4.1 - DNA, genes and chromosomes

Question 1

Describe the DNA molecules present in prokaryotic cells

Answer 1

Short, circular, not associated with proteins

Question 2

Describe the DNA molecules present in eukaryotic cells

Answer 2

In nucleus, long, linear, associated with proteins called histones

Question 3

What is a chromosome made up of?

Answer 3

DNA molecule and its associated proteins

Question 4

Describe the DNA found in chloroplasts and mitochondria

Answer 4

Short, circular, not associated with protein

Question 5

What is a gene?

Answer 5

Base sequence of DNA that codes for the amino acid sequence of a polypeptide and a functional RNA e.g rRNA or tRNA

Question 6

What is a locus?

Answer 6

The fixed position a gene occupies on a particular DNA molecule

Question 7

Define triplet

Answer 7

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

Question 8

Describe the 3 key features of the genetic code

Answer 8

Universal - the same in all living organisms
Non-overlapping - each triplet is only read once
Degenerate - more than one triplet codes for the same amino acid, which means there are less mutations which alter the amino acid sequence

Question 9

What is an intron?

Answer 9

Base sequence that does not code for a polypeptide

Question 10

What is an exon?

Answer 10

Base sequence coding for a polypeptide