GH Revision - Part 2 Flashcards
what happens when reproductive fitness changes?
- selection for more reproductively fit traits = alleles increase in frequency
- selection against less reproductively fit traits = alleles decrease in frequency
what is reproductive fitness?
ability for individuals to pass on their genes to subsequent generations
What are the 5 conditions for Hardy-weinberg?
1- Breeding population is large
2- mating is random
3- no mutation of alleles
4- no migration change
5- no selection
what is the hardy-weinberg equation for males
Hemizygous =
P + q = 1
how many decimal places does Craig want us to calculate to?
4
what is the formula for Chi-Squared?
(observed - expected )^2/ expected
What does chi-square indicate about hardy weinberg equilibrium?
is oberved = close to expected = equlibirum
what are the 5 exceptions of H-W equilibrium?
1- non-random mating
2- unequal survival
3- mutation
4- population subdivisionb
5- migration
Founder effect
small sub-pop becomes isolated
often reduces level of genetic diveristy
non-random sampling of original population = genetic drift
random genetic drift
stochastic nature of mendelian segregation
if population is small, alleles = readily lost to genetic drift
what are complex genetic traits caused by?
interplay of:
alleles of specific genes
environmental risk factors stochastic factors
Definition of complex quantitative traits
metric (continuous and measurable)
height, weight, organ weight, BP
distribution = normal
broad sense vs narrow sense
B= proportion that can be attributed to generic variation (all three sources)
N= phenotypic variation due to ADDITIVE genetic variation
what can be used to estimate variance in twins?
Correlation
if correlation = very high, variance = very low
When do you use:
a) H^2= 2(rmz-rdz)
b) h^2= R/S
c) Vp = Vg + VE, H^2= Vg/Vp
a) twins
b) comparing something (mean of offsping and parents(
c) variance is mentioned throughout the question)
What is the definition and features of a qualitative trait?
discontinious distribuation
genetic transmission preserves disease, they do NOT segregate according to mendelian ratios
What is measured in quantitative genetics vs qualitative genetics?
Quant= Correlation = r(correlation ceoficceint on scale 0-1)
Qual= concordance = p(probability that a relative of someone who has the trait will be affecetd) scale 0-1
Susceptibility vs liability
S= innate (genetic) tendency to develop trait
L= total risk of developing trait (all sources of varaition). reaches a threshold (do or don’t)
What is Epigentics?
molecular modifications to alter activation of specific genes
can create cellular memory
What is Euchromatin vs Heterochormatin
E= relaxed phsyical state = open and avalaible
H= condensed state with silent genes = switched off
What are the two methods of epigenetic change
Histone modification- acetylation or methylation
-acetylation = activation = euchromatin
DNA Methylation
= repression
addaition of Me to C5 of C
creates heterochromatin
What is the multigenerational effect of Epigenetic inheritance?
one generation to another via DIRECT exposure (maternal) affects three gens during preg)
Epigentic inheritance in males
analysis showed that grandfather’s factors influence grandchildren (via sperm cells)
Sweden: food grandfather ate between 9 and 12 influenced longevity of grandchildren
= transgenerational (absence of continued direct enviro influences)
What are HOX genes and how many are there?
What:
direct formation of body structures on early embryonic development.
function
each segment froms from early controlled expression of unique HOX combination
39 cross 4 clusters
what is the impact of HOX gene mutation
Syndactyly (abnormal joining of fingers or toes)
What does the SRY gene function for?
SRY = activator and encodes for Transcription Factor Protein (TDF)
TDF has a HMG box that binds to DNA = initiates sex determination and regulates male development
What is the PAX-6 Gene?
master controller of eye development
loss of function (change in 1 allele = truncated protein)
heterozygotes are affected
What arises from PAX-6 mutation?
Aniridia
-50% reduction in PAX6
haploinsuffiency
what disorders has excellent potential for gene therapy?
Auto recessive
(Haemophlia and cystic fibrosis)
replace missing or defective
how is a vector used in gene therapy?
vector inserted (in vivo, in situ)
reaches target cell
passes through cell memebrane
enter nucleus
delivers genetic materuial
genetic material instructs cell to make replacement gene and protein to correct defect
What are important regulators of epigenome?
enzymes that add acetyl or methyl groups to histones as WRITERS
enzymes that remove histone marks ERASERS
enzymes that recognise histone and DNA modification READERS
What gene therapy is used for dominant traits?
RNA interference
inhibits gene epression
introduction small siRNAs = cleavage of target mRNA = specfic loss of protein synthesis
can be allele specifific
SILENCES THE EXPRESSION OF TARGET GENES
what is used to treat mitochondrial disorders?
3 person babies
embryo repair work or eg repair wor
Steps in CRISPR
1- lipid nanparticles/virus
(cell transfected with DNA plasmid that expresses CAS-9 and gRNA)
2- CAS9 identifies corrsponding DNA seq and cuts both strands
3a- Non-homologous end joining
(cell’s attempt to repair break silences target gene by joining cleaved DNA)
3b- homology directed repair
(faulty gene may be corrected with replacement segment or new gene may be introduced
What are the three main categories of Stem cells?
1- Embryonic
(pluripotent= any cell type)
2- Adult stem cell
(multipotent, exists naturally in the body and repairs tissues
3- Induced plurioptent stem cells
(made via reprograming, potentail to become any cell in body
