Mastering Biology Chapter 17 & 18

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

complementary

Translation occurs in the _____.

cytoplasm

Forms of the Ras protein found in tumors usually cause which of the following events to occur?

excessive cell division

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

exons

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

false

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

false

What type of bonding is responsible for maintaining the shape of the tRNA molecule shown in the figure?

hydrogen bonding between base pairs

Which statements about the modification of chromatin structure in eukaryotes are true?

in phone

Which statements about the regulation of transcription initiation in these genes are true?

in phone

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'

Which of the following processes occurs in eukaryotic gene expression?

A cap is added to the 5 end of the mRNA.

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 frameshift missense will cause the codons downstream to be changed whereas substitution changes only one codon

Which of the following statements about mutations is false?

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

During the elongation phase of translation, 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 processes occurs when termination of translation takes place?

A stop codon is reached.

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

A-site

Which of the following molecules is/are produced by translation? Include molecules that are subject to further modification after initial synthesis.

Aminoacyl-tRNA synthetase & RNA polymerase

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 processes is an example of a post-translational modification?

Phosphorylation

Which of the following statements is the most current description of a gene?

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

What is the function of the release factor during translation in eukaryotes?

It binds to the stop codon in the A site in place of a tRNA.

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.

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.

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

P

Which of the following processes do normal proto-oncogenes typically exhibit?

Proto-oncogenes encode proteins that promote cell division, regulate cell differentiation, and inhibit cell death. They are most active during embryonic development, during the time when an organism is rapidly increasing its cell numbers. As an organism develops into an adult, proto-oncogenes are turned off in many cell types. There are only a few cell types, such as skin cells and the cells that line the intestines, in which proto-oncogenes remain active throughout adulthood to enable the continuous replacement of damaged cells. A proto-oncogene becomes an oncogene when it acquires a mutation or is altered in a way that increases its activity and encourages cells to continue to divide, regardless of the presence of growth inhibitory signals

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.

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

RNA processing

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

The large ribosomal subunit joins the complex.

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 meant by translocation?

The ribosome slides one codon down the mRNA.

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 is a ribozyme?

a biological catalyst made of RNA

uring 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

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

RNA processing converts the RNA transcript into _____.

mRNA

Which nucleic acid is translated to make a protein?

mRNA

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

_________mutation causes an early Stop codon to occur.

nonsense

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

organelles

Where does translation take place?

ribosomes

Which of the following molecules are produced by transcription?

ribozymes & mRNA

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

several transcription factors

mutation that has no affect

silent

Spliceosomes are composed of _____

snRNP's and other proteins

How does the primary transcript in the nucleus of a eukaryotic cell compare to the functional mRNA?

the primary transcript is larger than the mRNA

Which of the following is the first event to take place in translation in eukaryotes?

the small subunit of the ribosome recognizes and attaches to the 5 cap of mRNA

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 amino acids will be altered. The sequence will now be ATG CTC TAT CGT AAC

In the structural organization of many eukaryotic genes, individual exons may be related to which of the following?

the various domains of the polypeptide product

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

there.......amino acid

How does the primary transcript in a prokaryotic cell compare to the functional mRNA?

they're the same size

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

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