genetics the study of inherited characteristics chromosome dna code for traits
TRANSCRIPT
GeneticsGeneticsThe Study of Inherited The Study of Inherited
CharacteristicsCharacteristics
ChromosomeChromosomeDNACodefortraits
GeneGeneSegments of Segments of
DNA DNA Code for a Code for a
traittrait
HairColor
EyeColor
Gene Segment For Hair color
TraitTraitCharacteristicCharacteristicFeatureFeatureVariations in Variations in
a populationa population
Dominant TraitDominant Trait ““Dominates”Dominates” Shows in the Shows in the
outward outward appearanceappearance
Even when Even when recessive trait is recessive trait is presentpresent
BBbb
BBor
Bb
Recessive TraitRecessive Trait““hidden”hidden”May be May be
masked by a masked by a dominant dominant traittrait
BBbb
Albinism
bb
AllelesAlleles Letters of the Letters of the
alphabetalphabet Code for a traitCode for a trait One from One from
fatherfather One from One from
mothermother
Dominant Dominant Allele:Allele:
Upper case Upper case letter of the letter of the alphabetalphabet
Codes for Codes for dominant dominant traitstraits
Recessive Recessive Allele:Allele:
Lower case Lower case letter of the letter of the alphabetalphabet
Codes for Codes for recessive recessive traitstraits
Chromosomes in NucleusChromosomes in Nucleus
GeneSegmentsFor a Trait=“A” or “a”
Monohybrid CrossMonohybrid CrossCross for Cross for oneone trait trait
Example:Example:Hair colorHair color
BB bbBB BBBB BbBb
BB BBBB BbBb
Punnet Square
F1 GenerationF1 GenerationGenetic Genetic
Cross=Cross=
Mating Mating F1=F1=
ChildrenChildren11stst “filial” “filial”
generationgeneration
ParentsParents
BB bbBB BBBB BbBb
BB BBBB BbBb
22ndnd Filial Generation- Filial Generation- F2F2 ChildrenChildren of of
the cross the cross between the between the children of an children of an F1F1
““Incest” Incest” among F1among F1
Only after Only after pure x purepure x pure
F1=F1=
F2=F2=
BB BB
bb BbBb BbBb
bb BbBb BbBb
BB bb
BB BBBB BbBb
bb BbBb bbbb
PhenotypePhenotypeOutward Outward
appearanceappearanceTrait that is Trait that is
shownshownBb Bb lookslooks brown brown
(has “b” =white (has “b” =white allele)allele)
GenotypeGenotypeAllele setAllele setTrue genetic True genetic
makeupmakeup of of the the chromosomechromosome
BbBb
Homozygous:Homozygous:Pure Pure
conditioncondition2 same case 2 same case
allelesallelesBBBB= =
dominantdominantbbbb= recessive= recessive
Heterozygous:Heterozygous:Hybrid Hybrid
conditioncondition2 different case 2 different case
allelesallelesBbBb appears appears
dominantdominant
Dihybrid CrossDihybrid Cross Cross withCross with twotwo traits traits Example:Example:1.1. Hair ColorHair Color2.2. Eye ColorEye Color2 types of 2 types of allelesalleles
parentsparents
ChildrenChildren ChildrenChildren ChildrenChildren ChildrenChildren
ChildrenChildren ChildrenChildren ChildrenChildren ChildrenChildren
ChildrenChildren ChildrenChildren ChildrenChildren ChildrenChildren
ChildrenChildren ChildrenChildren ChildrenChildren ChildrenChildren
CodominanceCodominance ““Incomplete” Incomplete”
dominancedominance HybridHybrid is a is a blend blend of of
traitstraits Example:Example:
RR=redRR=redRrRr=pink=pinkrr=whiterr=white
Pink Carnation
Multiple AllelesMultiple AllelesMore than More than
one type of one type of allele for a allele for a traittrait
Example:Example:
Blood TypeBlood Type
TYPES:TYPES:
A A IIAAIIAA, I, IAAii
B B IIBBIIB B , I, IBBii
AB AB IIAAIIBB
O O iiii
X-Linked TraitsX-Linked Traits Sex-linkedSex-linked Trait in on the sex Trait in on the sex
chromosomechromosome XXXX== Female Female XYXY MaleMale Ex:Red & white Ex:Red & white
eyeseyes
Female=Female=XXXXAdd eye trait=Add eye trait=XXRRXXR R or X or XRRXXr r
XXrrXXrr
Male=Male=XYXYAdd eye trait=Add eye trait=XXRRY or XY or XrrYY““Y” is emptyY” is empty
KaryotypeKaryotype
Chromosome NumberChromosome Number
Different # for different Different # for different speciesspecies
Full setFull set = 2N= = 2N=DiploidDiploid N=N= # pairs# pairs 1 pair from mother1 pair from mother 1 pair from father1 pair from father Humans= Humans= 23 pairs23 pairs or or 46 total46 total
Homologous Chromosomes are the sets of each pair
Autosomes & Sex ChromosomesAutosomes & Sex Chromosomes
Autosomes = # 1-22 for all traits except sex
Sex chromosomes= Pair # 23 XX(female) orXY(male)
Down Syndrome= 3 of #21Down Syndrome= 3 of #21
Klinefelter’s = XXYKlinefelter’s = XXY
Pedigree ChartsPedigree Charts
Male =Male =
Female=Female=
Sexual Union=Sexual Union=
Offspring=Offspring=
Pedigree Chart -Cystic FibrosisPedigree Chart -Cystic Fibrosis