Take 5 11911 What is a gene What

Take 5: 11/9/11 • What is a gene? • What does meiosis produce? • What are the 2 divisions of Meiosis?

Meiosis Notes Ch 10

Mendel's Principle of Genetics • 1. Each organism must inherit a ____ copy of every gene from each of its parents. • 2. Each organism produces its own gametes (aka sex cells) and each gamete has _____ set of genes.

Diploid vs. Haploid • A cell with two copies of each chromosome = _____ or _______ • A cell with only one copy of each chromosome = ______ or ______

Diploid vs. Haploid 2 n = 6 n = ___

Number of Chromosomes in various organisms…

One chromosome from Dad • The two chromosomes of each pair in a diploid cell are called One chromosome from Mom

One chromosome from Dad • Each pair of homologous chromosomes has genes for the SAME traits • example: Chromosome pair #1 could code for eye color One chromosome from Mom

So how do you get one chromosome from each parent? Well, I think you already know that.

Fertilization, right? Yep!

So that must mean that the sperm and egg cell are haploid. Yep!

Are there any other cells in your body that are haploid? Nope!

How do you make haploid cells? Through meiosis

What’s that? The way you produce a haploid cell from a diploid cell.

• Definition: Meiosis is the process in which the number of chromosomes in a cell is cut _______ due to a separation of homologous chromosomes in a diploid cell. (2 n 1 n cell)

Meiosis involves two distinct divisions • __________

• Meiosis turns a single diploid cell into ________

Meiosis I • Prior to meiosis I: each chromosome is _______

Prophase I • Each chromosome pairs with the corresponding homologous chromosome to form a structure called a ____ – There are ______ chromatids in a tetrad

Prophase I • In addition to pairing up and forming tetrads, they ALSO exchange portions of their chromatids in a process called ________ • The results in an ______ of alleles to produce new _______ of alleles

• NOTICE: This is one difference from mitosis. In mitosis the chromosomes line up _____. In meiosis, they ______

Metaphase I • The pair of homologous chromosomes _____________ Anaphase I • The homologous chromosomes randomly ____. Telophase I • Two new cells are formed.

Now these two cells enter Meiosis II UNLIKE THE FIRST DIVISION, these cells DO NOT UNDERGO ______

• Prophase II: • _______________ • Metaphase II: _______________ • Anaphase II: _______________ • Telophase II: ________ are produced. http: //www. youtube. com/watch? v=D 1_-m. QS_FZ 0

Gamete Formation • In MALES, haploid gametes produced are called ______. In plants it is called _______ • In FEMALES, only ______ of the cells produced is involved in reproduction – AKA ______ – Other three = ________and are not used in reproduction

http: //www. cellsalive. com/meiosis. htm

The Simplified Version:

Let’s fill this in…

Crossing over

Chapter 12 Patterns of Heredity and Human Genetics

Pedigree • A graphic representation of genetic inheritance

Incomplete Dominancephenotype is a mixture between those of 2 homozygous parents

Codominance- both alleles are expressed equally

Sex Linked Inheritance

Karyotype- normal male

Karyotype - Down Syndrome (Trisomy) • http: //www. youtube. com/watch? v=ycr. PCT P 2 m. FE

http: //www. youtube. com/watch? v=ldjb-FR-PKo Karyotype –Turner Syndrome (monsomy)