Chapter 9: Mutations

Question 1

What is an intraspecific variation?

Answer 1

Differences between characteristics or phenotypes of individuals of same species

Question 2

What are mutations?

Answer 2

A change in a gene or chromosome relative to the original; may also refer to the process of generating change

Question 3

What is a mutagen?

Answer 3

Any agent capable of inducing mutation

Question 4

When can mutations occur?

Answer 4

They may arise spontaneously during the DNA replication part of the cell cycle, or during cell division

Question 5

What can impact the rate at which mutations occur?

Answer 5

It can be increased by physical or chemical mutagens

Question 6

What are spontaneous mutations?

Answer 6

Mutations occurring in the absence of exposure to mutagens

Question 7

When can spontaneous mutations occur?

Answer 7

During the non-dividing S (synthesis) phase of the cell cycle, when the DNA is unwound for replication and is exposed and vulnerable to damage (refer to figure 9.1.2 pg 174 for example)

Question 8

What is a point mutation?

Answer 8

A mutation that affects a single base-pair position within a gene

Question 9

What are single nucleotide polymorphism (SNP)

Answer 9

A nucleotide difference that occurs at one given position in the gene

Question 10

What is a substitution mutation?

Answer 10

A mutation in which a single nucleotide is swapped for another

Question 11

What are indels?

Answer 11

A collective term for mutations caused by insertions and/or deletions

Question 12

What is a frameshift mutation?

Answer 12

A mutation that dislocates the translational reading frame (refer to figure 9.1.3 pg 175 for diagram of frameshift)

Question 13

What are some examples of physical mutagens?

Answer 13

Ionizing radiation, UV radiation, and heat

Question 14

What is ionizing radiation?

Answer 14

Radiation that is strong enough to break chemical bonds in molecules, and removes tightly bound electrons from the orbits of individual atoms, causing atoms to become charged or ionized

Question 15

How does UV radiation cause mutations?

Answer 15

It can affect the chemical structure of nitrogen bases, fusing adjacent thymine or cytosine bases in the DNA sequence

Question 16

How do X-rays cause mutations?

Answer 16

They cause the deletion of adenine and guanine bases, creating gaps in the double helix. These aberrations disrupt complementary bases pairing during DNA replication

Question 17

What are double-strand breaks?

Answer 17

A mutation involving breaks in both of the sugar-phosphate backbones at the same nucleotide pair, resulting in the complete breakage of a chromosome

Question 18

What is apoptosis?

Answer 18

A programmed series of events lead to natural cell death when the internal contents of the cell are dismantled by various enzymes

Question 19

What are some chemical mutagens?

Answer 19

Refer to table 9.1.2 pg 175

Question 20

What is aneuploidy?

Answer 20

A genome variant having unconventional chromosome number due to loss or addition to one of or a small number of chromosomes

Question 21

What is non-disjunction?

Answer 21

The failure of homologous partner chromosomes in meiotic cell division or sister chromatids in mitotic division to separate to opposite poles

Question 22

What is trisomy?

Answer 22

When somatic cells contain three copies of a particular chromosome

Question 23

What is monosomy?

Answer 23

When somatic cells contain only one copy of a particular chromosome pair

Question 24

How does non-disjunction lead to aneuploidy?

Answer 24

If the homologous partner does not separate to opposite poles, there will then be an unconventional number of chromosomes in a genome (refer to figure 9.2.3 pg 179 for more info)

Question 25

What causes down syndrome?

Answer 25

An extra chromosome 21 in each cell (trisomy 21) (refer to figure 9.2.3 pg 179 for colour stain of a female with down syndrome)

Question 26

What does somatic mean?

Answer 26

A body cell that will not pass its genes onto nect generation

Question 27

What is mitosis?

Answer 27

A type of nuclear division that produces daughter cells with the same chromosomal content as the parent cells; the basis for growth and repair in multicellular individuals, and for asexual reproduction in many eukaryotic species (refer to figure 9.3.1 pg 185 for diagram of mutations in mitosis)

Question 28

What is a germ-line?

Answer 28

The cell line in eukaryotic organsims from which sex cells are produced

Question 29

What does congenital mean?

Answer 29

Present at birth; may or may not be inherited congenitally

Question 30

What impacts the variations in characteristics (phenotype) of individual species?

Answer 30

It is determined by the unque paired combinations of alleles in its coding genes (genotype) pg 193