Chapter 12 - Mutations & Gene Pools

Question 1

What is a species?

Answer 1

A group of individuals that share many characteristics and are able to interbreed to produce fertile offspring.

Question 2

What are alleles?

Answer 2

Alternative forms of a gene.

Question 3

What is a population?

Answer 3

A group of organisms of the same species living together in a particular place at a particular time.

Question 4

What is a gene pool?

Answer 4

The sum of all the alleles carried by the members of a population.

Question 5

What is allele frequency?

Answer 5

How often each allele of a gene occurs in a population.

Question 6

What does it mean when different populations differ in the characteristics they possess?

Answer 6

They are likely to have different frequencies of various alleles of a gene in their respective gene pools.

Question 7

The composition of the gene pool of a population ______________

Answer 7

May change over time

Question 8

What is a mutation?

Answer 8

A change on a gene or a chromosome leading to a new characteristic in an organism.

Question 9

How do mutations occur?

Answer 9

Suddenly and by chance

Question 10

What is a mutant?

Answer 10

An organism with a characteristic resulting from a mutation

Question 11

What are the two main types of mutations?

Answer 11

• gene mutations

- chromosomal mutations

Question 12

What are gene mutations?

Answer 12

Changes in a single gene so that the traits normally produced by that gene are changed or destroyed

Question 13

What are chromosomal mutations?

Answer 13

A change to the structure and/or number of chromosomes in an organism.

Question 14

When do gene mutations occur?

Answer 14

During the replication of DNA before cell division.

Question 15

DNA is a __________ and ___________

Answer 15

Complex molecule, any subtle alteration in its structure can produce changes in the usual characteristics of a species

Question 16

What are mutagens?

Answer 16

An agent that is known to increase the rate at which mutations occur

Question 17

What are some examples of mutagens?

Answer 17

• mustard gas
• formaldehyde
• Sulfur dioxide
• some antibiotics

Question 18

What are examples of ionising radiation mutagens?

Answer 18

• UV light
• X-rays
• cosmic rays

Question 19

Why do doctors try to avoid using X-rays early in pregnancy?

Answer 19

Because if a woman is treated with large doses of X-rays during the first trimester the child may be born with mental retardation, skeletal deformations, or a smaller head in relation to the rest of its body.

Question 20

What is a somatic mutation?

Answer 20

A change occurring in a gene in a body (somatic) cell

Question 21

Who does a somatic mutation effect?

Answer 21

Only the individual with the mutation

Question 22

What is a germ line mutation?

Answer 22

A change in the hereditary material in the egg or sperm that becomes incorporated into the DNA of every cell in the body of the offspring.

Question 23

What are the differences between somatic and germline mutations?

Answer 23

• occur in different cells

- germline are passed on to new generations

Question 24

What do the sequence of bases with in a gene code for?

Answer 24

Amino acids

Question 25

What is a point mutation?

Answer 25

A change in one of the bases in a DNA molecule.

Question 26

What can a point mutation do?

Answer 26

Alter a protein, have no effect at all, or prevent the protein from being produced.

Question 27

What are some examples of diseases caused by point mutations?

Answer 27

- albinism - Cystic Fibrosis - the Duchenne form of muscular dystrophy

Question 28

What are lethal recessive?

Answer 28

Recessive alleles, that inherited in the homozygous condition, result in the death of the embryo, foetus or child.

Question 29

How do lethal recessive cause changes in the gene pool?

Answer 29

People who inherit two such alleles would die before their alleles could be passed on to the next generation, so the proportion of lethal recessive sin the gene pool would generally reduce.

Question 30

What are chromosomal mutations?

Answer 30

A change to the structure and/or number of chromosomes in an organism.

Question 31

What are the types of chromosomal mutations?

Answer 31

- deletion - duplication - inversion - translocation - non-disjunction

Question 32

What is deletion?

Answer 32

Part of a chromosome is lost.

Question 33

What is duplication?

Answer 33

Part of a chromosome occurs twice. This may happen is part of a chromatid breaks off and joins into the wrong chromatid.

Question 34

What is inversion?

Answer 34

Breaks occur in a chromosome and the broken piece joins back, but the wrong way around. This changes the order of the genes on a chromosome and may disrupt the pairing of homologous chromosomes during meiosis.

Question 35

What is translocation?

Answer 35

Part of a chromosome breaks off and is re-joined to the wrong chromosome.

Question 36

What is non-disjunction?

Answer 36

During meiosis, a chromosome pair does not separate and so one daughter cell has one extra and one daughter cell has one less than the normal number.

Question 37

What is an aneuploidy?

Answer 37

A change in the chromosome number

Question 38

What is trisomy?

Answer 38

When there is 3 of one chromosome

Question 39

What is an example of trisomy?

Answer 39

Down syndrome, trisomy 21

Question 40

What is partial trisomy?

Answer 40

When part of an extra copy of a chromosome attaches to one of the other chromosomes.