Intro To Cell Division

What else do cells do?

Repair

Growth

ReproductionAsexualSexual

Repair

Cells are constantly repairing themselves

If a cell can’t be repaired new ones are produced to fill the void

Growth

Cells are also what create our size

As we grow our cells are constantly reproducing

If the reproduction rate is faster than normal we grow

ReproductionAsexual

Done by somatic or body cells

Creates identical daughter cells

Sexual

Done by sex cells

Creates genetically different daughter cells

Chromatin: a mass of DNA found in the nucleus (uncompacted)

Chromosome: a compacted piece of chromatin that is used for cell division

Sister Chromatids: A pair of identical Chromosomes

Centromere: The center section where the sister chromatids are connected

Sister chromatids

Centromere

TE

M 3

6,60

0

LE 8-4

Sister chromatids

Centromere

TE

M 3

6,60

0

Sister chromatids

Chromosomedistribution

todaughter

cells

Chromosomeduplication

CentromereSister chromatids

Draw this

How do cells divide?

Cell Cycle: an orderly sequence of events where cells divide

The cell cycle consists of two major phases

Interphase (90% of the time)Mitotic Phase (10% of the time)

LE 8-5

INTERPHASE

G1

G2

S(DNA synthesis)

Cytokinesis

Mito

sis

MITOTICPHASE (M)

InterphasePhase where all metabolic processes and functions happen

Ex:Cellular respirationProtein creationMovementGrowthOther desired function

Interphase

Interphase is also when the cell prepares for cell division

Ex:Increases proteinsDuplicates organellesGrows in sizeDuplication of DNA

Mitotic PhaseThe division phase of the cell

There are two main parts of M-phase

Mitosis Cytokinesis

Mitotic phaseMitosis

The division of a cells nucleus and DNA into two equal partsCreates two daughter nuclei

CytokinesisThe division of the cells cytoplasm

Together they create two identical daughter cells

MitosisInterphase:

DNA is duplicated

Prophase:Sister chromatids are formedFormation of spindleNuclear envelope breaks down

Metaphase:Sister chromatids line upSpindle is formed and attaching to chromosomes

LE 8-6a

INTERPHASE PROPHASE PROMETAPHASE

Kinetochore

Fragmentsof nuclearenvelope

CentrosomeEarly mitoticspindleChromatin

Centrosomes(with centriole pairs)

LM

250

Nucleolus Nuclearenvelope

Plasmamembrane

Chromosome, consistingof two sister chromatids

Centromere Spindle microtubules

MitosisAnaphase:

Separation of sister chromatidsSpindle pulls chromosomes to either side of the cell

Telophase:Spindle breaks downNuclear envelopes form (2)Chromosomes loosen to become chromatin

Cytokinesis:Cell pulls apart to create two identical cells

LE 8-6b

METAPHASE ANAPHASE TELOPHASE AND CYTOKINESIS

Metaphaseplate

Spindle Daughterchromosomes

Nuclearenvelopeforming

Cleavagefurrow

Nucleolusforming

CytokinesisAnimal Cells

Formation begins with indentation

Cell is pulled/ pinched until it breaks apart

Plant Cells

Formation begins with a disc containing cell wall materials

A cell plate forms between the two nuclei

Cytokinesis in animal cells

Plants

Formation begins with a disc containing cell wall materials

A cell plate forms between the two nuclei

Cleavage furrow

Cleavagefurrow

Daughter cells

Cleavagefurrow

Contracting ring ofmicrofilaments

SE

M 1

40

Cytokinesis in plant cells

Cell wall New cell wall

Daughter cellsCell plateVesicles containingcell wall material