MitosisChapter 8

Honors BiologyCell Division

G2 of Interphase

• Chromosomes are not clear (still chromatin)

• Nucleolus visible• Nuclear envelope• Centrosomes

duplicated (each centrosome has 2 centrioles)

Why is mitosis important?

• 1. Growth• 2. Cell replacement• 3. Asexual Reproduction

pp. 130-131 of textbookMitosis Stages

G2 Prophase Prometaphase

Name the structures and describe what is happening.

Prophase• Chromatin fibers coil

to become dense chromosomes

• They join at the centromere as sister chromatids

2 centrosomes made in G2

Prophase

• Nucleolus Disappears• Spindle Fibers Form as microtubules out

from the centrosomes (MTOC)• Asters form (shorter microtubules extending

from centrosomes)

See the chromosomes condense

• Centrosomes move away from each other, propelled by the lengthening microtubules between them

• Mitosis Animation (show through prophase)

Prometaphase• Nuclear envelope

disintegrates (vesicles)• Each sister chromatid has

a kinetochore at centromere

• Kinetochore spindles attach to kinetochore

• Non-kinetochore spindles pole to pole

Prometaphase• How many chromosomes

are there?How many sister chromatid pairs are there?

• ANSWER: 4, 4

Kinetochore :attach spindle fibers to chromatid

• Kinetochore in pink

Kinetochore*Microtubule dynamics animation (+/- ends,

jerking)• Spindle microtubules at centromere• During prometaphase some spindle

microtubules attach to the kinetochores• Chromosomes “tug of war” to poles begins

McGraw-Hill Mitosis and Cytokinesis

• Microtubules lengthen and shorten by the addition or removal of tubulin.

• Kinetochore microtubules shorten in the region of the kinetochore, pulling the chromosomes apart.

• Polar microtubules elongate to push against each other and thus, push the two centrosomes apart.

•

COOL SITE

• ** GO TO Biovision: Inner life of a cell-Harvard (microtubules build and break down) NARRATED VERSION

•

REAL FOOTAGE

• Animations Scroll down to Chapter 10• Microtubule dynamics in prophase• Capture of a kinetochore• Alignment of chromosomes• Aligned chromosomes oscillate

continuously – “jerking”• AND MUCH MORE

Metaphase Anaphase Telophase

Name the structures and describe what is happening.

Metaphase

Centrioles now at opposite poles

Sister chromatids line up at the metaphase plate (equator)

Each chromosome has its own kinetochore coming from opposite poles

Anaphase

• Spindle fibers pull the chromatids to the opposite poles

• Centromere split• Nonkinetochore

microtubules lengthen

Telophase• Chromatids are

now at the opposite ends of the cell

• Late: Chromatids back to chromatin

• Spindles dissolve

Reforming of nucleolus and nuclear envelope

Telophase: end with two equal daughter cells

NAME THE PHASES:

Interphase

Mitosis

nuclear envelope

pair of centrioles

Early Prophase Late Prophase Prometaphase

Metaphase

MitosisVCAC Mitosis Animation

(includes all of the cell cycle)Anaphase Telophase Interphase

Cell splits

SHOWTIME

• Mitosis Movie

• Mitosis (narrated movie)• Interactive human mitosis animation

Cytokinesis (actually at the end of telophase)

Separation of the cytoplasm

Cytokinesis

• Animals• Actin and myosin

form cleavage furrow

• Plants• Vesicles from the

Golgi make cell plate

Animal Cytokinesis

Mitosis is over, and the spindle is now

disassembling.

Band of microfilaments at the former spindle equator contracts.

The contractions continue and cut the cell in two.

Cleavage furrow

cell wall

former spindle equator

cell plate

vesicles converging

Plant Cytokinesis

Cell Plate

Cytokinesis Videos

• ANIMAL• Flash cytokinesis (:03

)• Cleavage of a fertilize

d frog egg (:25)

• cell division on contrast microscope (:58)

• PLANT• Mitosis and cell plate f

ormation of giant chromosomes Haemanthus (1:14)

• Endosperm cell division (:07)

• Cytokinesis Animal and Plant Cells (3:48)

• Mitosis and Meiosis Choose mitosis rap)

Mitosis differences

• ANIMAL• Centrioles in

centrosomes• Growth all over

the animal (usually)

• PLANT• No centrioles in

centrosomes• Growth only at meristems

What cells undergo mitosis?

• A LOT• Skin• Blood• Digestive tract

• NOT AT ALL• Nerve• muscle

Where does mitosis occur in organisms?

• PLANTSMeristems (growing tips)

• ANIMALS• Most places: skin,

hair, blood, digestive tract

• DNA tube mitosis real mitosis

NICE REVIEW OF MITOSIS

• Biology Animation: Cell Cycle + Quiz

• Can click on each phase

• Can take quiz (can review if incorrect answer)

Which phase of mitosis?

Interphase

Prophase

Metaphase

Anaphase

Telophase

A: Interphase

Which phase of mitosis?

Interphase

Prophase

Metaphase

Anaphase

Telophase

A: anaphase

Which phase of mitosis?

Interphase

Prophase

Metaphase

Anaphase

Telophase

A:metaphase

Which phase of mitosis?

Interphase

Prophase

Metaphase

Anaphase

Telophase

A:prophase

Which phase of mitosis?

Interphase

Prophase

Metaphase

Anaphase

Telophase

A. telophase

Which phase of mitosis?

Interphase

Prophase

Metaphase

Anaphase

Telophase

A. prophase

Which phase of mitosis?

Interphase

Prophase

Metaphase

Anaphase

Telophase

A. telophase

Which phase of mitosis?

Interphase

Prophase

Metaphase

Anaphase

Telophase

A. anaphase

Which phase of mitosis?

Interphase

Prophase

Metaphase

Anaphase

Telophase

A. metaphase

Which phase of mitosis?

Interphase

Prophase

Metaphase

Anaphase

Telophase

A. interphase

PLANT CELLS

Online Activity Worksheet

• Online Onion Root Tips

Practice Links

• Animal Cell Mitosis• Plant and Animal Cell

Mitosis• Nice Mitosis Animal C

ells

• Mitosis World (yes, it is as good as Disney World)