6.1.2 patterns of inheritance Flashcards
(58 cards)
1
Q
variation causes
A
- environmental (eg diet and etoliation)
- genetic
2
Q
complimentary epistasis
A
the presence of a particular allele at each locus is required for the expression of a particular phenotype
3
Q
sexual reproduction variation
A
- crossing over
- independent assortment
- random fusion of gametes during fertilisation
4
Q
eg things that can cause mutations
A
- x rays
- mustard gas
- some viruses
5
Q
etiolation
A
A condition in plants characterised by weak stems and small, pale leaves, due to insufficient exposure to light.
6
Q
monogenic inheritance
A
inheritance determined by a single gene
- usually DISCONTINUOUS VARIATION
7
Q
punnet square monogenic inheritance
A
eg tT X tt
8
Q
dihybrid inheritance
A
2x dominant traits
9
Q
genotype of. a parent DIHYBRID
A
eg YyRR
10
Q
punnet square of dihybrid inheritance
A
gametes are (Yy)
11
Q
dihybrid cross NORMAL ratio
A
9:3:3:1
12
Q
multiple alleles
A
characteristics for which there are 3+ alleles
13
Q
parents in multiple alleles
A
I b I o
14
Q
gametes of multiple alleles
A
Io … Ib … etc
15
Q
offspring genotype for multiple alleles
A
Io Ib
16
Q
non sex chromosome
A
autosome
17
Q
autosomal linkage
A
- when the loci of 2 different genes are on the SAME AUTOSOME
- they are likely to be inherited together, and are LINKED
18
Q
autosomal linkage, with NO CROSSING OVER
A
the locus of the 2 diff genes are on the same autosome, so are inherited together as one unit
19
Q
recombinant gametes
A
crossing over between genes
20
Q
chance of reecombinant gametes increases with …
A
- DISTANCE AWAY the loci for the 2 genes are on the autosome
- the further apart the gene loci, the greater the chance of recombinant gametes, as less chance of them being crossed over together
21
Q
epistasis
A
interaction of non linked gene loci where one masks the expression of the other
22
Q
recessive epistasis
A
when you hace the recessive aa, this takes over and masks the expression of whatever is on the second locus, the aa recessive phenotype is expressed
23
Q
common recesssive epistasis ratio
A
9:3:4
24
Q
dominant epistasis ratios
A
12:3:1
13:1
25
d ominant epistasis
having one of the dominant A alleles anywhere = it;s the A colour
26
null hypothesis chi squared
NO signifcant difference between observed + expected (follows a typical cross, no epistases)
27
probability and d o f chi squared
probability: 0.05
doe: number of categories (eg number of phenotypes) - 1
28
continuous variation is usuallt
polygenic
affected by genes and environment
29
describe autosomal linkage
-alleles
- loci for 2 diff alleles located close together on SAME chromosome
- inherited together
- corssing over produced some recombinant
- eg allele for red body and yellow tail imherited together, SO BOTH PHENOTYPES EXPRESSED TOGETHER
30
sex linkage
- when a gene is located ono a sex chromosome, so their epxression depends on whether the offspring is MALE (XY) or FEMALE(XX)
- if males inherit a recessive allele, they have the disase bc only one copy
31
chi squared conclusion refer to
SIGNIFICANT DIFFERENCE
32
problem with biodiversity with use of fertiliser?
- causes one species to grow loads
- outcompetes native species
- disrupts ecosystems and food chains
33
importance of biodiversity for AGRICULTURE
- loss of genetic diversity
- environemtns may change in future
- useful alleles would have been lost
- eg one for disease resistance
34
genotype defenition
combination of ALLELES possessed by an organism
35
when is HW suitable? (4)
- sexually reproducing organisms
- diploid
- large populations
- random mating
- NO MIGRATION
36
stabilising selection
-natural selection leading to more consistency
- average phenotypesf favoured, extremes selected against
- alleles for extremes may be removed
- REDUCES GENETIC VARIATION
- USUALLY unchanged environment
37
directional selection
- environmental change favours an EXTREME phenotype. eg if its cold so larger organisms are favoured, selected for
- the mean shfits to reflect this
38
speciation
formation of a new species through evolution
39
allopatric speciation
- geographic isolation (mountain, river etc)
- so populations occupy different environments
- diferent selection pressures
- Different random mutations, natural selection etc
40
sympatric speciation
in animals:
- sexual selection
- those with x charzcteristic only want to breed with those with y characteristic
- MORE COMMON IN PLANTS
- reproductive isolation within the SAME habitat
ANIMALS
- nocturnal vs the other
HYBRIDS
- hybrids arent able to mate with the parents that produced them , so they are a new species, can only mate w themselves
GENETIC
- Diff no chromosomes, so no gamete fusion chromosome pairing during meiosis cant occur
41
what do u need for a t test
mean
AND STANDADRD DEVIATION
42
artificial selection/ selective breeding
- choose those w desirable characteristics
- breed
- meausre characteristic of offspring
- breed
- repeat over many generations
43
inbreeding issues
- more chance of an individual inheritng 2 copies of a harmful recessive allele
- less genetic diversity
44
importance of conserving wild ancestral types
- in gene banks (genetic recourses)
- source of alleles eg for GE
- unknown future requirements (ref agriculutre), allel could be useful give eg
- inbreeders can cross breed the varieties with the wild tipes to increase proportion of heterozygous, genetic diversity, less susceptible to changing env or disease
- source of replacement if need be
-
45
genetic drift
- random changes in allele frequencies that occur due to mutation
- wihtout fitness conseqeunces
- one allele has a proportionally stronger effect in small populations, (so most significant after eg genetic bottleneck)
- more alleles lost
- more susceptible to eg disease
46
genetic bottleneck
- population is greatly reduced in size eg by a natural disaster
- AELLELES LOST
- rediced no alleles in the gene pool
- small population repopulate the area, LESS GENETIC VARIATION
47
founder effect
- example of genetic bottleneck
- small founding population with a few alleles
- repopulate a large population, low geentic diversity
48
If u have a haploid number of 8, how many gamete possibilities?
2^8
- if independent asortment is the only source of variation
49
problem with inbreedign
1. small gene pool (low genetic diversity)
2. susceptible to diseases
3. susceptible to changing environemnt
50
how can sexual reproduction increase genetic diversty
- all the meiosis stuff (inc genetically different gametses)
- random fertilisation of gametes
- have different alleles
51
if theres autosomal linkage the offsprings are...
higher proportion like the parents (heterozygpts)
- locus of allele for x and y located close together on same chromosome
- so inherited together
- few recombinants
52
why does (even if not epistasis or autosomal etc) the expected not match the observed exactly
random fertilisation of gametes
53
do carriers have the disease
NO
54
how to know sex linked is on X chromosome?
females can have it
55
graph for continuous variation
line graph
56
example of directional selection
natural selection
57
more detail when u discuss the selections
do the usual
- variation in pop due to rm etc
58
State three other conditions that must be present in order for speciation to occur (SYMPATRIC)
- natural selection
- lots of time
- random mutation
- different sp to other group
