3.4.2 DNA, genes, chromosomes

Question 1

Describe DNA molecules in prokaryotic cells:

Answer 1

Short, circular, not associated with proteins

Question 2

Describe DNA molecules in eukaryotic cells:

Answer 2

Long, linear, associated with proteins, called histones

Question 3

What forms a chromosome in a eukaryotic cell?

Answer 3

DNA molecule and its associated proteins

Question 4

The mitochondria in the chloroplasts of a eukaryotic cell contain…

Answer 4

DNA which, like the DNA of prokaryotes is short, circular and NOT associated with protein

Question 5

What is a gene?

Answer 5

A sequence of DNA which codes for:
- the amino acid sequence of a polypeptide
- a functional RNA (including ribosomal RNA and tRNAs)

Question 6

A gene occupies a…

Answer 6

Fixed position, called a locus, on a particular DNA molecule

Question 7

How many DNA bases code for an amino acid?

Answer 7

Three DNA bases, called triplet

Question 8

The genetic code is..

Answer 8

Universal, non-overlapping, degenerate

Question 9

What are exons separated within in a gene?

Answer 9

One or more non- coding sequences called introns

Question 10

In eukaryotes, much of the nuclear DNA does not code for polypeptides, so…

Answer 10

There are non-coding multiple repeats of the same sequences between genes. Even with a gene only some sequences, called exons, code for amino acid sequences