3.7.1 INHERITANGE
Genotype gcnetic constitulon of an organ1sm, descniscs all the aleles
Phenotype - obsvable charateistics of an orgaism detenincd by
the genatupe and the envronment.
Gene sequene ot bascs that codes tor apolypeptiae
Locus positiom 0f a qene 0.n a hrom0s0me
Alele- versom ot oa qene
Genetic characteristics
C.g- GG honaozygous dojm1nant
heteozygous
-
99 homozygous recess)ve
Dominant - always expressed in pheaotype if preseat i genctype
Recessive - ony expcessed it geaetype if homozygcus reessiwe
Monohsbrid
L
Inhertana
epreseat1ag genet coses
greea and yellow pod calou n pea plaats
gyelow
Monchybrd nhiataale
GGreen pod Green pod the inhentance ot
Parents sungle geae
Gametes In diplod organisms,
chaactenstcs ce
3 green pods determned by pas oF
Lyellow pod
3:)
aleles- ony Cae alele
9) cg 99 ratio goes to each qanete
Ratios
In reality, the obs erved results almost neuer natch the
expected rato. This is due to indepeadent segcegat.
Io reduce this statist1ead erat use a larger sanpe Size.
,3.7.1 DJHYBRID
Dihybrd inheitance -how two characteristics, determined by two
ditfe ent qenes located on two ditterent chromnosomes are
nheatd logethe.
e-g seed shape and seed colouc in pea plants
R-cound seeds G- yelow seeds
C- wcnklcd seeds 9 green sceds
Cross
Porent ph enotup esi Round. yelow Wanlkled., geeen
Parent genotypesi RRCGT Tgg
Gametes
Offspring AU round yello w
Cross 2
Paent phzactypes i Rourdl, yello w Round, yellaw
Porent qlnotypesi Rr cg Rrcg
Ganetes
RG RRGG RRGg RrGG Rcg
qround,yellow
3 round, green
RRGg RRg9 Rrlrg Rrgg 3 wcinkled, yellouw
wenlkled qceen
Rrgg rrág 9:3:3:ato
, 3.7.1 INHLRIANCE
Codominance'
where both alleles are expre ssed in the phenotype of a
heteo zugote
L
io at colour n catte
c - allele tor red pigment prodution
alele tor no red piqmet production
(ce- red coat
Cwc- white coat
roan coat
Paent ph Cactypés Roan
coat Roan coat
Parent gactypes
Gametes
25 ced coat
S0% cOan coat
2SY whste coat
Multiple alleles
whese a qene has more than twoalleles
ABO blood qroups in humGas
-
antiqen A on red bload cells membranes
JB - untigen B on red bload cells nenbanes
A
neither antigen
are codomnat,is cecesSive to both
Parent phenotypes Group AB
Parent genotypes i I^]
Gometes 9
S07 blocd qioup A
S0Y. blcod qroup B
Genotype gcnetic constitulon of an organ1sm, descniscs all the aleles
Phenotype - obsvable charateistics of an orgaism detenincd by
the genatupe and the envronment.
Gene sequene ot bascs that codes tor apolypeptiae
Locus positiom 0f a qene 0.n a hrom0s0me
Alele- versom ot oa qene
Genetic characteristics
C.g- GG honaozygous dojm1nant
heteozygous
-
99 homozygous recess)ve
Dominant - always expressed in pheaotype if preseat i genctype
Recessive - ony expcessed it geaetype if homozygcus reessiwe
Monohsbrid
L
Inhertana
epreseat1ag genet coses
greea and yellow pod calou n pea plaats
gyelow
Monchybrd nhiataale
GGreen pod Green pod the inhentance ot
Parents sungle geae
Gametes In diplod organisms,
chaactenstcs ce
3 green pods determned by pas oF
Lyellow pod
3:)
aleles- ony Cae alele
9) cg 99 ratio goes to each qanete
Ratios
In reality, the obs erved results almost neuer natch the
expected rato. This is due to indepeadent segcegat.
Io reduce this statist1ead erat use a larger sanpe Size.
,3.7.1 DJHYBRID
Dihybrd inheitance -how two characteristics, determined by two
ditfe ent qenes located on two ditterent chromnosomes are
nheatd logethe.
e-g seed shape and seed colouc in pea plants
R-cound seeds G- yelow seeds
C- wcnklcd seeds 9 green sceds
Cross
Porent ph enotup esi Round. yelow Wanlkled., geeen
Parent genotypesi RRCGT Tgg
Gametes
Offspring AU round yello w
Cross 2
Paent phzactypes i Rourdl, yello w Round, yellaw
Porent qlnotypesi Rr cg Rrcg
Ganetes
RG RRGG RRGg RrGG Rcg
qround,yellow
3 round, green
RRGg RRg9 Rrlrg Rrgg 3 wcinkled, yellouw
wenlkled qceen
Rrgg rrág 9:3:3:ato
, 3.7.1 INHLRIANCE
Codominance'
where both alleles are expre ssed in the phenotype of a
heteo zugote
L
io at colour n catte
c - allele tor red pigment prodution
alele tor no red piqmet production
(ce- red coat
Cwc- white coat
roan coat
Paent ph Cactypés Roan
coat Roan coat
Parent gactypes
Gametes
25 ced coat
S0% cOan coat
2SY whste coat
Multiple alleles
whese a qene has more than twoalleles
ABO blood qroups in humGas
-
antiqen A on red bload cells membranes
JB - untigen B on red bload cells nenbanes
A
neither antigen
are codomnat,is cecesSive to both
Parent phenotypes Group AB
Parent genotypes i I^]
Gometes 9
S07 blocd qioup A
S0Y. blcod qroup B
