GVR: DNA, genes and chromosomes

Question 1

Give the 3 traits of eukaryotic cells DNA molecules:

Answer 1

• Long
• Linear
• Associated with proteins (histones)

Question 2

Give the 3 traits of prokaryotic cells DNA molecules:

Answer 2

• Short
• Circular
• Not associated with proteins (histones)

Question 3

How does eukaryotic DNA exist in the nucleus?

Answer 3

Chromosomes

Question 4

What two things is a chromosome made up of?

Answer 4

One DNA molecule and its associated proteins.

Question 5

Why are there histones in our chromosomes?

Answer 5

• DNA molecules are very long so they have to be wound up around histones to be able to fit inside the nucleus.
• They help support the DNA.

Question 6

What is a histone?

Answer 6

A protein that DNA wraps around to form chromatin, which makes up chromosomes.

Question 7

How does prokaryotic DNA fit in its cell?

Answer 7

The DNA condenses by supercoiling.

Question 8

How does eukaryotic DNA fit in its nucleus?

Answer 8

Double-helix DNA wounds around histone proteins. The DNA and proteins are then coiled up repeatedly to form a single chromosome.

Question 9

Describe the structure of eukaryotic DNA:

Answer 9

• Thread-like structures made up of a long DNA molecule wound around histone proteins.
• The DNA and proteins are then coiled up to form a chromosome.

Question 10

What determines the order of amino acids in a polypeptide?

Answer 10

Order of base sequences

Question 11

Why are introns removed?

Answer 11

So they don’t affect the amino acid order.

Question 12

What are homologous chromosomes?

Answer 12

Pairs of matching chromosomes.

Question 13

What is a gene?

Answer 13

A base sequence of DNA that codes for the amino acid sequence of a polypeptide and functional RNA.

Question 14

How many DNA bases code for one amino acid?

Answer 14

Three

Question 15

Define genome:

Answer 15

The complete set of genes in the cell.

Question 16

Define proteome:

Answer 16

The full range of proteins that the cell can produce.

Question 17

Alleles for the same characteristic can be found at a particular point on a chromosome. What is the name given to this fixed point?

Answer 17

A locus.

Question 18

Alleles for the same characteristic on sister chromatids are found at the ______.

Answer 18

Locus.

Question 19

What is meant by the term degenerate code?

Answer 19

More than one triplet codes for a single amino acid.

Question 20

Why is the genetic code described as being universal?

Answer 20

In all organisms the same triplet codes for all amino acids.