Mastering Biology Chapter 17

What name is given to the process in which a strand of DNA is used as a template for the manufacture of a strand of pre-mRNA?

transcription

What name is given to the process in which the information encoded in a strand of mRNA is used to construct a protein?

translation

What name is given to the process in which pre-mRNA is edited into mRNA?

RNA processing

Polypeptides are assembled from _____.

amino acids

RNA processing converts the RNA transcript into _____.

mRNA

What is the process called that converts the genetic information stored in DNA to an RNA copy?

transcription

DNA does not store the information to synthesize which of the following?

Organelles

Transcription begins at a promoter. What is a promoter?

A site in DNA that recruits the RNA Polymerase

Which of the following statements best describes the promoter of a protein-coding gene?

The promoter is a nontranscribed region of a gene.

What determines which base is to be added to an RNA strand during transcription?

Base pairing between the DNA template strand and the RNA nucleotides

Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand?

Complementary

What happens to RNA polymerase II after it has completed transcription of a gene?

It is free to bind to another promoter and begin transcription.

During RNA processing a(n) _____ is added to the 5' end of the RNA.

modified guanine nucleotide

During RNA processing a(n) _____ is added to the 3' end of the RNA.

a long string of adenine nucleotides

Spliceosomes are composed of _____.

small RNAs and proteins

The RNA segments joined to one another by spliceosomes are _____.

exons

Translation occurs in the _____.

cytoplasm

Where does translation take place?

Ribosome

Which nucleic acid is translated to make a protein?

mRNA

Which of the following processes is an example of a post-translational modification?

Phosphorylation

Which of the following steps occurs last in the initiation phase of translation?

The large ribosomal subunit joins the complex.

At which site do new aminoacyl tRNAs enter the ribosome during elongation?

A-site

What is meant by translocation?

The ribosome slides one codon down the mRNA.

True or false. A tRNA with an anticodon complementary to the stop codon catalyzes the reaction by which translation is terminated.

False

Which of these is a tRNA?

b

What enzyme catalyzes the attachment of an amino acid to tRNA?

aminoacyl-tRNA synthetase

The tRNA anticodon, GAC, is complementary to the mRNA codon with the sequence _____.

CUG

What is the name of the process shown in the diagram?

initiation (of translation)

The initiator tRNA attaches at the ribosome's _____ site.

p

____________ of translation happens when the ribosome hits a stop codon on the mRNA.

termination

2. Amino acids are attached to tRNA by enzymes called

aminoacyl-tRNA synthetase.

3. The RNA that has an amino acid attached to it, and that binds to the codon on the mRNA, is called a .

tRNA

The process, performed by the ribosome, of reading mRNA and synthesizing a protein is called .
_______-

translation

_______ of translation always happens at the start codon of the mRNA.

initiation

True or false? A codon is a group of three bases that can specify more than one amino acid.

false

Which of the following statements about mutations is false?

A knock-out mutation results in a total absence of the mutated protein.

If a DNA sequence is altered from TAGCTGA to TAGTGA, what kind of mutation has occurred?

Deletion

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.

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

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.

Use the codon table to determine which mRNA triplets code for the amino acid cysteine, Cys.

UGU, UGC

Think about the DNA coding sequence of a gene. If an A were swapped for a T, what kind of mutation could it cause and why?

It could cause a silent, missense, or nonsense mutation because those are the types that can be caused by a nucleotide-pair substitution like this one.

Why is a frameshift missense mutation more likely to have a severe effect on phenotype than a nucleotide-pair substitution missense mutation in the same protein?

A substitution missense affects only one codon, but a frameshift missense affects all codons downstream of the frameshift.

Which of the following sequences shows a frameshift mutation compared to the wild-type mRNA sequence?

wild-type
5'-AUGCAUACAUUGGAGUGA-3'
mutant
5'-AUGCAUACAUCUGGAGUGA-3'

A _________ mutation causes a wild-type amino acid to be replaced by a different amino acid.

missense

A ___________ mutation causes an early Stop codon to occur.

nonsense

A ___________ mutation does not change the wild-type amino acid sequence.

silent

Suppose that the triplet of nucleotides indicated in bold (AGC) spans two codons, that is, CTA and GCC. If the triplet AGC were deleted from this DNA coding sequence, what effect would it have on the resulting protein?

The two flanking codons would be altered, but the rest of the amino acid sequence would be the same because there would be no frameshift.