THE CELL CYCLE

THE CELL CYCLE The events that occur during the cell cycle are a continuous process. The cell cycle can be broken down into two major steps: interphase and mitosis

1. Interphase Cell grows Produces new organelles Copies DNA

2. Mitosis Mitosis is the division of the nucleus or genetic material of a cell. Mitosis can be broken down into four phases: Prophase Metaphase Anaphase Telophase

Mitosis is followed by the division of the cytoplasm, cytokinesis.

Steps of the Cell Cycle Animal Cell

Interphase period of growth by protein synthesis G1- growth S - chromosomes replicate (DNA appears as chromatin) centrioles replicate G2- spindle fibers assembled not a true phase of mitosis, but prepares a cell for mitosis

Prophase able to see double chromosomes centrioles move to opposite poles spindle fibers appear and attach to asters from pole to pole nuclear membrane and nucleolus break down

Metaphase double chromosomes (paired chromatids) attached to spindle fibers by their centromere move to the middle of equator of the cell

Anaphase chromatids from each double chromosome separate and migrate to opposite poles centromere leads the way chromatids cluster together when they reach the poles

Telophase chromosomes form chromatin nuclei form around chromosomes asters and spindle fibers break down cytoplasm begins to divide

Cytokinesis division of the cytoplasm begins in late anaphase or telophase a cleavage furrow forms in animal cells at the equator

Cytokinesis a cell plate forms in plant cells and will become the cell wall

Differences in plant and animal cell division plants do not have asters or centrioles

Factors that Determine Mitotic Rate cell type faster in less specialized cells ex: skin age of the cell fast in young cells slow in older cells injured cells very fast temperature affects plants (seasons)

Cell Specialization cell differentiate or become specialized as an organism develops a specialized cell will have a specific function ex: nerve sells carry an Impulse muscle cells contract leaf cells carry out photosynthesis red blood cells carry oxygen

In multicellular organisms, all somatic cells (body cells) contain a complete generic code, but will only use a part of that code.