Unit 4 Review

Which of the following could cause less protein to be made?

• mRNA is destroyed before it is translated

• Promoters attach to DNA to start transcription

• A frameshift mutation occurs and codes for a start codon

• A silent mutation occurs on a strand of DNA

Answer explanation

This is an example of post-transcriptional gene regulation (Ch. 11)

A nucleic acid molecule is double stranded and has the bases adenine, cytosine, guanine, and thymine. What is the molecule and why?

• RNA because it is double stranded

• DNA because it has the base cytosine

• DNA because it has the base thymine

• RNA because it has the base thymine

Answer explanation

RNA is single stranded and contains the base uracil instead of thymine

Where does protein synthesis take place?

• Nucleus

• Ribosome

• Cytoplasm

• Mitochondria

Answer explanation

Protein synthesis = translation, occurring in the ribosome

Transcription and DNA replication occur in the nucleus.

Which of the following best describes what's happening in this diagram?

• In the absence of lactose, Lac operon is twisted so RNA polymerase can't attach to the promoter

• In the presence of lactose, the repressor protein attaches to the DNA to start transcription

• The repressor promotes histone building and makes DNA inaccessible

• The repressor removes the operon from the DNA and splices the DNA back together

Answer explanation

This is a form of gene expression regulation (Ch. 11)

If DNA and RNA are both present in a diagram, which process would it most likely be depicting?

• DNA replication

• Transcription

• Translation

• Protein Synthesis

Answer explanation

If it were DNA replication, ONLY DNA would be present

Translation = Protein Synthesis. If it were that, no DNA would be present because that process occurs in the ribosome

Which mRNA sequences code for the amino acid proline? Check all that apply

• CCU

• CCC

• CAU

• CAA

Which other substance did scientists originally think held the pertinent genetic information, before they realized it was DNA?

• Protein

• RNA

• Ribosomes

• Enzymes

Answer explanation

This was because DNA was more simple--there are many amino acids, while DNA only has 4 subunits (A,G,C,T)

Which process includes helicase, DNA polymerase, and DNA ligase?

• DNA replication

• Transcription

• Translation

Answer explanation

No RNA is involved in DNA replication

What is the role of DNA ligase during replication?

• Assembles nucleotides to their complementary base pair

• Signals the start of the process

• Seals gaps on the lagging strand between fragments

• Opens the double helix up

Why does gene expression need to be modified and controlled? Select all that apply

• Different cells need to express different proteins to carry out their individual functions.

• Cells need to respond to environmental changes.

• Cells need to use their energy to make ONLY the proteins they require and not waste it to make proteins they do not require.

• 1. Cells only carry the DNA (genes) that they will need.

Answer explanation

All cells have ALL your genes. Not all cells need to USE all your genes