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module 6 > patterns of inheritance > Flashcards

patterns of inheritance Flashcards

1
Q

chlorosis

A
  • leaves look pale/yellow
  • cells aren’t producing the normal amount of chlorophyll
  • reduces amount of food by photosynthesis
  • change in phenotype caused by environment
    lack of light :
  • plants turn off chlorophyll production to conserve resources
    mineral deficiencies :
  • lack of Fe/Mg
  • Fe = co-factor of some enzymes that make chlorophyll.
  • lacking ions = plant can’t make chlorophyll so leaves turn yellow
    virus infections:
  • when virus’ infect plants
  • interfere with cell metabolism
  • yellowing in the infected tissues because they can’t support the synthesis of chlorophyll
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2
Q

animal body mass

A
  • combination of genetic/env
  • env : obesity/anorexia : amount/quality of food/quantity of exercise
  • obesity can be because of genes : mutation
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3
Q

continuous variation

A
  • individuals within a population vary within a range
  • genetic and env
  • controlled by a number of genes
  • animal mass
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4
Q

discontinuous variation

A
  • characteristic that only appears in discrete values
  • mostly genetic / env has little effect
  • one/two genes
  • albinism
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5
Q

co-dominance

A
  • when 2 diff alleles occur for a gene
  • both alleles of one gene are dominant
  • both alleles of the gene are expressed in the phenotype of the organism
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6
Q

sex linked

A
  • some characteristics are determined by genes on the sex chromosomes
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7
Q

multiple alleles

A
  • more than two alleles of the same genes
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8
Q

dihybrid inheritance

A
  • inheritance of 2 characteristics which are controlled by different genes
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9
Q

autosomal linkage

A
  • linked genes that aren’t on the sex chromosome
  • genes on the autosome
  • when on the same autosome = autosomal linkage bc they stay together even during independent assortment in meiosis I
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10
Q

recombinant offspring

A
  • different combinations of alleles than either parent
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11
Q

recombination frequency equation

A

R.F = number of R-offspring / total number of offspring

  • measure of the amount of crossing over occurred in meiosis
  • RF of 50% = no linkage + genes on separate chromosomes
  • RF less than 50% = gene linkage + random process of I.A was hindered
  • as crossing over reduces , RF gets smaller
  • closer the genes are the less likely they are to cross over
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12
Q

what is the chi-squared test

A
  • statistical test
  • measures size of difference between the results you observe and the expected
  • whether difference is significant
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13
Q

chi-squared test formula

A 
X2 = Σ(O-E)2 / E
X2 : test statistic 
Σ : sum of 
O : observed 
E : expected
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14
Q

if X2 is smaller than critical value `

A
  • null hypothesis is accepted
  • diff between predicted and actual cross results is not significant at 5%
  • any diff between expected and actual results is due to chance.
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15
Q

epistasis

A
  • interaction between 2 non-linked genes
  • genes at diff loci
  • causes one gene to mask the expression of the other in the phenotype
  • the one supressing = epistatic gene , one being suppressed = hypostatic gene.
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16
Q

dominant epistasis

A
  • expression of the dominant alleles for the epistatic gene will suppress the expression of the hypostatic gene
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17
Q

recessive epistasis

A
  • two recessive alleles at first locus prevents expression of another allele at the second locus
18
Q

gene pool

A
  • range of alleles in a population
19
Q

define evolution

A
  • change in the frequency of an allele in a population
20
Q

factors affecting evolution

A
  • mutation
  • gene flow : movement of alleles between populations (imm/emigration)
  • genetic drift : changes allele freq in the gene pool by chance a not selection pressures
  • natural selection
21
Q

limiting factors for size of a population

A

density dependant :
- dependant on population size
- competition, predation, communicable disease
density independent :
- factors affect population of all sizes in the same way
- climate change, natural disasters, seasonal activities

22
Q

genetic bottle neck

A
  • catastrophic event
  • large reduction in population size + gene pool
  • decrease in genetic diversity
  • beneficial mutation will have a greater impact
  • quicker development of new species
23
Q

the founder effect

A
  • few organisms from a population start a new population
  • by chance these individuals are mostly one particular genotype
  • without any further gene flow (new alleles from outside)
  • new population grows wide reduced genetic variation
  • bc small population = more influenced by genetic drift
  • occurs bc of migration/geographical separation
24
Q

genetic drift

A
  • chance dictates which alleles are passed on
  • individuals within a population show variation in their genotypes
  • by chance, allele for one genotype is passed onto the offspring more often than others
  • no. of individuals with the allele increases
  • allele becomes more common in the population : leads to evolution
25
Q

stabilising selection

A
  • env isnt changing much
  • individuals with alleles for characteristics towards the middle are more likely to survive and reproduce
  • reduces range of possible phenotypes
26
Q

directional selection

A
  • change in env
  • individuals with alleles for characteristics of extreme phenotype type are positively selected
  • more likely to survive + reproduce
  • increase of a favoured allele over time
27
Q

disruptive selection

A
  • extremes selected for and the norm is selected against
28
Q

speciation

A
  • forming a new species through process of evolution
29
Q

how does speciation happen

A
  • variation as a result of genetic mutation exists within a population
  • members of a population become isolated
  • can’t interbreed
  • no gene flow between the two groups
  • allele undergo random mutations
  • different selection pressures
  • large changes in the phenotypes
  • become so different can no longer interbreed to produce fertile offspring
  • reproductively isolated
  • diff species
30
Q

allopatric speciation

A
  • when members of a population are separated from the rest of the group by a physical barrier
  • geographically isolated
  • diff selection pressures = diff physical adaptations
  • separation = founder effect = genetic drift = more difference
31
Q

sympatric speciation

A
  • forming 2 species from one original
  • due to reproductive isolation
  • whilst occupying the same geographical location
  • when members of diff species interbreed and form fertile offspring (plants)
32
Q

artificial selection

A
  • selective breeding of organisms
  • human selecting desired characteristics
  • interbreeding those phenotypes
  • selecting genotypes which contribute to the gene pool of the next gen
  • reduced diversity of the gene pool
  • inc chance of inheriting a recessive disorder
  • reduces the ability of the species to adapt to env changes
33
Q

problems of artificial selection

A
  • inbreeding : breeding of closely related individuals
  • limits the gene pool
  • dec genetic diversity
  • reduces chance of evolution and adapting to changes
  • genetic disorders are caused by recessive alleles
  • reduces ability to reproduce and survive
34
Q

hardy weinberg principle

A
  • allele frequency wont change from one gen to next under conditions :
  • large population
  • no immigration
  • no emigration
  • no mutations
  • no natural selection
  • random mating
  • if allele freq does change then immigration, emigration or NS must have happened
35
Q

HWP allele freq equation

A

p + q = 1
p = freq of dominant allele
q = freq of recessive allele

36
Q

HWP genotype freq equation

A

p2 + 2pq + q2 = 1
p2 = freq of homo dom genotype
2pq = freq of hetero genotype
q2 = freq of homo recessive genotype

37
Q

epistasis dom/recessive expected cross ration

A

dom : 12:3:1

rec : 9:3:4

38
Q

dihybrid unlinked / autosomally linked expected ratio

dom/rec

A

unlinked : 9:3:3:1

linked : 3:1

39
Q

codominance monohybrid autosomal (dom/rec) ratio

A

1:2:1

40
Q

monohybrid autosomal (dom/rec)

A

3:1

module 6 (3 decks)

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