Unit 3 – Lecture 10

Cell Reproduction 3 Reasons why cells reproduce: make the organism larger repair damaged cells replenish dead cells

Cell Cycle For Eukaryotes: Composed of: Interphase Mitosis Prophase Metaphase Anaphase Telophase Cytokinesis * IPMAT *

Cell Growth – Interphase Interphase [IPMAT] cell growth – doubling of structures before division longest phase of cell cycle proteins are synthesized DNA and other structures are replicated

Cell Division – Mitosis Mitosis = Cell Division Prophase [IPMAT] longest phase of mitosis two stages = early prophase, late prophase [pro-metaphase]

Mitosis – cont’d chromatin coils into chromosomes chromatin = strings of DNA in the nucleus chromosomes = X shaped structures made of two sister chromatids sister chromatids = sides of a chromosome made of duplicated DNA centromere = structure at center of chromosome

Mitosis – cont’d [prophase… IPMAT] nuclear envelope disappears spindle fibers form with centrioles centrioles organized by the centrosomes plant cells do not have centrioles

Mitosis – cont’d Metaphase [IPMAT] chromosomes attach to spindle fibers chromosomes line up at metaphase plate mp = middle of the cell lining up of chr. means that each new cell will get an equal share of the genetic information

Mitosis – cont’d Anaphase [IPMAT] separation of sister chromatids spindle fibers pull chromatids to cell poles

Mitosis – cont’d Telophase [IPMAT] telo = far / distant / at the end chromatids reach poles of the cell then, much like a reversal of what we did before this step: spindles disappear nuclear envelope reforms chromatids unwind cell begins to pinch inward in the middle called cleavage

Mitosis – cont’d Cytokinesis “kinesis” = movement differs between plants & animals animals – membrane pinches in middle to form two new cells plants – cell plate forms [because of the cell wall] & new membrane forms forms two “daughter” cells from the original “parent” cell Cell cycle repeats

Control of the Cell Cycle Enzymes control the rate of the reactions Cancer = uncontrolled cell division results in a tumor or mass of cells some malignant [harmful], some benign [non-harmful] “mal” = bad

Control of the C.C. – cont’d [Cancer …] caused by combination of genetic and environmental factors exposure to chemicals [ex: cigarette smoke] radiation [ex: sun] treatments chemotherapy biopsy immunotherapies

Control of the C.C. – cont’d [Cancer…] prevention [?] – healthy living vitamins, nutrients, low-fat & high-fiber diets, fruits & veggies… good genes