The cell cycle: is a series of events that cells go through as they grow and divide

Intro rap

http://www.youtube.com/watch?v=IPLTDVXCEqQ&feature=related 2:16

THE CELL CYCLETHE CELL CYCLE

THE CELL CYCLETHE CELL CYCLE As cells increase in size the ratio of surface area As cells increase in size the ratio of surface area

to volume decreases to volume decreases A cube: 2x2x2 S.A.= 24 & Vol. = 8 or 3:1A cube: 2x2x2 S.A.= 24 & Vol. = 8 or 3:1 A cube: 3x3x3 S.A = 54 & Vol. = 27 or 2:1A cube: 3x3x3 S.A = 54 & Vol. = 27 or 2:1 As cells increase in size there are increased As cells increase in size there are increased

demands on :demands on :

1.1. DNA: coding for proteins and regulating the cellDNA: coding for proteins and regulating the cell

2.2. Uses up food and oxygen more quicklyUses up food and oxygen more quickly

3.3. Cellular transfer functions: Cellular transfer functions: uptake of food & nutrientsuptake of food & nutrients Removal of waste materialsRemoval of waste materials

Cells must divide to maintain maximum efficiency.Cells must divide to maintain maximum efficiency.

THE CELL CYCLETHE CELL CYCLE

cell cycle overview http://www.youtube.com/watch?v=diXoAgH3LMk&feature=related 3:18

INTERPHASEINTERPHASE Interphase consists of 3 stages.Interphase consists of 3 stages. (G1):The Gap 1 phase is when cells grow (G1):The Gap 1 phase is when cells grow

and make RNA, proteins, and other and make RNA, proteins, and other macromolecules.macromolecules.

The S or Synthesis phase is when the cell is The S or Synthesis phase is when the cell is making DNA.making DNA.

(G2): The Gap 2 phase is when the cell (G2): The Gap 2 phase is when the cell prepares for cell division and makes prepares for cell division and makes proteins and organelles that are involved in proteins and organelles that are involved in cell divisioncell division

Note: If a cell “decides” not to divide, then it Note: If a cell “decides” not to divide, then it enters a dormant phase called Genters a dormant phase called G00, which is , which is a non-dividing phasea non-dividing phase

INTERPHASEINTERPHASE

ATP is synthesized.ATP is synthesized. Proteins are made.Proteins are made. Organelles are formed.Organelles are formed. Chromosomes are copied.Chromosomes are copied. Specialized tasks are performed Specialized tasks are performed Damaged parts are repaired..Damaged parts are repaired.. Wastes are excreted.Wastes are excreted.

DNA ReplicationDNA Replication

During the S phase of the cell cycle, During the S phase of the cell cycle, DNA replicates. DNA replicates.

A short section of the DNA uncoils. A short section of the DNA uncoils. New nucleotides bond to the open New nucleotides bond to the open

sections of the DNA.sections of the DNA. The “new” and “old” sections of DNA The “new” and “old” sections of DNA

separate and now there are 2 DNA separate and now there are 2 DNA strands.strands.

M-PHASEM-PHASEMitosis is the process by which the

nucleus of the cell is divided into two nuclei, each with the same number and kind of chromosomes as the parent cell.

this process occurs in body cells (somatic cells), for the purpose of: Growth Replacing damaged or old cells.

This is a complex process requiring different stages

MITOSISMITOSIS

Mitosis consists of four phasesMitosis consists of four phases ProphaseProphase MetaphaseMetaphase AnaphaseAnaphase Telophase Telophase

mitosis overview 3:18http://www.youtube.com/watch?v=3kpR5RSJ7SA&feature=related

ProphaseProphase

Longest phase. 50-60% of the time in Longest phase. 50-60% of the time in mitosismitosis

Chromatin coils. (condenses)Chromatin coils. (condenses) Nuclear membrane breaks downNuclear membrane breaks down Nucleolus disappearsNucleolus disappears Centrioles migrate.Centrioles migrate. Mitotic Spindle forms.Mitotic Spindle forms. Chromosomes attach to the spindles at Chromosomes attach to the spindles at

the centromere and coil tighter.the centromere and coil tighter.

MetaphasMetaphasee

Microtubules connect to the Microtubules connect to the centromere (kinetochore) of each centromere (kinetochore) of each Chromatid pairChromatid pair

Chromatids line up in the center of Chromatids line up in the center of the cellthe cell

AnaphasAnaphasee

Centromere splits.Centromere splits. Chromatids are separated. Sister Chromatids are separated. Sister

chromatids move to the opposite sides of chromatids move to the opposite sides of the cell, toward the centrioles.the cell, toward the centrioles.

Chromatids are now called chromosomes.Chromatids are now called chromosomes. Anaphase ends when the chromosomes Anaphase ends when the chromosomes

stop movingstop moving

TelophaseTelophase

Spindles break apartSpindles break apart 2 new Nuclear membranes reform.2 new Nuclear membranes reform. Chromosomes uncoil (revert to chromatin Chromosomes uncoil (revert to chromatin

form)form) Nucleolus becomes visible.Nucleolus becomes visible. Mitosis is complete; but Cell Division is notMitosis is complete; but Cell Division is not

CytokinesisCytokinesis Continuous with telophaseContinuous with telophase Cell elongatesCell elongates Animal cells:Animal cells:

Cleavage furrow formsCleavage furrow forms Plant Cells:Plant Cells:

Cell Plate formsCell Plate forms The cytoplasm divides and The cytoplasm divides and two identical two identical

daughterdaughter cells are formed. cells are formed.Mitosis: Animation/CAD 1:22http://www.youtube.com/watch?v=VGV3fv-uZYI&feature=related

Rat – epithelial cells

Mitosis – Bone Cells

1) Parent cell 2) Chromosomes copied

4) Copies separating

5) 2 daughter cells

Cells split

3) Chromosomes line up

Differences in Plants

1. No Centrioles

2. Centrosomes: these structures take the place of centrioles, and serve as “anchors” for spindle fibers.

3. During cytokinesis, a cell plate develops midway between the newly formed nuclei. Then, a cell wall develops between the two new cells

Plants – apical meristem

Cell CycleCell Cycle RegulatorsRegulators When cells come into contact with other cells,

they respond by not growing (p 250 fig. 10-7) Cyclins: regulate the timing of the cell cycle in

Eukaryotic cells (p251 fig. 10-8) Internal regulators: proteins that respond to

events inside the cell; they allow the cell to proceed only when certain processes have occurred. (i.e. cyclins)

External regulators: proteins that respond to events outside the cell; they direct cells to speed up or slow down the cell cycle (i.e. Growth Factors, neighboring cell’s marker proteins)

Uncontrolled GrowthUncontrolled Growth Cancer: is a disorder in which some of the

body’s own cells lose the ability to control growth (Cell Cycle)

Cancer cells do not respond to the signals that regulate the growth of most cells. As a result, they form masses of cells called tumors that can damage the surrounding tissues.

The p53 gene normally halts the cell cycle until all chromosomes have been properly replicated; this gene is defective in many cancer cells.

Cancer Raphttp://www.youtube.com/watch?v=1NXxH56mEUA&feature=related 3:16

Mitosis & Meiosis Mitosis & Meiosis VideosVideos

Mitosis Animation: optional 1:22http://www.youtube.com/watch?

v=VGV3fv-uZYI&feature=related

Mitosis & Meiosis Animation and Description: optional 11:00

http://videos.howstuffworks.com/hsw/17574-understanding-cells-how-cells-reproduce-video.htm

““POTPOURI”POTPOURI”KEY CONCEPTSKEY CONCEPTS

Cell Cycle Cell Division: Mitosis & Cytokinesis Cyclins Cancer Cells / Tumor Centromere Centriole Sister Chromatids (prophase & metaphase) P53 gene Surface Area / Volume Ratio: decreases with cell

growth

AnimationsAnimations

Lab bench: observing mitosisLab bench: observing mitosis

http://www.phschool.com/science/http://www.phschool.com/science/biology_place/labbench/lab3/mitfilm.htmlbiology_place/labbench/lab3/mitfilm.html

Lab bench: quiz Lab bench: quiz http://www.phschool.com/science/biologhttp://www.phschool.com/science/biology_place/labbench/lab3/quiz1.htmly_place/labbench/lab3/quiz1.html

Mitosis: interactive animationMitosis: interactive animation http://www.cellsalive.com/mitosis.htm http://www.cellsalive.com/mitosis.htm