1. What are these, and which process creates them?

2. MEIOSIS
Discovered by microscope examination of dividing cells, ovary cells in rabbits.
REDUCTION DIVISION: One diploid nucleus divides to produce 4 haploid nuclei
MEIOSIS 1: two nuclei produced that have haploid #, but 2 chromatids
MEIOSIS 2: 4 nuclei produced that have haploid #, with 1 chromatid

3. Sexual Reproduction
Halving the number of chromosomes allows for the fusion of gametes during fertilization
Fusion of gametes combines alleles from two organisms
Genetic Variation: this combination is likely to never have existed before

4. Chromosome Review

5. Meiosis 1: Separates homologous chromosomes
Replication of DNA occurs BEFORE meiosis during the ___ phase of ___________.

6. Meiosis 2: Separates Sister Chromatids

7. Make your Meiosis drawings neat and colorful!
A = All information included, neat, colored, labeled, answers thorough
B = All information included
C = Missing one or two items
D = Missing more than two items
F = Missing more than half the information

8. During Prophase 1: Synapsis and Crossing over
DNA condenses into chromosomes
Homologous chromosomes line up in a pairing process called synapsis.
Each pair is called a bivalent (4 chromatids and 2 chromosomes)
Crossing over occurs where chromatids exchange genes and create genetic diversity

9. Random orientation of Bivalents
During Metaphse the chromosomes attach to each pole, and it is random the way that they line up
Creates genetic diversity

10. Random orientation and Independent assortment

11. The Key Difference Between Mitosis and Meiosis is the Way Chromosomes Uniquely Pair and Align in Meiosis
Mitosis
The first (and distinguishing) division of meiosis

12. Non-Disjunction
During Anaphase if the chromosomes do not separate, can result in gametes with 22 or 24 chromosomes.
Fusing with a normal gamete (23) makes chromosome numbers of 45 or 47 chromosomes

13. How to Test for Chromosomal Abnormalities
Amniocentesis:
Needle through mothers abdomen to collect amniotic fluid with fetal cells
Chronic villus Sampling:
Sampling tool through vagina, obtain cells from the chorion, one of the membranes from the placenta.

14. Down Syndrome Trisomy 21 3 of #21 chromosome Symptoms:
Hearing loss, heart and vision disorders, mental and growth retardation
Maternal Age Correlation
DBQ in book