Cell Divison

Chromatid: each strand of a duplicated chromosome

Centromere: the area where each pair of chromatids is joined

Centrioles: tiny structures located in the cytoplasm

Spindle: a fanlike microtubule structure that helps separate the chromatids

Chromatin: DNA + histone proteins unraveled into DNA soup

Chromosomes: how we organize DNA

Mitosis: Asexual reproduction

Interphase: G1, S, G2

M phase: Mitosis, Cytokinesis

Mitosis: Prophase, Metaphase, Anaphase, Telophase

Prophase: duplicated chromosome condenses/becomes visible/ centrioles move to opposite sides of nucleus to help organize the spindle

Metaphase: chromosomes line up in the middle of the cell/spindle fibers connect the centromere to the two centrioles

Anaphase: centromeres are pulled apart + the chromatids separate to become individual chromosomes

Telophase: chromosomes spread out in a tangle of chromatin/nuclease re-forms around each cluster of chromosomes/spindle breaks apart, and nucleus becomes visible in each daughter cell

Cytokinesis: membrane is drawn in until cytoplasm is pinched into 2 = parts/ each part contains own nucleus/organelles

Meiosis: Mitosis for gametes

Steps in Meiosis: Meiosis 1, Meiosis 2, Fertilization

Meiosis 1: Homologous chromosomes are separated in 2 cells/there will be 2 cells but each cell was half ½ as many chromosomes

• Prophase 1: crossing over segments of non sister chromatids/ break and reattach to the other chromatid

• Metaphase 1: chromosomes line up in the middle of the cell/spindle fibers connect the centromere to the two centrioles

• Anaphase 1: centromeres are pulled apart + the chromatids separate to become individual chromosomes

• Telophase 1: chromosomes spread out in a tangle of chromatin/nuclease re-forms around each cluster of chromosomes/spindle breaks apart, and nucleus becomes visible in each daughter cell

Meiosis 2: similar process to mitosis

• Prophase 2: duplicated chromosome condenses/becomes visible/ centrioles move to opposite sides of nucleus to help organize the spindle

• Metaphase 2: chromosomes line up in the middle of the cell/spindle fibers connect the centromere to the two centrioles

• Anaphase 2: centromeres are pulled apart + the chromatids separate to become individual chromosomes

• Telophase 2: chromosomes spread out in a tangle of chromatin/nuclease re-forms around each cluster of chromosomes/spindle breaks apart, and nucleus becomes visible in each daughter cell/now there are 4 haploid (n) daughter cells

Fertilization: fusion of sperm and egg to form a zygote

Spermatogenesis: Process of using meiosis to make sperm— each sperm has 23 chromosomes

Oogenesis: Process of using meiosis to make egg— the result is 3 small polar bodies which gave all of its nutrients to the ovum

***Each Gamete can only have half of the chromosome by the end of the process

Regulating the Cell Cycle

Cyclins: a family of proteins that regulate the timing of the cell cycle in eukaryotic cells

Regulatory Proteins—

Internal regulators: respond to events inside the cell

External regulators: respond to events outside the cell

Growth factors: external regulators that stimulate the growth/division of cells

Apoptosis: process of programmed cell death/plays a role in development by shaping the structure of tissues, organs in plant, animals.

Cancer: body cells lose the ability to control all growth/ cancer cells divide uncontrollably to form a mass of cells (tumor)

Benign tumor: non cancerous

Malignant tumor: Cancerous/ spreads easily (metastasis)

Treatments: chemotherapy/radiation/surgery