REPRODUCTION: ASEXUAL & SEXUAL · Mitosis is how some organisms regenerate body parts. ... Sequence Images of Meiosis. ... •FERTILIZATION!! • gamete + gamete = zygote

REPRODUCTION: ASEXUAL & SEXUAL

You all started as a single cell, but now your body has

about 100 trillion cells. Where did all of those new cells

come from? Include a drawing in your answer.

Cells come from existing cells

cytoplasm

nucleus

cytoplasm

nucleus

cytoplasm

nucleus

http://www.mathsisfun.com/numbers/images/sunflower.jpg http://i-cdn.apartmenttherapy.com/uimages/kitchen/2008_09_04-fruitfly2.jpg

http://preview.turbosquid.com/Preview/Content_2010_12_03__11_39_30/ecoli06.jpg

What do you have in common with these?

E. coli

Sunflower Fruit Fly

you

http://www.mathsisfun.com/numbers/images/sunflower.jpg

http://i-cdn.apartmenttherapy.com/uimages/kitchen/2008_09_04-fruitfly2.jpg

http://preview.turbosquid.com/Preview/Content_2010_12_03__11_39_30/ecoli06.jpg33dc2a3d-2f0d-494e-8258-d2ce2080bf1dLarger.jpg

STRUCTURE OF DNA

• Double stranded helix

• Structure determined in 1953

by Rosalind Franklin, James

Watson and Francis Crick.

• Composed of nucleotides.

DNA is in all living things

DNA is instructions for a cell.

DNA is organized into chromosomes.

Each chromosome has different information.

We have 23 pairs of chromosomes - 1 copy

from dad and 1 from mom.

http://www.biotechnologyonline.gov.au/popups/img_karyotype.html








What if a cell didn’t have DNA?









NUCLEOTIDESREPEATING UNITS COMPOSED OF:

• Deoxyribose sugar

• Phosphate group

• Nitrogen base

• Adenine

• Thymine

• Cytosine

• Guanine

}

} pair

pair

NUCLEOTIDES CONTINUED ...

• Sugar-Phosphate Backbone

• Weak hydrogen bonds hold

nitrogen bases together

• Sequence of nucleotides

determines genotype of

organism.

Cell division and DNA

cytoplasm

nucleus

cytoplasm

nucleus

cytoplasm

nucleus


cytoplasm

nucleus

cytoplasm

nucleus

cytoplasm

nucleus

sequence images of cell division

1 2 3

4 5 6

Interphase Prophase Metaphase

Anaphase Telophase Cytokinesis


Before a cell divides, it has to copy its DNA.

This way, each new cell gets a complete copy of DNA.

cytoplasm

nucleus

cytoplasm

nucleus

cytoplasm

nucleus

DNA REPLICATION

• Enzyme breaks hydrogen bonds

that hold the nucleotides

together DNA unzips.

• Free nucleotides pair with

exposed nucleotides on both

strands.

ANIMATION

• http://www.stolaf.edu/people/giannini/biological%

20anamations.html

http://www.stolaf.edu/people/giannini/biological%20anamations.html

DNA REPLICATION

• T-A-C-A-C-G

• Complementary strand?

THE CELL CYCLE

Interphase - Preparing for cell divisionnuclear envelope

chromatin

nuclear envelope

chromatin

chromatin: loose DNA (looks like noodles)

Interphase - Preparing for cell division

nuclear envelope

chromatin

chromatin

condenses


nuclear envelope

chromatin chromosomes

chromatin

condenses


nuclear envelope


chromatin

condenses

chromatin condenses into chromosomes (DNA is compacted)


chromosomes

nuclear envelope

chromatin

chromatin

condenses


homologous chromosomes

chromosomes

nuclear envelope

chromatin

chromatin

condenses



chromosomes

nuclear envelope

chromatin

chromatin

condenses

homologous chromosomes: 2

chromosomes with similar DNA

(1 from dad, 1 from mom)



chromosomes

nuclear envelope

chromatin

chromatin

condenses

chromosomes

get copied



chromosomes

nuclear envelope

chromatin

chromatin

condenses

chromosomes

get copied


homologous chromosomessister

chromatids

nuclear envelope

chromatin

chromatin

condenses

chromosomes

get copied

chromosomes

sister chromatids: 2 IDENTICAL copies of a chromosome are made when DNA replicates



centromerenuclear envelope

chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids




chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

Ready to divide!


Prophase

Cell Division (mitosis)



chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

Prophase




chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

spindle

Prophase




chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

spindle

Nuclear envelope breaks down.

Spindle starts to attach to sister chromatids.

Prophase Metaphase




chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

spindle

Prophase Metaphase




chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

spindle

Sister chromatids line up in the middle of the cell.

Prophase Metaphase Anaphase




chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

spindle

Prophase Metaphase Anaphase




chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

spindle

Sister chromatids are pulled apart.

Prophase Metaphase Anaphase Telophase




chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

spindle

Prophase Metaphase Anaphase Telophase




chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

spindle

2 NEs form around 2 sets of chromosomes.

Cytokinesis

cytoplasm

Cytokinesis

cytoplasm

cleavage furrow

Cytokinesis

cytoplasm

cleavage furrow

Cytoplasm is split (cleaved) into 2 new cells.

MITOSIS

MITOSIS

cytoplasm

nucleus

cytoplasm

nucleus

cytoplasm

nucleus

MITOSIS PRODUCES 2

CLONES IN ASEXUAL

REPRODUCTION.

4 chromosomes

4 chromosomes

4 chromosomes

mitosis videohttp://jcb.rupress.org/content/176/6/757/suppl/DC1

http://jcb.rupress.org/content/176/6/757/suppl/DC1

Why is mitosis important?

Why is mitosis important?

Mitosis is how you grew (from 1 cell).

Mitosis is how your cells are maintained.

Mitosis is how some organisms regenerate body parts.

Mitosis is how single-celled organisms reproduce – ASEXUAL REPRODUCTION.

• Mitosis is needed for asexual reproduction.

ASEXUAL REPRODUCTION

• Mitosis is used to produce a NEW organism from part of

ONE other organism.

• DNA in new organism is IDENTICAL to DNA parent

(clone)

ASEXUAL REPRODUCTION

• Types:

1. Fragmentation

2. Budding

3. Parthenogenesis

4. Regeneration

5. Cloning

FRAGMENTATION

• Parent breaks into

several pieces, which

become new organisms.

• Ex. Some worms,

mushrooms, and plants.

FRAGMENTATION

FRAGMENTATION

FRAGMENTATION

REGENERATION

Lost body parts are

replaced.

Does not create a

whole new organism.

BUDDING

• Offspring develop as a growth (bud) on the body of the

parent.

• Ex. Jellyfish, yeast, corals, tapeworms.

BUDDING

BUDDING

PARTHENOGENESIS

• “Virgin birth”

• Female produces eggs that develop into a new organism

without being fertilized.

• Ex. Some species of fish, insects, lizards and frogs.

CLONING

• Making copies of organisms.

• New organism receives DNA from one parent.

• Offspring are genetically identical to parents.

CLONING

CLONING

CLONING

When might mitosis be a bad thing?

Cancer

Cancer is really several diseases.

Cancer occurs when cells that should not divide do divide.

Cancer cells continue dividing, which can lead to a tumor.

Cancer cells can invade other tissues - METASTISIS

When might mitosis be a bad thing?

http://ed.ted.com/lessons/how-do-cancer-cells-behave-differently-from-healthy-ones-george-zaidan

How do cancer cells behave

differently from healthy ones? -

George Zaidan

http://ed.ted.com/lessons/how-do-cancer-cells-behave-differently-from-healthy-ones-george-zaidan

INVESTIGATING CANCER

• http://media.hhmi.org/biointeractive/click/cellcycl

e/ - cell cycle and cancer

• Metastis - http://www.hhmi.org/biointeractive/vegf

• http://www.hhmi.org/biointeractive/angiogenesis

http://media.hhmi.org/biointeractive/click/cellcycle/

http://www.hhmi.org/biointeractive/vegf

http://www.hhmi.org/biointeractive/angiogenesis

• What would happen if mitosis was used for sexual

reproduction?

46 chromosomes 46 chromosomes 92 chromosomes

Sequence Images of Meiosis

MUST REDUCE THE NUMBER OF

CHROMOSOMES IN HALF.

HOW?

Meiosis 1

Meiosis II

Prophase IMetaphase I

Anaphase I Telophase I

Prophase I1 Metaphase 1I Anaphase 1I Telophase 1I

Interphase - Preparing for cell divisionnuclear envelope

chromatin

nuclear envelope


chromatin

condenses

chromatin condenses into chromosomes (DNA is compacted)



chromosomes

nuclear envelope

chromatin

chromatin

condenses

homologous chromosomes: 2

chromosomes with similar DNA

(1 from dad, 1 from mom)


homologous chromosomessister

chromatids

nuclear envelope

chromatin

chromatin

condenses

chromosomes

get copied

chromosomes

sister chromatids: 2 IDENTICAL copies of a chromosome are made when DNA replicates




chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids




chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

Ready to divide!


Prophase 1



chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

Meiosis 1

Prophase 1



chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

spindle

Meiosis 1

Prophase 1



chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

spindle

Nuclear envelope breaks down.

Spindle starts to attach to sister chromatids.

Meiosis 1

Prophase 1 Metaphase 1



chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

spindle

Meiosis 1




chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

spindle Tetrads (groups of 4) of homologous

chromosomes line up in the middle of

the cell.

Crossing over occurs - sister

chromatids exchange

pieces of DNA

Meiosis 1

CROSSING OVER

Result:

Increase in

genetic diversity

Prophase 1 Metaphase 1 Anaphase 1



chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

spindle

Meiosis 1




chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

spindle

Homologous chromosomes

are pulled apart.

Meiosis 1

Prophase 1 Metaphase 1 Anaphase 1 Telophase 1



chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

spindle

Meiosis 1

Prophase 1 Metaphase 1 Anaphase 1 Telophase 1

Meiosis 1



chromatin

chromatin

condenses

chromosomes

get copied

chromosomessister

chromatids

spindle

2 NEs form around 2 homologous

sets of chromosomes.

Prophase 11

Prophase 11NE disappears. Spindles return.

DNA is already condensed into chromosomes.


Prophase 11 Metaphase 11Sister chromatids line up

on the metaphase plate.



Sister chromatids separate.


Telophase 11


Telophase 11

4 daughter cells are produced.

Each cell has one copy of each chromosome.

SUMMARY OF MEIOSIS

• One parent cell produces 4 daughter cells.

• Daughter cells = gametes = egg & sperm

• The number of chromosomes in daughter cells is half

of what is in the parent cell.• Diploid - 2 copies of each chromosome

• Haploid - 1 copy of each chromosome

HOW IS THE NUMBER OF CHROMOSOMES

RESTORED?

• FERTILIZATION!!

• gamete + gamete = zygote

• haploid + haploid = diploid

• n + n = 2n

• 23 chromosomes + 23 chromosomes = 46 chromosomes

MEIOSIS & FERTILIZATION ALLOW FOR

GENETIC VARIATION

• Random alignment of

chromosomes during

metaphase 1.

• Crossing over.

• Random fertilization (any 2 parents

will produce a zygote with 70 trillion+

possible diploid combinations) - which

sperm fertilizes which egg?

REPRODUCTION: ASEXUAL & SEXUAL · Mitosis is how some organisms regenerate body parts. ... Sequence Images of Meiosis. ... •FERTILIZATION!! • gamete + gamete = zygote

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