Question

Summarize the relationship between genes and proteins . Explain the purpose of transcription and translation. Describe the steps of transcription I State the enzyme or structures that perform transcription and translation. Contrast prokaryotic and eukaryotic mRNA . Describe the process of translation .Describe the role of tRNA in translation . Explain the role of codons and anticodons in translation. Explain the significance of stop codons and start codons. Given a double stranded DNA gene sequence, be able to produce the base sequence of the mRNA made, the codons and anticodons involved, and the amino acid sequence of the finished protein. .Be able to use and explain the genetic code table

Answer 1

1. The central dogma of life:
DNA --------> RNA ---------> Protein
Genes are located in DNA. They produce RNA by transcription. RNA is translated to produce proteins.

2. Transcription: Production of RNA from DNA
It is the first step of gene expression.
Translation: Production of protein from RNA
The RNA is translated to produce protein.
Proteins are the functional units in the cell.

3. Transcription is mediated by DNA dependent RNA polymerase.
Three stages in transcription:
i. Initiation: Mediated by Sigma factor
ii. Elongation: Mediated by elongation factor
iii. Termination: Mediated by Rho factor

4. Transcription is mediated by DNA dependent RNA polymerase.
Translation process requires mRNA, tRNA and rRNA.
The peptidyl transferase activity is responsible for the peptide bond formation between two amino acids. It is located in the rRNA component of the large subunit.

5. Prokaryotic mRNA: Poly-cistronic, no introns, and no post-transcriptional changes
Eukaryotic mRNA: Mono-cistronic, presence of introns and occurrence of post-transcriptional changes