Post on 17-Jan-2016
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