What does the one-gene, one-enzyme hypothesis state?
– A single gene codes for a single protein.
The idea that the sequence of bases in DNA specifies the sequence of bases in an RNA molecule, which specifies the sequence of amino acids in a protein, is _______.
– the central dogma
– The central dogma is one of the basic underpinnings of biology.
According to the original central dogma, what macromolecule or phenomenon is directly responsible for an organism’s phenotype?
– protein
– Proteins carry out the majority of cell functions.
True or false? A codon is a group of three bases that can specify more than one amino acid.
– False
– A codon is a group of three bases that can specify only one amino acid.
Which of the following statements about mutations is false?
– A knock-out mutation results in a total absence of the mutated protein.
– A knock-out mutation refers to the loss of a protein’s function but not necessarily to its complete absence.
If a DNA sequence is altered from TAGCTGA to TAGTGA, what kind of mutation has occurred?
– Deletion.
– The original sequence has lost the base C.
Which mutation(s) would not change the remainder of the reading frame of a gene sequence that follows the mutation(s)?
– One addition and one deletion mutation.
– This combination results in no net change in the number of bases, so the reading frame would eventually be restored.
If the sequence ATGCATGTCAATTGA were mutated such that a base were inserted after the first G and the third T were deleted, how many amino acids would be changed in the mutant protein?
– Two
– The second and third codons in the new sequence are different from the original codons.
If a mutated DNA sequence produces a protein that differs in one central amino acid from the normal protein, which of the following kinds of mutations could have occurred?
– An addition mutation and a deletion mutation.
– If the mutations occur within the same codon, only that codon (amino acid) will be altered.
When an amino acid is specified by more than one codon, what is usually shared by the set of codons that specify this amino acid?
– the first and second bases
– This minimizes errors in translation.
A mutation that has no effect on fitness is a ______.
– neutral mutation
– Silent mutations are usually neutral.
A point mutation that results in the substitution of one amino acid for another within a protein is a ______.
– missense mutation
– The majority of point mutations do not benefit the organism.
Which of the following is an important exception to the central dogma of molecular biology?
– Many genes code for RNAs that function directly in the cell.
Which statement is most accurate concerning how a compound that blocks RNA synthesis will affect information transfer from DNA to proteins?
– Both transcription and translation will be inhibited.
– Transcription is RNA synthesis by RNA polymerase and will be inhibited directly; translation is protein synthesis and will be inhibited indirectly because ribosomes contain RNA molecules essential to their function.
What is gene expression?
– The process of converting archived information into molecules that actually do things in the cell
What are non functioning alleles called?
– Knock-out, null, or loss-of-function alleles

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