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Biology 1105 Virginia Tech, Exam 3 with 100- correct answers(graded A+)
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Biology 1105 Virginia Tech, Exam 3 with 100- correct answers(graded A+)
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Biology 1105 Virginia Tech,Exam 3 with 100% correct
answers(graded A+)
Imagine that during replication an extra base is added in the coding
region of a gene and that this is not recognized by the repair
mechanisms. Which of the following would result from this
mutation?
A. The chromosome that holds the DNA sequence will show an
inversion
B. The encoded protein would have a different sequence of amino
acids starting at the site of the new base and moving on.
C. The encoded protein would be produced normally
D. The encoded protein would have one altered amino acid, but
everything else would be normal - answer B. The encoded protein
would have a different sequence of amino acids starting at the site
of the new base and moving on.
This is because an addition of a base would shift the reading frame,
and therefore change how each codon is read. Example:
AAT GCA CTG CAT... would be read as those codons but with the
addition of a base this sequence is read differently.
AGA TGC ACT GCA... this changes the amino acids.
What role does a promoter play in the process of transcription in
prokaryotes?
,A. It is a special factor that facilitates termination of transcription
and dissociation of RNA polymerase
B. It is a carrier protein that carries mRNA out of the nucleus
C. It is a region of DNA that binds and correctly orients RNA
polymerase to initiate transcription
D. It is a component of the RNA polymerase holoenzyme that
unwinds the DNA template - answer C. It is a region of DNA that
binds and correctly orients RNA polymerase to initiate transcription.
Once the entire ribosome has assembled on the mRNA, what
reaction does it catalyze?
A. The formation of peptide bonds between incoming amino acids
and the growing peptide
B. The formation of phosphodiester bonds between nucleotides in
the mRNA
C. The formation of hydrogen bonds between 2 strands of DNA
D. The formation of phosphodiester bonds between rRNA
components of the ribosome - answer A. The formation of peptide
bonds between incoming amino acids and the growing peptide.
Crick originally proposed that there had to be an adaptor molecule
that linked amino acids to short sequences of the genetic code. This
linker molecule was later identified as?
A. mRNA
B. tRNA
C. rRNA
D. snRNA - answer B. tRNA
Which of the following is not true about the genetic code?
, A. It is almost universal - with few exceptions, all organisms use the
same code
B. It is a triplet code - groups of 3 nucleotides each encode one
amino acid
C. It is spaced - each codon has a single nucleotide space separating
it from the next one
D. It is degenerate - some amino acids are coded by more than one
codon - answer C. It is spaced- each codon has a single nucleotide
space separating it from the next one
This was discovered when Crick and Brenner did frame shift
mutations to test whether the genetic code was spaced.
Crick and Brenner reasoned that the genetic code most likely
consisted of a series of blocks of information called ___________, each
correspoding to an amino acid in the encoded protein. - answer
Codons
each codon consists of ___________ nucleotides, a triplet code, and
reading occurs continously without punctuation between the 3-nt
units. - answer Three
the experiments that crick and brenner did emphasized the
importance of the ____a_________ for the genetic message. Because
there is no punctuation, the _____a_____ established how each
following codon will be read. - answer Reading Frame
mutations that alter the reading frame of a genetic message are
called ____________________. - answer Frame Shift mutations
With only 20 amino acids and 64 codons, there is an abundance of
codons. this mean that the code is ________, which means that
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