Computers

Major Mode of Inheritance



 Review:

 A Gene is a unit of information about a heritable trait.

 A trait is a specific characteristics of an

organism.

Dominant

Recessive

Phenotype

genotype



complete dominance :only two trait will result.

 Incomplete dominance:

 one allele of a pair is not fully

dominant over its partner, so a

heterozygous phenotype in

between the two homozygous

phenotype emerges.

 Third phenotype will result .

 A mixture of both trait (the gene

combination is called Blending)

Example: Four-o’ clock flower are usually red or

white. Red and white are equally strong traits.

Neither colors is dominant .when pure red(RR)

crosses with white(WW),the colour blend.

RW(pink)



R R



W RW RW



W Rw RW

 Many gene in human show incomplete

dominance.

 they include genes for:

1.Hair

2.skin

3.eye colors

 Activity :

work on worksheet ( incomplete

dominance )

 co dominance: A pair of nonidentical alleles

that specify two phenotype are expressed at

the same time in heterozygote. e.g. ABO blood

type

 polygenic inheritance: is typical regulated by

more than one allele. e.g. weight

 Mitochondrial inheritance: only egg

mitochondria transmitted to the offspring. the

sperms mitochondria are contained in the

sperm's tail, which is never penetrate the egg.

 Blood types:

-Discovered by karl

Landstieiner,1900,Australian

-Agglutinate

-Special protien (antigen)on RBC

memberane cause clamping

 The presence or absence of these

antigen determine four different red blood

cells.

 LandSteiner labeled as :

A, B,AB,O

 Type A: has A antigen

 Type B: has B antigen

 Type AB :has AB antigen

 Type O: no antigen

 The type of antigen on a person’s blood

cells affects the type of blood he or she

can recieves in a transfusion.



 The alleles for the four blood type are

represented with three symbols.

 The letter I =dominant allele

i=recessive alleles

 Allelels the determine blood type A and

B are both dominant:

Written as : IA

IB

Type O = i ( Recessive)

 Type A

Genotype IAIA or IAi

 make a cross between:

blood type A x B

BxAB

OXA

AB x AB

Sex Determination

 History:Morgan,1900

-Drosophila Melanogater

- 10-15 days

- only four chromsome

-observed one pair of chromosome

in male is different from females

-Male=not the some size/shape

one is large and the other is small

- female=the same(both X)

Male=XY

 Activity on sex determination:

 Worksheet

 Sex Linked Inheritance

Female

Male

 Example :

Hemophilia

Father is affected

Mam is carrier

Offspring=

 Mam has the disease

 Father normal

 Offspring=

 Mam carrier

 Dad normal

 Offspring=20