Unit 2 - Topic 9 - Chromosomes, Genes and DNA

Question 1

Definition: Chromosome

Answer 1

Long strand of DNA (genetic structures) located in the nucleus.

Question 2

Definition: Gene

Answer 2

Short strand of DNA (located on a chromosome) which codes for a particular characteristic or amino acid, which are the building blocks for proteins.
Genes are often described as functional units.

Question 3

Chromosomes occur in …

Answer 3

Functional pairs

Question 4

What does DNA stand for?

Answer 4

Deoxyribonucleic acid

Question 5

Describe the shape of DNA

Answer 5

Double helix

Question 6

What does DNA consist of?

Answer 6

DNA consists of three sub-units.

Deoxyribose sugar (a pentose sugar)
Phosphate
Bases

Question 7

What are the four different types of bases?

Answer 7

Adenine
Thymine
Guanine
Cytosine

Question 8

What type of bond connects the bases of the coding strand to the bases of the anti-coding strand?

Answer 8

Hydrogen bonds

Question 9

What is the name given to a repeating unit of DNA, consisting of a phosphate, a sugar (deoxyribose) and a base?

Answer 9

A nucleotide

Question 10

What does adenine bond to?

Answer 10

Thymine

Question 11

What does thymine bond to?

Answer 11

Adenine

Question 12

What does guanine bond to?

Answer 12

Cytosine

Question 13

What does cytosine bond to?

Answer 13

Guanine

Question 14

Which side of the DNA molecule forms the genetic code?

Answer 14

The coding strand.

Question 15

How many bases are needed to form an amino acid and what is this hypothesis known as?

Answer 15

Three

Base triplet hypothesis

Question 16

In theory, how many combinations of amino acids are possible?

Answer 16

4*3 = 64

Question 17

What do bases code for?

Answer 17

Bases code for amino acids, which are the building blocks of proteins.

Question 18

Name the scientists who made contributions towards the discovery of DNA.

Answer 18

Erwin Chargaff
Rosalind Franklin
Maurice Wilkins
James Watson
Francis Crick

Question 21

What did Rosalind Franklin and Maurice Wilkins discover and what method did they use?

Answer 21

They discovered the overall 3-dimensional shape of DNA.

X-Ray diffraction (Crystallography).

Question 22

When did Erwin Chargaff make his discovery?

Answer 22

1950

Question 23

What did Erwin Chargaff discover?

Answer 23

Erwin Chargaff discovered, through chemical means, that although the arrangement of bases in DNA varied, there was always an equal amount of adenine and thymine. Similarly there was always an equal amount of guanine and cytosine.

Question 24

When did James Watson and Francis Crick discover the shape of DNA?

Answer 24

1953

Question 25

What method did James Watson and Francis Crick use to discover the shape of DNA (a double helix)?

Answer 25

Modelling

Question 26

What is peer review?

Answer 26

When new scientific knowledge is validated by other scientists to confirm its accuracy.

Question 27

The development of the scientific theory of the structure of DNA is an example of …

Answer 27

The collaborative nature of science.