Mendellian Genetics Flashcards
formula for determining # of unique gametes
2^# of heterozygotes
linkage
the tendency of alleles of particular genes to be inherited togehter
when is linkage seen?
when genes are on the same chromosome
difference between linkage and sex-linkage
linkage refers to two or more genes that are located on the same chromosome
sex-linkage refers to a single gene that is located on a sex chromosome
does sex-linkage indicate anything about location on a chromosome?
no
recombinant
alleles on chromosome are different tan the parent combinations because of crossing over
when does crossing over occur?
during prophase of meiosis I
what happens when genes are located far apart on the same chromosome?
it is more likely that crossing over will occur someplace between these genes
genetic map
a diagram showing the relative positions of genes along a particular chromosome
when are linked genes not inherited together?
when crossing over occurs
what is linkage an exception to?
Mendel’s principle of independent assortment
multiple allelism
more than two alleles of the same gene
example of multiple allelism
blood type
there are three alleles for blood type: A, B, i
codominance
simultaneous expression of the phenotype associated with each of the alleles in a heterozygote
example of codominance
the A and B alleles for blood type are codominant when together to form blood type AB
incomplete dominance
hetereozyotes show a blend of the two alleles
pleiotropic
a gene that influences many traits
are dominant traits more common?
not necessarily
is the wild type always dominant?
no
Are genes the only thing that control traits?
no
the environment plays an important role in the development of certain phenotypes
gene-gene interaction
two or more genes work together to determine a single trait
discrete traits
traits that are clearly different from each other
this is what Mendel worked with
quantitative traits
continuously varying traits
example of quantitative trait
human height and intelligence