Homework #3 due now

Bonus #2 posted

Homework #4 is due 12/3/07 (only if needed)

No class W 11/21

PhenotypeGenotype

Dominant

Recessive

Human blood types

AA orAO

AB

BB orBO

OO

If Frank has B blood type,

his Dad has A blood type,

And his Mom has B blood type…

Should Frank be worried?

possible

genotypes

Mom=B blood

BB or BO

Dad=A blood

AA or AO

Gametes all B / 50% B and50% O

all A / 50% A and50% O

possible

genotypes

Mom=B blood

BB or BO

Dad=A blood

AA or AO

Mom=B blood

BB or BO

Dad=A blood

AA or AO

Gametes all B / 50% B and50% O

all A / 50% A and50% O

possible

genotypes

Frank can be BO= B blood …no worries

Mom=B bloodBB or BO

Dad=A bloodAA

Gametes all B / 50% B and50% O

all A

possible

genotypes

Frank can be BO or BB= B blood …Uh-Oh

GrandparentsAB and AB

Pedigree, tracing the genetic past

Dom. Rec. Rec. Dom.

We can also predict the future

Fig 2.12

Mom = AB Dad = AB

Inheritance of blood types

Mom = AB Dad = AB

Gametes: A or B A or B

Inheritance of blood types

Mom = AB Dad = AB

Gametes: A or B A or B

A or B

A or B

AA

AB BB

AB

Chance of each phenotype for each offspring25% AA50% AB25% BB

Mom

Dad

Inheritance of blood types

Single genes controlling a single trait are unusual. Inheritance of most genes/traits is much more complex…

Dom. Rec. Rec. Dom.

PhenotypeGenotype

Genes code for proteins (or RNA). These gene products give rise to traits…

Human blood types

AA orAO

AB

BB orBO

OO

PhenotypeGenotype

Genes code for proteins (or RNA). These gene products give rise to traits…

It is rarely this simple.

Figs 1.15-17

Incomplete dominance givers rise to blending.

Human blood types

AA orAO

AB(Codominance)

BB orBO

OO

Sex determination is normally inherited by whole chromosomes or by number of chromosomes.

X/Y chromosomes in humans

The X chromosome has many genes; the Y chromosome only has genes for maleness.

• Human sex chromosomes

Fig 2.25

X/Y chromosomes in humans should give rise to equal numbers of males and females

105 males : 100 females (live births)Why?

105 males : 100 females (live births)Why?

Ratio of Males to Females, by Age Group(number of males per 100 females, total resident population)Age 1950 1960 1970 1980 1990 2000 2004Under14 years

103.7 103.4 103.9 104.6 104.9 104.9 104.7

14 to 24years

98.2 98.7 98.7 101.9 104.6 105.1 105.8

25 to 44years

96.4 95.7 95.5 97.4 98.9 100.2 101.4

45 to 64years

100.1 95.7 91.6 90.7 92.5 94.8 95.0

65 yearsand over

89.6 82.8 72.1 67.6 67.2 70.8 71.7

All ages 98.6 97.1 94.8 94.5 95.1 96.3 96.9

Sex-linked traits are genes located on the X chromosome

Color Blind Test

Sex-linked traits: Genes on the X chromosome

No one affected, female carriers

A= normal; a= colorblind

colorblindnormal

similar to Fig 2.27

Sex-linked traits: Genes on the X chromosome

50% of males affected, 0 % females affected

A= normal; a= colorblind

normalnormal

similar to Fig 2.27

Sex-linked traits: Genes on the X chromosome

50% males affected, 50% females affected

A= normal; a= colorblind

colorblindnormal

similar to Fig 2.27

Sex-linked traits: Genes on the X chromosome

No one affected, female carriers

50% of males affected, 0 % female affected

50% males affected, 50% females affected

A= normal ; a= colorblind

similar to Fig 2.27

Homework #3 due now

Bonus #2 posted

Homework #4 is due 12/3/07 (only if needed)

No class W 11/21