Human Heredity 14-1 BIO 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 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) I A, I B, and i.  A and B are co-dominant – AB blood type  I A I A, I A i, - 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