Bio 111 - Exam 4 - CH15 (Genes & How They Work)

The Shine-Dalgarno sequence is found on the ________.

mRNA.

When a tautomeric shift occurs, what is TRUE about the resulting mutation? 1. The resulting mutation is always corrected by DNA polymerase's proofreading ability. 2. The resulting mutation always changes a purine to a puring or a pyrimidine to a pyrimidine. 3. The resulting mutation always changes a purine to a pyrimidine or a pyrimidine to a purine. 4. The resulting mutation always changes an amino acid in the resulting protein. 5. The resulting mutation always results in a frame shift mutation, causing the resulting protein to be abnormally short.

2. The resulting mutation always changes a purine to a puring or a pyrimidine to a pyrimidine.

Which of the following statements about peptidyl transferase is TRUE? 1. It catalyzes the formation of peptide bonds. 2. It is present in the 50S ribosomal subunits. 3. It is a protein. 4. It catalyzes the formation of peptide bonds and It is present in the 50S ribosomal subunits. 5. It catalyzes the formation of peptide bonds, It is present in the 50S ribosomal subunits, and It is a protein.

4. It catalyzes the formation of peptide bonds and It is present in the 50S ribosomal subunits.

Which of the following is not involved in the initiation of translation? 1. mRNA 2. ribosomal subunits 3. initiator tRNA 4. RNA polymerase 5. all of these choices are involved

4. RNA polymerase.

Which of the following statements about structural gene is TRUE? 1. The gene itself is the only important region of a structural gene. 2. Transcription of a structural gene results in a protein. 3. Transcription of a structural gene could result in a tRNA molecule. 4. Transcription of structural genes requires DNA sequences that are not part of the gene itself.

4. Transcription of structural genes requires DNA sequences that are not part of the gene itself.

Which of the following best describes transcription?

DNA -> RNA.

During translation elongation, amino acids are brought to the ribosome with the help of...

EF-Tu.

Which part of the protein is formed during termination?

Free carboxylic acid group.

In a tautomeric shift ___ atoms move to form a nucleotide base with altered bonding properties.

Hydrogen.

What is a difference between DNA replication and RNA transcription?

In DNA replication the [helix] is never closed after it is opened by helicase, but once RNA polymerase has finished transcribing a region the double helix closes.

How is GTP used during elongation?

It aids in the binding of the incoming tRNA to the A site of the ribosome AND It aids in translocating the ribosome one codon down the mRNA. (longest answer)

All nascent proteins being with what amino acid?

Methionine.

Which of the following statements about termination is TRUE?

No tRNA can recognize a stop codon. [It is recognized by a release factor protein.]

How does the ribosome recognize the proper tRNA to bind?

Only a tRNA with an anticodon that is complementary to the codon will bind in the A-site.

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.

The transcription enzyme first attaches to the ________ of the gene.

Promoter.

Which of the following best describes translation?

RNA -> Protein.

When a tautomeric shift occurs, the resulting nulceotide is a(n) __________ of the nucleotide prior to the shift.

Structural isomer.

The following sequence of DNA is the normal, wild-type gene. 5' ATG C[G]G 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 gunine 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.

A nucleotide deletion in DNA replication causes...

The amino acids inserted after the deletion to be incorrect.

The following sequence of DNA is the normal, wild-type gene. 5' ATG C[G]G 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.

A single point mutation has occurred a gene causing a stop codon to appear early in the translation of the protein. What effect will this have on the protein?

The early stop codon will cause premature termination, and [the protein will be abnormally short.]

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.

How do you know that the gene being transcribed in the animation is a prokaryote?

The initiation of transcription involves a sigma factor.

If the Shine-Delgarno sequence was mutated, what might be a consequence?

The mRNA would not bind to the small ribosomal subunit in the proper location.

The protein that promotes translation termination is called...

The release factor.

Which of the following occurs as the ribosome shifts down the mRNA by a distance of three nucleotides?

The tRNA that was in the P site moves into the E site.

Why are nucleotide triphosphates used to polymerize RNA?

The triphosphate is a high energy molecule so that polymerization is spontaneous.

Why is GTP used during the initiation of translation?

To facilitate the binding of the mRNA, and the initiator tRNA to the ribosome.

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.