1. Cell Reproduction Introduction Cell reproduction is different for prokaryotes than eukaryotes. Why? What do you know about the two different types of cells?

2. Chromosome Terminology Chromatin: tangled mass of threadlike DNA in nondividing cell Chromosomes: condensed rod-shaped DNA molecules formed during division Sister chromatids: 2 exact copies of genetic information that make up each chromosome Centomere: location where sister chromatids are attached together Genes: segment of DNA that CODES FOR A PROTIEN

3. Each duplicated chromosome consists of two sister chromatids which contain identical copies of the chromosome’s DNA. As they condense, the region where the strands connect shrinks to a narrow area, is the centromere. Later, the sister chromatids are pulled apart and repackaged into two new nuclei at opposite ends of the parent cell. Fig. 12.3

4. Prokaryotic Cell Reproduction Binary fission Asexual reproduction Offspring are identical 2 stages: 1)DNA is copied 2)Cell divides a)New cell membrane formed between 2 copies of DNA b)Squeezes together and eventually pinches off to 2 cells

5. Eukaryotic Cell Reproduction Two types of Cell Reproduction For Eukaryotes –Cell Division/Reproduction involving Mitosis –Cell Division/Reproduction involving Meiosis Mitotic Reproduction: Asexual; produces 2 identical daughter cells from original mother cell. Meiotic Reproduction: Produces 4 non-identical “gametes” from one mother cell; reduces the number of chromosomes in the cell by ½; leads to sexual reproduction

6. Chromosome Number Terminology Diploid number (2N) : characteristic chromosome number in common somatic eukaryotic cells  chromosomes exist in pairs due to presence of two complete sets of chromosomes  one maternal set  one paternal set

7. Chromosome Number Terminology Haploid number (N): half the diploid number; only one set of mixed maternal and paternal chromosomes;  found only in gametes (Technically, all prokaryotes are haploid)

8. Cell Type Terminology Somatic Cells: All non-sex cells; normal body cells (skin, muscle, liver, root, leaf, stem, etc.) –Theoretically always Diploid Gametes (germ cells): Sex cells –sperm, egg (ovum), sexual spores –Theoretically always Haploid

9. Let’s Practice! Get out your packets and turn to page 19.