2.3.6 The Genetic Code

Question 1

What is a gene?

Answer 1

Sequence of nucleotides coding for the production of a specific protein

Question 2

What determines the shape and behavior of a protein?

Answer 2

• Primary structure
• Sequence of amino acids

Question 3

What is the triplet code?

Answer 3

• 3 bases (codon) code for 1 amino acid
• Triplets code for different amino acids (20 amino acids in total)

Question 4

What are start and stop codes?

Answer 4

• Triplets telling the cell where individual genes start and stop
• Resulting in cell reading DNA correctly and producing correct sequence of amino acids
• Start triplet is TAC (methionine)

Question 5

What does the genetic code being non-overlapping mean?

Answer 5

Each base only read once in which codon it is part of

Question 6

What does the DNA code being degenerate mean?

Answer 6

• 64 possible codons possible
• But only 20 amino acids occur in biology
• So multiple codons can code for the same amino acid
• Degenerate nature of genetic code can limit effect of mutations

Question 7

Why is the genetic code universal?

Answer 7

• Almost every organism uses the same code
• Same triplet codes for same amino acid in almost every living organism
• This is why genetic engineering is possible
• Where genes can be transferred from one organism to another