Inheritence Flashcards
ratio not expected
crossing over occurs
fertilisation is random
some alleles have selection advantage/disadvantage
monohydbrid inheritance
one gene
each gamete has one copy of gene
eg Tt crossed with TT
dihybrid inheritance
two features/characteristics determined by two genes
occur on different chromosomes!
not linked
eg TtRr crossed with TTRR
autosomal linkage
autosome is on a non sex chromosome
genes on same autosome (chromosome) = linked
they will always be inherited together unless they are separated by crossing over
sex linkage
genes found on sex chromosomes
males= X Y females= XX
if man has faulty allele on X chromosome they will always have the disease/trait that it codes for
they only have 1 X chromosome so there is nothing to mask it eg another X chromosome
epistasis
form of gene expression where one gene masks the phenotypic expression of another gene
expression of one depends on the expression of another gene
two genes on the same chromosome affect the same feature
chi squared
difference between expected and observed results
determines whether there is a sig dif between observed and expected results
∑(O-E)^2/E
degrees of freedom = number of classes- 1
chi^2> critical value= reject null hypothesis
chi^2
phenotype
expression of genotype and effect of environment
observable characteristics
genotype
genetic constitution of an organism
dom allele
always expressed/ shown in phenotype
rec allele
only expressed if it is homozygous recessive or when no dom allele is present
co dominant
both alleles are expressed/shown
sex linked
gene shown on X/Y chromosome
locus
specific position on a chromosome occupied by a specific gene
allele
alternate form of a gene
