Chapter 13 (Gene Expression)

How is the four-letter language of nucleic acids converted into the 20-word language of amino acids?

The four nucleic acid bases combine in three-letter sequences that define different amino acids.

The total number of different three-base combinations of the four nucleic acid base is:

64

Why is only one strand of DNA transcribed into mRNA?

Because transcribing both DNA strands would produce different amino acid sequences

The template DNA strand is described as being parallel to the complementary RNA strand.

False

Which of the following is characteristics of uracil?

It has the ability to bond with adenine

A(n) transposon is a DNA sequence that "jumps" into the middle of a gene.

True

The enzyme peptidyl transferase catalyzes peptide bond formation during the elongation stage of transition.

True

The notion that the genetic code is universal suggests a common ancestor for all living organisms.

True

Initiation of transcription requires:

a promoter sequence

The 3' end of eukaryotic pre-mRNA is changed by:

adding 100-250 adenine nucleotides; also known as a Poly A tail

Uracil forms a complementary pair with ______ in RNA and ______ in DNA.

adenine; adenine

Introns in pre-mRNA

are spliced out of the message.

A(n) nonsense mutation is a base-pair substitution that results in the replacement of one amino acid with another

false

A mutation that replaces one amino acid in a protein with another is called a _____ mutation.

missense

A ______ mutation results in the conversion of a codon specifying an amino acid to a termination (stop) codon.

nonsense

These noncoding sequences located within coding regions of ____ genes are called ____.

only eukaryotic; introns

Peptidyl transferase, a _____ molecule, catalyzes the formation of ____ between amino acids at the P and A sites.

ribozyme, peptide bonds

RNA is ______ and contains the nitrogenous base ______. which is absent in DNA.

single stranded; uracil

The molecule that connects a growing polypeptide chain and mRNA is called:

tRNA

Frameshift mutations result from the:

the insertion or deletion of one or two base pairs

If an mRNA transcript of the human XYZ gene was introduced into a yeast cell, the transcript would be:

translated into the human XYZ protein

A grouping of three nucleotides codes for one amino acid

true