8 Flashcards
law of segragation
one alle is inerited from each parent
law of independant assortment
different traits are inherited independently of each other
point mutation
miscopying of one or a small number of nucelotides
-substiution
-insertion
-deletion
chromosomal mutation
changes in postion of gene within the chromasone
whole chromasome mutation
an entire chromasome is lost during meiosis
random firtilisation
random sperm bind with random egg
homeozygous
if both alleles are identical
heterozygous
two alleles are different
dominant - expressive
recessive- only expressive when two ressesive
test cross
cross with homozygous recessive to see if a plant is heterozygous or homozygous dominant
co-dominance
both are dominant
e.g pink and blue form purple
base letter has to be written e.g blood group i
homogametic
female
-one gamete
heterogametic
male
two gametes
dihybrid inheritence
two characteristics are determined by two difference genes on different chromosomes
genetic kai squared
if number < crit
accept null hypothesis
there is no statistically significant difference between the observed numbers and the mendelian predicted outcomes
less than 5% chance that the results are not due to chance
autosomal linakge
when two or more genes that are being inherited are located on the same autosome (not sex chromosomes)
identify the allele pairs in the parent gametes
e.g when heterozygous the dominant/recessive are inherited together
pure breeding
homozygous
hardy weinberg equations
allele frequency
-p + q = 1
-p dominant
-q ressescive
p^2 + 2pq + q^2 = 1
-p^2 proportion homo dom
-2pq proportion hetero
-q^2 proportion homo recses
hardy weinburg assumtions
large population
mating is random
no mutations occur
no immigration or emigration
no natural selection
stabilising selection
frequency of a few alleles are high but others are reduced
so stable for a long time
common allele more likely to survive
directional selection
one extreme trait is favoured
pushing population in one direction
diruptive selection
selection against the mean
average trait eliminated
two rare traits survive and reproduce
genetic drift
change in allle frequency due to chance disappearance of particular genes as individuals die
founder affect
loss of genetic variation that occurs when a small number of individuals leave the main population and make up a new population where the alleles are unlikely to be representative of the whole population
genetic bottleneck
size of population dramatically decreases normally from a environmental disaster
reduction in gene pool
parent phenotypes
state before cross questions
sex chromasomes- gene at top of x/y
similarities and differences of stabilising and disruptive selection
s-
change frequency of alleles
select against phenotypes
d-
disruptive selection
selects against mean
2 distinct populations
stabilising
selects against extremes
maintains one population
