Mastering Biology Chapter 17

Synthesized RNA transcript is in the direction of?

5' -----> 3'

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

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

Which of the following contradicts the one-gene, one-enzyme hypothesis?

A single kinase gene can code for different related proteins, depending on the splicing that takes place post-transcriptionally

During elongation, which site in the ribosome represents the location where a codon is being read?

A site

Transcription begins at a promoter. What is a promoter?

A site in DNA that recruits the RNA Polymerase

Which of the following molecules is/are produced by translation? Include molecules that are subject to further modification after initial synthesis. A) RNA polymerase B) The amino acid glycine C) Aminoacyl-tRNA synthetase

A)RNA polymerase C) Aminoacyl-tRNA synthetase

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

A-site

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.

Which of the following statements about mutations is false? A) A deletion mutation results in the loss of a base in the DNA sequence. B) A knock-out mutation results in a total absence of the mutated protein. C) Addition and deletion mutations disrupt the primary structure of proteins. D) An addition mutation results in an added base in the DNA sequence.

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

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 statements best describes the promoter of a protein-coding gene? A) The promoter is a site found on RNA polymerase. B) The promoter is part of the RNA molecule itself. C) The promoter is a nontranscribed region of a gene. D) The promoter is a site at which only RNA polymerase will bind.

C) The promoter is a nontranscribed region of a gene.

DNA does not store the information to synthesize which of the following? A)Proteins B)DNA C)Organelles D)Messenger RNA

C)Organelles

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

CUG

Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand? A) Permanently base-paired B) Covalently bound C) Identical D) Complementary

D) Complementary

Which of the following mutations would likely be most dangerous to a cell?

Deletion of one nucleotide

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

Deletion.

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

False

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

False- There are no tRNAs complementary to the three stop codons; termination occurs when release factors recognize the stop codon in the A-site and catalyze the release of the polypeptide from the tRNA in the P-site.

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.

What does it mean when we say the genetic code is redundant?

More than one codon can specify the addition of the same amino acid.

The average length of a transcription unit along a eukaryotic DNA molecule is about 27,000 nucleotide pairs, whereas an averaged-sized protein is about 400 amino acids long. What is the best explanation for this fact?

Most eukaryotic genes and their RNA transcripts have long noncoding stretches of nucleotides that are not translated.

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.

How might a single base substitution in the sequence of a gene affect the amino acid sequence of a protein encoded by the gene, and why?

Only a single amino acid could change, because the reading frame is unaffected.

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

P

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

Phosphorylation

In the process of transcription, _____.

RNA is synthesized

What does RNA polymerase do?

RNA polymerase untwists a portion of the DNA double helix.

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

RNA processing

Where does translation take place?

Ribosome

The tRNA shown in the figure above has its 3' end projecting beyond its 5' end. What will occur at this 3' end?

The amino acid binds covalently.

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

The large ribosomal subunit joins the complex.

In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after she has removed its 5' cap and poly-A tail. Which of the following would you expect her to find?

The molecule is digested by enzymes because it is not protected at the 5' end.

What is meant by translocation?

The ribosome slides one codon down the mRNA.

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

Transcription

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.

Of the following, which is the most current description of a gene?

a DNA sequence that is expressed to form a functional product: either RNA or polypeptide

Which of the following DNA mutations is most likely to damage the protein it specifies?

a base-pair deletion

Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on the polypeptide product?

a deletion of two nucleotides

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

A ribozyme is _____.

an RNA with catalytic activity

Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the _____.

binding of the anticodon to the codon and the attachment of amino acids to tRNAs

Alternative RNA splicing _____.

can allow the production of proteins of different sizes and functions from a single gene

The anticodon of a particular tRNA molecule is

complementary to the corresponding mRNA codon.

Translation occurs in the _____.

cytoplasm

During transcription the DNA synthesized is _______ helix.

double

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

exons

The flow of information in a cell proceeds in what sequence?

from DNA to RNA to protein

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

A primary transcript in the nucleus of a eukaryotic cell is _____ the functional mRNA, while a primary transcript in a prokaryotic cell is _____ the functional mRNA.

larger than; the same size as

RNA processing converts the RNA transcript into _____.

mRNA

Which nucleic acid is translated to make a protein?

mRNA

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

modified guanine nucleotide

enzyme a enzyme b A ---------------->B---------------->C Refer to the metabolic pathway illustrated above. If A, B, and C are all required for growth, a strain that is mutant for the gene-encoding enzyme A would be able to grow on medium supplemented with _____.

nutrient B only

The ______ is the region of DNA at which the process of transcription begins.

promoter

A mutant bacterial cell has a defective aminoacyl-tRNA synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of the normal phenylalanine. The consequence of this for the cell will be that _____.

proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU

Transcription in eukaryotes requires which of the following in addition to RNA polymerase?

several transcription factors

In eukaryotic cells, transcription cannot begin until

several transcription factors have bound to the promoter.

Spliceosomes are composed of _____.

snRNPs and other proteins

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

Once a peptide bond has been formed between the amino acid attached to the tRNA in the P site and the amino acid associated with the tRNA in the A site, what occurs next?

translocation