Chapter 7A

Question 1

What structure does a molecule of DNA form?

Answer 1

Double helix

Question 2

The double helix looks like a twisted ladder— what are the rungs of the base composed of?

Answer 2

Base pairs

Question 3

The double helix looks like a twisted ladder— what are the sides of the ladder made of?

Answer 3

Sugar molecules and phosphate groups

Question 4

What is each DNA strand composed of?

Answer 4

Nucleotides

Question 5

What are the three components of a nucleotide?

Answer 5

1. Sugar molecule
2. Phosphate group
3. Nitrogenous base

Question 6

There are four nitrogenous bases that occur in DNA molecules. What are they?

Answer 6

Cytosine, Guanine, Adenine, and Thymine

Question 7

What does Adenine pair with?

Answer 7

Thymine

Question 8

What does Thymine pair with?

Answer 8

Adenine

Question 9

What does Cytosine pair with?

Answer 9

Guanine

Question 10

What does Guanine pair with?

Answer 10

Cytosine

Question 11

What is a gene?

Answer 11

Sequence of nucleotides that code for a protein.

Question 12

What is an allele?

Answer 12

A variant of a gene

Question 13

What is the structure of a chromosome?

Answer 13

DNA wrapped around histone proteins

Question 14

What is a centromere?

Answer 14

The region where the cells spindle fibres attach

Question 15

What are sister chromatids?

Answer 15

Copies of DNA joined at the centromere

Question 16

What are homologous chromosomes?

Answer 16

Pairs of chromosomes that are the same size with the same gene loci

Question 17

Explain how homologous chromosomes are inherited.

Answer 17

One inherited from mum (maternal) one inherited from dad (paternal)

Question 18

How many homologous chromosomes do we have?

Answer 18

We have 22 pairs and X/Y

Question 19

What is a karyotype?

Answer 19

Visual representation of homologous chromosomes + X/Y

Question 20

What is a key role of the karyotype?

Answer 20

Identify chromosomal abnormalities

Question 21

What is aneuploidy?

Answer 21

When an organism possesses an incorrect number of chromosomes

Question 22

When an organism possesses an incorrect number of chromosomes, what is this condition called?

Answer 22

Aneuploidy

Question 23

Draw the equation of Monosomy

Answer 23

2n - 1

Question 24

2n - 1 represents what chromosomal abnormality?

Answer 24

Monosomy

Question 25

What is an example of Monosomy?

Answer 25

Turner Syndrome

Question 26

Explain Turner Syndrome.

Answer 26

Only one X chromosome, no Y

Question 27

Draw the equation of Trisomy.

Answer 27

2n + 1

Question 28

The equation 2n + 1 represents what chromosomal abnormality?

Answer 28

Trisomy

Question 29

Name two examples of trisomy.

Answer 29

Down syndrome, Klinefelter syndrome

Question 30

Explain Down Syndrome.

Answer 30

Trisomy - extra copy of chromosome 21

Question 31

Explain Klinefelter Syndrome.

Answer 31

Trisomy - extra X chromosome in males

Question 32

Write an equation representing the chromosomal abnormality of tetrasomy.

Answer 32

2n + 2

Question 33

2n + 2 represents what chromosomal abnormality?

Answer 33

Tetrasomy

Question 34

Explain tetrasomy X

Answer 34

Tetrasomy - two extra copies of X chromosome

Question 35

Explain the term “Polyploidy”

Answer 35

An organism with more than two sets of each chromosome