What are the genotypic and phenotypic ratios of...
1.Homozygous Tall Pea Plants
Homozygous Short Pea Plants x
T = tall, t = short
2.Heterozygous Round Seed Shape x
Heterozygous Round Seed Shape
R = Round, r = wrinkled
3.Heterozygous Yellow Seed Color x
Homozygous Green Seed Color
Y = yellow, y = green

Gametogenesis and
You

Review of Mitosis
What is it?
– asexual, cellular reproduction
– results in clone of the parent cell
Purpose?
– replace damaged/dead cells (tissue repair)
# of cells produced from 1 parent cell?
– 2 daughter cells from 1 parent.

A.
Purpose
1.
to maintain chromosome # in the species.
2.
involves gametogenesis a.
creation of gametes (sex cells – sperm and egg)

I.
Meiosis (Gametogenesis)
B.
Background
1.
parent cells contain 2 copies of each gene (diploid) a.
each pair of chromosomes are “homologous” to each other
1.
same traits arranged in the same order
2.
not necessarily identical
(due to alleles)

I.
Meiosis (Gametogenesis)
B.
Background
2.
gamete parent cells split homologous chromosomes apart as they divide to become gametes

I.
Meiosis (Gametogenesis)
C.
Meiosis
1.
Prophase I a.
chromosomes form
2.
Metaphase I a.
homologous chromosomes pair up @ equator b.
bind tightly to each other
1.
“crossing over”

I.
Meiosis (Gametogenesis)
C.
Meiosis
3.
Anaphase I a.
chromosomes pulled to the poles
4.
Telophase I a.
two daughter cells result b.
each cell now “haploid”

I.
Meiosis (Gametogenesis)
C.
Meiosis
5.
Daughter cells now go through mitosis (due to extra genetic material) a.
Prophase II – Metaphase II –
Anaphase II – Telophase II
***END RESULT***
Each parent cells creates 4 daughter cells