Lecture 13

Question 1

Provide a correct definition for the term genetic code

Answer 1

is the set of rules used by living cells to translate information encoded within genetic material (DNA or mRNA sequences) into proteins. … The code defines how sequences of nucleotide triplets, called codons, specify which amino acid will be added next during protein synthesis

Question 2

Explain why the genetic code in termed ‘redundant’ and ‘newly universal’ and identify the important of these features in translation

Answer 2

Redundant
all amino acids, with the exception of Tryptophan and Methionine, are encoded by more than one codon (termed synonymous codons)
Newly universal
that each possible codon can code for one amino acid only
The important features in both redundant and newly universal, are amino acids, tryptophan, and codons

Question 3

Predict an amino acid sequence from a given mRNA or DNA sequence using a genetic code table

Answer 3

5’ GGTATT 3’
‘3 CCAUAA 5’
Codes for Pro, stop codon

Question 4

Describe a tRNA molecule and explain how its structure is related to its function

Answer 4

tRNA is composed of 80 nuclotides. Complimentary sequences in this molecule hydrogen bond with each other causing the molecule to fold upon itself into the general shape of an “L” with a loop that has the anticodon and an exposed 3” end that is the attachment site for an amino acid.

Question 5

Explain the function of amino acyl-tRNA-synthesize enzymes and how they help to ensure accuracy in translation

Answer 5

An aminoacyl-tRNA synthetase (aaRS or ARS), also called tRNA-ligase, is an enzyme that attaches the appropriate amino acid onto its tRNA. … Aminoacyl tRNA therefore plays an important role in RNA translation, the expression of genes to create proteins

Question 6

Apply the rules of base-pairing to show the relationship between the complementary sequences of codons and anti-codons

Answer 6

Codon AAA

Anticodon UUU