Human Genetics

110

Students will be able to

Understand the patterns of Human Inheritance

Demonstrate how sex chromosomes function

Describe sex-linked diseases Evaluate the effects of environment on

behavior

Single Gene with Two Alleles

111

Multiple Alleles

One gene has many different versions

Blood Typing

One gene for standard blood type: I gene

Three alleles A, B, OA modified blood surfaceB modified blood surfaceO No modification on

surfaceSo IA or IB or i

112

Blood Types due to 3 Alleles

Genotypes

IAIA

IAi IBIB

IBi ii IAIB

Phenotypes

A BloodA BloodB BloodB BloodO BloodAB Blood

112

Blood Type - Second Gene (Rh)

Genotypes

Rh No Rh

Phenotypes

+-

So you can have A + or – B + or – AB + or – O + or -

Traits with many genes

Height (4 different genes)

Skin color

Weight (130 genes)

112

Sex Chromosomes

Two different types X and Y X chromosome is complex Y chromosome causes male traits

X Y

X

X

X X

X X

X

X

Y

Y113

Sex-Linked Genes

Genes that are present on the X chromosome

Example: Colorblindness

114

Colorblindness

XC Y

XC

Xc

XC XC

Xc Xc

XC

XC

Y

Y

XC = Normal color visionXc = Color Blindness (recessive)

One copy you appear normal but have the disease gene “Carrier”

114

Environmental Effects

Height 4 genes Environmental Factors

Diet Vitamins & Minerals Exercise

Play Violin Muscle coordination Good Hearing Instruction & Practice

115

Hemophilia A

Xh = Hemophilia A Xh X

X

Y

X X

Y Y

Xh

Xh

X

Xa. What percentage will have hemophilia A?

b. What gender are they?

Hemophilia A

Xh = Hemophilia A Xh X

Xh

Y

Xh Xh

Y Y

Xh

Xh

X

Xa. What percentage will have hemophilia A?

b. What gender are they?

Hemophilia A

X X

Xh

Y

Xh Xh

Y Y

X

X

X

X

Xh YNone of sons get itFather has hemophilia

What are the genotypes of the parents?