Mitosis/Meiosis How do your cells divide?

A few words before we start…..

Haploid:

Diploid:

A Cell’s Life

Why Do Cells Divide?

Surface area

Damaged cells

Sex cells

Cell Reproduction

is either sexual or asexual

Asexual Reproduction(one parent)

Binary Fission-

Budding

Vegetative Propagation

Regeneration

Advantages of Asexual Reproduction

Speed

Desirable Characteristics

Replacement

DNA Replication

Before a cell can divide the

DNA must replicate (make a copy

of itself)

DNA Replication

Making a new strand of DNA is actually quite easy.

Replication occurs in 3 easy steps…

1. DNA Unzips

An enzyme unzips the molecule

The enzymes breaks the hydrogen bonds that hold the nitrogen bases together.

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DNA Replication DNA Unzips

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DNA Replication DNA Unzips

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DNA Replication DNA Unzips

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DNA Replication DNA Unzips

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DNA Replication DNA Unzips

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DNA Replication DNA Unzips

Left Strandof Original DNA

Right Strandof Original DNA

2. Base Pairing

Complementary bases match with each DNA strand in the open helix

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DNA Replication Base Pairing

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DNA Strand

DNA Replication Base Pairing

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DNA Strand

DNA Replication Base Pairing

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DNA Strand

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New LeftDNA Strand

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DNA Replication Base Pairing

3. DNA Zips Up

An enzyme zips the new molecules back up.

DNA Replication

Voila!Two identical strands of DNA!

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DNA Replication Review

Step 1 Step 2 Step 3

Remember - All this takes place in INTERPHASE

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Now that DNA has replicated, we are ready to begin Mitosis (nucleusof the cell divides)

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Parent Cell

DNA condenses into chromosomes

Chromosomes align on the equator

Chromosomes separate

DNA uncoils

Cytokinesis

Cleavage (indention in cell membrane) or cell plate formation occurs.

Cell divides.

Animal Cell Plant Cell

Mitosis Animation

It’s all about the chromosomes!– There are 46 in human body

cells– The number of chromosomes

remain constant during Mitosis

Which Cells Go Through Mitosis?

Growth

Repair

Work

Cells which help the body in:

Mitosis Review 1. Is the beginning parent

cell diploid or haploid (2n or n)?

2. Are the daughter cells diploid or haploid (2n or n)?

More Mitosis Review

3. How many daughter cells are produced?4. Are the resulting daughter cells different from the parent cell?

More Mitosis Review

5. Are the resulting daughter cells different from each other?

6. How many chromosomes are in a human parent cell?7. How many chromosomes are in a human daughter cell?

More Mitosis Review

8.What types of cells are produced by mitosis?

9. Why (when) does a cell go through mitosis?

Meiosis

Sexual Reproduction (two parents)

Why Meiosis?Meiosis -

How does Meiosis Occur?

Crossing Over

What is happening?How does this affect the

individual (offspring)?

Crossing Over

Meiosis Review1. Is the beginning parent cell

diploid or haploid (2n or n)?2. Are the resulting daughter

cells diploid or haploid (2n or n)?

More Meiosis Review

3. How many daughter cells are produced?

4.Are the resulting daughter cells different

from the parent cell?

More Meiosis Review5. Are the resulting daughter cells

different from each other?

7. How many chromosomes are in a human daughter cell?

6. How many chromosomes are in a human parent cell?

More Meiosis Review8. What types of cells are produced by meiosis?

Fertilization

New Individual46

Mom

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Dad

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This is how new organisms are made!!

Let’s reviewMitosis & Meiosis

Mitosis vs. Meiosis  

   Event Mitosis Meiosis

Produces 4 cells

Produces 2 cells

New cells identical

New cells different

New cells have the same number of chromosomes as parentNew cells have fewer chromosomes than parent

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Mitosis vs. Meiosis  

   Event Mitosis Meiosis

Beginning cells diploid (2n)Beginning cells haploid (n)Ending cells diploid (2n)Ending cells haploid (n)Produces egg and spermProduces body cells

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