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146 Cards in this Set

  • Front
  • Back
Genome-Wide Association Studies
Do NOT require many families to detect association.
Differentiation of four different bases in automated sequencing systems is that each base has a:
distinctive fluorescent tag
The whole-genome shotgun sequencing approach depends primarily on
rapidly sequencing thousands of small randomly cloned fragments.
Approx. what percent of the human genome consists of transposable elements?
45%
Which type of transposon is excised from one genomic position and inserted into another?
Cut and paste transposon.
Which of the following is true regarding cut and paste transposons in eukaryotes?
a) These have inverted repeats at their termini.
b) These elements create target site duplications.
c) They may encode a transposase enzyme.
d) All answers are correct.
D) All answers are correct.
Would you expect genes encoded by retrotransposons to contain introns? Why or Why not?
Introns are only excised during RNA processing so a retrotransposon being made from RNA into DNA, it does not have introns.
AZT works by blocking the reverse transcriptase enzyme used by HIV, the causitive agent of AIDS. Would you expect any transposons to be affected by AZT? If so, what class would be affected?
Retrotransposons would be affected since they use reverse transcriptase to go from RNA to DNA.
Compare and Contrast: Gene and Allele
A gene is a segment of DNA, located on a specific part of a chromosome, that encodes for a specific trait. An allele is an alternative variation of a gene that changes how the gene expresses. They are similar in that they both determine a trait in an organism.
Compare and Contrast: Chromosome and Chromatid
Both are the complex of DNA and associated proteins arrayed in a linear sequence. The difference depends on where you are looking in the cell cycle. At the beginning of Mitosis, a single strand could be called a single chromosome or a chromatid. After replication, a double strand is still called a chromosome but the strands are sister chromatids.
The fruit fly Drosophila melanogaster has four pairs of chromosomes in its somatic cells (2n=8). In the male fly, crossing over does NOT occur. Given this fact, how many chromosomally distinct types of sperm can be produced by a male fruit fly? Show your work.
Since 2n=8, 2^P where p = # of pairs chromosomes, 2^4=16. (Noted another way: Since each pair of chromosomes will produce one gamete with maternal DNA and one with paternal DNA; 2x2x2x2=16.)
Which of the following statements is true of BOTH spermatogenesis and oogenesis in humans?
a) Both produce haploid cells from diploid cells
b) Both divide genetic material equally into daughter cells
c) Both result in the formation of four functional gametes
d) Both processes are delayed until the start of puberty
A) Both produce haploid cells from diploid cells.
Clones are populations of cells that have divided into two cells and are:
genetically identical
What are the two featurs of meiosis that produces genetic variability in gametes?
a) Crossing over: When non-sister chromatids exchange genetic material by "crossing over" at chiasmatas essentially swapping that section of DNA. Ensures that even if all of one parent's DNA is inherited, there will still be some material from the other parent, so the offspring will be unique.
b) Assortment of non-homologous chromosomes: This is entirely random alignment of the chromosomes at the metaphase plate. This ensures a random distribution of genetic material to the gametes.
The type of bond that is broken during base excision repair is:
Glycosidic
Methylation is associated with each of the following EXCEPT:
a) CpG islands in promoters of genes
b) Reduced transcriptional activity
c) Open or relaxed chromatic states
d) Heritable changes to gene expression
C) Open or relaxed chromatin states
The chemical modification that targets proteins for degradation is:
Ubiquitination
Some individuals with Retinoblastoma (a form of cancer) are diagnosed in infancy, while others are diagnoes in adulthood. For those who are diagnosed in infancy, the mutation is:
Present in germ AND somatic cells.
The SNPs on a chromosome segment that tend to be inherited together define a genetic unit called a
Haplotype
Based on the sequencing data acquired from the Human-Genome Project, how many genes are in the human genome?
20,000-25,000
When comparing the genomes of two or more species, the content and organization of genes that is shared on their chromosomes is called:
Synteny
A set of overlapping DNA fragments that form a contiguous stretch of DNA is called a:
Contig
The average human gene (including introns) is approx. how many bp in length?
30,000 bp.
Homologous genes in the same species are called:
Paralogues
Two men responsible for the rapid progress of the sequencing activites of the Human Genome Project?
Francis Collins and Craig Venter
Which of the following properties is NOT characteristic of a malignant cell?
a) It no longer undergoes cell cycle regulation
b) It has undergone mutations in multiple genes
c) It cannot leave its site of growth in the tumor
d) It may have chromosome rearrangements
C) It cannot leave its site of growth in the tumor
Mutations in ____ can actively promote cell division.
Oncogenes.
Mutations in ____ lead to failure to repress cell division.
Tumor suppressor genes.
Burkitts lymphoma and chronic myelogenous leukemia are associated with which of the following:
a) Lack of tumor suppressor genes
b) Formation of thymidine dimers due to UV light exposure
c) Mutations induced by exposure to carcinogens in cigarette smoke
d) Reciprocal translocations on chromosomes.
D) Reciprocal translocations on chromosomes.
What types of genes characteristically controls enzymes that are involved in catabolic pathways, which break molecules down for energy?
Inducible genes.
Which type of genes typically control the enzymes involved in anabolic pathways, which build up macromolecules?
Repressible genes
Which level of gene regulation occurs via the action of inducible and repressable genes?
Transcription
Which of the following is NOT a consituent of an operon?
a) Operator
b) Structural genes
c) Promoter
d) Regulator gene
D) Regulator gene
If gene expression is regulated at the transcriptional level, where in a eukaryotic cell does this regulation take place?
Nucleus
Positive and negative regulator proteins that bind to specific regions of the DNA and stimulate or inhibit transcription in eukaryotes are known as:
transcription factors
By definition, enhancers are:
regions in the vicinity of a gene to which transcription factors bind.
Which of the following molecules participates in RNA interference?
a) siRNA
b) tRNA
c) rRNA
d) dsDNA
A) siRNA
What mutagen would only be active during DNA replication?
5-bromo uracil
Map-based sequencing:
Approach used by the publicly funded consortium to the sequence the human genome.
Whole genome shotgun sequencing:
Process of shattering the genome into many small pieces that are cloned and sequenced.
Dideoxy chain terminator sequencing:
Gold standard method for sequencing DNA developed by Frederick Sanger.
Automated DNA sequencing:
Use of fluorescent dyes to simultaneously detect all four nucleotides in a single sequencing reaction using a laser.
T or F: A dideoxy sequencing reactions contains all four deoxynucleotide triphosphates (dTNPs).
True
T or F: One way that eukaryotes coordinate expression of genes with similar function is through operons.
False
T or F: An insertion of 3 nucleotides into a coding sequence will alter the reading frame.
False.
T or F: Gene frequently mutated in cancer have normal functions in cell.
True
T or F: The function of most human genes identified by the HGP has been well characterized.
False. Only about half.
Primase:
Synthesizes small RNA molecule to provide 3'-OH
DNA helicase:
Unwinds DNA double helix at the replication fork.
DNA polymerase III
Elongates new nucleotide strand from RNA primer
DNA ligase:
Connects Okazaki fragments in lagging DNA strand.
DNA gyrase:
Reduces strain created ahead of the replication fork.
T or F: RNA polymerase requires a primer to initiate RNA synthesis.
False.
T or F: Peptide bonds are formed by the DNA component of the ribosome.
True.
The lac Operon is:
A negative, inducible regulated system.
T or F: Heritability is proportion of phenotypic variance due to genetic differences.
True
T or F: Wobble refers to relaxed base pairing at the first position of the codon.
False. It refers to relaxed base pairing at the third position of the codon.
T or F: The RNA base Inosine (I) can form base pairs with G, C, A or U.
True.
What is an example of a complex trait?
Body size, Blood pressure, Height.
The phenomenon in which genes on the same chromosome are separated from each other during meiosis and new combinations of genes are formed is known as:
Recombination
A frequency of recombination that is less than 50% implies:
The genes are linked on the same chromosome.
Typically, each crossover event produces how many recombinants?
2.
The distance between two points on the genetic map of a chromosome is equal to:
The average number of crossovers between them.
Over time, DNA replaced DNA as the primary carrier of genetic information and the chemical stability of DNA is believed to be the key reason for this. What attribute of DNA is the reason behind its chemical stability?
DNA lacks a free hydroxyl group on its sugar.
Which of the following statements concerning DNA structure is not true?
a) The two strands are complementary and anti-parallel
b) The structure was deduced by Watson and Crick
c) The final model was inconsistent with Chargaff's rule
d) X-ray diffraction patterns indicated a double helix.
C) The final model was inconsistant with Chargaff's rule.
Which type of chemical bond attaches deoxyribose molecules together to form the backbone of a DNA molecule?
Covalent.
The direction of DNA synthesis is:
Always 5' to 3'
The 3'-5' exonuclease activities of DNA polymerases read nascent strands as they are synthesized, removing any mispaired nucleotides at the 3' termini of the primer strands. This action is known as:
Proofreading.
Which of the following must be present in order for DNA polymerase to be active:
-Mg2+
-dNTPs
-a free 3' end
All of these.
DNA replication requires a free 3'-OH to initiate polymerase activity. This is accomplished by synthesizing:
A temporary RNA primer.
Central dogma of biology?
DNA--> RNA--> Protein
Consider the DNA template 3'- AAATTTTAGCCA -5'. When transcribed, what is the correct resulting transcript?
5'- UUUAAAAUCGGU -3'
RNA polymerase binds to a specific nucleotide sequence on the template strand known as:
Promoter
During a research event, the sigma subunit is removed from RNA polymerase enzyme. How will this affect the initiation of transcription?
Transcription will initiate at random spots along the template.
Which of the following is NOT a major modification that the primary transcript in eukaryotes undergo before translation?
a) Caps are added to the 5' ends of transcripts.
b) Poly (A) tails are added to the 3' end of the transcripts
c) Intron sequences are spliced out of transcripts.
d) Exon sequences are spliced out of transcripts.
D) Exon sequences are spliced out of transcripts.
What RNA molecules are involved in the translation process?
mRNA, tRNA, and rRNA.
What is the correct anti-codon sequence that corresponds with the codon sequence AUG?
CAU.
The initiation of translation with the 30S ribosomal subunit in E. coli does not involve:
ATP.
The function of aminoacly-tRNA synthetases is to:
Attach amino acids to the stem of tRNAs.
The genome of an alien race only has 2 types of nucleotide bases. If they have a single stop codon what is the maximum number of amino acids they could use if they have a triplet code?
2^3= 8
Minus one stop codon:
8-1=7
Which of the following DNA sequences from a gene are preserved in the amino acid sequence of the polypeptide it codes for?
a) the promoter
b) the 3' UTR
c) the start codon
d) the stop codon
e) the 5' UTR
C) The start codon.
You have assayed the DNA from a duckbill platypus and found it to be 22% cytosine (C). What are the percentages of the remaining bases of this organism?
A- 28%
G- 22%
T- 28% 100-44(G+C)= 56/2 = 28(A+T).
Why doesn't exchange between sister chromatids result in any recombinant chromosomes?
Sister chromatids are identical meaning they are copies of each other.
Why do eukaryotic chromosomes have multiple origins of replication, whereas prokaryotic chromosomes typically have only one region? Provide at least two reasons:
Prokaryotes only have one DNA molecule to copy, eukaryotic have more.
The rate of replication in eukaryotes is much too fast based on the number of nucleotides for only one origin.
Compare the structure of DNA to the structure of RNA:
Uracil instead of Thymine in RNA, RNA is single stranded DNA is double stranded, RNA has ribonucleic sugar, DNA has deoxyribonecleic sugar.
Define gene:
A gene includes the actual DNA code that will be translated into a gene product as well as any promoter elements up or downstream from the initiation and termination sites of the transcribed DNA.
A geneticist discovers that two different proteins in mouse are encoded by the same gene. One protein has 56 amino acids, and the other has 82 amino acids. Based on what you have learned about RNA processing in eukaryotes, provide a possible explination for how the same gene can produce two different proteins:
One possible explination is that RNA splicing occured differently during RNA processing for the proteins. This would lead to more or less amino acids being produces, which changes the produced protein.
Hardy-Weinberg genotype frequency expression:
p^2 + 2pq + q^2
Which of these could upset the Hardy-Weinberg equilibrium?
a) Mutation
b) Migration
c) Natural Selection
d) Genetic drift
All of these.
The frequency of sickle cell anemia, caused by a homozygous condition, (Hb^sHb^s) is approx. 0.0016. Assuming the Hardy-Weinberg equilibrium applies, what is the frequency of the (Hb^s) allele?
p^2= (Hb^s*Hb^s) = 0.0016
p= sqr rt of 0.0016= 0.04
Polygenic:
A character of trait determined by more than one gene.
Expressivity
The degree to which a character or trait is expressed
Codominance
Two alleles contribute independently to the phenotype
Penetrance
The % of individuals with a genotype that express the phenotype.
Pleiotrophy
Condition where a single gene influences more than one phenotype.
T or F: Epistasis involves interactions between alleles at a single genetic locus.
False
T or F: In humans, meiosis coincides with the onset of puberty in both males and females.
False. Females produce pre-gametes in utero, but meiosis occurs at puberty.
T or F: Homologous pairs of chromosomes separate (disjoin) during Meiosis I.
True
T or F: Mendel used the dihybrid cross to demonstrate the principle of independent assortment.
True
T or F: The environment has little effect on the expression of phenotypes.
False.
T or F: Alleles that cause lethality in the embryo can be dominant with respect to the trait they influence.
True.
Indicate the phenotypic sex in humans that will result from:
-XY with SRY gene deleted:
-XY with SRY gene on autosome:
-XX with SRY gene on autosome:
-XO with SRY gene on an autosome:
-XXY with SRY gene deleted:
Female
Male
Male
Male
Female
Indicate the number of barr bodies you would expect to see:
- XX
-XY
-XO
-XXY
-XXX
-1
-0
-0
-1
-2
A diploid somatic cell from a rat has a total of 42 chromosomes 2n=42. What is the total number of chromosomes present in the cell during metaphase I of meiosis?
42
What is the total number of telomeres in a rate cell following s-phase?
168 (84*2=168)
What term refers to mating between closely related people?
Consanguinity
Removal of the Xist gene from the X chromosome would have the following effects EXCEPT?
a) both alleles of genes on the X chromosome would be expressed.
b) Barr bodies would be visible in the nucleus of female cells
c) normal dosage compensation for x-linked genes in males
d) undetecable mosaicism in somatic cells taken from a female
B) Barr bodies would be visible in the nucleus of female cells.
All of the following contribute to genetic variation in an individual except:
a) Mutation
b) Gene flow
c) Mosaicism
d) Copy-number
B) Gene flow
The complete set of chromosomes possessed by an organism is called a:
karyotype
The Philedelphia chromosome is a specific chromosomal abnormality associated with chronic myelogenous leukemia (CML) that produces a fusion gene of novel function. What type of chromosomal rearrangement is it an example of?
Translocation.
Copy number variations (CNVs) cover approx. 360 megabases (Mb) or ___ of the human genome.
12%
What is the difference between positive and negative control of gene expression?
Positive gene control "turns on" activator to promote gene expression.
Negative gene control "turns off" or represses gene expression.
A mutation at the operator site that blocks the binding of a repressor in an inducible system would result in an operon that:
is expressed constitutively.
A mutation that prevents CAP from binding to the promoter of the lac operon will:
Make RNA polymerase bind poorly to the promoter.
A mutant strain of E. coli produces beta-galactosidase in the presence and absence of lactose. Where in the operon is the mutation likely to be?
In the operator of the lac promoter.
The blob operon produces enzymes that convert compound A to compound B. The operon is controlled by regulatory gene S. Normally the enzymes are encoded in the abscence of compound B. If the S gene is mutated, the enzymes are synthesized in the presence and absence of compound B.
-Does the S gene produce an activator or a repressor?
-Is this operon inducible or repressible?
-Repressor
-Repressible
Which of the following statements is NOT true about mutation?
a) mutation refers to a change in the genetic material
b) point mutations involve changes at specific sites in a gene
c) somatic mutations are passed on to the offspring
d) genetic mutation is the driving force for evolution
C) Somatic mutations are passed on to the offspring.
Which of the following is a known mutagen?
-UV light
-Irradiation
-5-Bromouracil
-Transposons
-All of these
All of these
Restoration of the wild type phenotype in a mutant organism can result from:
Back mutation or suppresor mutation
A mutation that has no phenotypic effect on the organism is known as:
Neutral mutation
Base-pair additions and deletions that alter the reading frame of all subsequent base-pair triplets are collectively referred to as:
Frameshift mutations
Genes that are continually being expressed in most cells are referred to as:
constitutive genes
Where does the regulator bind in order to control transcription?
Operator
Describe the type of regulation of the lac operon?
Negatively controlled inducible operon.
What happens in the lac operon when both lactose and glucose are present in the environment?
Transcription of the lac operon will not occur because of catabolite repression.
What type of operon is the trp operon?
Negative repressible operon.
Which of these is not required for transcription?
a) ribonucleotides
b) RNA primers
c) DNA template
d) RNA polymerase
B) RNA primers
How many introns are present on a gene that consists of 4 exons?
3
Which would not be found on an mRNA molecule?
a) Promoter
b) Protein-coding region
c) 3' untranslated region
d) 5' untranslated region
e) start and stop codons
A) Promoter
What establishes the reading frame of a nucleotide sequence in prokaryotes?
First start (AUG) codon.
The number of aminoacyl tRNA-synthetase enzymes is equal to the number of:
Amino acids
The form of cellular energy required for protein synthesis is:
GTP
Which mechanism allows for more than one polypeptide to be encoded by a single gene?
Alternative RNA splicing.
Telomerase activity is most likely to be found in what cells in humans?
Germ cells
Why did the Meselson and Stahl experiment require two rounds of replication?
The first round ruled out conservative replication since there was a band of hybrid isotopes. The second round was required to establish whether it was dispersive or semi-conservative since a single band of hybrid isotopes would result from the dispersive method and a band of lighter isotope and a band of hybrid isoptope weight would result from semi-conservative.
Which model best explains the inheritance of complex traits such as height, weight and IQ?
Control of the traits by more than one gene plus environmental effects.
You are studying genes X, Y and Z that are linked (in that order) in the Imperial Scorpion. The distance between X and Y is 10 cM, the distance between Y and Z is 8cM. You obtain 1500 progeny and 5 of those progeny show the phenotype of double crossover progeny. What is the interferance value for crossover formation in the X to Z interval?
0.1 * 0.08 = 0.008 *1500= 12
1-(5/12)= 0.58
What term implies genetic imbalance?
Aneuploid
The most common cause for trisomy events in human beings is:
Non-disjunction during meiosis
Genetic distances within a given linkage group:
a) cannot exceed 50 cM
b) depend on crossover frequencies
c) are measured in centiMorgans.
All of these are correct.
Red-green colorblindness is a human X-linked recessive disorder. A young man with a 47XXY karyotype (Klinefelter syndrome) is completely colorblind and cannot distinguish red and green colors at all. His 46, XY brother also is colorblind. Both parents have normal color vision. Where did the nondisjunction that gave rise to the young man with Klinefelter syndrome take place?
Meiosis II in the mother.
Given an individual with a single recessive allele, explain how a deletion could result in the expression of the recessive phenotype.
Deletions of masking dominant alleles can "uncover" recessive alleles, causing them to be expressed.
If a geneticist refers to a "true-breeding" strain s/he means a group of organisms that:
Are homozygous for a particular trait.
In a cross between true-breeding tall plants with true-breeding short plants, all the F1 are tall. When these plants are allowed to fertilize themselves, the F2 plants occur in a ratio of 3 tall to 1 short. What is a valid conclusion?
The tall and short traits assort independently of each other.
Phenylketonuria (PKU) is a metabolic disease that results from inheriting two recessive alleles. Two normal parents produce a child with PKU. What is the probability that their next child will have PKU?
25%
In the endangered Australian watchamakallit, the offspring of a true-breeding black parent and a true-breeding white parent are all gray. When the gray offspring are crossed among themselves, their offspring occur in a ration of 1 black 2 gray 1 white. Upon close examination of the coats, each hair of a gray animal is gray. What is the mode of inheritance?
Incomplete dominance.