3.2 Chromosomes

Question 1

Describe a prokaryotic chromosome. Why is it considered to be naked.

Answer 1

Consists of a circular DNA molecule containing all the genes needed for the basic life processes of the cell. Considered naked because it is not associated with any proteins.

Question 2

What are plasmids? Why are they useful to bacteria? How are they useful to humans?

Answer 2

• Small extra DNA molecules that are commonly found in prokaryotes. They are small, circular, and naked.
• Plasmids contain a few genes that may be useful in the bacteria
• We can use them to transfer genes between species artificially

Question 3

How are eukaryotic chromosomes different that prokaryotic ones?

Answer 3

• Composed of DNA and associated with histone proteins

- DNA is a single immensely long DNA molecule

Question 4

Differentiate between haploid and diploid nuclei.

Answer 4

Haploid nuclei have one chromosome of each type while diploid nuclei have two homologous chromosomes of each type.

Question 5

How is sex determined in humans?

Answer 5

Crossing of XX and XY parents. If XY, it’s a boy. If XX, it’s a girl.

Question 6

What do karyograms show?

Answer 6

The chromosomes of an organism in homologous pairs of decreasing length.