Notatki Danniego part 6 Flashcards
Huntingtons disease causes … damage
- shows effects in …
brain
middle age
Incomplete dominance pedigree:
-> Dominant mother has son without phenotype but then passes allele on to children
Variable expressivity:
-> Gene can be expressed more or less in certain individuals
Quantitative genetics 2 groups:
- > Continuous
- > Discreet
Quantitative genetics: soldier height:
Mean soldier height:
1914 - 5ft 7
1996 - 5ft 8
Max soldier height:
1914 - 6ft 1
1996 - 6ft 5
- > Must be environmental factors as 2 generations isn’t long enough to have a genetic change in height that much
- > Galton’s height diagram showed that tall parents had taller children and vice versa
- > He also observed, when parents are taller that the mean, their children tend to be shorter than them
Quantitative genetics: tomatoes:
- > Tomatoes used to be small, green and hard, weren’t really eaten until 1800s
- > Bred them for sweetness, juiciness, softer
Quantitative genetics: maize:
- > Maize yield has gone up around 8x since 1876
- > feeds most of the world
- > fertilizer & quantitative genetics
- > accumulation of genes that increase size
Wheat cross:
red seeds X white seeds 2 loci
P1: AABB X aabb
F1: All AaBb (pink)
self fertilise
F2: 1 Red 4 Light red 6 Pink 4 Light pink 1 White
The amount of red depends on the amount of red alleles compared to white alleles e.g. AABB red 4+ AaBB light red 3+ AaBb pink 2+ Aabb light pink 1+ aabb white 0+ -> depend on number of + -> continuous character
Quantitive inheritance 5 loci
green post-it (2pg)
Heritability equation
Genetic variance Vg divided by phenotypic (total) Variance Vp
H^2 = Vg/Vp
Heritability - about
- > Heritability is a proportion
- > can change genes or environment - > The proportion of the total variation in the population that is due to genetic variation
Achillea plant
- > Grows at a range of altitudes:
- sea level
- medium
- 10,000 ft Mountains
- > Cross breeds from different breeds as they have a variation in height
- > You find heritability as height is passed on - > Plants that usually grow well at low altitudes can grew worse at lower altitudes but better at higher than medium
- > different norms of reaction
Heritability equation2
H^2 = Vg/Vp Vp = Vg + Ve + Vge
H^2 = Vg/(Vg + Ve + Vge)
Broad sense of heritability
-> Plant and animal breeders need the NARROW sense of heritability
Vg = Vg + Ve + Vge
Additive ++ = 2 cm +- = 1 cm – = 0 cm
Dominance ++ = 2 cm +-= 2 cm – = 0 cm
Interaction ++++ = 2 cm +++- = 1-2 cm ++– = 0 cm
NARROW sense heritability only uses …
Additive inheritance
H^2 = Vg/Vp
-> Never been used for human characteristics
Covariance
tendency for parents and offspring to vary together grom normal distribution
4 parents and offspring are always same height
-> correlation coefficient of 1. => r = 1
Father Son Covariance 1.4 1.6 -0.2^2 = 0.04 1.5 1.7 -0.1^2 = 0.01 1.6 1.6 0 x –0.2 = 0.00 1.7 1.9 0.1^2 = 0.01 1.8 2.2 0.2 x 0.4 = 0.08 = 0.14 Mean father= 1.6 Mean son= 2.2
Covariance = difference of father from mean & difference of son from mean
Covariance = 0.14
Simplified (?) of correlation coefficient:
Covariance (fathers & sons) / [sd (fathers) x sd (sons)]
Simer fox experiment (?)
- minus “aggressive” foxes & plus “tame” foxes
- Usually incredibly aggresive/scared towards humans but a tame, domesticated species has been bred
- Dmitry K Belyaev (?) in the 50s
- > bred the 1% most tame foxes over generations
- > is generations (?) - changed morphology
- > floppy ears, piebald coat, dog-like bark - domestication gene associated with melanin & adrenaline
- > less adrenaline, less fight or flight
Neotorous (?)
(?) retains, juvenile characteristics in adulthood
-> pyreneon mountain dog (?)
Average drosophila no. of (?) is …
(?) -> select & breed only flies with 467 -> next gen average 45, gain of 5 Narrow sense heritability 5/6 = 0.83 High heritability -> Same but new mean is 43, gain of 3 3/6 = 0.50. intermediate heritability
R = 4^2 S
Heritability of schizophrenia:
Identical twins 48%
Siblings 9%
Parents 6%
General pop. 1%
Twins also have a high degree of environmental similarities
Two embryos fuse -
chimaera
Common in foetuses, can have 2 (?) sers of genes
Monochorionic twins (?)
Dichorionic twins (?)
early split in womb, share a placenta - causes problems
split later
Uniwersal common ancestor around … BC
MRCA -
3000
Most Recent Common Ancestor
Inbreeding can encome (?) genetic disease as higher risk of getting double recessive alleles
/// I don’t understand what’s this “setting in a plant” thing////
Inbreeding flow diagram
ADD A PICTURE OF THIS DIAGRAM
One locus, A
4 alleles : 1, 2, 3, 4
Brother I & sister II mate
What is increased chance of homozygosity by (?) for Ai in child III?
