Unit 4 9A: Mutations

Question 1

Genotype

Answer 1

the genetic makeup or alleles of an organism

Question 2

Phenotype

Answer 2

A physical characteristic determined by genotype and environment

Question 3

Genetic diversity

Answer 3

The genetic variability within a species

Question 4

Adaptations

Answer 4

The behavioural, physiological, biochemical and structural features of an organism that help them survive in an environment

Question 5

Population

Answer 5

A group of individuals of the same species living in the same region at a given time

Question 6

Species

Answer 6

A group of organisms that can interbreed, producing fertile and viable offspring

Question 7

Gene pool

Answer 7

The sum total of alleles present in a population of organisms

Question 8

Allele frequency

Answer 8

The proportion of a particular allele within a population

Question 9

Evolution

Answer 9

A change in the allele frequencies of a population over time

Question 10

Mutation

Answer 10

A permanent change in the nucleotide sequence of a section of DNA

Question 11

Mutagenic agents

Answer 11

Agents known to cause mutations; for example, some radiation sources and chemicals; also called mutagens

Question 12

Point mutation

Answer 12

A change to one base in the nucleotide sequence of a section of DNA; includes base substitutions and frameshift mutations

Question 13

Substitution mutations

Answer 13

A type of point mutation that occurs when one nitrogenous base in a gene is replaced with another base; includes silent, missense and nonsense mutations

Question 14

Silent mutation

Answer 14

A mutation where the change in the nucleotide sequence doesn’t change the amino acid that is coded for

Question 15

Missense mutation

Answer 15

A mutation in which the base change in the nucleotide sequence of the DNA changes the amino acid that is coded for; a type of substitution point mutation

Question 16

Nonsense mutation

Answer 16

A mutation that occurs when the base change in the nucleotide sequence of the DNA codes for a STOP codon, prematurely halting the production of the polypeptide; a type of substitution point mutation

Question 17

Frameshift mutation

Answer 17

A type of point mutation that occurs when one base is inserted into or deleted from a gene, causing an incorrect reading of the codons due to a shift in the reading frame

Question 18

Block mutation

Answer 18

A type of mutation that affects large sections of DNA, typically containing multiple genes; also called chromosome mutation

Question 19

Types of block mutations

DDIT

Answer 19

1. Deletion
2. Duplication
3. inversion
4. Insertion
5. Translocation

Question 20

What is a deletion block mutation

Description and effects on the individual

Answer 20

A section of DNA is removed from the chromosome
Leads to disrupted/missing genes.
Large impact on growth and development, sometimes fatal

Question 21

What is a Duplication block mutation

Description and effects on the individual

Answer 21

A section of chromosome is repeated multiple times (sometimes thousands of times) on the same chromosome
Can lead to an increase in gene expression

Question 22

What is an Inversion block mutation

Description and effects on the individual

Answer 22

A section of chromosome is removed, rotated 180 degrees and reattached in reverse order.
Can be as small as two bases, or as large as several genes
Usually does not cause abnormalities, but can cause lowered fertility

Question 23

What is a Translocation block mutation

Description and effects on the individual

Answer 23

A section of one chromosome ataches to a non-homologous chromosome or sections are exchanged between the two.
Leads to disruptions in gene sequences or interruptions in gene regulation
Can cause some cancers

Question 24

Chromosome abnormality

Answer 24

Mutation that involves a whole chromosome or a change in the number of chromosomes, which can be identified using a karyotype;
examples are aneuploidy and polyploidy

Question 25

Karyotype

Answer 25

a pictorial representation of chromosomes that allows the determination of diploid number, gender and chromosomal abnormalities

Question 26

Aneuploidy

Answer 26

When a cell has one more or one less chromosome than expected, usually due to non-disjunction during meiosis

Question 27

What is non-disjunction

In meiosis

Answer 27

When the chromosomes fail to separate. The result is daughter cells of gametes forming with an incorrect number of chromosomes.

Question 28

Polyploidy

Answer 28

A condition in which an organism has more than two full sets of chromosomes in its cells; more common in plants than animals

Question 29

What is an insertion mutation

Answer 29

a type of mutation that involves the addition of one or more nucleotides(nitrogenous bases) into a segment of DNA.