3. 4. 1 DNA, genes and chromosomes

Question 1

How is DNA stored in prokaryotic cells?

Answer 1

In prokaryotic cells DNA molecules are short, circular & not associated with proteins

Question 2

How is DNA stored in the nucleus of eukaryotic cells?

Answer 2

In the nucleus of eukaryotic cells, DNA molecules are very long, linear & associated with proteins, called histones. Together a DNA molecule & its associated proteins form a chromosome.

Question 3

How is DNA stored in the mitochondria and chloroplasts of eukaryotic cells?

Answer 3

The mitochondria & chloroplasts in eukaryotic cells have their own DNA. This is similar to prokaryotic DNA because it’s circular & shorter than DNA molecules in the nucleus. It is not associated with histone proteins

Question 4

What is a gene?

Answer 4

A gene is a sequence of DNA bases that codes for either a polypeptide or functional RNA (including ribosomal RNA & tRNAs).