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Human Biology Unit 3 + 4 > Mutations and Gene Pools > Flashcards

Mutations and Gene Pools Flashcards

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1
Q

What is a species

A

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

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2
Q

What is a population

A

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

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3
Q

What is an allele

A

Alternative forms of a gene

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4
Q

What is a gene pool

A

The sum of all the alleles in a given population

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5
Q

What is allele frequency

A

How often each allele of a gene occurs in the gene pool for that population which can change due to mutations or changes in the environments, this will differ between populations

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6
Q

What is genetic drift

A

A type of activity which causes allele frequencies within Gene pools to change

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7
Q

What is the bottleneck effect

A

Division of genetic drift

Occurence of characteristics in a populations as a result of chance rather than natural selection which causes allele frequencies to change as there are different genes being passed on

This can cause alleles to be fixed or lost

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8
Q

What can cause the bottleneck effect

A

Natural Disasters, Can limit populations and eliminate people from the community which causes allele frequencies to change

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9
Q

What is the founder effect

A

Division of genetic drift

Occurs when a small group purposely moves away from its homeland and establishes a new community, which later expands

The migrants group is usually not genetically representative of the original community, so the next community generally shows features that are not typical of original homeland population

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10
Q

What is an example of the founders effect?

A

The Dunkers Populations

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11
Q

What is a mutation

A

Permanent change in a gene or chromosome which occurs by chance

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12
Q

What is a mutant

A

An organisms resulting from a mutation

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13
Q

What is a mutagen

A

Increases the rate at which mutations occur

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14
Q

What is a somatic mutation

A

Occurs in body cells in which only the individual is affected and can only be passed through daughter cells in mitosis

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15
Q

What is a Germline Mutation

A

Occurs in reproductive cells which results in gametes having altered DNA but the individual who had the mutation is no affected

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16
Q

What is a frameshift mutation

A

When a base has been added or deleted

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17
Q

What is a gene mutation

A

Changes in DNA of a single gene

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18
Q

What are the 3 types of gene mutations

A

Insertion - Implementing a base
Deletion - removing a base
Substitution - Replacing a base

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19
Q

What are the 4 types of effects from mutations

A

Missense - Changes amino acid and protein
Nonsense - codes to STOP due to changes in base sequence
Silent - Not change in amino acid
Neutral - Change in amino acid but no change in protein produced

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20
Q

Examples of Gene Mutations

A

Albinism

Cystic Fibrosis

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21
Q

What are chromosomal mutations

A

Involved mutation of some or all parts of a chromosome

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22
Q

What are the 5 types of Chromosomal mutations

A

Deletion - the loss of parts of a chromosome
Duplication - Where a section of a chromosome occurs twice
Inversion - when a breakage in chromosome occurs but rejoin wrong way around
Translocation - part of chromosome breaks off and rejoins a different chromosome
Nondisjunction - When a chromosome pair does not seperate so one daughter cell has an extra chromosome and one daughter cell has less

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23
Q

What are examples of chromosomal mutation

A

Turners syndrome

Down Syndrome

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24
Q

What is migration

A

Type of evolutionary mechanism also known as gene flow

When immigrants travel to another country. As they travel they can bring alleles that are not already in the population therefore, overtime, the allele frequencies will change

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25
Q

Example of migration changing allele frequencies

A

Chinese Rh blood group factor

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26
Q

What can cause restrictions to gene flow

A
  1. Barriers that inhibit the amount to interbreeding
  2. Environmental differences
  3. Which characteristics are favourable for survival
  4. Members of different religious groups or different language are tended not to interbreed
  5. Economic status
27
Q

What is mutations (evolutionary)

A

Mutation is a permanent shift in a gene or chromosome which causes a different variation of the trait

Mutations introduce new and different alleles into a gene pool so, can change allele frequency

28
Q

What is natural selection

A

Process by which species become adapted to its environment as those with favourable characteristics have a survival advantage

29
Q

What is speciation

A

The process of forming two seperate species

30
Q

Steps of speciation

A
  1. Variation
  2. Isolation
  3. Selection
  4. Speciation
31
Q

What is variation step?

A

A range of variations exist within the population which shares a common gene pool

32
Q

What is the isolation step?

A

A barrier has formed, dividing the population into two. Causing no interbreeding to occur between the two populations so each population has their own gene pool

33
Q

What is the selection step?

A

Different selection pressures act on each of the two populations over generations. This brings about a change in the gene frequencies of each gene pool. Such changes lead to the evolution of seperate subspecies

34
Q

What is the speciation step?

A

Over a long period of time, the changes in the gene frequencies may be great enough to prevent the production of fertile offspring between the two populations from ever occurring again, this causes two species to exist

35
Q

What is natural selection

A

Process by which a species becomes adapted to its environment where those individuals with favourable characteristics have a survival advantage

36
Q

What is a selective agent

A

Any factor which causes the death of an organisms with certain characteristics but has no effect on individuals without those characteristics

37
Q

What is survival of the fittest

A

Where organisms with favourable traits survive, but organisms with unfavourable traits die before they have time to reproduce

38
Q

What is a variation

A

The differences which exist between individuals or populations of a species

39
Q

What is the struggle for existence

A

The number of organisms is greater than the resource amount in the environment can support, therefore there is competition between the organisms

40
Q

What is the Natural Selection Theory

A
  1. A mutation occurs in a population
  2. Lead to variation within species
  3. More offspring produced than can survive
  4. Selection pressures for the populations causing a competition for survival
  5. Individuals with favourable characteristics have a survival advantage ‘survival of the fittest’
  6. They have better reproductive success
  7. Favourable characteristics passed on
  8. The alleles frequency that produce favourable characteristics, increases
41
Q

Body Shape Natural Selection

A
  1. Human genes pool has a wide range of body types
  2. Short bodies and long-limbed physiques gives them large S.A to V ratio, causing heat loss
  3. The long-bodies and short limbed physiques allow smaller S.A to V ratio and ability to lose less heat
  4. Overtime, as the alleles in the gene pool decreased so much that they were completely lost, evolution has taken place
42
Q

Sickle-cell Anemia Natural Selection

A
  1. Those with 2 sickle cells are susceptible to sickle cell disease so they die before reproducing
  2. Those with 1 of each alleles are susceptible to malaria, therefore having a survival advantage therefore, reproduce
  3. Those with 2 normal alleles are susceptible to malaria therefore, they can pass these traits on
43
Q

Tay Sachs Inheritance

A

Recessive trait

44
Q

Tay Sachs Causes

A

Missing enzyme which is essential for lipid metabolism

45
Q

Tay Sachs Effects

A

Results in the accumulation of fatty substances in the nervous system in the white matter which causes issues with nervous system transmissions

46
Q

Tay sachs Symptoms

A

Children can develop mental and physical disabilities, death can occur by age 4 or 5, build up of fatty substances in the nervous system

47
Q

Benefits of Tay Sachs

A

Provides survival advantage for heterozygotes of the trait in environments where Tuberculosis is prevalent

48
Q

Effects on gene pool of Tay Sachs

A

Homozygous dominant - susceptible to TB

Homozygous Recessive - susceptible to Tay-Sachs

Heterozygote - has a survival advantage to TB, more likely to survive and pass alleles onto offspring therefore Tay-Sachs alleles freq. is increased and maintained

49
Q

Sickle Cell Anaemia Inheritance

A

Recessive trait

50
Q

Sickle Cell Anaemia Causes

A

A point mutation of the gene responsible for the beta-globulin proteins in haemoglobin

51
Q

Effects of sickle cell anaemia

A

Results in sickle shaped RBC which reduces their oxygen carrying capacity which blocks capillaries

52
Q

Symptoms of Sickle Cell Anaemia

A

Fatigue, shortness of breath, anaemia

53
Q

Impacts of Sickle Cell Anaemia

A

Fatal before 7 years

54
Q

Benefits of sickle cell disease

A

Sickle-cell provides a survival advantage in environments where malaria is prevalent, such as Africa as it provides a resistance to Malaria

55
Q

Sickle Cell impact on gene pool

A

Homozygous Dominant - susceptible to Malaria
Homozygous recessive - susceptible to Sickle-cell disease
Heterozygote - have the sickle-cell trait, they have a survival advantage therefore more likely to survive and pass alleles onto offspring, allowing sickle cell alleles frequency to increase and be maintained in the black African populations

56
Q

Thalassemia Inhertiance

A

Recessive trait

57
Q

Causes of Thalassemia

A

Mutation of the gene responsible for haemoglobin production, severity varies depending on number of genes affected

58
Q

Alpha Thalassemia Causes

A

Due to mutation on Chromosome 16, which reduces formation of alpha globin

59
Q

Beta Thalassemia Causes

A

Due to mutation on Chromsome 11, which reuces formation of beta globin

60
Q

Effects of Thalassemia

A

Abnormal shaped haemoglobin molecules leading to fewer functions RBC with reduced oxygen carrying capacity

61
Q

Symptoms of Thalassemia

A

Anaemia, fatigue, heart defects, slower functioning RBC, abnormal haemoglobin shape

62
Q

Impacts of Thalassemia

A

Fatal before 30 years if has a heart complication

63
Q

Benefits of Thalassemia

A

Thalassemia provides a survival advantage in environments where malaria is prevalent (South East Asia and Mediterranean Sea)

64
Q

Thalassemia effects on Gene Pool

A

Homozygous Dominant = susceptible to malaria

Homozygous Recessive = susceptible to Thalassemia, however Alpa is fatal and Beta is less fatal therefore, Beta is more likely to reproduce

Heterozygote = have a survival advantage therefore more likely to survive and pass alleles onto offspring therefore Thalassemia alleles frequency is increased and maintained in South-East Asia and Mediterranean Sea populations

Human Biology Unit 3 + 4 (7 decks)

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