Genetics The Study of Inherited Characteristics

Chromosome DNA Code for traits

Gene Segments of DNA Segments of DNA Code for a trait Code for a trait Hair Color Eye Color

Gene Segment For Hair color

Trait Characteristic Feature Variations in a population

Dominant Trait “Dominates” “Dominates” Shows in the outward appearance Shows in the outward appearance Even when recessive trait is present Even when recessive trait is present Bb Bb BB or Bb

Recessive Trait “hidden” May be masked by a dominant trait b Bb Albinism bb

Alleles Letters of the alphabet Code for a trait One from father One from mother

Dominant Allele: Upper case letter of the alphabet Upper case letter of the alphabet Codes for dominant traits Codes for dominant traits Recessive Allele: Lower case letter of the alphabet Codes for recessive traits

Chromosomes in Nucleus Gene Segments For a Trait= “A” or “a”

Monohybrid Cross Cross for one trait Cross for one trait Example: Example: Hair color Hair color Bb BBBb B BBBb Punnet Square

F1 Generation Genetic Cross= Genetic Cross= Mating Mating F1= F1= Children Children 1 st “filial” generation 1 st “filial” generation Parents Bb BBBBb BBBBb

2 nd Filial Generation- F2 Children of the cross between the children of an F1 Children of the cross between the children of an F1 “Incest” among F1 “Incest” among F1 Only after pure x pure Only after pure x pure F1= F2= F2= BB bBbBb bBbBb BbBBBBb bBbbb

Phenotype Outward appearance Outward appearance Trait that is shown Trait that is shown Bb looks brown (has “b” =white allele) Bb looks brown (has “b” =white allele)

Genotype Allele set Allele set True genetic makeup of the chromosome True genetic makeup of the chromosome Bb

Homozygous: Pure condition Pure condition 2 same case alleles 2 same case alleles BB= dominant BB= dominant bb= recessive bb= recessive Heterozygous: Hybrid condition 2 different case alleles Bb Bb appears dominant

Dihybrid Cross Cross with Cross with two traits two traits Example: Example: 1. Hair Color 2. Eye Color 2 types of alleles parents ChildrenChildrenChildrenChildren ChildrenChildrenChildrenChildren ChildrenChildrenChildrenChildren ChildrenChildrenChildrenChildren

Codominance “Incomplete” dominance “Incomplete” dominance Hybrid is a blend of traits Hybrid is a blend of traits Example: Example:RR=red Rr=pink rr=white Pink Carnation

Multiple Alleles More than one type of allele for a trait More than one type of allele for a trait Example: Example: Blood Type TYPES: I A I A, I A i A I A I A, I A i I B I B, I B i B I B I B, I B i I A I B AB I A I B ii O ii

X-Linked Traits Sex-linked Sex-linked Trait in on the sex chromosome Trait in on the sex chromosome XX= XX= Female Female XY XY Male Male Ex:Red & white eyes Ex:Red & white eyes Female= XX Add eye trait= RR Rr X R X R or X R X r rrXrXrrrXrXr Male= XY Add eye trait= Rr X R Y or X r Y “Y” is empty

Karyotype

Chromosome Number Different # for different species Different # for different species Full set = 2N=Diploid Full set = 2N=Diploid N= N= # pairs # pairs 1 pair from mother 1 pair from mother 1 pair from father 1 pair from father Humans= 23 pairs or Humans= 23 pairs or 46 total 46 total Homologous Chromosomes are the sets of each pair

Autosomes & Sex Chromosomes Autosomes = # for all traits except sex Sex chromosomes= Pair # 23 XX(female) or XY(male)

Down Syndrome= 3 of #21

Klinefelter’s = XXY

Pedigree Charts Male = Male = Female= Female= Sexual Union= Sexual Union= Offspring= Offspring=

Pedigree Chart -Cystic Fibrosis