CELL CYCLE & MITOSIS

Cell Cycle

90% of the cell cycle is in interphase, other 10% is mitosis (cellular division)

Interphase composed of 3 phases: G1, S, and G2 G1 (Gap 1) phase: cellular growth and protein synthesis, in

preparation for the S phase S (Synthesis) phase: DNA synthesis/replication of each

chromosome in the cell, forms sister chromatids. G2 (Gap 2) phase: cellular growth as well as protein & lipid

synthesis, in preparation for mitosis Ex. Synthesis of proteins used to form mitotic spindle

Mitosis

Cellular division of a cell Makes exact copy of mother cell Produces 2 identical daughter cells Each product has same # of chromosomes Purpose of mitosis?

To form a multicellular organism from a zygote To replace dead or lost cells, such as skin and red

blood cells

Phases of Mitosis: (PMAT) + cytokinesis

Prophase: chromosomes become visible, begin to condense

Prometaphase: nuclear envelope disappears and chromosomes attach to mitotic spindle

Metaphase: chromosomes line up at metaphase plate/equatorial plane

Anaphase: sister chromatids separate by kinetochores Telophase: two daughter nuclei reform at the 2 poles

Cytokinesis (division of the cytoplasm) occurs simultaneously

Interphase Prophase

Metaphase Anaphase

Mitosis in plant cells differ from mitosis in animal cells Plant cells do not form centrioles during mitosis Plant cell walls are too rigid to form cleavage furrow

Forms cell plate instead

cell plate

Telophase/cytokinesis in a plant cell

cleavage furrow

Telophase/cytokinesis in an animal cell

Some terms

Gene: portion of DNA that encodes RNA and protein; determines your characteristics—freckles, height, eye color…

Chromosomes: contain DNA and protein; compact way of carrying all genetic info

Sister chromatids: copies of chromosomes joined together

Activities

A. Bead modeling B. View plant/animal cell slides

Part 1:View & draw Alium onion root tip, estimate % of time in each phase, answer questions

Part 2: View & draw White fish blastulae, estimate % of time in each phase, answer questions Exercise B: write answers on whiteboard (details on next

slide)