1 / 6

The Cell Cycle

The Cell Cycle. Unit 3 Organization and Development. Growth. Question: Can cells grow indefinitely? Is their size limited? Why?

malana
Download Presentation

The Cell Cycle

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. TheCell Cycle Unit 3 Organization and Development

  2. Growth • Question: Can cells grow indefinitely? Is their size limited? Why? • Answer: NO. YES. Because of the surface area to volume area ratio. If cells get too big then substances cannot get to all parts of the cell. Transport becomes inefficient. Cellular processes cannot occur properly. • Question: If cells cannot grow indefinitely, how can organism grow? • Answer: Cells divide! They make more of themselves through cell reproduction or cell division.

  3. Cell Reproduction • All cells come from pre-existing cells (this is part of cell theory). • Enables the genes from a parent cells to be passed on to daughter cells. • Cells must reproduce for: • Growth of the organisms • Repair of damaged cells • Replacement of worn-out or dying cells • REPRODUCTION

  4. Cell Division • There are two kinds of cell division: mitosis and meiosis. • Mitosis: somatic cells divide by mitosis • Mitosis is essentially a duplication process: It occurs in somatic cells and produces two genetically identical "daughter" cells from a single "parent" cell. • Meiosis: gametes are made by meiosis • We will learn all about meiosis in our next unit… • So, basically, mitosis is for growth and maintenance, while meiosis is for sexual reproduction.

  5. The Cycling Cell • This cycle begins when the cell is produced by mitosis and runs until the cell undergoes its own mitosis and splits in two. • The cycle is divided into distinct phases: G1 (gap 1) S (synthesis), G2 (gap 2), and M (mitosis). As you can see, mitosis only occupies a fraction of the cycle. The rest of the time-phases G1 through G2—is known as interphase.

  6. How Long is the Cycle? • It depends… • Some cells are constantly cycling and divide more often. • Some cells take a long time to cycle; division does not happen often; they spend most of their time in G1. • Some cells divide only when induced – an internal environmental factor triggers division.

More Related