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217 Cards in this Set
- Front
- Back
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The Hershey and Chase experiments involved the preparation of two different types of radioactively labeled phage (with Phosphorus and Sulfur). Which of the following best explains why two preparations were required? |
It was necessary that each of the two phage components, DNA and protein, be identifiable upon recovery at the end of the experiment. |
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Which of the following statements best represents the central conclusion of the Hershey-Chase experiments? |
DNA is the identity of the hereditary material in phage T2. |
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In their famous experiment, which of the following would Meselson and Stahl have observed after one cycle of replication in ^14N medium if DNA replication was conservative? |
An equal number of DNA molecules containing two ^15N-DNA strands and DNA molecules containing two ^14N-DNA strands. |
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In 1944, Avery, Macleod, and McCarty provided direct evidence that DNA was the hereditary molecule. They treated heat-killed extracts from lethal SIII bacteria with various enzymes and found that transformation was prevented only upon treatment with ___________. |
DNase |
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In 1928, Frederick Griffith conducted a series of experiments that demonstrated which of the following> |
A "transformation factor" could be released from a bacterial cell and picked up by another cell, thus changing the genetic identity of the recipient cell. |
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What prevents the formation of supercoils (twists in DNA helices) out ahead of replication forks in both prokaryotes and eukaryotes? |
Topoisomerase (gyrase) |
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A tRNA's anticodon is 3' GGA 5'. What amino acid is attached to it? |
Proline |
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What stabilizes single strand DNA during replication? |
SSB's |
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Specific to replication initiation for a bacterial chromosome |
Ori C |
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Seals gap in DNA 3'-OH and 5'PO4 |
Ligase |
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Replaces the RNA primers on the lagging strand of prokaryotes with DNA |
DNA polymerase 1 |
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The function of a ribosome is... |
...to hold mRNA and tRNAs in the correct positions to enable translation |
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Which of the following is FALSE, or NOT a difference between replication in eukaryotes and prokaryotes? |
Gyrase, helicase, SSB's not needed in eukaryotes |
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The area labeled as 3 in the above diagram is the (or a) ________, and is where _________. |
Intron....a segment of the mRNA is 'edited' out |
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What makes it possible for a bacterial cell to express an edited human gene? |
Because the genetic code is (nearly) the same in both organisms. |
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During the initiation step of transcription , what component listed can bind to the promoter region of a DNA molecule (esp. prokaryotes)? |
RNA polymerase |
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In the process of replication of DNA, what enzyme manufactures a 10-12 base segment of RNA complementary to a template strand of DNA? |
Primase |
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Required for attachment of RNA polymerase to the promoter in eukaryotes |
Transcription factors |
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Associated with rho-independent termination or transcription |
poly-U sequence and a stem loop in mRNA |
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Associated with the (intrinsic) promoter for RNA Polymerase |
TATAAT |
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Attachment point for rho protein in the termination of transcription |
rut sequence |
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Which parts of a eukaryotic gene are translated? |
Only the exons |
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An example of the wobble hypothesis in translations is: |
tRNA with the anti-codon 3'-GAG-5' can bind with mRNA 5'-CUC-3' and 5'-CUU-3' |
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Following transcription, the mRNA has a complementary sequence of which of the following? |
The template strand of DNA |
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The quaternary structure of a protein is directly associated with ___________. |
The interaction and combination of two or more polypeptide chains or subunits. |
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In translation, the "reading frame" begins with a _________and is read ___________. |
start codon; in groups of three |
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A mutation causes a G to be inserted in the DNA after the first codon for methionine (start). How will this affect the growing polypeptide chain? |
The reading frame will be shifted to the right, and the wrong amino acids are likely to be translated into the protein from this point on. |
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What is the purpose of raising the temperature to 90-95 degrees C at the beginning of each cycle of PCR? |
To separate the double stranded DNA |
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Polymerase chain reaction has revolutionized genetics because... |
All of the above:
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Which of the following is needed for a PCR reaction? |
All of the answers are correct:
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What occurs during the annealing stage of a PCR reaction? |
The primers bind to the desired ends of the template DNA |
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What is the most important function that telomerase performs in DNA replication? |
Both b and c:
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During DNA replication in E. coli, what is the role of DNaA? |
DNaA bends DNA, hydrolyzing the hydrogen bonds in the 13-mer region of oriC and creating an open complex. |
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As an Austro-Hungarian immigrant to the U.S., biochemist Erwin Chargaff demonstrated that if there is 24% guanine in a DNA molecule, then there is _________ thymine. |
26% |
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What is the complementary DNA sequence to 5'--ATGCTTGACTG--3' ? |
3'--TACGAACTGAC--5' |
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Compare and contrast: Monocistronic vs. Polycistronic mRNA |
Eukaryotes such as human cells contain monocistronic mRNA. This means only one protein is coded for on each piece of mRNA produced. This is necessary because eukaryotic DNA contains so much information and eukaryotic mRNA requires so much processing before it leaves the nucleus. Prokaryotic mRNA such as that in E. coli is polycistronic, meaning one piece of mRNA can code for many proteins and can be translated at more than one place at a time. |
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Compare and contrast: Centromeres vs. Telomeres |
Both of these are pieces of repetitive, inactive DNA. Centromeres are located in the middle of the chromosome and are the location spindle fibers attach during cell replication. Telomeres are located at the ends of chromosomes and are repeating base pairs. Telomerase extends telomeres due to the shortening of the DNA strand with each replication to prevent the shortening from reaching important/active DNA that must be transcribed. |
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Mendel crossed a true breeding purple flowered plant with a true breeding white flowered plant. The resulting seeds all grew up to be purple flowered plants. That hybrid generation of purple flowered plants is also called __________. |
The first filial (F1) generation |
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The observable physical characteristics of an organism are called its ___________. |
Phenotype |
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Which is the most correct description of a dominant trait? |
The trait that is seen in a heterozygous organism (hybrid). |
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A(an) ____________ is a variant of a gene, or alternate form of a gene. |
Allele |
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In dogs, black fur color is dominant to white. Two heterozygous black dogs are mated. What would be the probability of getting a homozygous white dog (one puppy)? |
0.25 |
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In Garden peas, orange pods (P) are dominant to green pods (p). True breeding parental plants were crossed, and the resulting F1 plants were heterozygous at both loci. Then the F1 plants were crossed, with the observed results yielding 124 orange pod plants, and 36 green pod plants. What is the closest to the goodness-of-fit value (chi-square total value)? |
0.53 |
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A pea plant is heterozygous for two genes; one controlling height, one controlling color. The genotype is written PpTt. Based on the Law of Independent Assortment, approximately what proportion of the pollen produced by this plant should have the genotype PT? |
1/4 |
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During which stage or phase of the cell cycle does the cell replicate its chromosomes? |
S |
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The figure shows two diploid cells with two homologous chromosomes. Cell A is at the ________phase of ____________. Cell B is undergoing the same phase of ____________. |
Metaphase....mitosis....meiosis I |
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In a dihybrid cross using Mendelian inheritance, if both parents are heterozygous for both traits, what will be the phenotypic ratio of their offspring? |
9:3:3:1 |
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In dogs dark color coat is dominant over albino, and short hair is dominant over long hair. If these effects are caused by two independently segregating gene pairs, choose the most probable GENOTYPES for the parents of each of the following cross (the symbols D and d stand for the dark and albino coat-color alleles, and L and l for the short and long-hair alleles, respectively). Parental phenotypes: Dark/Short hair x Dark/Long hair Offspring phenotypes: dark, short:18 dark, long: 19 albino, short: 0 albino, long: 0 What are the genotypes of the parents? |
DDLl xD_ll |
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In single factor crosses between two true breeding strains of tree frog, a scientist discovers that plain green tree frogs and tree frogs with a red 'racing stripe' always produce offspring that have red racing stripes. Why? |
Stripes are dominant to plain green coloration. |
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X-linked recessive inheritance means that a recessive trait is... |
only carried on an X-chromosome |
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Which of the following statements is true for X-linked genes in mammals? |
Males are hemizygous for X-linked genes. |
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Mendel needed to know the genotype of his dominant phenotype purple flowered plants, so he used a test cross with a ____________ pea plant. He found that all the offspring from the test cross were purple, so he knew the purple plants he started with originally were __________. |
homozygous recessive (white)....homozygous dominant |
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Certain kinds of cells (some cells in the eyes and bones) mature and differentiate into a state in which they have a specialized function but do not divide or progress through the cell cycle. These cells are in which stage? |
G0 |
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The coat color patterns of calico cats is primarily a result of _____________. |
X chromosome-inactivation |
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What molecular parameter causes linear DNA fragments to have different electrophoretic mobility? |
Size (length) |
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What functional role do you think restriction endonucleases serve in the bacteria from which they are derived? (Hint: The restriction endonuclease produced by a bacterium cannot cut the bacterium's DNA.) |
The restriction enzyme is able to cut foreign DNA. It decreases the likelihood that the bacteriophage will successfully infect the bacterium. |
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According to the theory of X-chromosome inactivation (dosage compensation) in mammals, a person with the sex chromosome karyotype of XXXY would have ______ Barr bodies. |
2 |
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Morgan found that white eye color in fruit flies was an X-linked recessive trait. When he performed a cross of a white-eyed male to a heterozygous red-eyed female, he found... |
...a ratio of 1 white-eyed female and male to 1 red female and 1 red male |
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Exam 2-22 |
Exam 2-22 answer |
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In selecting recombinant bacteria, cells are chosen that are resistant to a specific antibiotic. How are the bacteria made resistant? |
The antibiotic resistance is encoded in the vector. |
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You create a partial diploid with lac i+, lacZ-, lacY-, lac A+ on the plastid, while the main chromosome is lac i-, lacZ+, LacY-, lac A+. What would happen in this cell with lactose present? (disregard CAP and glucose levels for this question) |
B-galactosidase and Transactylase would be produced but no functional Lactose permease. Lactose already in the call would be processed and metabolized until depleted, but then effectively stop. |
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You create a partial diploid with lac i-, lacZ-, lacY+, lacA+ on the plastid, while the main chromosome is laci-, lacZ+, LacY+, lac A-. What would happen in this cell with lactose absent? (disregard CAP and glucose levels for this question) |
There would be constitutive production of all of the structural genes. Normal lactose metabolism would be possible should lactose become available in the environment. |
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Most of the regulation of gene expression in bacteria occurs at the _______ level. |
Transcriptional |
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How is the transcription of heat shock genes activated in E. coli? |
By expression of an alternative sigma factor that forms an alternate RNA polymerase holoenzyme that specifically transcribes heat shock genes. |
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Which of the following features of the trp operon is likely least essential to the process of attenuation? |
The order of the structural genes, E, D, C, B, A |
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Suppose you have engineered a plasmid vector in order to produce a functional animal protein in E. coli. But the product you collect, while it has the correct amino acid sequence, is in fact nonfunctional. What might you try that would have a greater chance of success? |
Treatment of the post-translation proteins collected from E. coli with processing enzymes from the original animal cells. |
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Which of the following is one advantage of using haploid organisms in forward genetic screens? |
Recessive loss-of-function mutations may be identified directly among the mutagenized progeny. |
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An initial step in reverse genetic analyses is typically _________. |
Creation of mutant alleles of a gene that is identified only by its DNA sequence |
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One use of PCR has been to monitor the trafficking of endangered organisms. Suppose that one suspect was accused of illegally importing a specific animal, but he suspect asserts that the young animal had been bred in this country from two resident zoo animals. How would you best proceed? |
Use DNA from hair follicles of supposed zoo parents and of the supposed offspring to compare sequences amplified with primers for a highly polymorphic region. |
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Golden rice has been genetically engineered to produce which of the following? |
Provitamin A, a precursor for vitamin A synthesis proteins that confer resistance to herbicides |
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In BLAST, which section of the search results can you find nucleotide-by-nucleotide comparisons between your query sequence and similar database sequences? |
Alignments |
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One of the key features of BLAST is that it permits you to make quantitative comparisons of sequence similarities (alignments) between your query sequence and every other sequence in the database. The quantity that is most frequently reported in a statistical comparison of sequence than that particular hit. How do the E values change as you go from the top of the list of hits to the bottom? |
The E values get larger |
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You have evidence that a gene, VTE4, of known sequence and well-understood transcriptional regulation, is available from another lab. The product of this gene enables sees to produce a significantly increased amount of vitamin E from a substrate already produced in Brassica napus, the plant that gives us canola oil. To produce canola oil wiht increased vitamin E, how would you proceed? |
Introduce the gene and necessary cis elements into Brassica, along with a reporter gene, then measure the vitamin E produced. |
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You have a DNA sequence of 1600 bp. To characterize it, you decide to make a restriction map. Cutting with the first enzyme, you show by electrophoresis that the fragments produced are 400 and 1200 bp, respectively. After using the second enzyme, you recover 700 bp and 900 bp fragments. After treatment with both enzymes, fragments were 300, 400, and 900 bp. Which is the correct map? |
-400-/300-/---900----- |
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Which of the following vectors would be most efficient to use to amplify fragments ~300 kb in length? |
YACs |
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True of False? The products of restriction digestions can be visualized by gel electrophoresis, which separates fragments based on their size. |
True |
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A 1.5-kb fragment of DNA is cloned into a plasmid vector that is 5.5 kb long at the EcoRI site, and the plasmid vector is then used to transform bacteria. If the plasmid DNA is then extracted from a single bacterial colony and digested with EcoRI, what digestion products will be produced if the plasmid contains the fragment? |
One 1.5-kb fragment and one 5.5-kb fragment |
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Digestion of a 1.1-kb fragment of DNA with BamHI produces two fragments of 700 bp and 400 bp. Digestion of the same 1.1-kb fragment wiht Xhol produces two fragments of 300 bp and 800 bp. Digestion with both enzymes produces three fragments of 100 bp, 300 bp, and 700 bp. Which of the following statements is true about the DNA fragment? |
The Xhol sit is located within the BamHI 700-bp fragment. |
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Snuppy, a male Afghan hound, was created by transferring the nucleus from an ear cell of the mail Afghan, Tai, into an enucleated egg from a donor. The embryo was transplanted into a surrogate mother to develop to term. Which of the following animals would be a genetic match for Snuppy if nuclear DNA were tested? |
Tai |
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Snuppy, a male Afghan hound, was created by transferring the nucleus from an ear cell of the mail Afghan, Tai, into an enucleated egg from a donor. The embryo was transplanted into a surrogate mother to develop to term. Which of the following animals would be a genetic match for Snuppy if mitochondrial DNA were tested? |
The egg donor |
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An _________ is a stretch of DNA consisting of an operator, a promoter, and genes for a related set of proteins, usually making up an entire metabolic pathway. |
Operon |
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The __________________ is/are arranged sequentially after the promoter. |
genes of an operon |
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A ___________ is a specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place. |
promoter |
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A ____________ codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes. |
regulatory gene |
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Regulatory proteins bind to the ______ to control expression of the operon. |
operator |
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A _______ is a protein that inhibits gene transcription. In prokaryotes, this protein binds to the DNA in or near the promoter. |
repressor |
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A(n) ________ is a specific small molecule that binds to a bacterial regulatory protein and changes its shape so that it cannot bind to an operator, this switching an operon on. |
inducer |
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Memorize |
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Memorize |
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Which of the following mutations could lead to constitutive expression of the genes of the lac operon? |
A mutation in the operator sequence |
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Which of the following best describes the biological role of the lac operon? |
It ensures that a cell dedicates resources to the production of enzymes involved in lactose metabolism only when lactose is available in the environment. |
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The placement of the operator sequence between the promoter and the structural genes is critical to the proper function of the lac operon. True or False? |
True |
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Which of the following occurs as a result of an abundance of tryptophan in E. coli? |
The 5 trp genes (TrpA – TrpE) are not transcribed. |
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Which of the following features of the trp operon is likely least essential to the process of attenuation? |
The order of the structural genes, E, D, C, B, A |
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Attenuator systems such as the one described for regulation of tryptophan synthesis would be just as likely to occur in eukaryotes as in prokaryotes. |
False |
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In the lac operon, what are the likely effects on operon gene transcription of the mutations identified below? Mutation of consensus sequence in the lac promoter. |
Transcription is blocked. |
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In the lac operon, what are the likely effects on operon gene transcription of the mutations identified below? Mutation of the repressor binding site on the operator sequence. |
Transcription is constitutive. |
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In the lac operon, what are the likely effects on operon gene transcription of the mutations identified below? Mutation of the lac I gene affecting the allosteric site of the protein. |
Transcription is blocked. |
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In the lac operon, what are the likely effects on operon gene transcription of the mutations identified below? Mutation of the lac I gene affecting the DNA-binding site of the protein. |
Transcription is constitutive. |
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In the lac operon, what are the likely effects on operon gene transcription of the mutations identified below? Mutation of the CAP binding site of the lac promoter. |
Transcription is blocked. |
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Suppose the lac operon partial diploidcap− I+P+O+ Z− Y+/ cap+ I−P+O+ Z+Y−is grown. (cap- indicates that the CAP-cAMP binding site is not functional.) Will this partial diploid strain grow on a lactose medium? |
No |
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Suppose the lac operon partial diploidcap− I+P+O+ Z− Y+/ cap+ I−P+O+ Z+Y−is grown. (cap- indicates that the CAP-cAMP binding site is not functional.) Is transcription of β-galactosidase inducible, constitutive, or noninducible? |
Noninducible |
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Suppose the lac operon partial diploidcap− I+P+O+ Z− Y+/ cap+ I−P+O+ Z+Y−is grown. (cap- indicates that the CAP-cAMP binding site is not functional.) Is transcription of permease inducible, constitutive, or noninducible? |
Noninducible |
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How is the transcription of heat shock genes activated in E. coli? |
By expression of an alternative sigma factor that forms an alternate RNA polymerase holoenzyme that specifically transcribes heat shock genes |
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The meiotic phase represented in figure "a" is ________. |
Anaphase I |
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Why is heterozygosity for SCD (betaA betaS) beneficial in regions where malaria is prevalent? |
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The mutation resulting in the allele for sickle cell anemia removes a restriction site from the beta-globin gene such that a specific probe hybridizes to one 1.3-kb fragment instead of two fragments of 1.1 kb and 0.2 kb. What restriction pattern will be seen in sickle-cell carriers? |
Three fragments of 1.3, 1.1, and 0.2 kb |
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The end result of meiosis in animals is __________. |
Four haploid cells |
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A known segment of radioactively labeled DNA (a probe) may be used to identify species or cells with similar sequences in their genome. This technique, originally using a brick to adhere the sample DNA to a membrane, is called _________. |
Southern blotting |
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The pedigree above shows a pattern of ... |
Autosomal recessive inheritance |
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Individuals 1 and 2 in Generation III must have a ___________ genotype. |
Homozygous |
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The betaS allele results in which of the following changes in the beta-globin polypeptide (wild type)? |
A single amino acid substitution-valine for glutamate |
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There are various SNP's (mutations) that lead to varying degrees of Sickle Cell Disease (e.g. betaS, betaC, betaE). But they all confer some degree of protection from malaria. What is their common mechanism? |
They disrupt the life cycle of Plasmodium parasites in human hosts by speeding RBC destruction/replacement |
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What phenotypic ratio would you expect as a result of a test cross between a dihybrid organism and one that is homozygous recessive for alleles at two independent loci? |
1:1:1:1 |
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A cross was made betweentwo pea plants with genotypes TtAa and Ttaa, where T=tall and t=dwarf, A=axial (flower in middle of stem), and a=terminal (end of stem flower). What is the expected ratio of the resulting offspring? |
3 tall, axial: 3 tall, terminal: 1 dwarf, axial: 1 dwarf, terminal |
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Constructing pedigrees for human genetic traits is important because: |
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A mutation in DNA may lead to the production of an enzyme that is less functional than the "wild type" normal enzyme. These type of mutations are referred to as _________________. |
hypomorphic |
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The active srY gene in humans... |
leads to development of male sex organs and urinary tract |
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Gene interactions in which an allele of one gene modifies or prevents expression of alleles of another gene is known as |
Epistasis |
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In sheep, coat color is influenced by two genes. Gene A influences whether or not any pigment is produced (no pigment production=dominant), while gene B produces black (dominant) or brown pigment. If two heterozygous white sheep were crossed and offspring were produced in a ratio of 12 white sheep to 3 black sheep to 1 brown sheep, what are the genotypes of the black sheep? |
aaB_ |
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Bateson and Punnett crossed two white-flowered lines and saw all purple flowers in the F1 generation. They concluded this was an example of complementary gene interactions because a cross of the F1 plants yielded what ratio in the F2 generation? |
9 purple to 7 white |
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A diploid organism with the genotype TTRrYYAa forms haploid gametes. Assuming that each of the allele pairs for all four traits are on four different homologous pairs of chromosomes (i.e. there is independent assortment), what gametes are possible in this individual? |
2^2=4 TRYA, TrYA, TrYa, TRYa |
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a. Autosomal recessive b. Gen 1: aa x Aa Gen 3: Aa x Aa c. The pattern of inheritance must be auosomal because if affects males and females equally. It must be recessive because no generations are skipped and parents II6 and II7 are unaffected and produce ONLY unaffected children. The father in Gen 1 is homozygous recessive because he is unaffected. The mother is heterozygous because she is affected but produces both affected and unaffected children. Both parents in Gen 3 must be heterozygous because they are affected but produce both types of offspring. |
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In laborador retrievers, pigment color is influenced by two genes. Gene A determines the type of pigment produced and gene B affects whether the pigment gets deposited in the hair shaft. If two black laborador retrievers were crossed (heterozygous for both Gene A and Gene B, i.e. AaBb), and offspring were produced with the phenotype ratio of 9 black dogs to 3 brown dogs to 4 yellow dogs, what is the genotype of the black, brown, and yellow dogs respectively? |
9 black, 3 brown, 4 yellow Black: A_B_ Brown: aaB_ Yellow: __bb |
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Compare and contrast mitosis and meiosis |
Both methods are used for cell replication and contain similar steps (prophase, metaphase, anaphase, telophase and in meiosis these occur twice). Mitosis will produce two identical somatic cells, whereas meiosis will produce four haploid gametes. Crossing over can occur in meiosis to help produce this variation in gametes, but this does not occur in mitosis. |
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SA vs. AA survival in areas of high malaria infection |
Heterozygotes have a "heterozygote advantage" in areas of high malarial infection because the presence of the S allele contributes to a faster rate of red blood cell death and regeneration. This disrupts the life cycle of the Plasmodium parasite that causes malaria. Furthermore, symptoms of SCD are minimal or nonexistent. While those homozygous for AA alleles do not have SCD, they are more susceptible to malaria and therefore have lower survival rates in these areas. |
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Sniffles is a male mouse with a brown colored coat, and was mated with Esmeralda, an alluring albino. The resulting litter of six young all had brown colored fur. The next time she came into estrus, Esmerelda was mated with Whiskers who was also brown-colored like Sniffles. Some of Esmeralda's next litter were white (albino).
What are the probable genotypes of Sniffles, Whiskers, and Esmeralda? Show with Punnett squares and explain. |
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The figure below shows a Southern blot with a radioactive probe for three DNA fragments that were generated by the Ddel restriction enzyme. Remember: The mutation resulting in the allele for sickle-cell anemia removes a restriction site from the wild type. Use the information in the figure on the next page to determine the phenotype and genotype of each person tested. |
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The figure below shows a Southern blot with a radioactive probe for three DNA fragments that were generated by the Ddel restriction enzyme. Remember: The mutation resulting in the allele for sickle-cell anemia removes a restriction site from the wild type. Suppose the mating couple (Gen I-1 and I-2) are expecting a fifth child. Is it possible that their child will have SCD? If so, what is the probability? If not, explain why. |
Because both parents are heterozygous, it is possible. The probability is 1/4 because |
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The figure below shows a Southern blot with a radioactive probe for three DNA fragments that were generated by the Ddel restriction enzyme. Remember: The mutation resulting in the allele for sickle-cell anemia removes a restriction site from the wild type. Fetal DNA is collected and analyzed by Southern blotting; a single 1.35 kb band is found. What is the interpretation/explanation for this result? |
This sample tested positive for sickle-cell anemia because the mutation resulting in the SCD allele removes a restriciton site and will therefore remain in one piece and not travel as far the the gel. It would look the same as II-1. |
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The Beatle and Tatum experiments were based on all of the following assumptions EXCEPT: |
...prototrophs cannot grow on complete medium. |
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Two genes that are located next to each other on the same chromosome are said to be _________.
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Linked |
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Assume that the loci for genes Follicles and Gargantuan are located on the same chromosome. On one chromosome alleles F and G are found, while the homologue contains alleles f and g. Which of the following would be an example of the outcome of a recombination (crossing over) event? |
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Which of the following is correct regarding a prophage? |
It is copied along with the bacterial chromosome during replication. |
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While mapping two linked genes in Drosophila, you observe 30 recombinants among 200 total offspring. What is the distance between these genes? |
15 map units |
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In a mapping experiment with three linked genes, which phenotypes should occur most often in the F2 (result of test-cross) offspring? |
Parental genotypes |
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Which of the following is NOT true regarding bacterial genetics? |
The patterns of inheritance in bacteria may be studied using the same mechanisms as eukaryotic organisms |
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Which of the following is correct concerning F factors? |
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During conjugation, one gene (A) is found to transfer to the recipient bacteria 16 minutes following the start of conjugation, while a second gene (M) is found to transfer 27 minutes following the start of conjugation. A third gene (T) transfers 35 minutes following the start of conjugation. Based on this information, which of the following is true? |
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If two genes on the same chromosome exhibit complete linkage, what is the expected F2 phenotypic ratio from a selfed heterozygote with the genotpye a+b+/ab? |
3:1 |
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Genetic linkage leads to the production of a significantly greater than expected number of gametes containing chromosomes with... |
...parental combinations of alleles. |
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Davis' U-tube apparatus had a filter that prevented direct contact of bacterial cells, but as it turns out, allowed viruses and DNA to pass through. But which of the following processes did this design specifically prevent? |
Conjugation |
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In freshwater snails, pigment color is influenced by tow genes. If two heterozygous pigmented freshwater snails were crossed and offspring were produced in a ratio of 9 pigmented snails to 7 albino snails, what are the genotypes of the albino offspring? |
aaB_ |
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Which of the following is incorrect regarding bacteriophages? |
The phages injects only coat proteins into the host cell |
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Antibiotic resistance may occur by which of the following mechanisms? |
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Which of the following mutations could lead to no expression of genes of the lac operon, even in the presence of lactose? |
A mutation in the lac Z gene |
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Which of the following best describes the biological role of the lac operon? |
It ensures that a cell dedicates resources to the prodution of enzymes involved in lactose metabolism only when lactose is available in the environment. |
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If there is a mutation in the repressor binding site on the operator sequence in a lac operon , what is the consequence for transcription of the structural genes? |
Transcription is constitutive (at least at the basal levels), even without presence of lactose. |
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A testcross for mapping purposes is always performed between the individual that is heterozygous for the genes to be mapped and an individual who is ___________. |
...homozygous recessive for the genes. |
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This process includes infection by a bacteriophage as an intermediary for transfer of genetic information. |
Transduction |
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This process involves the uptake of pieces of DNA from the environment that changes the genome of a bacterium. |
Transformation |
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Which of the following is true regarding conjugation? |
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An auxotroph labeled pro-, met-, str^R would grow on a medium containing... |
...minimal medium plus proline and methionine. |
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The process of interrupted mating in bacteria may be used to do which of the following? |
Determine the relative position of bacterial genes |
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When viruses undergo their lytic cycle and incidentally incorporate random pieces of bacterial DNA into their viral DNA in daughter viruses, they may subsequently transfer bacterial gene sot a future host cell. This process is called... |
...generalized transduction. |
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Which of the following is correct regarding a temperate phage? |
It may integrate in the DNA of an infected cell, staring a lytic cycle in the future. |
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In 1928, Frederick Griffith conducted a series of experiments that demonstrated which of the following? |
A "transformation factor" could be released from a bacterial cell and picked up by another cell, thus changing the genetic identity of the recipient cell. |
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To map genes of a bacterial strain, conjugation must be interrupted at given times. Suppose you have Hfr cells of genotype a+ b+ c+ d+ e+ str^S and F- cells of genotype a- b- c- d- e- str^R and you combine these two cultures in liquid medium in four blenders at time 0. After intervals of 3, 6, 9, and 12 minutes you turn on successive blender. What role does the blender play in the experiment? |
Shears the sex pili of conjugants and ends conjugation |
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To map genes of a bacterial strain, conjugation must be interrupted at given times. Suppose you have Hfr cells of genotype a+ b+ c+ d+ e+ str^S and F- cells of genotype a- b- c- d- e- str^R and you combine these two cultures in liquid medium in four blenders at time 0. After intervals of 3, 6, 9, and 12 minutes you turn on successive blender. The resulting cultures were then plated on medium containing streptomycin. Why? |
To selectively eliminate cells that have taken in F+ genes. |
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This graph show the results of plating the cultures of each blender. "d" appears on plates at 20 minutes of recombination. What is the correct order of the genes on this chromosome? |
a, c, e, b, d |
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The activated CAP binds to DNA in the neighborhood of the promoter and... |
...leads to increased affinity of RNA polymerase to the site and increased transcription rates for the lac structural genes. |
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In the lac operon, if CAP could not bind to its CAP site (due to a DNA mutation), then what would be the result? Assume lactose is present in the scenario. |
Transcription would occur, but at low, basal levels of lac structural genes. |
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In what order are the genes transferred? |
strR, leu+, cys+, met+ |
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In laborador retrievers, pigment color is influenced by two genes. Gene A determines the type of pigment produced and gene B affects whether the pigment gets deposited in the hair shaft. If two black lab retrievers were crossed (heterozygous for both Gene A and Gene B, AaBb), and offspring were produced with the phenotype ratio of 9 black dogs to 3 brown dogs to 4 yellow dogs, what is the genotype of the black, brown, and yellow dogs respectively? |
Black: A_ B_ Brown: aa B_ Yellow: _ _ bb |
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Transformation vs. Conjugation |
Transformation is the intake of DNA from the environment into a bacterial cell. Conjugation is the donation of DNA from one bacterial cell to another bacterial cell. These two are similar in the sense that in both cases, a bacterial cell is incorporating new DNA into its chromosome. In the case of transformation, the DNA is from the environment and doesn't require a living cell or vector. The DNA can be that of a virus or bacteria. In conjugation, physical contact between two bacterial cells is required and the recipient cell has the potential to become a donor cell or not. |
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F+ vs. Hfr |
An F+ bacterium contains the F-factor and is therefore considered a donor, as is Hfr bacterium. When F+ donates to F-, the F- receives only the F-factor and becomes a donor cell. When Hfr donates to F-, the donation of the F-factor is incomplete and so the F- does not become a donor. The Hfr also donates a portion of bacterial DNA along with the F-factor. |
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Phenylketonuria (PKU) is extremely common in Ireland, affecting approximately 1 in 4500 live births. Assuming that the population is in Hardy-Weinberg equilibrium, what is the frequency of PKU carriers? |
2.9% |
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In a group of 500 people, the frequency of genotype NN is 40%. Assuming both autosomal inheritance and that the population is in Hardy-Weinberg equilibrium, how many individuals would you expect to have the MN genotype? |
232 |
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Which of the following is a basic assumption underlying Hardy-Weinberg equilibrium? |
Random mating occurs in the population |
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In a Hardy-Weinberg population, 16% of individuals display the homozygous recessive phenotype. What proportion of the population will be heterozygous carriers of the recessive allele? |
0.48 |
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Mexican hairless dogs are heterozygous (Hh), carrying a single copy of the recessive lethal allele. In a given population, the Hh genotypic frequency is 60% and the frequency of each homozygote is 20%. Assuming w = 1 for the Hh and hh dogs, what is the estimated genotypic frequency of the lethal HH genotype after reproduction? |
14% |
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In an isolated population of 1000 individuals, 444 are genotype MN, 478 are MM, and 78 are NN. What are the frequencies of the M and N alleles in this population? |
f(M) = 0.7, f(N) = 0.3 |
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What is the process by which changes in allele frequencies occur in response to natural selection? |
Differential reproduction |
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Which of the following processes tends to increase genetic variation in a population? |
Mutation |
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Which of the following is NOT true of gene flow? |
Gene flow generates new alleles |
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Which aspect of population genetics refers to chance fluctuations of allele frequencies resulting from sampling error and is more prominent in small, isolated populations? |
Gene drift |
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All Old Order Amish families from Lancaster County with Ellis-van Creveld syndrome can trace their genealogies to Mr. and Mrs. Samuel King, who immigrated to Lancaster County in 1744. This is an example of |
Founder Effect |
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Which of the following is a common consequence of inbreeding in a population? |
increased frequency of homozygous genotypes |
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If the frequency of the M allele in the human MN blood group system is 0.65 in a population at equilibrium, then the frequency of the N allele must be 0.04. |
False |
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If a recessive disease is found in 50 out of 100,000 individuals, what is the frequency of the heterozygote carriers for this disease? |
0.043 |
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In a population of birds in Africa, it was observed that birds with small or large beaks could efficiently crack and eat small or large seeds, respectively. Birds with intermediate beaks had trouble with both types of seeds. What type of selection would be expected to occur in this population if small and large seeds were the only types of food available to these birds? |
Disruptive |
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Galactosemia is an autosomal recessive disorder. If untreated, the disease can cause mental retardation in children. It is characterized by an inability to metabolize galactose (which comprises part of lactose found in milk), due to a deficient enzyme.In one population, the frequency of the normal allele, A1 , is 0.92. The frequency of the galactosemia allele, A2 , is 0.08. Assuming that this population is in Hardy-Weinberg equilibrium, calculate the frequency of homozygous dominant individuals, heterozygous individuals, and homozygous recessive individuals. |
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Cystic fibrosis is an autosomal recessive disorder. In one population, the frequency of affected individuals (A 2 A2) is 0.0004. Assuming that this population is under Hardy-Weinberg equilibrium, calculate all allele frequencies and genotype frequencies. |
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In chickens, having feathers on legs is dominant to having featherless legs. In a population of 200 chickens, 128 have featherless legs. How many chickens are heterozygous for the “feathered leg” allele? Assume the population is in Hardy-Weinberg equilibrium. |
62 |
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The frequency of carriers for a rare autosomal recessive genetic condition is 0.04 in a population. Assuming this population is in Hardy-Weinberg equilibrium, what is the allele frequency of the recessive allele? |
Not enough information |
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The three major mechanisms of evolution differ in how they work, and as a result often have different effects on a population. Review your understanding of natural selection, genetic drift, and gene flow by sorting the statements below into the correct bins. |
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Populations evolve for many reasons. Suppose there is a population of plants that have either purple flowers or white flowers, and the allele for purple flowers is dominant. This means that plants with two purple alleles have purple flowers. Plants with one purple allele and one white allele also have purple flowers. Only plants with two white alleles have white flowers.For each event or condition described below, answer the following questions.Which mechanism of evolution is at work?How does this event affect the population’s gene pool? Do the frequencies of the two alleles change, and if so, how? |
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Which of the following statements about mapping bacterial genes by conjugation is NOT true? |
The closer a gene to the Hfr origin (oriT), the more likely it will be transferred to the recipient during conjugation, regardless of which side of oriT it is on. |
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Temperate bacteriophages can be either lytic or _______. |
lysogenic |
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Which of the following is/are true of generalized bacteriophage transduction? |
a.The bacteriophage chromosome has a region homologous to the bacterial chromosome at some location.b. The bacteriophage must enter the lysogenic cycle.c.The bacteriophage packages random fragments of bacterial DNA into new phage particles.d. Both a and c are correct.e. None of the other answers are correct. |
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Bacteria which can grow on minimal media are referred to as |
Prototrophic |
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Bacteria which cannot grow on minimal media (it must be supplemented with a nutrient) are referred to as |
Auxotrohpic |
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A bacterial strain that is pro+ thi+ leu− met− will grow on |
minimal media plus leucine and methionine |
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Which of the following can be inferred from the Beadle and Tatum experiments? |
For a mutation resulting in the production of a defective enzyme involved in a biosynthetic pathway, the compound preceding the corresponding step will accumulate. |
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In an interrupted mating experiment, the purpose of plating cells on a selective medium is _______. |
to ensure that conjugation has been completed |
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Observe the figure below. What is the correct order of the genes following oriT on the Hfr chromosome? |
met -- his -- pro --- bio |
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The distance between genes on the gene map is measured in minutes because the distance between genes is measured by the time it takes for the gene to be transferred from the host cell into the recipient cell. This distance can be determined by looking at the first appearance of each phenotype on the graph.Observing the graphs and map you assumed above, what is the distance between the met and his genes? |
approximately one minute |
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What form of genetic exchange in bacteria does not require a vector or living cell? |
trasnformation |
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Using the information from the time of entry experiment above, answer the following question.The leu gene was found to be entering the F- cells 5 minutes after the pro gene. In which location in the gene map could the leu gene be located? (Note that the distances depicted between the genes on the map are not to scale.) |
E |
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The Beadle and Tatum experiments were based on all of the following assumptions except that _______. |
two different strains of auxotrophic Neurospora that grow on minimal medium supplemented with biotin have mutations in the same gene. |
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What plasmid includes both DNA of the F+ plasmid and bacterial chromosome? |
F' |
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Before Muller's discovery that radiation induces mutation, scientists had to work on mutations that were found solely by phenotype differences in natural populations. Which of the features of Drosophila made it a fortuitous choice for Morgan and his colleagues? |
large number of easily visible phenotypes |
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Which of the following is one advantage of using haploid organisms in forward genetic screens? |
Both dominant mutations and recessive loss-of-function mutations may be identified directly among the mutagenized progeny |
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What is typically the initial step in reverse genetic analyses? |
creation of mutant alleles for a gene that is identified only by its DNA sequence, not by its function |
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The lacZ gene CANNOT be used as a reporter gene in which of the following cell types? |
plant |
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Besides the obvious fact that chemical mutagens are dangerous to handle, another major disadvantage to their use is that ________. |
most chemically induced changes are detectable only by sequencing |
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Which of the following is an advantage of using GFP instead of lacZ as a reporter gene in mice, C. elegans, and Drosophila? |
It is more useful for analyzing whole live animals |
