Chapter 17 mastering

A___mutation does not change the wild-type amino acid sequence.

silent

A___mutation causes a wild-type amino acid to be replaced by a different amino acid.

missense

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

modified guanine nucleotide

A___mutation causes an early Stop codon to occur.

nonsense

Which component is directly involved in translation?

ribosome

In eukaryotic cells, transcription cannot begin until

several transcription factors have bound to the promoter.

spliceosomes are composed of _____.

small RNAs and proteins

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

P

Translation occurs in the _____.

cytoplasm

After transcription begins, several steps must be completed before the fully processed mRNA is ready to be used as a template for protein synthesis on the ribosomes. Which three statements correctly describe the processing that takes place before a mature mRNA exits the nucleus?

1.Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes. 2.A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA. 3. A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA.

A particular triplet of bases in the template strand of DNA is 5'-AGT-3'. What would be the corresponding codon for the mRNA that is transcribed

3'-UCA-5'

The direction of synthesis of an RNA transcript is _____.

5' —> 3'

Use this model of a eukaryotic primary transcript to answer the following question. E = exon and I = intron5'-UTR E1 I1 E2 I2 E3 I3 E4 UTR-3' If the primary transcript is processed and transported to the cytosol, which of the following molecules best represents the mRNA that will be produced?

5'-UTR E1 E2 E3 E4 UTR-3'

The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following statements to be true?

A gene from an organism can theoretically be expressed by any other organism.

Transcription begins at a promoter. What is a promoter?

A site in DNA that recruits the RNA Polymerase

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.

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

Which of the following processes correctly describes alternative RNA splicing?

It can allow the production of proteins of different sizes and functions from a single mRNA.

Which of the following is true of a codon?

It can be either in DNADNA or in RNARNA

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.

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.

Which of the following statements about the function of RNA polymerase is correct?

It unwinds the double helix and adds nucleotides to a growing strand of RNA.

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

Organelles

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

RNA processing

Which of the following statements best describes the termination of transcription in prokaryotes?

RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.

Two mRNAs (mRNA X and mRNA Y) are synthesized with the same exon sequences but poly-A tails of very different lengths. mRNA X is 7,500 bases long. mRNA Y is 6,900 bases long. The mRNA's are added to separate in vitro translation mixtures containing radioactive methionine and the reactions are allowed to proceed for 30 minutes. When the mixtures are analyzed which of the following outcomes will most likely occur?

The mRNA X mixture will contain more radioactive proteins than the mRNA Y mixture

Which of the following is most likely to occur if a researcher removes the 5' cap and poly-A tail of an mRNA and inserts the mRNA molecule into a eukaryotic cell?

The molecule will be degraded by enzymes.

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

The promoter is a nontranscribed region of a gene.

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

Transcription

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

a long string of adenine nucleotides

Polypeptides are assembled from _____.

amino acids

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

aminoacyl-tRNA synthetase

The anticodon of a particular tRNAtRNA molecule is

complementary to the corresponding mRNAmRNA codon

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

exons

After an RNA molecule is transcribed from a eukaryotic gene, what are removed, and what are spliced together, to produce an mRNA molecule with a continuous coding sequence?

introns, exons

Where does RNA polymerase begin transcribing a gene into mRNA?

it starts after a certain nucleotide sequence called a promoter

RNA processing converts the RNA transcript into _____.

mRNA

During transcription in eukaryotes, a type of RNA polymerase called RNA polymerase II moves along the template strand of the DNA in the 3'→5' direction. However, for any given gene, either strand of the double-stranded DNA may function as the template strand.

the base sequence of the gene's promoter

Which answer correctly compares the primary transcript in the nucleus of a eukaryotic cell with the functional mRNA?

the primary transcript is larger than the mRNA

Which answer correctly compares the primary transcript in a prokaryotic cell with the functional mRNA?

the primary transcript is the same size as the mRNA

A codon consists of __________ bases and specifies which __________ will be inserted into the polypeptide chain.

three, amino acid

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