1. May 2, 2011 Of the two causes we looked at Friday, which do you think is most likely responsible for frog malformations? Why? How many chromosomes do humans have? How many copies of each chromosome?

2. # of chromosomes in parent cell = 46 chromosomes (2n) promotes genetic variation in organisms synapsis does not occur daughter cells are haploid

3. daughter cell is diploid DNA replication occurs during Interphase (S-phase) occurs during asexual reproduction (example = binary fission) includes 1 nuclear division

4. synapsis occurs: crossing over between non- sister chromatids daughter cell is identical to parent cell includes 2 nuclear divisions # of chromosomes in daughter cell = 46 chromosomes (2n)

5. production of gametes body does this for growth or repair daughter cells are unique, not identical to the parent cell or each other also called reduction division # of chromosomes in daughter cell = 23 chromosomes (n)

6. Levels of Organization Nucleotides  DNA  Genes  Chromosome  Nucleus  Cell

7. Levels of Organization Chromosome = lots of DNA Usually shown as Xs 23 sets in humans (total 46) First 22 sets of chromosomes called autosomes 23rd set of chromosomes called sex chromosomes –Females XX, Males XY Shown in a karyotype