Human Heredity14-1BIO 1004

Flora

Scientists take pictures the complete set of chromosomes during cell division.

They then place all of the chromosomes next to each other A picture of chromosomes arranged in this way

is a karyotype One listed on page 341 is a result of

fertilization and formation of the zygote with 46 chromosomes

Human Chromosomes

Two of the chromosomes out of the 46 are known as sex chromosomes, because they determine an organisms sex

X chromosomes are much larger that the Male Y chromosome

The remaining 44 chromosomes are known as autosomal chromosomes

Cont.

All human eggs carry X chromosomes Sperm….on the other hand carry 50% X

chromosomes and 50% Y chromosomes This ensures a 50/50 split between the sexes

Gametes and Chromosomes

Pedigree Charts – chart which shows the relationships within a family

Symbols: Circles – female Squares – male

Human Traits

Some of the most obvious human traits are impossible to associate with a single gene

Some traits are not genetic at all……even height is largely impacted by nutritional during the body’s development Ex: Europe since 1880’s Genes can be expressed solely due to residing

in favorable conditions

Genes and the Environment

The human Genome: Our complete set of genetic information Includes tens of thousands of genes Some genes do code for specific traits – ex:

blood type Mapping of Human genome……….started in

the 80’s…..finally finished in 2000.

Human Genes

2 major genes determining blood type ABO and Rh

Rh – determined by a single gene with two alleles (+ and -)……Rh+ are homozygous dominant or heterozygous…..people who are homo recessive are Rh-

ABO blood groups are much more complex (3 alleles for this gene) IA, IB, and i. A and B are co-dominant – AB blood type IAIA, IAi, - A blood type – same scenario with B are type B Ii – are type O Negative and positive come from the Rh gene and letters

come from the ABO gene

Blood Group Genes