MITOSIS CELL DIVISION Notes and lab activity Why

MITOSIS & CELL DIVISION • Notes and lab activity

Why do cells divide to become 2 cells? 1. Problems with surface area to volume ratio – diffusion of food and wastes is not efficient & takes too long. 2. DNA Overload – DNA cannot manage and control a cell past a certain size; cell functions (manufacturing of proteins) don’t get accomplished & cell can’t survive 3. It is a means of reproduction – single-celled organisms produce offspring; multi-celled organisms grow & repair.

DEFINITIONS • • • Nucleus Chromosomes Cell Division Mitosis Cytokinesis

NUCLEUS • Definition: Large structure inside some cells that contains the cell’s genetic material (DNA) and controls the cell’s activities.

CHROMOSOMES • Definition: Threadlike structure within the nucleus containing genetic information that is passed from one generation of cells to the next.

CELL DIVISION • Definition: Process by which a cell divides into two new daughter cells.

MITOSIS • Definition: Part of eukaryotic cell division during which the cell nucleus divides. • What does “eukaryotic” mean again?

CYTOKINESIS • Division of the cytoplasm during cell division.

THERE ARE 4 STAGES OF MITOSIS. And they are…

PROPHASE • Chromosomes become visible • Nuclear envelope breaks down • Spindle fibers appear • Are you writing this down? ?

Nuclear envelope breaking down Chromosomes becoming visible PROPHASE “Plate of spaghetti” Spindle fibers

METAPHASE • Chromosomes line up along equator of cell on spindle fibers

Sister chromatids (2 copies of the same chromosome) Spindle fibers METAPHASE Line up in the “middle”

ANAPHASE • Spindle fibers pull sister chromatids to opposite poles (ends) of cell • Each half of cell (future daughter cells) has identical set of genes

Two halves of a sister chromatid ANAPHASE Pull “apart” or “away”

TELOPHASE • Chromatin unravels (decondenses) • New nuclear envelopes form • Spindles vanish

1 2 TELOPHASE “Two” nuclei (NOT two cells)

CYTOKINESIS • “division of cytoplasm” • Occurs simultaneously with mitosis • takes place differently in plants and animals.

Cellplateformation

Whitefish or Onion? 1 2 3

Whitefish or Onion? 1 3 2

IDENTIFYING STAGES: • You will be shown cells going through one of the stages of mitosis discussed earlier. • You and your partner must decide (1) what type of cell it is and (2) what stage of mitosis it is in.

IDENTIFYING STAGES (cont’d): • When you & your partner have your answer, raise your hand I will give you a “yes” or “no. ” • If you get a “yes, ” draw a picture of the cell in your lab IN THE CORRECT PLACE. (Page 22 for whitefish, page 23 for onion root) • If you get a “no, ” try again.

Use the flowchart in your lab to help you…

Whitefish or Onion? What stage of mitosis is shown?

Whitefish or Onion? What stage of mitosis is shown?

Whitefish or Onion? What stage of mitosis is shown?

Whitefish or Onion? What stage of mitosis is shown?

Whitefish or Onion? What stage of mitosis is shown?

Whitefish or Onion? What stage of mitosis is shown?

Whitefish or Onion? What stage of mitosis is shown?

Whitefish or Onion? What stage of mitosis is shown?