strings of three-letter codons on the mRNA, each of which codes for a specific amino acid or stop signal.
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Before mRNA can be translated into an amino acid sequence, what must happen?
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the mRNA must first be synthesized from DNA through transcription.
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In what way is base pairing in mRNA synthesis slightly different than in DNA synthesis?
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Uracil (U) replaces thymine (T) in pairing with adenine (A).
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In RNA, what takes the place of thymine.
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Uracil.
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The direction of synthesis of an RNA transcript is _____.
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5' ----> 3'
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Nucleotides are added to the what end of RNA.
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Nucleotides are added to the 3' end of RNA.
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Which RNA contains an anticodon?
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tRNA
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Which RNA as amino acids covalently attached?
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tRNA
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Which RNA contains exons?
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mRNA
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Which RNA specifies the amino acid sequence for a protein?
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mRNA
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Which RNA is the most abundant form of RNA?
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rRNA
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What type of RNA is a component of ribosomes?
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rRNA
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Where is the site of protein synthesis?
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The ribosome; rRNA is a part of the ribosome.
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What RNA carries genetic information from DNA?
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mRNA
-> the information specifies the sequence of amino acids in the new protei |
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Which RNA interprets the information from the mRNA and brings the appropriate amino acids to the ribosome?
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tRNA
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According to the central dogma, what occurs during replication?
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a faithful copy of a DNA molecule is made.
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According to the central dogma, what occurs during transcription?
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the DNA “message” is copied onto a molecule of mRNA.
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According to the central dogma, what occurs during translation?
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the information carried in the mRNA is transferred to molecules of tRNA to build a protein on the ribosomes.
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What is the central dogma of biology?
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The understanding that genetic information flows in one direction:
From DNA to RNA to protein. DNA | RNA | PROTEIN |
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During which step of the replication-transcription-translation process does tRNA first play a role?
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Translation.
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During which step of the replication-transcription-translation process does rRNA first play a role?
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Translation.
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During which step of the replication-transcription-translation process does mRNA first play a role?
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Transcription/RNA processing.
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Which component is not directly involved in translation?
A) Ribosomes B) Mma C) DNA D) GTP E) tRNA |
c) DNA
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Which of the following is not true of a codon?
a) It consists of three nucleotides b) It extends from one end of the tRNA molecule c) It never codes for more than one amino acid d) It is the basic unit of the genetic code e) It may code for the same amino acid as another codon. |
b) It extends from one end of the tRNA molecule.
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What composes a test cross?
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A cross between a plant of unknown genotype and one that is known to be homozygous recessive is called a test cross because the recessive homozygote tests whether there are any recessive alleles in the unknown.
Because the recessive homozygote will contribute an allele for the recessive characteristic to each offspring, the second allele (from the unknown genotype) will determine the offspring’s phenotype. |
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What does the law of segregation state?
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The law of segregation states that the two alleles for a gene separate during gamete formation, and end up in different gametes.
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During which part of meiosis (meiosis I or meiosis II) do the two alleles of a gene separate? During which phase does the separation occur?
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Meiosis I, anaphase
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Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. What does this suggest?
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That the parents were both heterozygous for a single trait.
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Which of the following differentiates between independent assortment and segregation?
a) The law of independent assortment requires describing two or more genes relative to one another. b) The law of segregation requires having two or more generations to describe. c) The law of segregation requires describing two or more genes relative to one another. d) The law of independent assortment is accounted for by observations of prophase I. e) The law of segregation is accounted for by anaphase of mitosis. |
a) The law of independent assortment requires describing two or more genes relative to one another.
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Why did Mendel continue some of his experiments to the F2 or F3 generation?
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To observe whether or not a recessive trait would appear.
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Which of the following is an example of polygenic inheritance?
a) skin pigmentation in humans b) white and purple flower color in peas c) the ABO blood group in humans d) pink flowers in snapdragons e) Huntington's disease in humans |
A) skin pigmentation in humans.
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What describes the ability of a single gene to have multiple phenotypic effects?
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Pleiotropy.
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Consider pea plants with the genotypes GgTt and ggtt . These plants can each produce how many type(s) of gametes?
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Four...one.
-> GgTt individuals can produce the following gametes: GT, Gt, gT, and gt. A ggtt plant can produce only gt. |
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T/F: Like incomplete dominance, codominance produces a distinct phenotype for each of the three genotypes in a monohybrid cross. Unlike incomplete dominance, however, codominance results in both alleles fully expressing their phenotype in the heterozygote.
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TRUE!!!
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Consider the following family history:
Bob has a genetic condition that affects his skin. Bob’s wife, Eleanor, has normal skin. No one in Eleanor’s family has ever had the skin condition. Bob and Eleanor have a large family. Of their eleven children, all six of their sons have normal skin, but all five of their daughters have the same skin condition as Bob. -> Based on Bob and Eleanor’s family history, what inheritance pattern does the skin condition most likely follow? |
X-linked dominant.
If the skin condition is caused by an X-linked dominant allele, a father would pass the allele on to all of his daughters, who would all have the skin condition. In contrast, the father would not pass the allele on to any of his sons because the sons would receive the father’s Y chromosome, not his X chromosome. As a result, none of the sons would inherit the skin condition. |
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Which of the following is true of an X-linked gene, but not of a Y-linked gene?
a) sister chromatids separate during mitosis b) it is only expressed in female offspring c) it doesn't segregate like other genes d) it is expressed in half of the cells of either male or female e) the gene is present in both males and females |
e) the gene is present in both males and females.
-> all cells have at least one functional X chromosome. |
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What is true of linkage?
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The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.
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Males are more often affected by sex-linked traits than females because
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Males are hemizygous for the X-chromosome.
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What is a nondisjunction?
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An error in cell division that causes homologous chromosomes or sister chromatids to move on the same side of the dividing cell.
-> Nondisjunction refers to the failure of pairs of chromosomes or sister chromatids to separate during meiosis or mitosis. |
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When can nondisjunction occur?
a) in mitosis, when sister chromatids fail to separate b) in meiosis, when homologous chromosomes fail to separate c) in meiosis, when sister chromatids fail to separate d) all three answers are correct |
d) all three answers are correct
Nondisjunction errors can occur in meiosis I, when homologous chromosomes fail to separate, or in either mitosis or meiosis II, when sister chromatids fail to separate. |
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Which syndrome is characterized by the XO chromosome abnormality?
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Turner syndrome.
-> Turner syndrome is characterized by a chromosome pattern of XO, or one X chromosome and no Y chromosome. |
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What kind of cell results when a diploid and a haploid gamete fuse during fertilization?
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A triploid cell.
-> A triploid cell has three sets of chromosomes: the two from the diploid gamete and the one from the haploid gamete. |
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Of the following chromosomal abnormalities, which type is most likely to be viable in humans?
a) haploidy b) triploidy c) trisomy d) monosomy |
c) trisomy
-> Some trisomies are viable in humans, but they result in developmental abnormalities, such as Down syndrome (trisomy 21). Only humans with trisomies of the small chromosomes (13, 18, or 21) or the sex chromosomes survive past birth. |
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If a diploid cell undergoes meiosis and produces two gametes that are normal, and one with n − 1 chromosomes, and one with n + 1 chromosomes, what type of error occurred?
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A nondisjunction error occurred in meiosis II, in which both sister chromatids of a chromosome migrated to the same pole of the cell.
-> When this error occurs in meiosis II, only half of the gametes are affected. |
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If a diploid cell undergoes meiosis and produces two gametes with n + 1 chromosomes and two gametes with n− 1 chromosomes, what type of error occurred?
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A nondisjunction error occurred in meiosis I, in which both members of a homologous pair migrated to the same pole of the cell.
-> When this type of error occurs, half of the gametes receive one too many chromosomes, and the other half receive one too few. When all of the gametes are affected, the error probably occurred in meiosis I. |
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Deletion:
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is the loss of part of a chromosomal segment.
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Duplication:
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s the repetition of a segment. The repeated segment may be located next to the original or at a different location, and its orientation may be the same as the original or the reverse.
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Inversion:
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s the removal of a segment followed by its reinsertion into the same chromosome in the reverse orientation.
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Translocation:
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s the transfer of a segment to a nonhomologous chromosome. Translocations may be reciprocal (two nonhomologous chromosomes exchange segments) or nonreciprocal (one chromosome transfers a segment without receiving one).
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If one chromosome pair undergoes nondisjunction in meiosis I
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half the gametes will have twice the normal haploid number of chromosomes (2n), and half will have no chromosomes.
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If one chromosome undergoes nondisjunction in meiosis II
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half the gametes will have the normal haploid number of chromosomes (n), one-quarter will have an extra chromosome (n +1), and one-quarter will be missing a chromosome (n – 1).
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If all chromosomes undergo nondisjunction in meiosis II
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half the gametes will have the normal haploid number of chromosomes (n), one-quarter will have twice the haploid number (2n), and one-quarter will have no chromosomes.
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What is Down syndrome caused by?
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Down syndrome is caused by trisomy 21, the presence of three copies of chromosome 21. The extra copy usually results from nondisjunction during meiosis.
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In the cells of some organisms, mitosis occurs without cytokinesis. This will result in:
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cells with more than one nucleus.
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The F1 generation differed from the F2 generation in Mendel's experiments in that
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All of the F1 showed the dominant phenotype, but only 3/4 of the F2 did.
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Homologous pairs of chromosomes often:
a) carry different genes for different traits b) differ in length c) contain different alleles d) are not both present in diploid somatic cells |
c) contain different alleles
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Human blood groups are governed by what three alleles?
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A, B, and O.
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A man who has type B blood and a woman who has type A blood could have children of which of the following phenotypes?
a) A, AB, and O b) only A c) only O d) A, B, AB or O |
d) A, B, AB or O
The genotypes could be homozygous dominant or heterozygous: BB/Bi AA/Ai |
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If two genes are linked:
a) they're on the same chromosome b) they're on the sex chromosome c) they assort independently d) they code the same amino acid sequence |
a) they are on the same chromosome
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If independently assorted are genes close together?
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No; if independently assorted genes will be on different chromosomes or very far apart.
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In an X-linked, or sex-linked trait, it is the contribution of _______ that determines whether a son will display the trait.
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The mother.
The father always carries the Y chromosome so isn't responsible for the x-linked trait. |
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What is the role of topoisomerase during replication?
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Removing tension ahead of the replication fork.
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The MPF protein complex turns itself off by
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Activating an enzyme that destroys cyclin.
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A mutation results in a cell that no longer produces a normal protein kinase for the M-phase checkpoint. Which of the following would likely result of this mutation?
a) cell would prematurely enter anaphase b) cell would never leave metaphase c) cell would never enter metaphase d) cell would be unaffected and would continue dividing |
b) cell would never leave metaphase.
-> anaphase produces normal kinase. |
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What result was unexpected in Thomas Hunt Morgan's experiments with white eyed mutant flies?
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Among the F2 progeny, only males had white eyes. All of the females had red eyes.
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You perform a test cross using F1 dihybrid flies. If in the resulting offspring the percentages of parental and recombinant offspring are about the same, this would indicate the two genes are ______.
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Linked.
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Chemical modifications, like methylation, on __________ contribute to epigenetic inheritance.
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Chemical modifications, like methylation, on HISTONES contribute to epigenetic inheritance.
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What is a type of protein enzyme that catalyzes the transfer of phosphates from ATP target proteins?
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Kinase.
-> Two examples are MPF and ATP synthase. |
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What phase in interphase is where the DNA is replicated?
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The S phase (synthesis).
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What is a protein regulator that acts on nearby cells to stimulate cell proliferation and differentiation?
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Growth factor.
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What's the key difference between origins of replication in eukaryotic and prokaryotic cells?
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In eukaryotes, because the DNA is linear there are multiple origins of replication.
In prokaryotes, because the DNA is loose (and circular) there is only one origin of replication. |
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What cell organelles/structures possess their own DNA?
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1) Mitochondria
2) Chloroplasts |
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The _________ between two gene loci is greater as the distance between two loci increases.
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Recombination frequency.
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Eukaryotic chromosomal DNA molecules have special nucleotide sequences which postpone the erosion of genes near the ends of DNA called ______.
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Telomeres.
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Hemophilia is a sex-linked disorder. The daughter of a father with hemophilia and a carrier mother has a ______ probability of having hemophilia.
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50%
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Suppose that having 3 nostrils is a Y-linked character. A woman with two nostrils mates with a man with three nostrils. What is the expected phenotypic ratio of their offspring?
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1 daughter - 2 nostrils
1 son - 3 nostrils It's carried on the Y chromosome, therefore would only affect a son and not a daughter. |
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WHAT IS THE CENTRAL DOGMA OF BIOLOGY?
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DNA -> RNA -> PROTEIN
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In the central dogma, what takes place within DNA?
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Replication.
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In the central dogma, what occurs between DNA and RNA?
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Transcription: still a similar language, as they're still talking in nucleotides.
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In the central dogma, what occurs between RNA and proteins?
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Translation: totally different language, from nucleotides to amino acids.
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Helicase:
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unwinds DNA, opens the replication fork.
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Ligase:
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seals Okazaki fragments.
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Primase:
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DNA primer to lagging strand
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SSB:
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Single strand binding protein
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What six proteins are involved in DNA replication? Additionally, describe its main function.
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1. Helicase: opens replication fork
2. Topoisomerase: breaks tension 3. DNA polymerase: adding template 4. Ligase: seals Okazaki fragments 5. Primase: RNA primer to lagging strand 6. SSB: single strand binding protein |
