| A | B |
|---|
| why do cells divide rather than grow indefinly | a. larger a cell becomes, the moe demands the cell places on it DNA and b. the more trouble the cell has moving nutrients and wastes across cell membrane |
| rate of food and oxygen are used up and waste products prodcued | cell volume |
| ration of surface area to volume | divde the surface area by the volume |
| if volume increases in the ratio the ratio gets | smaller |
| Cell division is | the process by which a cell divides into two new daughter cells |
| cell division solves the problem of increasing size | by reducing the volume |
| what does each chromosome consist of | each chromosome consists of two identical sister chromatids |
| a pair of chromatis are | centromere |
| period of growth inbetween cell divisoin is | interphase |
| cell cycle | the cell cycle is the series of events that cells go through as they grow and divide |
| divison of cell nucleus | mitosis |
| interphase's three divisions are | G1, S, G2 |
| G1 | cells do most of their growing incrasing in size and synthesizing new proteins and organelles |
| S | chromosomes are replicated and the synthesis of DNA molecules takes place |
| G2 | many of the organelles and molecules require for cell division are produced |
| four phases of mitosis | prophase, metaphase, anaphase,telophase |
| the spindle is | a fanlike microtubule structure that helps separate the chromosomes |
| Cytokinesis | is the division of cytoplasm |
| what happens to the cells at the edges of an injury when a cut in the skin or a break in a bone occurs | the cells at the edge of the injury are stimulated to divide rapidly |
| what happens to the rapidly dividing cellls when the healing process nears completion | the rate of cell division slows down, controls on growth are restored and everything returns to nomral |
| what do cyclins regulate | cyclins regulate the timing of the cell cycle in eukaryotic cells |
| internal regulators are | proteins that respond to event inside |
| cancer | is a disorder in which some of the body's own cells lose the ability to control cell growth |
| cancers dont respons to signals that regulate | growth |
| cancer cells form masses of cells called | tumors |
| cancer cells break loose and spread throughout the | body |
