Chapter 12: Cell Cycle Flashcards

Question

What causes the movement alone the chromosome?

Answer 1

Kinetochores use motor proteins that “walk” chromosome along attached microtubules Microtubules shortens by dismantling at kinetochore (chromosome) end

Answer 2

Chromosomes arrive at poles Daughter nuclei form Nucleoli form Chromosomes disperse No longer visible under light microscope Spindle fibers disperse Cytokinesis begins — cell division

Answer 3

constriction belt of actin micro filaments around equator of cell Cleavage furrow forms Splits cell in two Like tightening a draw string

Answer 4

Cell plate forms Vesicles line up at equator Derived from Golgi Vesicles fuse to form 2 cell membranes New cell wall laid down b/tw membranes New cell wall fuses with existing cell wall

Answer 5

Molecular control system, the frequency of cell division varies w/ the type of cell The cell cycle differences result from regulation at molecular level

Answer 6

Cell signaling

Answer 7

A multicellular organism needs to coordinate cell division across different tissues & organs Critical for normal growth, development & maintenance Coordinate timing of cell division Coordinate rates of cell division Not all cells can have the cell cycle

Answer 8

Embryo Cell cycle< 20 minutes Skin Cells Divide frequently throughout life 12-24 hours Liver cells Retain ability to divide, but keep it in reserves Divide once every year or two Mature nerve & muscle cells Do not divide at all after maturity Permanently in G0

Answer 9

The sequential events of the cell cycle are direct by cell cycle control system Regulated by internal and external controls The clock has specific checkpoints where the cell cycle stops until the go-ahead signal is received

Answer 10

G1/S Can DNA synthesis begin? G2/M Has DNA synthesis been completed correctly? Spindle Checkout Are all chromosomes attached to spindle Can sister chromatids separate correctly

Answer 11

Most critical Primary decision point “Restriction point” If cell receives “Go” signal it divides Internal signals: cell growth (size), cell nutrient External signals: “growth factors” If cell does not receive signal, it exits cycle & switches to G0 phase non/dividing, working state

Answer 12

Non-dividing, differentiated state Most human cells in G0 phase

Answer 13

Protein signals that promote cell growth & division —internal signals “Promoting factors” —external signals “growth factors” Primary mechanism of control — phosphorylation Kinase enzymes either activates or inactivates cell signals

Answer 14

Cell Cycle controls cyclins Regulatory proteins Levels cycle in the cell Cdks Cyclin-dependent kinase Phosphorylates cellular proteins activates or inactivates proteins Cdk- cyclin complex (MPF maturation promoting factor) Triggers passage through different stages of cell cycle The activity of cyclins and Cdks fluctuates during cell cycle

Answer 15

Growth factors Coordination b/tw cells Proteins signals released by body cells that stimulate other cells to divide Density- dependent inhibition Crowed cells stop dividing Each cells binds a bit of growth factor Not enough activator left to trigger division in any one cell. Anchorage dependence To divide cells must attached to a substrate “Touch sensor” receptors

Answer 16

made by platelets in blood clots Binding of PDGF to cell receptors stimulates cell division in connective tissue heal wounds

Answer 17

Growth factor can create cancers —Porto-oncogenes Normally activates cell division growth factor genes becomes oncogenes (cancer/causing) when mutated If switched “On “ can cause cancer Ex: RAS(Activates. Cyclins). Tumor-Suppressor Genes Normally inhibits cell division If switched “OFF” can cause cancer Ex: p53

Answer 18

Cancer is essentially a failure of cell division control — unrestrained, uncontrolled cell growth What control is lost Lose checkpoint stops Gene p53 plays key role in G1/S restriction point p53 proteins halts cell division if it detects damaged DNA 4 options stimulates repair enzymes to fix DNA Forces cell into G0 resting stage Keeps cell in G1 arrest Cause apoptosis of damaged cell All cancers have to shut down p53 activity

Answer 19

Unlimited growth — turn on growth promoter genes Ignore Checkpoint — turn off tumor suppressor genes (p53) Escape Apoptosis — turn off suicide genes Immortality = unlimited divisions — turn on chromosomes maintenance genes Promotes blood vessels growth — turn on blood vessels growth genes Overcome anchor & density dependence — turn off touch-sensor gene

Answer 20

UV radiation Chemical exposure Radiation exposure. Heat Cigarette smoke Pollution Age Genetics

Answer 21

Mass of abnormal cells

Answer 22

Abnormal cells remain at original site as a lump. — p53 has halted cell divisions Most do not cause serious problems & can be removed by surgery Malignant Tumor Cells leave original site Lose attachment to nearby cells Carried by blood & lymph system to other tissues Starts more rumors= metastasis Metastasis: development of secondary malignants growth away from primary site Impair functions of organs throughout body

Chapter 12: Cell Cycle Flashcards

(46 cards)