0206 - Intro to Genetics - RM

Question 1

What is the central dogma of genetics?

Answer 1

DNA->RNA (transcription in nucleus)

RNA->Protein (translation in cytoplasm)

Question 2

Identify the nucleotides. How do they pair up?

Answer 2

Purine (Adenine and Guanine)
Pyrimdine (Cytosine and Thymine (DNA) or Uracil (RNA))

In DNA – A-T, C-G. C-G is a stronger bond.

Question 3

What is RNA? How does it differ from DNA?

Answer 3

Single strand of nucleotides, produced in nucleus via TRANSCRIPTION and used for peptide/protein production in the cytoplasm via TRANSLATION.

RNA is an exact copy of the coding (5’-3’, non-template) strand of DNA from which it was transcribed, except that RNA contains Uracil instead of Thymine. This is because it matches the A-T/U, C-G bonds of the template (3’-5’, non-coding) strand.

While DNA is the same in every cell (except erythrocytes), RNA differs around the body.

Question 4

What is a codon?

Answer 4

A sequence of three nucleotides that codes for an amino acid. There are 20 ‘normal’ amino acids in the human body.

Question 5

What is a gene?

Answer 5

A portion of the genetic code that codes for a protein or functional RNA.

Question 6

Briefly describe Transcription (genetics).

Answer 6

RNA polymerise binds to the DNA and unwinds a section of it - INITIATION

RNA polymerase moves 3’-5’ along the template (non-coding) strand of DNA. It produces a pre-mRNA that is an exact copy of the 5’-3’ strand (except that T is replaced by U) - ELONGATION

RNA polymerase releases completed pre-mRNA – TERMINATION

Exons are spliced together, and introns are degraded/eliminated to produce a strand of mRNA – RNA PROCESSING

Question 7

Briefly describe Translation (genetics)

Answer 7

mRNA leaves the nucleus for the cytoplasm.

Ribosome binds the mRNA to catalyse protein translation.

tRNA transfers amino acids to the ribosome, commencing with a ‘start’ codon.

The amino acids are bound together in the ribosome, forming a polypeptide chain that will become a protein.