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Chapter 9 MITOSIS

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

9.1 The Cell Cycle **Orderly set of steps between eukaryotic cell divisions Why do Cells Divide? Growth Reproduction (in single celled organisms) Repair

Cell Cycle:

G1 -growth, normal cell functions S -synthesis, DNA replication G2 -cell prepares for mitosis (growth 2) M -mitosis C -Cytokinesis

Cell Cycle:

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

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

Growth factors: signaling proteins - received at cell membrane, signal cell growth and division

Cyclin: a family of proteins that control the progression of cells through the cell cycle by activating enzymes a certain times

What happens if there is an error in DNA replication?

G0 – non dividing state (permanent or temporary) ex: nerve cells, heart cells, seeds, spores

Control of Cell Cycle

Growth Factors: signal cell growth Cyclin: family of internal signaling proteins that increase or decrease the cell cycle (feedback/ homeostasis) P53: stop cell at G1 if there is damage to DNA RB: protein responsible for interpreting growth signals and available nutrients Somatic Cells: body cells Apoptosis: programed cell death

What if these are damaged, mutated, don’t work?

Check for understanding

Describe what each checkpoint is for: 1. G1checkpoint 2. G2 checkpoint 3. M checkpoint

Read pg 154 “science focus” on the G1 checkpoint Answer in notebook:

1.  What is the G0 stage? Is it permanent? 2.  What is RB and explain it’s function? 3.  What conditions could prevent a cell form

dividing? 4.  What is the function of the p53 protein?

9.2 Mitosis & Cytokinesis

Mitosis - The division of the nucleus that results in identical complete copies of chromosmes packaged into two new nuclei Cytokinesis - The division of the cytoplasm that results in two daughter cells

Vocab

•  Chromatin •  Chromosome •  Chromatid •  Spindle fiber •  Centriole •  Centromere •  Aster

Interphase • Prophase • Metaphase • Anaphase • Telophase

IPMAT

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

**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 at the cleavage furrow

Mitosis produces 2 daughter cells The two daughter cells contain the exact same number of chromosomes as the original parent cell Daughter cells are DIPLOID= 2n= complete set of chromosomes

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 • Mutation cause oncogenes: cancer genes that keep the cell

replicating • Inactivate tumor suppressors (p53 and RB) • form tumors • undergo metastasis & angiogenesis

Origin of Cancer

HeLa Cells

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.

Article on Henrietta Lacks

Telomeres

•  Shorten as the chromosome replicates

•  At a certain length, tigers apoptosis

•  Some cancer cause them to remain at a constant length

Binary Fission: asexual reproduction by prokaryotes

Stem Cell

unspecialized cells capable of renewing themselves through cell division - stem cells may replicate many times, or proliferate. They have the potential to develop into many different cell types in the body during early life and growth.

Major types of stem cells

Embryonic Stem Cells

n  Pluripotent : cell can develop into all cell types

n  “Immortal”: can self-

renew indefinitely n  Plentiful (easy to

find)

Adult Stem Cells n  Multipotent: cell can

develop into a few cell types but not all

n  Located in few

organs or may be unidentified

n  Hard to find

1. Name the phases starting at the top.

1. Name the phase 2. Identify X 3. 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? __________