2 2 Cell Cycle Cell cycle- The sequence of stages through which a cell passes between one cell...

MitosisBody Cell Reproduction

2 2

Cell Cycle

Cell cycle- The sequence of stages through which a cell passes between one cell division and the next. (The cycle begin growth and division. )

Cell Cycle The cell spends most of its time in

interphase.

Stage 1- G1- cell grows, organelles may begin to duplicate, cytoplasm increases and protein synthesis occurs

Stage 2- S- DNA replicates

Stage 3- G2-cell continues to grow, organelles double, and microtubules synthesize

Mitosis Mitosis is a type of cell division

that generates two identical daughter cells.

Mitosis occurs in body cells.

Body cells are called somatic cells.

Mitosis Mitosis is a part of the cell cycle. It has 4

phases. (PMAT)

Human cells have 46 chromosomes or 23 pairs. This is called a diploid number. (2N)

Mitosis requires only one parent -asexual reproduction.

How do little elephants grow up to be BIG elephants?

Why do animals shed their skin?

Three reasons why cells reproduce by mitosis:

1. Growth 2. Repair 3. ReplacementSkin cancer - the abnormal growth of skin cells - most often develops on skin exposed to the sun.

Cell that reproduce by asexual reproduction reproduce constantly.

Animated Mitosis Cyclehttp://www.cellsalive.com/mitosis.htm

• Interphase

• Prophase

• Metaphase

• Anaphase

• Telophase & Cytokinesis

Interphase occurs before mitosis begins

• Chromosomes are copied (# doubles)• Chromosomes appear as threadlike coils

(chromatin) at the start, but each chromosome and its copy(sister chromosome) change to sister chromatids at end of this phase

CELL MEMBRANENucleus

Cytoplasm

Interphase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Prophase 1st step in Mitosis

• Mitosis begins (cell begins to divide)• Centrioles (or poles) appear and begin to

move to opposite ends of the cell. • Spindle fibers form between the poles.

CentriolesSister chromatids

Spindle fibers

Prophase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Spindle fibers

Metaphase 2nd step in Mitosis

• Chromatids (or pairs of chromosomes) attach to the spindle fibers.

Centrioles

Spindle fibers

Metaphase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Anaphase 3rd step in Mitosis

• Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell.

Centrioles

Spindle fibers

Anaphase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Telophase 4th step in Mitosis

• Two new nuclei form. • Chromosomes appear as chromatin

(threads rather than rods).• Mitosis ends.

NucleiNuclei

Chromatin

Telophase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Cytokinesisoccurs after mitosis

• Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes.

Animal Mitosis -- Review

Interphase

Prophase

Metaphase

Anaphase

Telophase

Interphase

Plant Mitosis -- ReviewInterphase

Prophase

Metaphase

Anaphase

Telophase

Interphase

24

Cell Cycle

Questions Sec 1 1. What is a gene? 2. What are chromosomes? 3. Describe a prokaryotic chromosome. 4. Describe a eukaryotic chromosome. 5. What is chromatin? 6. What is a chromatid? 7. What is a centromere?

Questions Sec. 2 and 3

1. Define Cell Cycle.1. 2. What is mitosis? 3. What is cytokinesis? 4. What is a spindle

fiber?

Questions Sec. 2 and 3

1. Define Cell Cycle.1. 2. What is mitosis? 3. What is cytokinesis? 4. What is a spindle

fiber?

CHROM…words

Chromatin – uncoiled DNA + proteins (threads)

Chromosome – coiled DNA + proteins (Looks like an X)

Chromatid – only half of a chromosome

Sister chromatids – Two chromatids joined together, by a centromere, to form a chromosome

Mitosis Animation

http://www.cellsalive.com/mitosis.htm