Chapter 4Chapter 4

CELL REPRODUCTIONCELL REPRODUCTION

CELL DIVISION AND MITOSISCELL DIVISION AND MITOSIS

Cell cycle-every cell has a lifecycle – Cell cycle-every cell has a lifecycle – birth, growth and development and birth, growth and development and deathdeath

Length of cycle variesLength of cycle varies

I P M A TI P M A T

INTERPHASEINTERPHASE

When a cell copies its genetic When a cell copies its genetic material (chromosomes) in the material (chromosomes) in the nucleus and prepares for cell divisionnucleus and prepares for cell division

PROPHASEPROPHASE

Nuclear membrane disappearsNuclear membrane disappears

Centrioles move to opposite ends of Centrioles move to opposite ends of the cell in an animal cellthe cell in an animal cell

Spindle fibers begin to form in animal Spindle fibers begin to form in animal and plant cellsand plant cells

METAPHASEMETAPHASE

Pairs of chromatids line up across Pairs of chromatids line up across from each other (like football line of from each other (like football line of scrimmage)scrimmage)

Spindle fibers connect to centomere Spindle fibers connect to centomere of each pair of chromatidsof each pair of chromatids

ANAPHASEANAPHASE

Spindle fibers pull chromosomes to Spindle fibers pull chromosomes to opposite ends of the cellopposite ends of the cell

TELOPHASETELOPHASE

Spindle fibers disappearSpindle fibers disappear

Chromosomes become encased in a Chromosomes become encased in a new nuclear membranenew nuclear membrane

TELOPHASETELOPHASE

Cell membrane pinches in and the Cell membrane pinches in and the cytoplasm divides for an animal cell cytoplasm divides for an animal cell and two new identical cells are and two new identical cells are formed - cytokinesisformed - cytokinesis

In a plant cell a new cell plate forms In a plant cell a new cell plate forms as the cell divides and will become a as the cell divides and will become a new cell wall for the new cellsnew cell wall for the new cells

Process repeats itselfProcess repeats itself

cytokinesiscytokinesis

RESULTS OF MITOSISRESULTS OF MITOSIS

Two new, identical cells form from Two new, identical cells form from mitosismitosis

Mitosis is for growth and repair of Mitosis is for growth and repair of organismorganism

ASEXUAL REPRODUCTIONASEXUAL REPRODUCTION

Only one parent neededOnly one parent needed

Offspring are identical to the parentOffspring are identical to the parent

Some plants reproduce by sending Some plants reproduce by sending out shoots or runners, strawberry out shoots or runners, strawberry plantplant

ASEXUAL REPRODUCTIONASEXUAL REPRODUCTIONFission – when one organism divides itself Fission – when one organism divides itself in twoin two

Budding – a new organism grows off the Budding – a new organism grows off the side of the parent and then releases when side of the parent and then releases when readyready

Regeneration – process of regrowing a lost Regeneration – process of regrowing a lost body part, or forming new, identical body part, or forming new, identical organisms from the separated body part – organisms from the separated body part – seastar or spongesseastar or sponges