Humans have 23 pairs of chromosomes (total of 46 .

• Humans have 23 pairs of chromosomes (total of 46.

• One pair of

chromosomes is related to the sex of an individual , these chromosomes are called sex chromosomes

• Other 22 pairs of chromosomes are called autosomes (1-22)

Blood Types-what’s the difference?

Blood Donation ChartType O can’t receive any other blood type, but can be given to any other blood type.

Universal Donor is a type of blood that can be given to any other type because it has no antigens on its surface .

Type AB can receive all other blood types because it has A and B antigens.

Universal Receptor

Codominant: A condition in which both alleles are expressed

phenotypically• Blood Typing:• A, B are codominant• O is recessive to A or B• IAIA, IBIB are pure breed/homozygous• ii is 0• IAIB is the codominant heterozygous• IAi or IBiare the heterozygous pattern.

Codominant/Recessive Blood Typing

IA

i

IB i

• In humans, the sex of kid depends on the presence or absence of the Y chromosome

 XX = female

XY = male

• Genes that are located on the X or Y chromosome are called sex-linked genes. There are many more traits on the X

• Traits determined by sex-linked genes are called sex-linked traits

 (c = colorblind, C = normal)

Ex. Color blindnessfemale Xc Xc

male Xc Y

Are you colorblind?

• Most sex linked traits are recessive, this means both x chromosomes must have the gene in order for the trait to be expressed.

Inheritance of X-linked recessive traits

• Hemophiliac female: Xh Xh

– must inherit recessive alleles from both parents

– Rare: 1 in 100,000,000• Hemophiliac male: XhY

– only inherit from mom (dad donates Y chromosome)

– Much more common: 1 in 10,000

A hemophilia carrier x a normal male

• If only one x chromosome is present (in males)and has the sex linked gene, then the trait will be expressed

• Sex-influenced traits are traits that have a different expression in males and females.

• Examples of Sex-linked:• Color blindness, hemophila, muscular dystrophy• Examples of sex-influenced:• Male pattern baldness

• A carrier is a person that has the trait on only one chromosome and does not express the trait.

• Only females can be carriers of sex linked traits.

(C= normal, c= colorblind)

Ex. Color blind carrier XC Xc

• A colorblind male marries a normal female. What are the offspring genotypes and phenotypes? (C = normal, c = colorblind)

Xc YXC

XC

• A colorblind male marries a normal female. What are the offspring genotypes and phenotypes?

(C = normal, c = colorblind)

Xc Y XC XC Xc XC Y XC XC Xc XC Y

• A normal male (not colorblind) marries a carrier. What are the offspring genotypes and phenotypes?

XC Y XC

Xc

• A normal male (not colorblind) marries a carrier. What are the offspring genotypes and phenotypes?

XC Y XC XC XC XC Y

Xc Xc Xc Xc Y

• A normal male (not colorblind) marries a colorblind female. What are the offspring genotypes and phenotypes?

XC Y Xc

Xc

• A normal male (not colorblind) marries a colorblind female. What are the offspring genotypes and phenotypes?

XC Y Xc XC Xc Xc Y

Xc XC Xc Xc Y

Comparison to autosomal traits

• Recessive autosomal traits require that all individuals (males and females) inherit two recessive copies in order to exhibit the recessive phenotype.

• Inherit one recessive allele from mom and one from dad

Example: Cystic Fibrosis• A recessive trait whose gene is

located on an autosome (a chromosome that is not a sex chromosome).

• CFTR gene is responsible for making a protein that controls movement of salt and water into and out of cells– C: makes normal-functioning

protein– c: makes disfunctional protein

• Leads to thick, sticky mucus that damages lungs

• Hemophilia is characterized by uncontrolled bleeding

• It is a sex linked disorder caused by errors in the DNA that codes for the proteins involved in clotting