1 1 asexual reproduction mitosis. how do little elephants grow up to be big elephants?

1 1

Asexual ReproductionMitosis

How do little elephants grow up to be BIG elephants?

The process of asexual reproduction begins

after a sperm fertilizes an egg.

Skin 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

• 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

Animal Cell Plant Cell

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

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

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

CentriolesSister chromatids

Spindle fibers

Animal Cell Plant Cell

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

Spindle fibers

Centrioles

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

Centrioles

Spindle fibers

Animal Cell Plant Cell

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

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

Centrioles

Spindle fibers

Animal Cell Plant Cell

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

• Two new nuclei form. • Chromosomes appear as chromatin

(threads rather than rods).• Mitosis ends.

NucleiNuclei

Chromatin

Animal Cell Plant Cell

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

• 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

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- Cell Division

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A cell grows, prepares for division, and divides to form 2 daughter cells

FOUR phases:1. G1 (gap 1)2. S phase (synthesis, DNA replication)3. G2 (gap 2)4. M phase (mitosis)

Interphase(G1, S, G2)

MitosisProphaseMetaphaseAnaphaseTelophase

Cytokinesis

chromosome: X-shaped coiled piece of two identical DNA pieces

chromatid: individual pieces of coiled DNA (1/2 of the X)

Interphase

Prophase

Metaphase

Anaphase

Telophase

Cytokinesis

Interphase

Prophase

Metaphase

Anaphase

Telophase

Cytokinesis

two daughter cells have identical copies of the parent cell’s DNA

# of chromosomes is the same in both cells (called the diploid #)

A microscope was used to examine onion root tips. 4 different fields (A, B, C, and D) were used. In each field, the cells in the mitotic phases were identified and counted. Cells in interphase were also counted. What does this data reveal?

Area A Area B Area C Area D Total

Interphase 30 23 34 22 109

Prophase 3 4 3 2 12

Metaphase 6 3 2 4 15

Anaphase 3 1 2 1 7

Telophase 0 2 1 1 4

A human cell has 46 individual chromosomes in its cells. After the S phase of the cell cycle, how many chromosomes will the cell contain?

How many homologous (or matching) pairs of chromosomes will the cell have at prophase?