Mutations And Gene Pools

Question 1

What is a mutation?

Answer 1

A permanent alteration in DNA.

Mutations can occur due to various factors including environmental agents and cellular errors.

Question 2

What are the causes of mutations?

Answer 2

mutagens and cellular errors during cell division or DNA replication.

Spontaneous mutations can also occur.

Question 3

What are somatic mutations?

Answer 3

Changes that occur in non-reproductive cells, and cannot be passed on to offspring.

The effect is localized to the impacted tissue.

Question 4

What are germline mutations?

Answer 4

Changes that occur in reproductive cells, before conception, and can be passed on to offspring.

The effect is on the entire organism.

Question 5

What are point mutations?

Answer 5

Mutations that can cause an amino acid change or have no effect at all.

Point mutations involve a change in a single nucleotide.

Question 6

What are gene mutations?

Answer 6

can affect the processing of genes, potentially changing or destroying them.

can lead to various genetic conditions.

Question 7

What is a chromosomal mutation?

Answer 7

A change to the structure and/or number of chromosomes in an organism, affecting multiple genes and potentially leading to genetic disorders.

Chromosomal mutations can have significant impacts on an organism’s health.

Question 8

What is a missense mutation?

Answer 8

A mutation that causes changes in an amino acid, resulting in a different protein being produced.

This type of mutation can alter the function of the protein.

Question 9

What is a nonsense mutation?

Answer 9

A mutation that results in a stop codon, producing a shorter peptide chain due to the protein synthesis stopping.

Nonsense mutations can severely impact protein function.

Question 10

Neutral mutations

Answer 10

Causes a change in an amino acid; but doesn’t cause an overall change in the protein.

Question 11

Silent mutations

Answer 11

Does not cause a change in amino acid sequence or protein.

Question 12

Frameshift mutation

Answer 12

Involves an insertion or deletion of a base, resulting in a change in the way the sequence is read.

Question 13

Mutagens

Answer 13

Agent(s) which can change the structure of DNA, causing a mutation.

Question 14

Electromagnetic radiation mutagens

Answer 14

Waves which carry electrochemical energy.
- uv light, gamma rays, x-rays: cause mutations.

Question 15

How electromagnetic radiation mutagens cause damage

Answer 15

High energy EM radiation causes atoms to vibrate & lose electrons; breaking bonds and damaging DNA.
E.g.) sun, radioactive elements, medical imaging machines.

Question 16

Chemical mutagens

Answer 16

Cause mutations in different ways;
1) incorporate themselves into DNA.
2) insert themselves into DNA.
3) make gaps in DNA.

Question 17

Naturally occurring mutagens

Answer 17

Microbe: mycotoxins are poisonous chemicals produced by fungi.

Plant: cycasin is a mutagenic chemicals, found in the leaves of cycad plants.

Animal: dimethylnitrosamine is produced in the stomach when nitrite is consumed.

Question 18

Spontaneous mutations

Answer 18

A mutation that occurs due to an error in a natural biological process.

Question 19

Induced mutation

Answer 19

A mutation caused by a mutagenic agent

Question 20

Population

Answer 20

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

Question 21

Gene pool

Answer 21

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

Question 22

Allele frequencies

Answer 22

How often each allele of a gene occurs in a population

Question 23

Natural selection

Answer 23

Process which a species becomes better adapted to its environment.

Question 24

Genetic variation

Answer 24

Difference in DNA sequences between individuals w/in a population.

Question 25

Survival of the fittest

Answer 25

Principle where organisms w favourable characteristics survive, but those w unfavourable characteristics die before they reproduce.

Question 26

Selection pressures

Answer 26

Factors in environment that affect an organism’s chance of survival.

Question 27

Selective agent

Answer 27

Any factor that causes the death of organisms w certain characteristics, & have no effect on individuals w/o those characteristics.

Question 28

Positive selection pressures

Answer 28

Increases chance of organisms survival as environment suits the characteristics it has.

Question 29

Negative selection pressures

Answer 29

Decreases organisms chance or survival as the environment doesn’t support its characteristics.

Question 30

Favourable characteristics

Answer 30

Characteristics that increase chance of survival, as they’re better suited to the environment.

Question 31

Unfavourable characteristics

Answer 31

Characteristics that decrease chance of survival, as they’re selected against.

Question 32

Selective advantage

Answer 32

When organisms have favourable characteristics for a particular selection pressure, allowing for their survival.

Question 33

Beneficial allele

Answer 33

Increases chances of survival, therefore passes to offspring. E.g.) sickle-cell anaemia provides resistance to malaria.

Question 34

Adaptation

Answer 34

Process of change by which an organism becomes better suited to its environment.

Question 35

Speciation

Answer 35

Process of a new species developing.

Question 36

Migration

Answer 36

Movement of people from one area to another w the intention of settling permanently.

Question 37

Sickle-cell anaemia

Answer 37

An inherited disease; two recessive alleles for sickle-cell anaemia, causes early death. -a point mutation in haemoglobin gene, causing abonormally shaped RBC’S that can block blood flow.

Question 38

Heterozygous advantage

Answer 38

Heterozygous genotypes has a higher chance of survival than homozygous.

Question 39

Species

Answer 39

Where members are capable of interbreeding & produce fertile offspring.

Question 40

Struggle for existence

Answer 40

Principle where # of organisms is greater than the resources in the environment; competition between organisms for the resources.

Question 41

Gene frequency

Answer 41

The presence of a particular allele in a population.

Question 42

Subspecies

Answer 42

A group w/in a species that has become physically & genetically different from the rest of the group.

Question 43

Spatial isolation

Answer 43

Occurs when individuals from a population are separated by large distances, or inhabit different parts of an area.

Question 44

Geographical isolation/barriers

Answer 44

Occurs when individuals from a population are separated by a physical barrier. E.g.) oceans, rivers, mountains, desserts.

Question 45

Gene flow

Answer 45

Transfer of alleles from one population to another via migration.

Question 46

(Random) genetic drift

Answer 46

Occurrence of characteristics in a population as a result of chance rather than natural selection.

Question 47

Sickle-cell anaemia (example for natural selection)

Answer 47

-if someone is heterozygous for sickle-cell gene (HbA/HbS) they have increased resistance for malaria. -homozygotes often die young, but heterozygotes survive and reproduce. -creates selection pressure: HbS allele is maintained in pop despite being harmful to homozygotes, therefore heterozygotes have heterozygote advantage.

Question 48

heterozygote advantage

Answer 48

When having a recessive allele provides resistance to a particular disease, increasing survival for the carrier. e.g.) sickle-cell anaemia- malaria.

Question 49

The bottle neck effect

Answer 49

Extreme form of genetic drift that occurs when the size of a population is severely reduced due to a sudden event (natural disaster); allele frequency of survivors may not reflect population.

Question 50

The founder affect

Answer 50

Type of genetic drift where a new population is formed by a small # of individuals; the small sample size can cause marked deviations in allele frequencies from original population.