The Cell Cycle Focus Questions: Why do cells need to grow and divide? How do cells divide? What happens when cells divide incorrectly?

Reasons we need our cells to grow! _____________________ of organisms ________________ of tissues

There are limits to a cell’s growth A larger cell may experience “_________ ______________” As cells get __________________ they become less ________________ at exchanging nutrients and materials such as oxygen, water, and food with its ________________________

DNA Overload If a cell is large, there are more demands on its single copy of __________________ Think of a book in a library: the more people there are, the greater the likelihood that they will have to ________________ to read it

Exchanging Nutrients As a cell gets larger, what gets bigger? Its ________________ Its ___________________ _____________ also gets larger, but not large enough! Only so many materials are able to pass through the cell membrane at once The surface area of many small cells is greater than one cell (or ever a few large cells)

Remember, cells must use diffusion and osmosis to obtain important nutrients, like ______________ and __________________

Cell Division - process by which a cell splits into two identical ________________ ______________ Occurs in two main phases:  Interphase – cell _______________ its DNA and prepares for division Mitosis – chromosomes separate into ______ _________ cells

Chromosomes DNA containing cell’s genetic code During interphase, chromosomes are copied - this produces two identical “sister __________________________”

The Cell Cycle

The Cell Cycle Interphase (longest phase) G1 - first growth (gap) phase, new organelles produced Synthesis - DNA makes a copy G2 - second growth (gap) phase, preparing for mitosis G0 - no growth phase, a cell may enter this phase Mitosis - nucleus divides, ensuring each new cell has the exact number of chromosomes as parent