Chapter 3.10 - The genetic code

Question 1

How are DNA molecules condensed into chromosomes?

Answer 1

DNA molecules are wound around proteins known as histones to form a DNA-histone complex, these complexes coil further to form chromatin, with helps pack the DNA into chromosomes. Each chromosome contains just a single molecule of DNA

Question 2

What is genetic code?

Answer 2

This term refers to the sequences of bases in DNA which are the instructions for the sequences of amino acids in the production of proteins

Question 3

What is a codon?

Answer 3

A three-base sequence of DNA or RNA that codes for an amino acid

Question 4

What is a gene?

Answer 4

A section of DNA that contains the complete sequence of codons to code for a protein

Question 5

What are the six features of the genetic code?

Answer 5

1. Triplet code
2. Specific
3. Degenerate
4. Universal
5. Non-overlapping
6. Punctuated

Question 6

Why is genetic code written in triplet code?

Answer 6

A three base code provides 64 possible codes for amino acids, if it was written in two base code, there would be only 16 possible amino acids(4²=16), and there are 20 amino acids needed to function properly, 4³ = 64

Question 7

What does it mean when we say that genetic code is specific?

Answer 7

Each triplet code(codon) codes for only one amino acid

Question 8

What does it mean when we say that genetic code is degenerate?

Answer 8

Multiple codons can code for the same amino acid during protein synthesis, this reduces the affects of mutations

Question 9

What does it mean when we say that genetic code is universal?

Answer 9

Each DNA codon codes for the same amino acid in all organisms

Question 10

What does it mean when we say that genetic code is non-overlapping?

Answer 10

Each base in the DNA sequence is only read once (e.g CGTATC is read as CGT and ATC)

Question 11

What does it mean when we say that genetic code is punctuated?

Answer 11

Genetic code has codons which signal the start or end of a protein chain