Important Vocabulary

Important Vocabulary

Genotype Phenotype

Two alleles make up one genotype Alleles are either dominant or recessive

There are exceptions to these rules that will be discussed

Important Vocabulary Genotypes are heterozygous or

homozygous

HH – homozygous dominant

Hh – heterozygous

hh – homozygous recessive

Gregor Mendel developedmany of the principles ofgenetics during his researchon pea plants

Monohybrid CrossA cross between parents that are homozygous

for different alleles of one trait

Complete Dominance – the dominant allele is completely dominant over the recessive allele

#1 - Complete DominanceP: RR rrF1: Genotype Phenotype Type of Genotype

Rr red heterozygousF1 Cross: Rr RrPunnett Square:

F2: Genotype Phenotype Type of GenotypeRR red homozygousRr red heterozygousRr red heterozygousrr white homozygous

RR Rr

Rr rr

R

r

R r

F2 Genotypic Ratio:1 RR : 2 Rr : 1 rrF2 Phenotypic Ratio:3 red: 1 white

Monohybrid CrossA cross between parents that are homozygous

for different alleles of one trait

Incomplete Dominance – the dominant and recessive allele blend together

#4 - Incomplete Dominance

RR Rr

Rr rr

R

r

R r

Monohybrid CrossA cross between parents that are homozygous

for different alleles of one trait

Codominance – both alleles are equally dominant

#7 - Codominance

RR RW

RW WW

R

W

R W

Complete Dominance

Dihybrid CrossA cross between parents that are homozygous

for different alleles of two traits

#8 - Complete DominanceP: yyrr YYRRF1: Genotype Phenotype Type of Genotype

YyRr yellow/round heterozygousF1 Cross: YyRr YyRrPunnett Square:

yR

yr

YR

Yr

YYRR YYRr YyRR YyRr

YYRr YYrr YyRr Yyrr

YyRR YyRr yyRR yyRr

YyRr Yyrr yyRr yyrr

YR Yr yR yr

F2: Genotype Phenotype9 Y_R_ yellow/round3 Y_rr yellow/wrinkled3 yyR_ green/round1 yyrr green/wrinkled

Additional Crosses

Sex Determination

Sex Linkage

ABO Blood Typing

#11 - Sex DeterminationP: XY XX

XX XX

XY XY

X

Y

X X

Ratio:1 XX : 1 XY

Sex Linkage

Sex linked genes are located on either the X or Y chromosome

Most sex linked genetic disorders areX-linked

X-Linked Genetic Disorders

Normal XAXA XAY

Carrier XAXa

Affected XaXa XaY

#12 - Sex LinkageP: XHY XHXh

Punnett Square:

F1: Genotype Phenotype Sex Type of GenotypeXHXH normal F homozygousXHXh carrier F heterozygousXHY normal M hemizygousXhY hemophilia M hemizygous

XHXH XHXh

XHY XhY

XH

Y

XH Xh

ABO Blood Typing

ABO Blood Typing% of Blood Types in U.S. Caucasions

O+38%

O-7%AB+

3%AB-1%

A+34%

A-6%

B+9%

B-2%

ABO Blood Typing

A B AB O

A Y Y

B Y Y

AB Y

O Y Y Y Y

DONOR

RECIPIENT

#15 - Blood TypingP: IAi IBiPunnett Square:

F1: Genotype PhenotypeIAIB ABIAi AIBi Bii O

IAIB IAi

IBi ii

IA

i

IB i

PolygenicInheritance

Examples:Skin/Eye/Hair Color, Height/Body Shape,Rh (+/- Blood), etc.

Most human traits are polygenically inherited

Pedigrees

Pedigrees

Normal

Affected

Carrier

PedigreesExample:You are a normal female (homozygous). Both of your parents are normal. Your younger brother is normal and your older brother has hemophilia.

You!

XHXh XHY

XHYXhY XHXH

#18 - Pedigrees

XCXC XcYXCXc XCY

XCY XCXc XCY

XcYXCXC

You!

Chromosome Mapping

ChromosomeMap

8% 9%

8% 9%

#19 - Chromosome Mapping

A B C D E

A - 8 12 4 1

B 8 - 4 12 9

C 12 4 - 16 13

D 4 12 16 - 3

E 1 9 13 3 -

Gene

Gene

Recombinationsper 100

fertilized eggs

D EA B C

3 1 8 4

16