cell cycle

Cell Cycle

The cell cycle begins when the cell is formed and ends when the cell divides and forms new cells.

DNA

Before a cell divides, DNA is copiedDNA is organized into structures called

chromosomesDNA is in the nucleus

Cell Cycle (Prokaryotic) BACTERIA

Bacteria are not complexBacteria contain ribosomes and a single

circular molecule of DNABacteria have no membrane bound

organelles, making cell division simpleCell division is called binary fission-

splitting into two partsThey make a copy of the DNA and split

with each cell containing a copy

Binary Fission in Bacteria

Bacteria

Binary Fission

Bacteria

Eukaryotic Cell DivisionCHROMOSOMESChromosomes contain lots of DNA and

proteinsNumber of chromosomes is different in

each organism-humans=46, potatoes=48, and fruit flies=8

Chromosomes can line up in pairs containing similar information (homologous chromosomes)

CHROMOSOMES

Making More Eukaryotic CellsINTERPHASE STAGE 1

Three stages, Interphase, Mitosis, and Cytokinesis

Stage 1(INTERPHASE)=Cell grows and copies organelles, centriole, and chromosomes

Strands of DNA and proteins are like loosely coiled thread

After chromosomes are duplicated, the copies are now called chromatids

Chromatids are held together by a centromere

INTERPHASE

INTERPHASE

Making More Eukaryotic Cells MITOSIS STAGE 2Three stages, Interphase, Mitosis, and

Cytokinesis

Stage 2 (Mitosis) Chromosome Separation

4 Phases OF MITOSIS = Prophase, Metaphase, Anaphase, and Telophase

Mitosis STAGE 2Separation – PHASE1Phase 1(Prophase) Mitosis beginsNuclear membranes break apartChromosomes condense into rod like

structuresTwo pair of centrioles move to opposite

sides of the cellFibers form between the centrioles and

attach to the centromeres

MITOSIS – STAGE 2PHASE 1 PROPHASE

MORE PROPHASE

Mitosis STAGE 2Separation – PHASE 2Phase 2 (Metaphase)Chromosomes line up along the equator of

the cellRemember M for Middle

METAPHASE

MORE METAPHASE

Mitosis – STAGE 2Separation – PHASE 3Phase 3 (Anaphase)Chromatids separate and are pulled to

opposite sides of the cell by fibers that are attached to the centrioles

Remember A for Apart

ANAPHASE

ANAPHASE

Mitosis – STAGE 2Separation – PHASE 4Phase 4 (Telophase)Nuclear membrane forms around two sets

of chromosomes and they unwindFibers disappearMitosis is completedRemember T for TwoThe kindergarten teacher said “Do not p

on the mat! (PMAT)

TELOPHASE

Stage 3 CYTOKINESIS-Animal Cell

After mitosis, the cytoplasm splits in two, (Cytokinesis)

Result is two identical cells, identical to the original cell they came from

After cytokinesis, cell cycle is complete and will start over again

Stage 3 CYTOKINESIS-Plant Cell

When plant cells divide, a cell plate forms and the cell is split in two

Cell plate becomes the new cell membrane that will separate the two cells

After split, new cell wall forms

CYTOKINESIS

CELL CYCLE COMPLETE!