Bi 112 Ch 15 Questions (2nd Batch)

Match each event with the appropriate stage of transcription. ELONGATION

-RNA polymerase leaves the promoter. -A process called clearance or escape. -New nucleotides are added to the 3' end of the growing RNA transcript. -The transcription bubble created by RNA polymerase moves along the DNA template.

Match each event with the appropriate stage of transcription. TERMINATION

-Reaching a terminator sequence causes formation of phosphodiester bonds to stop. -The RNA-DNA hybrid within the transcription bubble dissociates. -RNA polymerase releases the DNA template.

Match each event with the appropriate stage of transcription. INITIATION

-The RNA polymerase holoenzyme is formed. -The RNA polymerase holoenzyme binds to the promoter. -Once bound to the promoter, RNA polymerase begins to unwind the DNA.

Place the following in order, starting with the smallest (#1) and ending with the largest (#4).

1) Nucleotide 2) Codon 3) Gene 4) Chromosome

One or a few base pairs are gained.

Addition

Which of the following best describes transcription?

DNA -> RNA

One or a few base pairs are lost.

Deletion

All codons code for amino acids.

False

Deleting a single base from an mRNA molecule usually alters one codon only.

False

Most codons code for more than one amino acid.

False

Only 20 different codons are used to code for amino acids.

False

Special "spacer" proteins are used to mark the end of one codon and the start of the next codon.

False

Stop codons have a dual function because each one also codes for an amino acid.

False

There are 66 possible codons.

False

The genetic code is read in groups of 4 bases.

False read in groups of 3 bases

An addition or deletion that alters the codons downstream from the mutation.

Frameshift Mutation

Changes a codon for one amino acid into a codon for a different amino acid.

Missense Mutation

An addition or deletion that alters the codons upstream from the mutation.

None of these

Changes a codon for one amino acid into a stop codon.

Nonsense Mutation

CCR5 is a cell surface receptor protein of white blood cells that attracts them to specific tissue and organs to elicit an immune response. It is also the receptor to which R5 strains of HIV bind to and enter T cells. Between 5-14% of people from Northern European descent possess an allele known as CCR5-Δ32. In this allele, a 32 base pair section of the gene has been deleted. What phenotype do people carrying the CCR5-Δ32 allele exhibit?

People with CCR5-Δ32 will have impaired immune function, but they will exhibit resistance to infection by HIV.

Which of the following best describes translation?

RNA -> Protein

Why is RNA synthesis called 'transcription' and protein synthesis called 'translation?'

RNA synthesis produces nucleic acid from nucleic acid and protein synthesis produces polypeptides from nucleic acid.

Changes a codon for one amino acid into a different codon for the same amino acid.

Silent Mutation

Name start and stop codons.

Start: AUG Stop: UAA, UGA, UAG

One or a few base pairs are replaced by different base pairs.

Substitution

The following sequence of DNA is the normal, wild-type gene. 5' ATG CGG GTA GTT AGC CGA TAG 3' An addition occurs during DNA replication, causing an additional guanine to be inserted into the nucleotide strand after the guanine shown in red. What effect will this have on the final protein?

The addition of the G will cause a frame shift, resulting in a premature stop codon and a truncated protein.

The following sequence of DNA is the normal, wild-type gene. 5' ATG CGG GTA GTT AGC CGA TAG 3' A deletion occurs during DNA replication, causing the guanine shown in red to be removed from the nucleotide strand. What effect will this have on the final protein?

The deletion of the G will cause a frame shift, resulting in a premature stop codon and a truncated protein.

What stimulates the ribosome to move down one codon?

The formation of a bond between the peptide in the P site and the amino acid in the A site

A mutation occurred in the third codon position of a gene, but the protein still functions normally. How is this possible?

The genetic code is redundant, so that mutations in the third position of the codon often result in the same amino acid being specified.

What may result from a mutation in a sequence of DNA that codes for a protein?

The protein will not function correctly.

A lack of amino acid availability would affect what stage in gene expression?

Translation

This type of mutation causes Huntington's disease and has only been observed in humans and mice.

Triplet repeat expansion

AUG is a "start" codon or it can code for methionine.

True

In some cases, it is possible to change the sequence of bases in a codon and it will still code for the same amino acid.

True

Most amino acids are specified by more than one codon.

True

The codons do not overlap each other.

True

The genetic code is the same in almost all living organisms.

True

The start codon has a dual function because it also codes for an amino acid.

True

At what point in gene expression do molecules go from being information storage molecules to metabolic and structurally functional molecules?

When RNA is translated into protein

a. RNA is used as a template to make a complementary strand of DNA. b. DNA is used as a template to make a complementary strand of DNA. c. RNA is used as a template to make a complementary strand of RNA. d. DNA is used as a template to make a complementary strand of RNA. e. RNA is used as a template to make a polypeptide.

a. Reverse transcription b. DNA replication c. None d. Transcription e. Translation

A nucleotide deletion in DNA replication

causes the amino acids inserted after the deletion to be incorrect.

Segments of a chromosome that are lost are called ____.

deletions.

Segments of a chromosome that are repeated are called ___________.

duplications.

Segments of a chromosome that are broken in 2 places, reversed, and then put back together are called ______.

inversions.

The nucleic acid sequence in mRNA is determined by

nucleotide sequence in DNA.

Translation is the synthesis of

proteins from mRNA

If two chromosomes are broken and they exchange non-homologous segments, this is called a ___________ translocation.

reciprocal

If a duplication occurs directly next to the original segment, it is termed a ________ duplication.

tandem

If a frameshift mutation causes a stop codon to be inserted into the DNA sequence

the resulting protein will be too short and non-functional.

Segments of a chromosome that break off and attach to another chromosome are called __________.

translocations.