CHAPTER 10 THE CELL CYCLE

CELL GROWTH A LIVING THING GROWS BECAUSE IT PRODUCES MORE AND MORE CELLS

CELL GROWTH SURFACE AREA OF A CELL DETERMINES HOW LARGE IT CAN GROW

–Surface area is critical for passage of food, oxygen, and water entering and leaving the cell

*** to solve the problem of getting too large, the CELL DIVIDES

RATES OF CELL GROWTH CELLS CAN GROW AT ASTONISHING RATES UNDER IDEAL CONDITIONS, BUT REAL CONDITIONS ARE FAR FROM IDEAL

CONTROLS ON CELL GROWTH Depends on function /images/skin2stem_630x.jpg

Depends on food, crowding, conditions in surrounding area.

If injury occurs (cells will grow rapidly at the site)

Consequences of uncontrolled cell growth are severe.

Cancer cells have lost their ability to control their growth rate. Breast cancer cells m/2009/06/breastcancercells.jpg

Definitions

CELL DIVISION - The process whereby the cell divides into 2 daughter cells TeY/R4Cy_XjDNjI/AAAAAAAAABk/P7 fx2NiM-zM/s320/cytokin.gif

MITOSIS – process by which the nucleus of a cell is divided into 2 nuclei; occurs in somatic (body) cells; produces diploid cells

Diploid vs. Haploid n Diploid – a cell that contains both sets of homologous chromosomes (two sets); represented by the symbol 2N –Found in somatic or body cells (ex. Skin, digestive tract) –Example : Humans – 2N = 46 n Haploid – a cell that contains only a single set of chromosomes (one set); represented by the symbol N or 1N –Found in gametes or sex cells – sperm & egg –Example: Humans – N = 23

CHROMOSOMES – Structures in the cell that contain the genetic information that is passed on from one generation of cells to the next

CHROMATIN – The material of which chromosomes are made projects.com/science_fair_projects_encyclopedia/upl oad/7/79/Chromatin_chromosome.png

CHROMOSOMES THE CELLS OF EVERY ORGANISM CONTAIN A SPECIFIC NUMBER OF CHROMOSO MES

HUMANS HAVE 23 PAIR OR 46 CHROMOSOMES _2_014i.jpg

THE CELL CYCLE Interphase -- > MADE UP OF 3 PARTS – preparing to divide

Mitosis --> MADE UP OF 4 PARTS - the division of the nucleus osis_300_364.jpg

Cytokinesis --> MADE UP OF 1 PART division of the cytoplasm

INTERPHASE A. GAP 1 (G 1 ) Cellular growth and development takes place

B.DNA SYNTHESIS (S) DNA is replicated

C. GAP 2 (G 2 ) Synthesis of Organelles

PHASES OF MITOSIS

A. PROPHASE –C–Centrioles separate from each other and move to the poles

–Nuclear Envelope breaks down and Nucleolus disappears

–CHROMATIN COILS UP AND BECOMES VISIBLE AS CHROMOSOMES

–Chromosomes become attached to the Spindle Fibers at the centromere

B. METAPHASE Chromosomes line up across the equator (middle) of the cell CENTRIOL ES SPINDL E FIBERS CHROMOS OMES

C. ANAPHASE CENTROMERES SPLIT CAUSING THE CENTER CHROMATIDS TO SEPARATE, BECOMING INDIVIDUAL CHROMOSOMES Continue to move in 2 groups near the poles

D. TELOPHASE Opposite of Prophase –Chromosome s uncoil into a tangle of chromatin

Nuclear Envelope reforms around chromati n Nucleolu s becomes visible again

CYTOKINESIS Division of the cytoplas m into the 2 daughter cells

SHORTCUT TO REMEMBER THE CELL CYCLE I nterphase P rophase M etaphase A naphase T elophase C ytokinesis I Passed Math At Tom Clark

Animation of Mitosis n ps/CDBio.html ps/CDBio.html n K1-9QB0 K1-9QB0