10.1 Meiosis
------ the production of haploid cells with unpaired chromosomes - word means "to diminish".

Key points of Meiosis

  • The process results in 4 daughter cells
  • Daughter cells are haploid (N)
  • Daughter cells have unique combinations of chromosomes
  • Daughter cells do not have homologous pairs
  • Meiosis creates gametes (sperm and eggs)
  • Meiosis ensures variability in offspring
  • Gametes combine to create a zygote which is diploid (2N) - process of sexual reproduction

Homologous Pairs of Chromosomes

Chromosomes also have banding patterns unique to each one. These bands are caused by certain dyes. Chromosome banding can help to determine homologs on a karyotype.

Each chromosome has mane alleles, or alternate forms of genes

Homologous Chromosomes - each chromosome has a match, called a homolog. This is why normal organisms always have an even number of chromosomes. One homolog you received from your mother, the other you received from your father. They are not exactly alike, but they are the same size, shape, and have the same banding pattern.


Homologous Chromosomes
Diploid Number = 4

**Sex Chromosomes

In humans, there are two chromosomes that determine sex. The X and the Y chromosome.

If you have an XX - you are female
If you have an XY - you are male

 

Overview of Meiosis --- occurs in two stages - Meiosis I and Meiosis II

10.2 Genetic Variation

Crossing-Over - during prophase I, homologous pairs join together (synapsis) and exchange genetic information

Independent Assortment - Depending on how the chromosomes arrange themselved during metaphase I, the cells formed can have a variety of different chromosome combinations.

Fertilization - combining the genes from two parents

10.3 The Phases of Meiosis

**NOTE: PLANT CELLS DO NOT HAVE CENTRIOLES

10.5 The Human Life Cycle

Haploid Life Cycle (protists, algae, fungi)

Diploid Life Cycle (animals)

GAMETOGENESIS - process of creating gametes (Oogenesis & Spermatogenesis)

 

View the following animations:

Meiosis Animation I
Meiosis Animation II
Meiosis Animation III

Meiosis Animation IV