8.2 DNA and chromosomes

Question 1

Describe DNA of prokaryotic cells

Answer 1

The DNA molecules are shorter, force a circle and are not associated with histones. They have no chromosomes

Question 2

Describe the DNA of eukaryotic cells

Answer 2

The DNA molecules are longer, form a line rather than a circle and occur in association with histones to form chromosomes

Mitrohondria and chloroplasts contain DNA which is more similar to Prokaryotic DNA

Question 3

When is the only time chromosomes are visible

Answer 3

When a cell is dividing

Question 4

What is the DNA in chromosomes held around

Answer 4

Histones

Question 5

What are homologous chromosomes

Answer 5

A pair of chromosomes, one maternal and one paternal, with the same gene loci

Question 6

What is the diploid number

Answer 6

The total number

Question 7

What is an allele

Answer 7

An allele is a variation of a gene

Question 8

What happens when a mutation occurs

Answer 8

A new allele of that gene is produced. The different amino acid sequence will lead to the production of a different polypeptide, and hence a different protein. When the protein produced is an enzyme, it may have a different shape. The new shape may not fit the enzymes substrate. As a result, the enzyme may not function and this can have adverse consequences