3.4.1

Question 1

Describe DNA in prokaryotes

Answer 1

DNA molecules are short, circular and not associated with proteins

Question 2

Describe nuclear DNA in eukaryotes

Answer 2

Found in nucleus
DNA molecules are long, linear and associated with proteins called histones

Question 3

Other than the nucleus, describe where DNA is found in eukaryotes

Answer 3

Mitochondria and chloroplasts
Like prokaryotic DNA - short, circular and not associated with proteins

Question 4

What is a gene?

Answer 4

A base sequence of DNA that codes for the amino acid sequence of a polypeptide or functional RNA

Question 5

What is a locus?

Answer 5

A fixed position on a particular DNA molecule that a gene occupies

Question 6

What is a triplet?

Answer 6

A sequence of 3 DNA bases which codes for a specific amino acid

Question 7

Describe 4 features of the genetic code

Answer 7

Triplet code- 3 bases=1 amino acid
Degenerate code- most amino acids are coded for by more than one triplet
Non overlapping code- only read each base once
Universal code- same in all known living things

Question 8

What is a mutation?

Answer 8

A change in a base

Question 9

Describe features of the genetic code which protect against mutations

Answer 9

Degenerate code- most amino acids are coded for by more than one triplet -> means if mutation occurs it is less likely to affect the amino acid produced
Non overlapping code- each base is only read once -> if a mutation occurs it would only affect one triplet

Question 10

What is an exon?

Answer 10

A base sequence within a gene which codes for an amino acid sequence

Question 11

What is an intron?

Answer 11

A non coding base sequence which separates exons to reduce the impact of mutations

Question 12

What does a base sequence determine?

Answer 12

Amino acid sequence in a polypeptide