Chapter 12 b The Cell Cycle Cell Division

Chapter 12 b. The Cell Cycle

Cell Division: Key Roles b b b Genome: cell’s genetic information Somatic (body cells) cells Gametes (reproductive cells): sperm and egg cells Chromosomes: DNA molecules Diploid (2 n): 2 sets of chromosomes Haploid (1 n): 1 set of chromosomes

Cell Division: Key Roles b b b Chromatin: DNA-protein complex Chromatids: replicated strands of a chromosome Centromere: narrowing “waist” of sister chromatids Mitosis: nuclear division Cytokinesis: cytoplasm division Meiosis: gamete cell division

The Cell Cycle b Interphase (90% of cycle) b G 1 phase~ growth b S phase~ synthesis of DNA b G 2 phase~ preparation for cell division

The Cell Cycle Mitotic phase b Mitosis~ nuclear division b Cytokinesis~ cytoplasm division b

Mitosis b Prophase b Prometaphase b Metaphase b Anaphase b Telophase

Mitosis Animation

Prophase b Chromosomes visible b Nucleoli disappear b Sister chromatids b Mitotic spindle forms b Centrosomes move

Prometaphase b Nuclear membrane fragments b Spindle interaction with chromosomes b Kinetochore develops

Metaphase b Centrosomes at opposite poles b Centromeres are aligned b Kinetochores of sister chromatids attached to microtubules (spindle)

Anaphase b Paired centromeres separate; sister chromatids liberated b Chromosomes move to opposite poles b Each pole now has a complete set of chromosomes

Telophase b Daughter nuclei form b Nuclear envelopes arise b Chromatin becomes less coiled b Two new nuclei complete mitosis

Cytokinesis b Cytoplasmic division b Animals~ cleavage furrow b Plants~ cell plate

Cell Cycle Regulation b Growth factors b Density-dependent inhibition b Anchorage dependence

Cancer b Transformation b Tumor: benign or malignant b Metastasis