Cell Size

Surface Area (length x width x 6)

Volume (length x width x height)

Ratio of Surface Area to Volume

Surface Area: Volume RatioAs Cells grow in size their SA/Vol ratio decreases and they become less able to feed themselves and get to a point where they must divide

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Why Should I care about Mitosis?

grow in size.heal wounds.stay healthy.

Because I need to make new cells in order to…

The Life expectancy of three different cells

0102030405060708090

100110120

Days

stomach epidermis red bloodcells

Cell type

What does a new cell need?

Nucleus - (DNA!!!) Organelles Cytoplasm Cell membrane

The Cell nucleus then DIVIDES during Mitosis

All DNA and Organelles are copied during INTERPHASE

The rest of the cytoplasm and organelles divide during Cytokinesis

After the DNA copies itself, it then coils up into CHROMOSOMES

We can see these chromosomes during MITOSIS

Chromosomes – made of DNA + protein

• DNA: Instruction book with genetic information used to direct the cell.

• Protein: Holds DNA in coiled structure.

• Any Cell that has pairs of chromosomes is said to be DIPLOID

• Human cells contain 23 pairs of each type of chromosome in the nucleus (except egg and sperm cells). 23 (mom) + 23 (dad) = 46 total

1 pair of chromosomes:

HomologousChromosomesPaired copies of the same chromosome(mom + dad)

Sister ChromatidsThese are chromosomes which have copied each other and are ready to divide

What is mitosis? Nuclear cell division

where copied chromosomes are separated to form two identical nuclei.

Phases: PROPHASE METAPHASE ANAPHASE TELOPHASE

includes

is divided into is divided into

Concept MapSection 10-2

Cell Cycle

M phase (Mitosis)

Interphase

G1 phase S phase ProphaseG2 phase Metaphase TelophaseAnaphase

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Cytokinesis

M phase

G2 phase

S phase

G1 phase

The Cell CycleSection 10-2

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Phases of cell cycle: INTERPHASE G1: Cell growth occurs. S: Chromosomes replicate. G2: Organelles replicate MITOSIS M: Copied chromosomes are equally

divided and new nuclei formed. CYTOKINESIS (cell divides)

Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Section 10-2Interphase, Mitosis and Cytokinesis

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Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Section 10-2Interphase, Mitosis and Cytokinesis

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Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Section 10-2Interphase, Mitosis and Cytokinesis

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Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Section 10-2Interphase, Mitosis and Cytokinesis

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Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Section 10-2Interphase, Mitosis and Cytokinesis

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Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Section 10-2Interphase, Mitosis and Cytokinesis

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HOW DOES MITOSIS KNOW WHEN TO STOP?

Suppose you had a paper cut on your finger. Although the cut may have bled and stung a little, after a few days, it will have disappeared, and your finger would be as good as new.

Section 10-3

1. How do you think the body repairs an injury, such as a cut on a finger?

2. How long do you think this repair process continues?3. What do you think causes the cells to stop the repair

process?

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Control of Cell DivisionSection 10-3

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Cells will continue to grow UNTIL they touch another cell - this is called CONTACT INHIBITION

A sample of cytoplasm is removed from a cell in mitosis.

A sample is injected into a second cell in G2 of interphase.

As a result, the second cell enters mitosis.

 Effect of CyclinsSection 10-3

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Scientists discovered that a set of proteins they called “Cyclins” control the start of the cell cycle

Internal Regulators Internal Regulators - a series of proteins

that make sure mitosis is controlled. Some make sure the cell does not enter mitosis until all chromosomes have been copied

Others will not let the cell start anaphase until chromosomes are attached to the spindle

External Regulators Proteins that respond to events outside the

cell They speed up or slow down the rate of cell

division Growth factors tend to speed up rate of

mitosis Molecules found on the surface of

neighbouring cells tend to slow down rate so cells don’t interfere with each other