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Missed Test 4 Questions

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1
DNA methylation and histone acetylation are examples of which of the following processes?
  • genetic mutation
  • chromosomal rearrangements
  • epigenetic phenomena
  • translocation
  • transformation
2
In eukaryotic cells, transcription of pre-mRNA cannot begin until which of the following occurs?
  • the 2 DNA strands have completely separated and exposed the promoter
  • several transcription factors have bound to the promoter and the specific enhancer to loop the DNA
  • the 5' caps are removed from the mRNA
  • the DNA introns are removed from the template
  • DNA nucleases have isolated the transcription unit
3
In the structural organization of many eukaryotic genes, individual exons code for which of the following?
  • the sequence of the intron that immediately precedes each exon
  • the number of polypeptides making up the functional protein
  • the various domains of the polypeptide product
  • the number of start sites for transcription
4
Which of the following explains how some eukaryotic DNA sequences act as introns in some tissue cells and as exons in other tissue type cells?
  • differential gene repression in the different cell types
  • alternative splicing and recombination of DNA in the different cell types
  • gene amplification in some tissue cells and none occurs in other tissue cells
  • alternative splicing of pre-mRNA into mRNA in the different cell types
  • splicing of DNA gene occurs differently in each type of cells
5
Which describes how gene loci in eukaryotic nuclei are expressed in heritable traits information in the cell?
  • DNA from a single gene is replicated and transferred to the cytoplasm, where it serves as a template for protein synthesis
  • pre-mRNA is transcribed from single gene loci in the nucleus and modified into mRNA before being transported to cytoplasm, where they are translated into polypeptides which are modified into specific functional proteins
  • histone proteins in the chromosomes transfer information from the nucleus to the ribosome, where protein synthesis takes place
  • transfer RNA takes information from DNA directly to a ribosome, where protein synthesis takes place
6
Which of the following processes will occur at the 3' end of tRNA?
  • the excess nucleotides (ACCA) will be cleaved off at the ribosome
  • the small and large subunits of the ribosome will attach to it
  • specific amino acyl tRNA synthetase catalyzes a dehydration reaction that bonds the specific amino acids carboxyl group to the 3' end of tRNA
  • the 5' cap of the mRNA will become covalently bound to the 3' end of tRNA
  • the 3' OH group of the tRNA serves as the recognition site for the small ribosomal subunit to initiate translation
7
Once a peptide bond has been formed between an amino acid in the ribosome P site and the amino acid in the A site, which process occurs next?
  • translocation movement of the mRNA codon from the A site to the P site
  • reading of the next codon of mRNA
  • initiation of separation of the ribosomal subunits
  • the codon-anticodon hydrogen bonds holding the tRNA in the A site are broken
  • the next charged tRNA enters the vacant E site
8
Post-translation modifications of polypeptides in eukaryotic ER and Golgi include which of the following processes?
  • removal of introns
  • addition of a 5' cap
  • addition of a poly-A tail
  • addition of carbohydrates to form a glycoprotein
  • addition of methyl groups to inactivate the protein
9
Which of the following statements correctly describes the effect a nonsense mutation would have on a gene?
  • it changes an amino acid in the encoded protein
  • it has no effect on the amino acid sequence of the encoded protein
  • it introduces a premature stop codon into the mRNA
  • it alters the reading frame of the mRNA
  • it changes a hydrophobic amino acid to a hydrophilic amino acid
10
In the structural arrangement of nucleotide sequences coding for individual exons in eukaryotic genes for pre-mRNA, code for which of the following?
  • the sequence of the intron that immediately precedes each exon
  • the number of polypeptides making up the functional protein
  • each specific exon type code for a specific shaped domain in the polypeptide product translated from a eukaryotic mRNA
  • each exon is a specific site recognized by a specific restriction enzyme cutting site
  • each exon codes for a specific start site for transcription
11
The functioning of enhancers is an example of which of the following?
  • a eukaryotic equivalent of prokaryotic promoter functioning
  • transcriptional control of gene expression
  • the stimulation of translation by initiation factors
  • post translational control that activates certain proteins
12
Cell differentiation always involves which of the following?
  • transcription of the myoD gene
  • the movement of cells
  • the synthesis of tissue specific proteins
  • the selective loss of certain genes from the genome
13
Which of the following statements describes a cell that is considered, to be differentiated?
  • the cell replicates by the process of mitosis
  • the cell loses connections to the surrounding cells
  • the cell produces proteins specific to a particular cell type
  • the cell has a shape and characteristics demonstrated by the zygote
  • the cell appears to be different from the surrounding cells
14
Which of the following describes an example of epistasis?
  • recessive genotypes for each of two genes (aabb) results in an albino corn snake
  • the allele b17 produces a dominant phenotype, although b1 through b16 do not
  • in rabbits and many other mammals, one genotype (cc) prevents any fur color from developing
  • in Drosophilia (fruit flies), white eyes can be due to an X-linked gene or to a combination of other genes
  • in cacti, there are several genes for the type of spines
15
Homozygous true-breeding red, axial flower pea plants are crossed with homozygous white, terminal flower pea plants. All F1 individuals have red, axial flowers. The genes for flower color and flower position on stems assort independently. What fraction of the offspring could be expected in the F2 to have red, terminal flowers?
  • 9/16
  • 3/16
  • 4/16
  • 1/16
  • none
16
The flower color trait in radishes is an example of which of the following?
  • epistasis
  • a multiple allelic system
  • sex linkage
  • co-dominance
  • incomplete dominance
17
If true-breeding red, long radishes are crossed with true-breeding white, oval radishes, which fraction of the F2 generation would be expected to express purple flowers and longs radishes?
  • 9/16
  • 3/16
  • 6/16
  • 2/16
  • 1/16
18
Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines wheteher or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. The relationship between genes S and N is an example of which of the following?
  • incomplete dominance
  • complete dominance
  • epistasis
  • pleiotropy
  • co-dominance
19
In one type cross of black Labrador retrievers x black, the results were as following: 9/16 black; 4/16 yellow; 3/16 braown. The genotype bbee must result in which of the following?
  • black
  • brown
  • yellow
  • a lethal result
  • white
20
If snapdragons are heterozygous for heights as well as for flower color, a mating between them will result in what ratio of tall (T) to dwarf (dd)?
  • 1/2 tall:1/2 dwarf
  • 3/4 tall:1/4 dwarf
  • 1/4 tall:2/4 tall:1/4 medium
  • 1/4 dwarf: 2/4 tall:1/4 medium
  • 9/16 tall: 7/16 dwarf
21
If the parents of a fault already have two boys, what is the probability that the next two offspring will be girls?
  • 1.0
  • 1/2
  • 1/3
  • 1/4
  • 1/8
22
The first offspring from the parents are called which of the following?
  • P1
  • F1
  • F2
  • a testcross
  • a backcross
23
In a dihybrid cross AABB x aabb to produce F1 hybrids, what portion of heterozygotes for both gene pairs (AaBb) is expected among the F2 offspring?
  • 1/4
  • 1/2
  • 3/4
  • all are heterozygotes
  • none are heterozygotes
24
In response to either external or internal environment signaling, prokaryotes can do which of the following?
  • turn off translation of their mRNA
  • alter the production of various proteins required by the cell to function in its changing environment
  • increase the number of ribosomes to speed up synthesis of various enzymes
  • inactivate their mRNA molecules
  • alter the sequence of amino acids in certain proteins
25
Which is a prokaryotic single DNA unit that enables bacteria to simultaneously regulate expression of more than one gene in response to signal molecules due to their environmental changes?
  • promoter
  • operator
  • regulator
  • inducer
  • operon
26
Which type of prokaryotic regulatory proteins of a specific operon are the products of expression of a specific regulatory gene and translation of its mRNA codes?
  • cyclic AMP-CRP complex
  • inducer
  • operator
  • repressor
  • co-repressor
27
Which of the following are characteristics of a prokaryotic mRNA primary transcript?
  • it codes for many different polypeptides and it's 5' end sequence is bound by a small ribosome subunit
  • it begins to be translated before the mRNA has been completely formed
  • it must be spliced, capped, and add a 3' poly A tail before it can be translated
  • it attached to charges serves as the primer for the start of DNA replication
  • it is a corepressor
28
Which signals bacterial repressible operon such as the tryptophan operon to be actively transcribed?
  • occurrence of repressor molecules binding to the promoter
  • occurrence of a low supply of the end products formed by the enzyme pathway encoded by the operon's genes
  • the accumulation of a high supply of the end products of the enzyme pathway encoded by the operon's genes
  • the occurrence of high quantities of precursor substrate molecules
  • the lack of other substrates for alternative biochemical pathways in the cell
29
Which of the following molecules is a co-repressor for the bacterial tryptophan operon?
  • glucose
  • cAMP
  • lactose
  • tryptophan
  • CRP
30
Under what conditions does the tryptophan repressor block transcription of the tryptophan operon?
  • when the repressor binds to the inducer
  • when the accumulation of excessive amounts of tryptophan facilities binding of repressor to tryptophan
  • when the repressor is not bound to tryptophan
  • when the repressor is not bound to the operator
31
Which bacterial cellular conditions induce an increase in cyclic AMP receptor protein (CRP) initiating positive control of the transcription of the lactose metabolism operon?
  • as glucose levels increase in cells there is an increase in cAMP which binds CRP to form a complex that attaches to the lactose operon's promoter to speed up transcription
  • as glucose levels decrease in cells there is an increase in cAMP which binds CRP to form a complex that attaches to the lactose operon's promoter to speed up transcription
  • as glucose levels increase in cells there is an decrease in cAMP which binds CRP to form a complex that attaches to the lactose operon's promoter to speed up transcription
  • as glucose levels decrease in cells there is a decrease in lactose repressors that block expression of the lactose operon
32
Under what conditions does the bacterial tryptophan repressor block transcription of the tryptophan operon?
  • when the repressor binds to the inducer
  • when the repressor is not bound to tryptophan
  • when tryptophan binds to the repressor
  • when the repressor is not bound to the operator
33
Which of the following molecules binds with the bacterial lactose repressor to alter its allosteric conformation structure and therefore affects its function?
  • inducer
  • promoter
  • transcription factor
  • cyclic AMP
  • activator proteins
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