8.3 DNA and chromosomes

Question 1

What are the two types of cell?

Answer 1

Prokaryotic cells and eukaryotic cells.

Question 2

Describe the prokaryotic DNA.

Answer 2

The DNA is smaller and form a circle and are not associated with protein molecules. They do NOT have chromosomes.

Question 3

Describe the eukaryotic DNA.

Answer 3

DNA molecules are larger, they form a line (linear) and associate with proteins to form CHROMOSOMES.

Question 4

CHROMOSOME STRUCTURE. Where are they dispersed?

Answer 4

Throughout the nucleus.

Question 5

What are the threads of a chromosome called?

Answer 5

A chromatid.

Question 6

What are the DNA in chromosomes held in place by?

Answer 6

Proteins.

Question 7

The steps that DNA is packed into a chromosome?

Answer 7

• DNA molecule
• DNA combined with proteins
• DNA-protein complex is coiled
• Coils fold to from loops
• Loops coil and pack together to form the chromosome.

Question 8

Humans have how many chromosomes?

Answer 8

46

Question 9

Chromosomes occur in pairs called?

Answer 9

Homologous pairs.

Question 10

What is the total number of homologous pairs called?

Answer 10

The diploid number.

Question 11

What is an allele?

Answer 11

Genes are sections of DNA, they occur in two forms called alleles.