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April 2015 Genetics Exam

Terms in this set (46)

The physiological conditions in cells...
Favor formation of hydrogen bonds between complementary nucleic acid polymers
What describes bacterial and eukaryotic promoters?
Bacterial and eukaryotic promoters contain conserved sequences
Assessory proteins modulate RNA polymerase binding to both eukaryotic and bacterial promoters
What is the role of sigma protein in transcription
Binds to RNA polymerase to permit binding to promoter sequences, initiating transcription
snRNAs play a role in....
RNA processing, functioning as catalysts of intron removal
Which the following are examples of sacrificial nucleic acid sequences?
3'-poly (A) sequences and telomeres
What is the role of rho protein in transcription?
Binds to RNA polymerase to force separation of RNA polymerase from DNA terminating transcription
Which of the following is a unique feature of telomerase?
It carries its own template RNA strand
Where do the processes of 7'-methyl guanine addition, poly(A) addition, and intro removal occur in eukaryotic cells?
Nucleus
Which os the following is common to the two mechanisms of bacterial termination of mRNA synthesis?
Formation of a stem-loop structure in the mRNA is involved in termination
Compared to promoters in bacterial cells, promoters in eukaryotic cells are...
Analogues
Which of the following is responsible for "proof-reading" DNA during replication?
The 3' --> 5' exonuclease activity of DNA polymerase
A number of different mRNAs can be produced from a single gene that contain introns
Possible
Conserved sequences
DNA sequence hat is found in a variety of different genes
Promoter sequences in eukaryotes...
have a great number of conserved sequences than promoters of bacteria
What would be the consequence on transcription of the antibiotic-degrading gene of deleting 5 base pairs in the sequence between the -10 and -35 conserved sequences?
Decrease transcription
What would be the consequence on transcription of the antibiotic-degrading gene of substituting all the A-T base pairs with the same number of G-C base pairs in the sequence between the -10 and -35 conserved sequences?
Would not influence transcription
What would be the consequence on transcription of the antibiotic-degrading gene of changing all the A-T pairs in the sequence 10-bases upstream from the mRNA transcription start site to G-C pairs?
Decrease transcription
What is the activity of RNA polymerase?
RNA polymerase adds 5'-NTPs following a template DNA strand without the need for a DNA primer
What distinguishes "rolling circle" DNA replication from semi-conservative DNA replication?
In "rolling circle" replication there is covalent addition of bases to parental DNA
If given the nucleotide sequence of a eukaryotic gene, what could be employed to identify introns?
Find mRNA sequence related to the 5'- and 3'-consensus sequence of introns for the particular organism
Generally speaking for an individual eukaryotic gene, the intervening sequences make up...
More of the DNA than the exons
What are examples of nucleic acid hybridization involved in translation?
Both mRNA: rRNA and tRNA: mRNA hybridization
What distinguishes the processes of transcription in bacteria and humans?
In humans, nuclear mRNA contains intervening sequences
In humans, the 5'-end of the mRNA is modified by the addition of N-methyl guanine
What is an advantage of the presence of intervening sequences in genes?
More than one mRNA can be spliced together form the initial transcript
What involves the hybridization of RNA molecules in cells?
mRNA processing and transcription termination in bacteria
Where does RNA processing occur?
In the nucleus
Is it possible for a gene with a mutation in the coding region for a protein to encode with the same amino acid sequence as the protein from the non-mutant gene?
Yes
Which end of the protein is synthesized first?
The amino terminus
The genetic code is...
Triplet, non-overlapping, universal
What would characterize a mutant strain of E. coli that lacks the 3'--> 5' exonuclease activity of DNA polymerase
Higher frequency of mutation
You map a mutation in a gene and find that it is located near the 5' end of the mRNA. Where would the changed amino acid be located in the protein?
At the amino- or N-terminus
The mRNA binds to the ribosome through...
hybrid formation between a sequence at the 5' end of the mRNA and a sequence at the 3' end of rRNA
What would be one effect of preventing the addition of adenines at the 3'-end of mRNA in red blood cells producing hemoglobin?
The amount of globin mRNA would fall more rapidly than it would normally
If you are given the amino acid sequence of a protein, you would know the exact nucleotide sequence of the gene encoding that protein.
False
What is the molecular basis for the ability of cells to correct a mis-incorporated base in the newly synthesized DNA strand after the replication fork has moved away from the mismatch?
The strand with fewer methyl groups is repaired by excision and base replacement
Which of the following would characterize a mutant strain of E Coli that lacks DNA ligase?
Delayed joining of DNA fragments into longer DNA strands
What is the relationship between RNA repair and the need to get an influenza virus vaccination annually?
Because RNA polymerase lacks "proof-reading", influenza virus has a higher frequency of mutants
What is the function of the 5'--> 3' exonuclease activity of DNA polymerase?
Degradation of RNA primers in Okazaki fragments
What is an Okazaki fragment?
Short single stranded DNA fragments initiated with an RNA primer and complementary to a template DNA strand
Are the poly(A) sequences at the 3-ends of eukaryotic mRNAs encoded in the genes' DNA
No, the poly(A) sequence in mRNA is not encoded in DNA
What describes the direction of translation of proteins?
Initiation with the amino-terminal amino acid and termination with the carboxyl-terminal amino acid
Why does protein synthesis halt when the ribosome encounters a chain-termination codon?
There are no tRNAs for the three chain-terminating codons
What type of RNA molecules are only found in the nucleus of eukaryotic cells?
snRNA
Why are rRNAs relatively more stable to RNase digestion compared to mRNAs?
rRNAs have folded, stem-loop structures and are complexed with proteins; mRNAs don't
What can result in the expression of the insulin gene in a bacterial cell?
Get rid of the insulin gene's promoter and use a promoter form the bacterial cell for transcription
How would the deletion of the ribosome-binding site in DNA affect translation of a bacterial mRNA?
Abolish translation
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