genetic makeup of populations Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Define allele

A

a variation of the same gene. e.g.) gene = eye colour , Allele= blue, green , hazel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define Population

A

the total no. of 1 species in a particular area

May be large and occupy large areas or exist in small pockets e.g.> island

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define species

A

A group of interbreeding individuals reproductively from other such groups.Often composed of different populations ( often I different habitats ) that are quite distinct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are differences in species called ?

A

Races or varieties depending on the degree of reproduction isolation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a gene Pool

A

The sum total of all the genes present in a population at any given time.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Gene pools are subject to processes that alter allele frequencies.This process are … ?

A
  • Mutation -spontaneous mutations can alter allele frequencies and create new alleles
  • Gene Flow-Genes can be exchanged with other gene pools as individuals move between them.
  • Natural Selection-Pressue against certain alleles combinations may reduce reproductive success.
  • Non-random mating-Individuals seek out particular phenotypes with which to mate with.
  • Small population + Genetic drift-Alleles may be lost or foxed.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is genetic Drift ?

What population is it the strongest in ..

A

Is a mechanism of evolution in which allele frequency within a population change over generations due to chance
- Strong in small populations , may result in a loss of alleles or a rise to 100% however in large population their is little or no genetic drift therefore stable in popn

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Whats 4 mechanisms of genetic drift ?

A
  • natural selection
  • gene flow
  • mutation
  • Bottle Neck + Founder effects
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is gene flow

A

Is the movement of genes into to out of a population ( immigration / emigration ) May gain or lose alleles thru gene flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does differences get reduced

What stops gene flow … ?

A
  • Tends to reduce differents because the gene pool becomes more similar
  • Barriers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Selective breeding

A

Humans have controlled the breeding of domesticated animals and plants for centuries this is know as selective breeding.
Involves breeding from individuals with the most desirable phenotypes.
N

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Define Natural Selection

A

Populations of sexually reproducing organisms consist of varied individuals with some variants leaving more offsprings than others

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

The rules of Nature Selection

A

1- Their is phenotypical variation amongst individuals of the population
2-In changing environments individuals with a favoured phenotype will have an improved chance of surviving and reproducing
3-Over time there is greater chance of offsprings having favoured phenotypes
4-The favoured phenotype (allele frequency will increase if selection pressures do not change)
IN TIME A NEW SPECIES MAY EVOLVE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The no. of factors that cause variation

A
1- Sexual Reproduction
~crossing over of chromosomes 
~random assortment of chromosomes during meiosis
~Combination of gametes
~Random selection of mate 
2-Mutation
3-Gene Flow
4-Environment Factors 
Genetype + Environment  = phenotype
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Mutation

What are 3 ways .. ?

A

Some mutations can be fatal , whereas some mutations can bring about a favoured phenotype

  • Point / Base mutations
  • Block mutation
  • Whole chromosome mutation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Define Degeneracy

A

More than 1 Condon that codes for the same amino acid

17
Q

Neutral / silent mutations what are they ?

A

Mutations are neither harmful nor beneficial to the organism in which they occur. Have no observable phenotypic effect , but can be detected using genome analysis.
May be important in an evolutionary sense.

18
Q

Block mutations

  • how do they occur
  • What do they cause
  • 4 ways they are described
A
  • some occur as a result of errors in crossing over during meiosis.Mutagens can also cause it
  • Cause genetic imbalances which usually disrupt development.
  • Described as
  • Inversion = Pieces of chromosome are * flipped * so the genes appear in reverse order.
  • Translocation = Pieces of chromosome are moved from 1 chromosome into another
  • Duplication= Pieces of chromosome are repeated so there are duplicate segments
  • Deletion = Pieces of chromosome are * lost* ~Probably has the greatest effect
19
Q

Mutagens what are they and examples

A

An agent which cause genetic mutation

  • UV light
  • Radiation
20
Q

What is Whole Chromosome Mutations

A

Due to whole chromosome being “ misplaced “ usually due to a mistake in the process of cell division
A mistake in meiosis is known as non-disjunction.

21
Q

The 2 forms of non-disjunction mutation and what are they .. ?

A

Aneuploidy ~ A condition where 1 or more chromosomes are missing from or added to the normal somatic cell chromosome to the normal somatic cell chromosome number.
Polyploidy ~Describes the state of having 3 or more complete sets of chromosomes ( 3N or greater )
NOTE- Is rarely observed in humans, but it is thought to be one of the more common cause of spontaneous abortion

22
Q

Bottleneck Effect

  • how does it occur
  • Whats the impact
A

-occurs when the size of a population is drastically reduced for at least one generation.Could be due to seasonal climatic change or some disaster or disease causes a rapid decrease in the size of a large population.
-The impact is the few survivors that reproduce to give the next generation may by chance be an unrepresentative sample of the gene pool of the original population.
So when the population rebuild , the allele frequencies can be very different from those in the original (pre-disaster) population, and the genetic diversity that is the population’s insurance policy may be greatly reduced.

23
Q

isolation of genes can occur two ways

A
  • Allopatric speculation - caused by geographic isolation
    example- Separation by a river , mountain range , canyons , glacier ,oceans
  • Sympatric Speciation- Is genetic isolation caused by behaviour , chromosome differences , seasonal behaviour.
24
Q

Founder Effect

  • how does it occur
  • Whats the impact
A
  • Occurs when a small no. of individuals may migrate or become isolated from their original population
    -This founder population will have a small and probably non-representative sample of alleles from the parent population pool.
    As a consequence of this may evolve into a different direction than the parent population
    Typically seen in the populations of islands which are colonised by individuals from the mainland population