One of the key differences between experts and novices is an experts ability

to recognize important

information from less important

information.

Today: Inheritance for 1 gene

Sexual reproduction creates genetic diversity by combining DNA from 2 individuals, but also by creating genetically unique gametes.

{Producing more cells}

{Producing gametes}

Fig 12.3

haploid

diploid

X 23in humans X 23

in humans

X 23in humans

Inheritance = The interaction between genes inherited from Mom and Dad.

Do parents’ genes/traits blend together in offspring?

In many instances there is a unique pattern of inheritance.

Traits disappear and reappear in new ratios.

Fig 13.4

Genotype Phenotype

Human blood types Box 44.2

One gene with three alleles controls carbohydrates that are found on Red Blood Cell membranes

RBC

A A

A

A

AA

AA

A

RBCRBC

B B

B

B

BB

BB

B

Allele A = A carbs Allele B = B carbs Allele O = no carbs

Box 44.2

Human blood types Box 44.2

RBC

A A

A

A

AA

AA

A

We each have two versions of each gene…

So

Genotype could be A and AORA and O

RBC

A A

A

A

AA

AA

A

Recessive alleles do not show their phenotype when a dominant allele is present.

Genotype could be A and AORA and O

What about…

Genotype = ??

RBC

What about…

Genotype = OO

RBC

RBC

AA

A

B

A A

B

B

B

What about…

B

RBC

AA

A

B

A A

B

B

B

What about…

B

Genotype = AB

Human blood types

AA orAO

AB

BB orBO

OO

Box 44.2

Phenotype

GenotypePhenotype Result of transfusion

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

Some simple dominant/recessive relationships in humans

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

Testcross:determining dominant/ recessive and zygosity

Fig16.21

Sickle-cell anemia is caused by a point mutation

Sickled and normal red blood cells

Mom = HS Dad = HS

H or S

H or S

HH

HS SS

HS possible offspring75% Normal25% Sickle-cell

Mom

Dad

S=sickle-cell

H=normal

Sickle-Cell Anemia:A dominant or recessive allele?

Coincidence of malaria and sickle-cell anemia

Mom = HS Dad = HS

H or S

H or S

HH

HS SS

HS

possible offspringOxygen transport:75% Normal25% Sickle-cell

Malaria resistance:75% resistant25% susceptible

Mom

Dad

Sickle-Cell Anemia:A dominant or recessive allele?

S=sickle-cell

H=normal

Variation in pea shape and color

Phenotype

Genotype

Fig 13.5

Fig 13.5The inheritance of genes on different chromo-somes is independent.

Y y

r R

Gene for seed color

Gene for seed shape

Approximate position of seed color and shape genes in peas

Chrom. 1/7 Chrom. 7/7

Fig 13.8

Fig 13.8The inheritance of genes on different chromosomes is independent:independent assortment

Fig 13.8

meiosis I

meiosis II

Fig 13.8The inheritance of genes on different chromosomes is independent:independent assortment

Fig 13.5