4.4 SG

Question 1

Role of mRNA (codons) in the process of translation

Answer 1

Each mRNA dictates the order in which amino acids should be added to a growing protein as it is synthesized.

Question 2

The role of tRNA (anticodons) in the process of translation

Answer 2

Anticodons are found on molecules of tRNA. Their function is to base pair with the codon on a strand of mRNA during translation.

Question 3

The role of RNA (ribosomes) in the process of translation

Answer 3

During translation, ribosomal subunits assemble together like a sandwich on the strand of mRNA, where they proceed to attract tRNA molecules tethered to amino acids (circles).

Question 4

Gene Regulation- positive/negative transcription factors

Answer 4

A positive transcription factor controls the differential expression of two 5S RNA genes. Cell. Negative transcription factors (repressors) prevent transcription of certain pieces of DNA.

Question 5

Different types of mutations

Answer 5

Point mutations - which fall into 3 categories
- Missense mutations cause a single amino acid change in the protein.
- Nonsense mutations make a premature “stop” codon. Any codons after that are not translated, and the resulting protein is missing amino acids.
- Silent mutations code for the same amino acid as before.
Insertion mutations add one or more DNA bases. Deletion mutations remove one or more DNA bases. Unless they happen in multiples of 3 bases, insertions and deletions shift the reading frame—which is why they’re also called frameshift mutations.