California Genetics Standard 2E # 9 Half of all our genetic information comes from each parent. EGG Sperms Sperms Magnified

Genetics Standard 2E Know why approximately half of an individual’s DNA sequence comes from each parent.

It is because when our parent got together they both shared their genetic make-up. This genetic sharing is designed to make a person better then each parent because we are a combination of both.

This genetic sharing occurs at the instance of fertilization (2N). When sperm (1N) and egg (1N) unite. Egg and sperm cells are also called gametes.

The formation of stronger & smarter offspring, however, begins during the formation of eggs in a female’s ovaries and during the formation of sperm in the male’s testes.The process of making sperms (testes) and eggs (ovaries) is called meiosis.

During meiosis the cells in the ovaries and the testes use whole body cells that have two set of genetic information that we get from each of our parents.

Because the whole body cells get one set of genetic info from the sperm and the other from the egg they are considered to be Diploid 2N. During meiosis the whole body cells undergo a reduction division in which the number of chromosomes is cut in half 1N (haploid). This means gametes only have one allele for each trait.

A multicellular organism develops from a single zygote or fertilized egg, and its phenotype depends on its genotype, which is established at fertilization (Standard 2D). Sperm 1N Egg 1N + = Body Cell 2N Haploid Diploid Haploid

1. What is the process that allows for genetic sharing? A.Meiosis B. Mitosis C. Fertilization D. Transformation

2. What is the process that makes sperm and eggs called? A.Meiosis B. Mitosis C. Fertilization D. Transformation

3. Where are sperms made? A. Ovaries B. Testes C. Urinary bladder D. Fallopian Tubes

4. Where are eggs made? A. Ovaries B. Testes C. Urinary bladder D. Fallopian Tubes

5. During meiosis the diploid 2N body cell undergoes a reduction to become? A. 4N B. 1N C. Haploid D. B & C