Summary Genetics and Inheritance

mentions



thetendencyforthecharacteristicsofparentstobepassedtotheiroffspringiscalled
heredity

thescienceofgeneticsstudies
how
these anddifferenceshappens
s imilarities



andalleles
GenesDominantrecessive



are
characteristicsinherited both
from m other father

these foundatthe
g enesare same orlocusonhomologouschromosomes
p osition

analleleisusedtodescribetwoormore ofageneorgenesatthe
forms
alternative onhomologouschromosomes
locus
same
homozygous are
alleles b t
oth hes ame iebblBB
heterozygous aredifferentieBb
alleles



BBBborbbshowthegenotype
theallelesfor
the characteristics


phenotype isthedescriptionofphysicalcharacteristicsasaresultofthegenotype

adominantalleleisshownwithacapital letter
shows inthe w
phenotype henit inahomozygous heterozygouscondition
occurs


a alleleisshown
recessive
withlowercaseletters

not in
shown the when
phenotype
it inheterozygouscondition onlyhomozygousrecessive
occurs



ofgenetics
Mendel father


Mendel10221884 fromAustriamade
thefirstbreakthroughinunderstandingnowcharacteristicswereinherited
heuseavegetablepeas
with
started pure p lants
breeding
allplantswereidentical were
homozygous
foranycharacteristic
hethencrosspollinatedpurebreedingplantswith for
other
each onecharacteristic iehomozygoustanxhomozygous
short

hethenselfpollinatedthefirstgenerationtoproducethesecondgeneration




Mendelis as
regarded thefatherofgenetics

, Inheritanceandvariationimmm




and
Mononybriacrossesphenotypes andheterozygous
homozygous
g enotypes



anybridistheottspringthatresuitstromacrossbetweentwopurebreedingparentsthataregeneticanyaitterent


was
Mendel studying inheritance
m ononybria



InMendel'sinvestigation thetirstottspringproduceaiscaneathetirsttilialgenerationora
TheFlplantswere
thenselfpollinated anatheseconatilialgenerationorrewasproanced


Itwasnotedthat
thecharacteristics neverbienaedienomediumneightionistanisnort

Fioniyaisplayeatheaominantaneleietal

allele
recessive
only infoi.eshort
appeared




Mendelslawot
inheritance Lawofsegregation
an are
characteristics determined
organisms
byinternaltactorswnionoccurinpairsigenesonhomologouschromosomes

Ageneticcross


PlGenotype TT tt t short
recessive Proenotype Tt Tt
dd dd dd dd


Y
meiosis meiosis
gametes T T t t gametes T t t t

fertilization
T T µ T t
T TT Tt
t Tt tt

FlGenotypeTtTtTtTt Fabenotype TtTt.tt.tt
i loottall ratioottalitoshortistO nm mm
ratioottalitoshortiss


bitterentkinasotaominance




completeDominance



toreachpairotcharacteristicsoneisdominantanatheotherrecessive


only aominantaneleisshowninphenotype
unless recessive
homozygous




orpartialDominance
incomplete



amixtureottheaneresinthegenotypeisseeninthe phenotype


ieareaswhitetlowerproduceapinicone

codominance

bothallelesinthegenotypeareseeninthephenotypernotblended


ie abrown whitecowproducearoancow