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LEC 141 evolutionary biology > lecture 6 the nature of biological variation > Flashcards

lecture 6 the nature of biological variation Flashcards

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1
Q

what is macro evolution

A

evolutionary change, over long periods of time, on a large scale

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2
Q

what are examples of macroevolution

A

origin of new taxonomic groups
evolutionary trends, e.g. convergence
new kinds of organisms penetrating new habitats, e.g. adaptive radiation
mass extinctions

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3
Q

what is microevolution

A

It is the basis of natural selection, whereby a population progressively adapts to its environment
Change at/below species level

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4
Q

what do we mean by population

A

A group of individuals of the same species living in a particular geographical location

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5
Q

what are some examples of microevolution

A

natural selection

variation based on location

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6
Q

genotype

A

– the genetic ‘makeup’ of an individual

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7
Q

phenotype

A 
observable characteristics 
(genotype and environment)
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8
Q

chromosomes

A

gene carrying’ structures found in nucleus

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9
Q

what are homologous chromosomes

A

chromosomes that carry genes controlling the same characteristics
Most eukaryotes have pairs of homologous chromosomes; one set from each parent

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10
Q

what are genes made of

A

DNA

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11
Q

what are alleles

A

alternative forms of a gene = variation in the DNA sequence for a given gene

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12
Q

how many homologous pairs do humans have

A

23

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13
Q

what does it mean to be homozygous

A

the homologous pair have the same allele for the gene

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14
Q

what does it mean to be heterozygous

A

the homologous pair has different alleles for the same gene

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15
Q

alleles can be B or b

A

dominant or submissive

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16
Q

how does three meters of dna fit into every cell???????

A

super coiling

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17
Q

what is karyotyping

A

pair and order chromosomes

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18
Q

how does asexual reproduction happen

A

mitosis

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19
Q

what is mitosis

A

splitting of a parent cell into two daughter cells that are genetically identical to each other and the parent

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20
Q

4 ways asexual reproduction can occur

A

Fission
Budding
Parthenogenesis
vegetative reproduction and fragmentation

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21
Q

how much genetic variation occurs with asexual reproduction

A

little

22
Q

what is binary fission

A

one cell divides into two cells of similar size with the same genetic material

23
Q

what is budding

A

new individuals spilt off from parent cell, genetically identical but smaller

24
Q

what is parthenogenesis

A

development of unfertilised egg

obligate in some species facultative in other species

25
Q

what is vegetative reproduction

A

A form of asexual reproduction in plants, in which multicellular structures become detached from the parent plant and develop into new individuals that are genetically identical to the parent plant.

26
Q

what is fragmentation

A

A form of asexual reproduction wherein a parent organism breaks into fragments, each capable of growing independently into a new organism.

27
Q

what happens in sexual reproduction

A

haploid gametes formed by meiosis fure to form a diploid zygote

28
Q

what meiosis

A

one cell splits into 4 daughter cells with different dna and only one half of a each homologous chromosome

29
Q

how does meiosis drive variation for evolution

A

independant assortment
exchange of DNA between homologous chromosomes
random fertilisation

30
Q

what is independant assortment of chromosomes

A

how the chromosomes line up in the cell each time before being seperated in meiosis

31
Q

what is exchange of DNA between homologous chromosomes

A

by crossing over in meiosis wherein a pair of homologous chromosomes may swap sections in DNA

32
Q

what is random fertilisation

A

Zygotes contain chromosomes from two parents
Different alleles from each parent which are chosen randomly from loadsssss of combinations
each zygote has 1 of 70 trillion possible diploid combinations + variation from crossing over

33
Q

advantages of sexual evolution

A

in a stable environment the best genotype is perpetuated

uses less energy and is quicker

34
Q

advantages of sexual reproduction

A

produces a lot of variation- new combinations may work better than older ones
in a changing environment veriation may promote overall survival

35
Q

how are different alleles generated?

A

chromosomal mutations

36
Q

multi level variation, what are the levels

A

chromosomal, alleles, single point mutations, single nucleotide polymorphisms

37
Q

how do single nucleotide polymorphisms contribute to variation

A

hey can change an amino acid, therfore a protien, therefore a function

38
Q

what is polypolidy

A

multiple sets of chromosomes
Occurs at cell/ tissue/ whole organism level
Common in plants (~50-70% angiosperms)
Liver cells are often polyploid

39
Q

what are the two types of polypolidy

A

autopolyploidy and allopolyploidy

40
Q

what is Autopolyploidy

A

error in mieosis/mitosis
- Single species genome duplication (single parent)

e.g., Chromosome number increases from a diploid to a tetraploid (4 copies per cell).

41
Q

what is allopolyploidy

A

error in mieosis/mitosis- Two different, related species interbreed, hybridise, then chromosome number doubles- not common

42
Q

what does polyploidy result in

A

reproductive isolation

43
Q

is there substantial variation within species

A

yes

44
Q

most DNA is non coding and was thought to be

A

silent DNA and not important

45
Q

while it isn’t subject to natural selection, non coding DNA…

A

it will change by mutation and genetic drift

and it can have a functional role which affects how genes are expressed

46
Q

what is the normal genotype for haemaglobin

A

HnHn

47
Q

what happens to red blood cells if there is a single point mutation and HsHs occurs or HnHs

A

HsHs is fatal

HnHs can lead normal lives with blood transfusions

48
Q

how does anaemia show co dominance

A

normal allele is not dominant over sickle allele they both are expressed

49
Q

sickle cell heterozygotes are better adapted in

A

areas where malaria occurs

50
Q

why is this “sickle cell heterozygotes are better adapted in areas where malaria occurs

A

Selection pressure from malaria maintains lethal sickle cell allele in the gene pool of the population

LEC 141 evolutionary biology (7 decks)

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