Objective: You will be able to give the purpose

of mitosis. Do Now:• Read “Division of the Cell” on p. 243• What must a cell do BEFORE cell division

occurs?

Mitosis

• When a cell becomes too big it will divide in half

• We call cell division mitosis

DNA and Chromsomes

• Taking DNA and packing it together forms chromosomes

– So for us these two terms are synonymous

• We can see DNA when it is packed into chromosomes

Figure 12.2 Eukaryotic chomosomes

Mitosis overview

• The whole point of mitosis is to copy DNA (chromosomes) exactly and then split into two cells.

– You end up creating two cells that are exactly alike

– Two new cells are called daughter cells

Mitosis is used for:

• Growth

• Repair

• Asexual reproduction

Activity

• View onion slides to look for chromosomes

• Find a cell that has chromosomes

• Draw the cell and its chromosome

• Find another cell with chromosomes doing something different

• Draw at least 4 cells

Figure 12-09x Mitosis in an onion root

Objective: You will be able to draw the stages of mitosis.

Do Now:• Read “Chromosomes” on p. 244-245• Define Chromatids and centromere

Chromosomes

• When chromosomes copy themselves they form a double chromosome

– Each piece is called a sister chromatid• They are exactly the same

• A centromere holds the two sister chromatids together

• Chromosomes double during a stage called interphase

Figure 12.3 Chromosome duplication and distribution during mitosis

Figure 12.9 Mitosis in a plant cell

Prophase

Figure 12.0 Mitosis

Individual activity• You are going to draw and label a cell

undergoing mitosis• Use your notes to help• Draw a cell that has 4 chromosomes• Use a different color for each part• Label:

– Chromosomes– Nuclear membrane– Spindle fibers– Centrioles

Objective: You will be able to compare and contrast cell division in plant and animal cells.

Do Now:• Read “Cytokinesis” on p. 248• Define cytokinesis

Figure 12.4 The cell cycle

Cell Cycle

• During Interphase:– Cell grows– Chromosomes double

• Mitosis is the division of the nucleus (chromosomes)

• Cytokinesis is the division of the cell (cytoplasm)

Figure 12.8 Cytokinesis in animal and plant cells

Plant versus animal division

• Plants don’t use centrioles, animals do

• In animals, the cell pinches inward

• In plants, Cytokinesis happens be forming a cell plate

Paired activity

• Use the microscope to view animal cells undergoing mitosis

• Find one cell for each phase– Prophase, metaphase, anaphase and

telophase

• Draw one cell for each stage in your notes