The Cell Growth & Division Mitosis The Cell Growth & Division

Page 1: Limits to Cell Growth- 2 main reasons cells divide rather than continuing to grow indefinitely: More Demands on DNA- When cell increases in size it does not make extra copies of DNA If cell grew without limits “information crisis” would occur.

Page 1 continue Exchanging Materials- Food, oxygen, & water have to enter the cell through the cell membrane Waste products have to leave The rate at which this exchange takes place depends on the surface area of the cell (total area of the cell membrane)

Page 1 continue Ratio of Surface Area to Volume Volume increases more rapidly than the surface area Therefore, ratio of surface area to volume decreases This decrease causes serious problems for the cell If too large becomes to difficult to get enough oxygen and nutrients in and wastes out This is why cells do not grow much bigger even if the organism of which they are a part of does. Quick Lab (p. 242) Analyze & conclude 1-2

Page 2 Define from the chapter: Cell Division Mitosis Chromosome Chromatid Draw a picture of chromosome & Chromatid 5. Centromere 6. Cell cycle 7. Spindle fibers 8. Centrioles Draw a picture of Centrioles & Spindle fibers

Page 3 Cell Growth Describe: G1- period of activity in which cells do most of their growing. Cells increase in size and synthesize new proteins and organelles S- Chromosomes are replicated and synthesis of DNA molecules takes place G2- Many organelles and molecules required for cell divisions are produced M phase- Mitosis Add Color!

Cytokinesis (cytoplasmic division) Interphase G1 phase (gap) growth & metabolic activity S phase (DNA replication) G2 phase (gap) cells prepares for division Mitosis Cytokinesis (cytoplasmic division)

Page 4 Add Color! Draw, label, & describe the phases of: Interphase Prophase Add Color!

Page 5 Add Color! Draw, label, & describe the phases of: Metaphase Anaphase Add Color!

Page 6 Telophase Cytokinesis- for both plant & animal Add Color! Draw, label, & describe the phases of: Telophase Cytokinesis- for both plant & animal Add Color!

A Cell’s Appearance During Interphase Plasma membrane Nucleoplasm Cytoplasm Nuclear envelope

Prophase Replicated chromosomes, which are being held together by a centromere, condense. Centrioles move to opposite poles of the cell. Nuclear envelope and nucleolus disperse. Microtubules are assembled from tubulin proteins in the cytoplasm, and these structures associate with the centrioles and the chromosomes. A spindle-shaped array of microtubules (spindle fibers) forms between the centrioles as they move apart.

Metaphase The doubled chromosomes become attached to the spindle fibers by their centromeres. The chromosomes begin to line up on the midline

Anaphase The centromers split apart and chromatid pairs from each chromosome separate from each other The chromatids are pulled apart by the shortening of the microtubules in the spindle fibers.

Telophase The chromatids reach the opposite poles of the cell. The spindle breaks down, the nucleolus reappears, & a new nuclear envelope forms around each set of chromosomes. A new double membrane begins to form between the 2 new nuclei.

Cytokinesis Animal Cells- the plasma membrane pinches in along the equator and 2 new cells are separated. Plant Cells- Have a rigid cell wall, so the plasma membrane does not pinch in. The cell plate is laid down across the cell equator. A cell membrane forms around each cell, & new cell calls form on each side of the cell plate until separation is complete.

Mitosis Animation

Now, name and then order these phases of mitosis. B C Now, name and then order these phases of mitosis. D E F G H I

Page 7 Regulating the Cell Cycle: Cell cycle regulators- early 1980’s biologists found a protein that increased & decreased the time with the cell cycle They called it cyclin because it seemed to regulate the timing of the cell cycle Since, they have discovered a whole family of cyclin proteins

Page 7 Continued Two types of Regulator Proteins Internal Regulators- proteins that respond to events inside the cell Allows cell cycle to proceed only when certain processes have occurred inside the cell Ex: doesn’t let the cell enter mitosis until all chromosomes have been replicated External Regulators- Proteins respond to events outside the cell Direct cells to speed up or slow down cell Ex: Growth factors- stimulate growth & cycle division of cells. Important in embryonic cells & wound healing

Page 8 Uncontrolled Cell Growth Cancer- disorder in which some of the body’s own cells lose the ability to control growth. Cancer cells do not respond to the signals that regulate the growth of most cells, they divide uncontrollably & form masses of cells called tumors that can damage surrounding tissue.

Page 8 Continued Two types of tumors: Benign- does not spread to surrounding tissue (non cancerous) Malignant- Spreads & destroys healthy tissue (cancerous) Causes: Biological Agent- viruses Chemical Agent- carcinogens- tobacco Physical Agent- radiation Genetics

Page 8 Continued Treatments: Surgery Radiation Chemotherapy The End

Onion Root Tip Under Low Power… Look for this 1st then SWITCH TO HIGH POWER!!!!!

Onion Root Tip Identify the stages

Onion Root Tip

Page 9 DNA Scientists Chart

Pg. 10 DNA NOTES

Pg. 11 DNA REPLICATION