gen test3
Most TNRE repeats involve expansion of which codon? GAA CAG Any codon containing three of the same bases CCC ATG
CAG
Spontaneous mutations include: Depurination, deamination, errors in DNA replication UV light, deamination, depurination, errors in DNA replication UV light, radiation, deamination, depurination UV light, radiation, errors in replication, deamination
Depurination, deamination, errors in DNA replication
A wholphin is a rare hybrid animal born from mating a female bottlenose dolphin with a male false killer whale. Wholphins are diploid, and interestingly are fertile. What can you conclude from the fact that wholphins are fertile? Dolphins and false killer whales likely have the same number of chromosomes One of the parents must have been aneuploid Wholphins are allotetraploid Dolphins and false killer whales are actually the same species
Dolphins and false killer whales likely have the same number of chromosomes
Q1. A short genetic sequence, which may be recognized by DNA primase, is repeated many times throughout the E. coli chromosome. Researchers have hypothesized that DNA primase may recognize this sequence as a site to begin the synthesis of an RNA primer for DNA replication. The E. coli chromosome is roughly 4.6 million bp in length. How many copies of the DNA primase recognition sequence would be necessary to replicate the entire E. coli chromosome?
For making Okasaki fragments a primer is needed. The length of Okasaki fragments is considered to range from 1000 - 2000 bp. If we assume the average length of an Okasaki fragment as 1500 bp, the number of primase recognition sequences for a bacterial genome of 4.6x10^6 bp size = 4.6x10^6/1500 = 3066.67 or 3067 copies.
Telomeric sequences are typically: CG rich AG rich GT rich AT rich
GT rich
One way that bacterial cells regulate DNA replication is by GATC methylation sites within the origin of replication. Would this mechanism work if the DNA was conservatively (rather than semiconservatively) replicated? Why or why not?
This would not work in conservative replication. In conservative replication, one of the double helices would always be completely methylated, and the other would not. Therefore, the cell would not be able to delay the next round of DNA replication by controlling the methylation of DNA strands.
Which of the following processes accounts for the tremendous variation in antibody structure? RNA editing integrase activity physiological adaptation site-specific recombination hot spots of mutation in the immunoglobin genes
site-specific recombination
The common goldfish Carrassius auratushas 100 chromosomes and is tetraploid. The goldfish therefore has___ sets of chromosomes containing ____chromosomes each. 2; 50 4; 25 4; 100 1; 100
4; 25
A temporary change in the conformation of a nitrogenous base is called: Dupurination A tautomeric shift Deamination None of these answers are correct
A tautomeric shift
Q3. The compound known as nitrous acid is a reactive chemical that replaces amino groups (NH2) with keto groups (=O). When nitrous acid reacts with the bases in DNA, it can change cytosine to uracil and adenine to hypoxanthine. A DNA double helix has the following sequence: TTGGATGCTGG AACCTACGACC A. What would be the sequence of this double helix immediately after reaction with nitrous acid? Let the letter H represent hypoxanthine and U represent uracil. B. After the nitrous acid is removed, suppose this DNA was replicated for two generations. Illustrate the sequences of the DNA products after each replication. Note: During replication, uracil hydrogen bonds with adenine, and hypoxanthine hydrogen bonds with cytosine.
A. TTGGHTGUTGG HHUUTHUGHUU B. TTGGHTGUTGG HHUUTHUGHUU . TTGGHTGUTGG CCAAACACCAA AACCCACAACC HHUUTHUGHUU TTGGHTGUTGG TTGGGTGTTGG CCAAACACCAA CCAAACACCAA AACCCACAACC AACCCACAACC GGTTTGTGGTT HHUUTHUGHUU
A mutagen is: A depurinated base An agent that can alter the structure of DNA and cause mutations A DNA polymerase without a 5' to 3' exonuclease A deaminated base
An agent that can alter the structure of DNA and cause mutations
What is an allodiploid? What factor determines the fertility of an allodiploid? Why are allotetraploids more likely than allodiploids to be fertile?
An allodiploid is an organism having one set of chromosomes from two different species. Unless the two species are closely related evolutionarily, the chromosomes do not synapse during meiosis. Therefore, they do not segregate properly, which produces aneuploid gametes that are usually inviable. By comparison, allotetraploids that have two sets of chromosomes from each species are more likely to be fertile because each chromosome has a homolog to pair with during meiosis.
An example of a suppressor mutation would be: An intergenic mutation that activates a transcription factor that increases the expression of a normal protein An intragenic mutation that restores the inactive protein's structure A mutation that suppresses cell growth An intergenic mutation that increases the activity of a protein performing a different function as the mutated protein
An intragenic mutation that restores the inactive protein's structure
Q3.Male honeybees, which are monoploid, produce sperm by meiosis. Explain what unusual event (compared to other animals) must occur during spermatogenesis in honeybees to produce sperm? Does this unusual event occur during meiosis I or meiosis II?
Complete nondisjunction occurs during meiosis I. One nucleus receives all the chromosomes and the other nucleus does not get any. The nucleus without any chromosomes will die off. The nucleus with all the chromosomes will proceeds through a normal meiosis II to produce two haploid sperm cells.
Mutations that change the configuration of a protein at a specific temperature are called ___ mutations. Neutral Conditional Deleterious Beneficial
Conditional
Which of the following domain types is unique to the heavy chain of an immunoglobin polypeptide? C V J D
D
Which of the following attaches adjacent Okazaki fragments, forming a continuous DNA strand: DNA Polymerase III Topoisomerase DNA primase DNA ligase DNA Polymerase I
DNA ligase
Which of the following may account for the process of gene conversion? nucleotide excision repair DNA mismatch repair retrotransposition photolyase activity
DNA mismatch repair
Synthesizes the lagging strand of the DNA. DNA primase DNA polymerase I DNA polymerase III Topoisomerase DNA ligase
DNA polymerase III
Which of the following fills in small regions of DNA where the RNA primers were located? DNA polymerase III DNA helicase DNA ligase DNA primase DNA polymerase I
DNA polymerase III
The conversion of cytosine to uracil in DNA is an example of: Depurination Deamination Demethylation Tautomeric shifts
Deamination
Dam methylase (DNA adenine methyl transferase) recognizes which of the following sequences: CATG GATC GTAC CAAG
GATC
Which repair mechanism utilizes MutL, MutH, and MutS proteins in E. coli? Base excision repair Nonhomologous end joining (NHEJ) Direct repair Mismatch pair Nucleotide excision repair
Mismatch pair
Describe three naturally occurring ways that chromosome number can change.
Nondisjunction is a mechanism whereby the chromosomes do not segregate equally into the two daughter cells. This can occur during meiosis (#1) to produce cells with altered numbers of chromosomes, or it can occur during mitosis (#2) to produce an individual with genetic mosaicism. A third way to alter chromosome number (#3) is by an interspecies cross that produces an alloploid.
Which types of mutations are least likely to be subjected to natural selection? Nonsense Missense Insertion Silent
Silent
3' ends of the eukaryotic linear chromosomes are replicated by: DNA polymerase a Primase DNA polymerase b DNA polymerase I Telomerase
Telomerase
How does position effect influence gene expression? Translocations always result in a gene being recombined into an area of heterochromatin Translocations may result in a promoter that is normally used for one gene now controlling an entirely different gene Since this mechanism relies on recombination it relies on the positioning of one allele so that it is under the control of the other allele. Point mutations in promoters frequently occur by this mechanism
Translocations may result in a promoter that is normally used for one gene now controlling an entirely different gene
Which of the following stops the replication of DNA in prokaryotes? Okazaki fragments Tus proteins the end of the chromosome DNA ligase
Tus proteins
All light chain polypeptides in an immunoglobin contain which of the following? a C region a V region a J region only a C and a V region all of the above
all of the above
What term describes an organism with two complete sets of chromosomes from two different species? allotetraploid aneuploid tetrapoid allodiploid
allotetraploid
Okazaki fragments do which of the following? assist in the synthesis of DNA from the lagging strand assist in forming the replication fork reform the double helix following replication bind to the oriC region
assist in the synthesis of DNA from the lagging strand
Humans with aneuploidy who survive usually have incorrect numbers of chromosome 13, 18, 21, or the sex chromosomes. This may be due to: the chromosomes have clusters of genes that aid in embryonic growth the chromosomes are small and carry relatively few genes X-chromosome inactivation both b and c may be correct
both b and c may be correct
The term endopolyploidy refers to the phenomenon of having: extra sets of chromosomes in gametes extra chromosomes in the cell nucleus too many chromosomes certain cells of the body with extra sets of chromosomes
certain cells of the body with extra sets of chromosomes
A drug that is used to experimentally produce polyploidy in organisms is: colchicine karyocine polymosca doxorubicin penicillin
colchicine
Which of the following most likely accounts for the majority of the recombination events during both DNA repair and meiosis? a nick in only one strand of the DNA DNA gap repair synthesis heteroduplex formation double-stranded breaks in DNA
double-stranded breaks in DNA
If eukaryotic cells evolved such that lagging strand DNA synthesis could occur continuously (without the use of Okazaki fragments), what enzyme would likely no longer be needed for DNA replication? topoisomerase primase flap endonuclease helicase
flap endonuclease
Gene conversion requires recombination and which of the following events? excision repair inversion reversion heteroduplex formation suppression
heteroduplex formation
Which human cells exhibit endopolyploidy? red blood cells sex cells nerve cells all somatic cells liver cells
liver cells
The polytene chromosomes of Drosophilaare an example of: inversion loops aneuploidy polyploidy translocations none of these answers are correct
polyploidy
Which of the following best describes the function of the RecA protein in E. coli recombination? is involved in the initial formation of the Holliday junctions promotes strand invasion and formation of the D loop resolves Holliday junctions into separate chromosomes recognizes double-stranded breaks in the DNA
promotes strand invasion and formation of the D loop
The process of ___ is extremely important in generating genetic diversity. translation replication transcription recombination
recombination
The Holliday model is used to explain which of the following: recombination between homologous chromosomes the migration of transposons recombination between sister chromatids the generation of antibody diversity
recombination between homologous chromosomes
Which of the following often leads to deletion in chromosome sequences? the creation of harlequin chromosomes recombination between sister chromatids the action of transposons recombination between homologous chromosomes
recombination between homologous chromosomes
Meiotic nondisjunction usually occurs during meiosis I. What is not separating properly: bivalents or sister chromatids? What is not separating properly during mitotic nondisjunction? In meiotic nondisjunction, the bivalents are not
separating correctly during meiosis I. During mitotic nondisjunction, the sister chromatids are not separating properly.
Which of the following is NOT correct concerning the initiation of bacterial replication? Topoisomerase II moves ahead of the replication fork to remove supercoils the strands are initially separated at GC-rich regions of DNA it involves a region o DNA called oriC DNA proteins bind to the DNA to begin separation of the strands
the strands are initially separated at GC-rich regions of DNA
What type of plants are usually seedless? tetraploid triploid diploid aneuploid
triploid
The somatic cells of an allotetraploid contain: one set of chromosomes from four different species one set of chromosomes from two different species four sets of chromosomes from one species two sets of chromosomes from two different species
two sets of chromosomes from two different species