THE CELL CYCLETHE CELL CYCLEMAKING BRAND NEW MAKING BRAND NEW

CELLS!CELLS!

CHROMOSOME

LABEL THE IMAGES AS WE GO!

CHROMOSOME STRUCTURE

CENTROMERE

CHROMATIDCHROMATID

PARENT CELLS

DAUGHTER CELLS

SPINDLE FIBERS

NUCLEAR ENVELOPE

CENTRIOLES

SPINDLE FIBERSSISTER

CHROMATIDS

CHROMOSOMES

THE CELL CYCLE (the life of a cell)

What is the Cell Cycle?What is the Cell Cycle?It is the life of a eukaryotic cell: The

way the cells grow, make new copies and divide!

It happens in all of your somatic(body) cells in order to get the same DNA inside each cell. (your reproductive cells do something different)

What is the Cell Cycle?What is the Cell Cycle? Parent cells are diploid and make 2

daughter cells that are also diploid with their own new nuclei.

Diploid means 2 of each chromosome: 2 (n)= 2 (23) = 46 chromosomes

Phases of the cell cycle: Interphase, Prophase, Metaphase, Anaphase, Telophase and Cytokinesis

I P M A T C I Peed on the MAT, see?

INTERPHASEINTERPHASE The largest phase in which 95% of growth occurs This is the time between cell divisions The cell is growing,copying it’s DNA andpreparing for division The copying of DNA is called synthesis or replication. 3 phases of interphase:

G1, S & G2.

1. G1Growth of the cell in size and development (differentiation-the cell is told what to become).2. SSynthesis of DNA, also called REPLICATION:1. The DNA double helix is unzipped completely by an

enzyme called HELICASE.2. One DNA nucleotide at a time is added to BOTH sides of the DNA strand (AT and CG) with the help of

another enzyme called DNA POLYMERASE.3. The nucleus is left with TWO exact copies of ALL the

chromosomes/DNA.

3. G2the cell prepares for division and checks for errors.

INTERPHASE (3 phases)INTERPHASE (3 phases)

REPLICATION:REPLICATION: http://www.johnkyrk.com/DNAreplication.htmlhttp://www.johnkyrk.com/DNAreplication.html

http://www.stolaf.edu/people/giannini/flashanimat/http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/dna-rna2.swfmolgenetics/dna-rna2.swf

NOW, YOU PRACTICE! NOW, YOU PRACTICE! Go back to the DNA template in your

notebooks. Open the strand of DNA (you are helicase).

DRAW in each individual nucleotide that matches the bases you have already glued in… YOU HAVE JUST REPLICATED DNA!

Mitosis is considered “Cell Division”Four Phases are a part of Mitosis:

ProphaseMetaphaseAnaphaseTelophase

Cytokinesis is after mitosis

STAGES OF THE CELL CYCLE:STAGES OF THE CELL CYCLE:Remember: IPMATCRemember: IPMATC

MITOSIS is after Interphase…

PROPHASEPROPHASE the first phase in mitosisTHREE THINGS TO LOOK FOR:1.chromosomes can be seen as two

chromatids, in the shape of an “X”2.Nuclear envelope dissolves3.Centrioles arepresent with some spindle fibers

METAPHASEMETAPHASESecond phase in MitosisTHREE THINGS TO LOOK FOR:1.chromosomes line up in the middle2.Nuclear envelope is gone (no nucleus)

3.Spindle fibers (on opposite poles) are stretching towards the chromosomes

ANAPHASEANAPHASE Third phase of Mitosis THREE THINGS TO LOOK FOR:1.Spindle fibers pull chromosomes towards

the separate poles2.Chromosomes are split in HALF3.Sister chromatids are now their OWN

chromosome.

TELOPHASETELOPHASE the final stage of Mitosis THREE THINGS TO LOOK FOR:1. The nuclear envelope reforms around each set of

chromosomes (so daughter cells each have one) and chromosomes straighten out (uncoil)

2. Spindle fibers are gone3. Cleavage furrow is forming between the cells

CYTOKINESISCYTOKINESIS Interphase Mitosis CytokinesisFinal step in the Cell CycleActually means “cell moving”The final pinching of the cell into

two complete identical cells!

Certain genes and enzymes Certain genes and enzymes trigger the start of the cell cycle trigger the start of the cell cycle

(replication) and also tell the (replication) and also tell the cells what to do.cells what to do.

Importance of the cell cycle to Importance of the cell cycle to the growth of organisms:the growth of organisms:

UNICELLULAR:UNICELLULAR:

Cell cycle is how they reproduce offspringCell cycle is how they reproduce offspring

MULTICELLULAR:MULTICELLULAR:

Cell cycle is how they become an adult Cell cycle is how they become an adult from only one fertilized zygote cell.from only one fertilized zygote cell.

Cell Cycle in Multicellular Cell Cycle in Multicellular Organisms:Organisms:

GROWTH: increase in number of cells and GROWTH: increase in number of cells and the size of cells (interphase G1)the size of cells (interphase G1)

DIFFERENTIATION: cells are told by a gene DIFFERENTIATION: cells are told by a gene to become specialized (ex. Muscle cells are to become specialized (ex. Muscle cells are told to do that job) told to do that job)

MORPHOGENESIS: the patterned formation MORPHOGENESIS: the patterned formation of specialized cells to become TISSUES!of specialized cells to become TISSUES!

Disruptions in the cell cycle:Disruptions in the cell cycle:

If certain enzymes and genes tell the If certain enzymes and genes tell the cell cycle to begin too rapidly, cell cell cycle to begin too rapidly, cell division becomes out of control.division becomes out of control.

=CANCER!=CANCER!