MITOSIS and the Cell Cycle Chapter 9 MITOSIS and the Cell Cycle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

The Cell Cycle **Orderly set of steps between eukaryotic cell division Why do Cells Divide? Allow for growth Reproduction and to make more cells Repair/Replace dead or injured cells

Why are cells so small? Diffusion is inefficient over long distances. Surface to volume ratio

Control of the Cell Cycle  G1 Checkpoint - Check to see if DNA is damaged G2 Checkpoint - Check to see if DNA is replicated properly M Checkpoint - spindle assembly checkpoint, check for alignment of chromosomes  Apoptosis - programmed cell death, if any of the checks fail

*sister chromatid: to either of the two identical copies (chromatids) *Centromere holds together chromatids

How many chromosomes and why? Chromosome video Human chromosome # is ________ # of pairs is______

9.2 Mitosis & Cytokinesis Interphase - cell growth, preparation for division, DNA synthesis. Cells spend most of their lives in interphase, it is the longest part of the cell cycle. (Some cells never leave interphase)

Mitosis Funnies:

Mitosis - The division of the nucleus that results in identical complete copies of chromosomes packaged into two new nuclei. Occurs in 4 phases: Prophase, Metaphase, Anaphase, Telophase Cytokinesis - The division of the cytoplasm that results in two daughter cells, occurs at the end of telophase. **In plant cells, cytokinesis begins when a new cell wall forms between the two new cells. **In animal cells, the two new cells pinch and pull apart

Interphase • Prophase • Metaphase • Anaphase • Telophase I-PMAT

STEPS OF MITOSIS: PROPHASE -Nuclear membrane disappears -Spindle fibers appear -Chromosomes become visible spindle fiber: fine threads that extend from the poles attaching to the chromosomes

METAPHASE -Chromosomes line up in the middle (the equator)

ANAPHASE -Chromatids move AWAY to opposite poles -Phase ends when chromatids reach the poles

TELOPHASE -The last “phase” -Cell membrane pinches inward -Daughter cells form -Chromosomes disappear -Asters and spindle fibers disappear

CYTOKENESIS -Division of cytoplasm after Telophase

Interphase:  Resting Prophase: Chromosomes visible, spindle forms as centrioles move Metaphase:  Chromosomes line up along equator Anaphase:  Chromatids separate Telophase:  Nuclear membrane forms on each side, cytokinesis begins

Mitosis starts with a Parent cell and produces 2 daughter cells!!!!!! The two daughter cells contain the exact same number of chromosomes as the original parent cell Daughter cells are DIPLOID

**In plant cells, cytokinesis begins when a new cell wall forms between the two new cells. **In animal cells, the two new cells pinch and pull apart

9.3 The Cell Cycle and Cancer neoplasm: abnormal growth of cells benign: non-cancerous malignant: cancerous Cancer: cellular growth disorder that results from the mutation of genes that regulate the cell cycle Cancer cells lack differentiation have abnormal nuclei form tumors undergo metastasis & angiogenesis 

HeLa Cells Article on Henrietta Lacks A HeLa cell (also Hela or hela cell) is a cell type in an immortal cell line used in scientific research. It is the oldest and most commonly used human cell line. The line was derived from cervical cancer cells taken from Henrietta Lacks, a patient who eventually died of her cancer on October 4, 1951.

Name the phases starting at the top.

Name the phase Identify X Identify Y

5. Name the phase

6. Name the phase

10. In humans, each cell (except sex cells) has how many chromosomes 11.  After mitosis, how many daughter cells are produced?  _______ 12.  After mitosis (in a human cell), each daughter cell has how many chromosomes? _____ 13.  How many phases are in MITOSIS? ___________ 14.  Which phase of the cell cycle is the longest?  _________ 15.  During which phase does cytokinesis begin?  __________