genetics Flashcards
allele
a different from of the same gene/trait eg) wrinkley seed and round seed. each parent contributes one allele (half their genetic info) . can be dominant or recessive.
gene
segment of dna that codes for a specific trait eg) height, colour
law of segregation states
each diploid parent creates haploid gametes which receive just one of the pair of alleles of a specific gene. the gamete from male parent fuses with random gamete from female parent to produce a diploid offspring
simply: homologous chromosomes seperate during meiosis (two alleles seperate into each gamete)
locus
specific location of chromosome for a gene. (address fro a gene)
homozygous vs heterozygous
homozygous: pair of either both dominant or recessive alleles for a gene (AA or aa)
heterozygous: pair of both recessive and dominant gene (Aa)
homologous pair
2 chromosomes of same shape/ size that code for the same trait. can have different alleles but still the same trait.
law of segregation and meiosis
mendel came up w law before meiosis but it can still be applied to meiosis. First diploid cell replicates the homologous pair to create sister chromatids (meiosis 1) then sister chromatids split and we have 4 chromosomes which then each gamete gets therefore haploid gamete cells.
law of independent assortment
states that different pairs of genes seperate individually. they do not move in groups. homologous pairs seperate and the pairs do not follow any other pair they seperate independently.
draw both laws in accordance with meiosis
look at notes
what stage of meiosis is law of segregation documented in
anaphase 1 (seperating)
what stage is law of independent assortment documented in
anphase 1 (serperating)
metaphase 1 (lining up)
genotype
type of variant present at a given location (i.e., a locus) in the genome eg) AA, Aa. determines phenotype
incomplete dominance
heterozygous individuals show an
intermediate phenotype eg) red and white flower cross to produce pink flower
codominance
Codominance allows both alleles to
get expressed when individuals are
heterozygous for the trait (expressed in exponent form)
polygenic trait
when multiple genes work together for one trait eg) height and skin colour can be coded for by AABbCc
epistasis
one gene depends on another for it to be expressed eg)albino llamas
enviornmental influence
eg) sun can change skin colour and diet can change height
pleiotropy
a single gene has multiple phenotypic effects
eg) a bald mouse lacks a thymus gland and lacks an immune response
monohybrid cross
cross between pure-line parents (homozygous parents), 4 sqaure punnett.practice ine question
dihybrid cross
16 square punnett, F1 gen crossed. looks smthn like GgHh practice one question
what chromosome are sexlinked traits found on and why
only found on x chromosomes since y is too small and contains less genes than x.
what genotype is needed for testcross
test cross is an experimental cross of an individual organism of dominant phenotype but unknown genotype and an organism with a homozygous recessive genotype (and phenotype).
which sex are sexlinked conditions expressed more in and why
males since only the x carries the trait and if they have the one allele they have the condition whereas femaleshave two alleles and one dominant in the pair will be expressed even if there is a recessive in the pair. (only for recessive as males and females equally express when affected allele is dominant)
pedigree
a family tree of affected and unaffected individuals
x-linked recessive pedigree
homozygous recessive individuals are affected and condition can skip generations. female can be a carrier
every affected son has a carrier mother when father is healthy
x-linked dominant pedigree
heterozygous and homozygous dominant are affected. condition does not skip generations
males and females equally affected.
if father is affected- all daughters will have it but not sons
if mother is affected-about half of all her children affected
autosomal chromosomes vs sex chromosomes
chromosomal pairs 1-22 are autosomes in humans
chromosomal pair 23 is the sex chromosome in humans
when do you use multiplictation rule when solving genetic problems and how is it done
when the genes are on different chromosomes/ far apart. u take punnet square of each gene seperately and then multiply broth fractions to find probability.
recessive sex linked pedigree
mostly males will be affected and females can be carriers (half shaded)
how to check if pedigree is x-linked or autosomal
to check if it is X-linked, you can check if affected son has an affected mom, and if affected daughter has an affected dad.
