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module 6 Genetics and ecosystems > 6.2 patterns of inheritance > Flashcards

6.2 patterns of inheritance Flashcards

1
Q

define genotype and phenotype

A

genotype = genetic makeup of an organism
phenotype = visible characteristics of an organism

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2
Q

name the genetic factors that lead to phenotype variation

A

gene mutations
chromosome mutations
sexual reproduction

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3
Q

define polyploidy

A

more then two sets of chromosomes

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4
Q

define aneuploidy

A

chromosome number is not an exact multiple of the haploid number
when chromosomes/ chromatids fail to seperate

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5
Q

explain what non disjunction is

A

one pair of chromosomes or chromatids fails to seperate leaving one gamete with an extra chromosome

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6
Q

explain how sexual reproduction causes genetic variation

A

random fertilisation
crossing over
independent assortment in metaphase/ anaphase 1 and 2

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7
Q

explain what etoilation in plants

A

plants grow long and spindly due to trying to find light

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8
Q

explain how environmental factors causes variation

A

eg. dialect, losing a limb
environment can interact with genes

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9
Q

define allele

A

different versions of a gene

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10
Q

define homozygous

A

having identical alleles at a gene locus on a pair of homologous chromosomes

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11
Q

define heterozygous

A

having different alleles at a particular gene locus on a pair of homologous chromosomes

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12
Q

define monogenic

A

determined by a single gene

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13
Q

explain what monogenic inheritance is

A

inheriting one allele from each parent of a particular gene
dominant and recessive alleles
phenotype can be predicted through a test cross/ punnett square

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14
Q

ratio for monogenic heterozygous parents

A

3:1

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15
Q

define dihybrid

A

involves two gene loci

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16
Q

explain what dihybrid inheritance is

A

inheriting alleles for two different characteristics

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17
Q

ratio for heterozygous dihybrid cross

A

9:3:3:1

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18
Q

define multiple alleles

A

characteristic for which there are 3 or more alleles in a populations gene pool

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19
Q

example of inheritance of multiple alleles

A

human blood group
rabbit coat colours

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20
Q

define codominance

A

both alleles inherited are expressed
results in different phenotypes

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21
Q

ratio for codominance heterozygous parents

A

1:2:1

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22
Q

explain what codominance is

A

you inherit two alleles for a particular gene
need two for the phenotype to be displayed

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23
Q

define sex linked

A

gene present on one of the sex chromosomes (the 23rd pair)

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24
Q

sex chromosomes for males and females

A

males = XY
females = XX

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25
why are males more likely to suffer from genetic disease
males only have XY so disease carried on the X allele is the only version females are likely to contain s functioning allele on the other X males are haploid for X linked genes so cannot be hetero or homo. for X linked genes (only get one)
26
what are humans sex linked for
haemophilia A colour blindness
27
define autosomal linkage
gene loci that is present on the same autosome (not sex linked) that are inherited together
28
what is autosomal inheritance
genes inherited on autosomes/ not sex chromosomes
29
define epistasis
the interaction of other genes when one gene masks or supresses the expression of another
30
recessive epistasis
two recessive alleles at one locus masks the expression of alleles at the second locus
31
ratio for recessive epistasis
9:4:3
32
dominant epistasis
a dominant allele at one of the gene locus will mask the expression of alleles at the second locus
33
ratio of dominant epistasis of heterozygous parents
12:3:1 or 13:1
34
complimentary epistasis
the presence of a particular allele at each locus is required for the expression of a particular phenotype
35
purpose of chi squared
find out if difference between observed and expected data is significant or due to chance
36
define continuous variation
genetic variation in a population shows a range with a smooth gradient between the intermediates
37
define discontinuous variation
when phenotype classes are distinct and discrete, no intermediates between
38
what determines continuous and discontinuous variation
continuous = many genes and environment discontinuous = one gene
39
define population
members of a species living in the same place at the same time and can successfully interbreed
40
define natural selection
gradual change in allele frequencies in a population may lead to the development of a new species
41
name the types of selection
directional selection stabilising selection
42
define stabilising selection
natural selection leading to consistency in a population
43
define directional selection
natural selection that occurs when an environmental change favours a new phenotype so results in a change in the population mean
44
explain what genetic drift is
gradual change in allele frequencies down to chance instead of selection pressures - small populations = less genetic variation = chance can affect allele frequencies drastically = large genetic drift - large populations = more genetic variation = chance is less likely to impact allele frequencies = less genetic drift
45
define genetic bottleneck
large reduction in size of a population due to environmental catastrophes = reduces genetic diversity when population increases again = large reduction in the gene pool
46
define the founder effect
occurs when a small number of individuals from a large parent population start a new population will experience a loss of genetic variation
47
explain what the hardy weinburg principle is
if certain conditions are met then the allele frequencies of a gene within a population will not change from one generation to the next calculates allele and genotype frequencies within populations
48
what assumptions need to be met for the hardy weinburg principle
large population random mating occurs no migration, mutation, or selection no selective advantage
49
What does p, q, p2, q2 stand for
p= frequency of dominant allele q= frequency of recessive allele p2 = frequency of phenotype q2= frequency of genotype 2pq= frequency of heterozygous genotype
50
Name the two types of isolating mechanisms
Geographical Reproductive
51
Define speciation
The splitting of a genetically similar population into two or more populations which revolve into different species
52
what is needed for speciation to occur
mutation/ genetic diversity natural/ directional selection selection pressure is different to other population time
53
Explain what geographical isolation is
Populations are separated by geographical features Acts as a barrier to gene flow between populations
54
Define allopatric speciation
Formation of two different species from one original species due to geographical isolation
55
Explain how allopatric speciation occurs/ geographical isolation
Isolated populations experience different selection pressures Change to allele frequencies due to natural selection/ genetic drift Each population has now adapted to environment = new species
56
Explain reproductive isolation
Biological and behavioural changes in a species may lead to reproductive isolation of another population Seasonal changes - different mating seasons Mechanical changes - change sun genetilia preventing successful mating Behavioural changes - different courtship rituals
57
Define sympatric speciation
Formation of two different species from one original species due to reproductive isolation whilst in the same location
58
Define artificial selection
Selective breeding of organisms
59
Define inbreeding depression
When related individuals are crossed inbreeding occurs, more likely to inherit two copies of a harmful allele
60
Define hybrid vigour
Breeders outcross individuals belonging to two different varieties to obtain individuals that are heterozygous at many gene loci
61
principles of artificial selection
organism with desirable trait is selected selectively bred together individuals are selected by their phenotype not their genotype
62
artificial selection in cows and plants example
female cow with highest milk yield bred with bull with the highest milk yield plants bred with the most disease resistance, crop yield, tolerance to weather
63
ethical issues with artificial selection
lead to inbreeding - reduces gene pool - inbreeding depression greater chance of organisms inheriting genetic defects, vulnerable to new diseases
64
ethical issues of artificial selection in dogs
bred to improve species has created issues - pugs and breathing

module 6 Genetics and ecosystems (6 decks)

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