Cross TT X Tt

Give the genotypic and phenotypic ratios

Male - spermatogenesis Occurs frequently Produce sperm cells

Female - Oogenesis Occurs every 28 days Produce one egg

Do not copy

One mother cell produces four daughter cells

Each daughter cell has haploid chromosome # (1/2 of what mother had)

Occurs in sex cells (sperm and egg)

1. Interphase - mature cell ready for cell division

2. Prophase I - chromosomes are short, thick and double attached by centromere

3. Metaphase I - tetrads align at equator 4. Anaphase I - Tetrads split and move to

opposite poles 5. Telophase I - events occur in the

reverse of prophase I Don’t copy

6. Metaphase II - chromatids align at equator

7. Anaphase II - chromatids split and move to opposite poles

8. Telophase II - 4 cells with haploid #(new sperm and egg cells)

Don’t Copy

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

Mitosis Asexual and sexual Identical cells

produced Same

#chromosomes (46)

Body cells One Division Two cells made 20 minutes to one

hour

Meiosis Sexual cell

division Cells different Different number

of chromosomes (23)

Sex cells Two divisions 4 cells made Occurs in days

Crossing Over Genetic Recombination

Trisomy - extra chromosome (down syndrome)

Monosomy - lacking a chromosome (most lethal, Turner Syndrome)

Triploidy - three sets of chromosomes Polyploidy - more than the usual number

of chromosomes (rare in animals, common in plants)

Gene - portion of DNA that is genetically active, controls traits

Chromosome - Thread like, humans 23 pairs

Haploid chromosome # (n) - single set of chromosomes

Diploid chromosome # (2n) - two of each kind in a cell

Homologous Chromosome - same Allele - one-half of a gene pair (T or t) Gamete - Sex cell, reproductive cell

Sperm - male haploid # (Father) 23 chromosomes

Egg - female haploid # (Mother) 23 chromosomes

Zygote - fertilized egg by a sperm, diploid number (2n) = 46 chromosomes, 23 pairs

•Organized photo of a person’s chromosome

•Autosomes vs. sex chromosomes