Cell Division & Biotechnology

How did you go from a single-celled zygote to the trillions of cells you are today?

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The process by which one parent cell divides into two or more daughter cells

Cell Division - Learning Goal

• Distinguish between cell division during asexual reproduction (mitosis) and cell division during sexual reproduction (meiosis)

The cells in your body undergo cell division for several reasons

• Development and growth• Cell repair or replacement• Regeneration (only some organisms)• Asexual reproduction (only some organisms)• Sexual Reproduction (production of gametes)

There are two kinds of cell division:

◦ Mitosis – division of somatic (body) cells for growth, development, cell replacement, asexual reproduction

◦ Meiosis – division of sex cells to make gametes for sexual reproduction

1. Parent cell has 46 chromosomes (diploid)

2. DNA is copied

3. Cell division occurs

4. 2 daughter cells each have 46 chromosomes (diploid) and are identicalto the parent cell

Your body does mitosis when:• healing a cut, • building muscle, • replacing dead skin

cells, • growing hair &

fingernails• growing from a zygote

to an embryo to a fetusto a baby

One parent cell contains 46 chromosomes (diploid)

DNA is copied

2 cell divisions occur

4 daughter cells produced and each has 23 chromosomes and is not identical to parent cell.

When a cell only has 23 chromosomes (half the full amount), it is called haploid

Your body does meiosis when:• making sperm or egg

cells• That’s it.

gametes

Identical to parent Not identical to parent

https://www.youtube.com/watch?v=Ba9LXKH2ztU (0:51)

A more raunchy comparison:

https://www.youtube.com/watch?v=qH4WUUQ5pOI

• Makes 2 daughter cells• A kind of cell division• 46 chromosomes (diploid) 23

chromosomes (haploid)• Involves DNA replication• Daughter cells are identical to parent• 46 chromosomes (diploid) 46

chromosomes (diploid)• Makes 4 daughter cells• Hair & nail growth• Occurs in body cells• Occurs in sex cells• Occurs from birth to death• Occurs during reproductive age only• Daughter cells are not identical to parent• Transmits (passes down) genetic information• Makes gametes

• Makes 2 daughter cells• Daughter cells are

identical to parent• 46 chromosomes

(diploid) 46 chromosomes (diploid)

• Hair & nail growth• Occurs in body cells• Occurs from birth to

death

• 46 chromosomes (diploid) 23 chromosomes (haploid)

• Makes 4 daughter cells• Occurs in sex cells• Occurs during

reproductive age only• Daughter cells are not

identical to parent• Makes gametes

• A kind of cell division

• Involves DNA replication

• Transmits (passes down) genetic information

Adult gametes zygote embryo Adult

This cycle of life repeats

• Which arrow indicates is occurring?

• Which arrow indicates is occurring?

• Which arrow indicates is occurring?

Adult gametes zygote embryo Adult

This cycle of life repeats

• Which arrow indicates is occurring?

• Which arrow indicates is occurring?

• Which arrow indicates is occurring?