Name ______
Date ______Period ______
6.1 – Chromosomes & Meiosis
Key Concept: Gametes have half the number of chromosomes that body cells have.
You have somatic cells and gametes.
-Somatic Cells
-Are ______
-Make up ______
-______on to children
-Gametes
-Are ______
-______on to children
You cells have autosomes and sex chromosomes.
-Somatic cells have ______of chromosomes (46 total)
Somatic cells are diploid; gametes are haploid.
Diploid (_____)• Has ______of each
chromosome (1 from ______
& 1 from ______)
• _____ autosomes, _____ sex chromosomes
• ______are diploid
• Produced by ______
/ Haploid (_____)
• Has ______of each chromosome
• _____ autosomes, _____ sex chromosome
• ______are haploid
• Produced by ______
Mitosis vs. Meiosis
-Chromosome number must be maintained in animals.
-Many plants have more than two copies of each chromosome (can be tetraploid [4n] or hexaploid [6n])
-Mitosis and meiosis are types of nuclear division that make different types of cells.
6.2 – Process of Meiosis
Key Concept: During meiosis, diploid cells undergo two cell divisions that result in haploid cells.
Cells go through two rounds of division in meiosis.
-Meiosis ______and creates ______.
-Homologous chromosomes (sometimes called ______)
-______of chromosomes
-Inherit one from each ______
-Carry ______(code for different traits)
-Separate during ______
-Sister chromatids
-Duplicates of ______
-Each ______of a duplicated chromosome
-Attached together at the ______
-Separate in ______
Mitosis vs. Meiosis
Mitosis• One cell division
• Homologous chromosomes do not pair up
• Results in diploid cells
• Daughter cells are identical to parent cell / Meiosis
• Two cell divisions
• Homologous chromosomes pair up (Metaphase I)
• Results in haploid cells
• Daughter cells are unique
Haploid cells develop into mature gametes.
-Gametogenesis differs between males and females.
-Sperm (______)
-Become streamlined and motile (able to move)
-Primarily ______to the embryo
-Males produce over 250 million sperm per day
-Egg (______)
-Contribute ______to the embryo
-During meiosis, the egg gets most of the contents; the other 3 cells become polar bodies
-Females produce a few hundred eggs over a lifetime
6.6 – Meiosis & Genetic Variation
Key Concept: Independent assortment and crossing over during meiosis result in genetic diversity.
Sexual reproduction creates unique combinations of genes.
-Fertilization
-______
-Increases unique ______
-In humans, the chance of getting any one combination of chromosomes from any one set of parents is
one out of 223 x 223 (which is one out of over ______combinations)
-Independent assortment of chromosomes
-Homologous chromosomes ______along the cell equator
-Increases the number of unique combinations of genes
-In human cells, about 223 (8 million) different combinations could result
-Crossing over
-______
-Increases genetic diversity
-Occurs during Prophase I of Meiosis I
-Results in new combinations of genes (chromosomes have a combination of genes from each parent)
Genetic linkage
-Chromosomes contain many genes.
-The ______two genes are located on a chromosome, the ______they are to be separated by crossing over
-Genetic linkage: ______
______