Biology Unit 8 – Cell Division Notes #1 (Chapter 5)

Cell Division For cells, bigger is not better As cells get bigger, volume increases faster than surface area This makes it difficult for the cell to take in enough nutrients and get rid wastes efficiently When a cell reaches its max size, the nucleus initiates cell division

Results of Cell Division The cell cycle is important for: reproduction in some organisms asexual reproduction = identical offspring Regeneration (ex – sea star) Budding Fission growth in multicellular organisms Cell differentiation Repair replacement of worn out or damaged cells, and repair of damaged tissues. Lesson 1

The Cell Cycle (cont.) Most cells in an organism go through a cycle of growth, development, and division called the cell cycle. There are two main phases in the cell cycle—interphase and the mitotic phase.

Part 1 -Interphase Interphase occurs in three stages: G1, S, and G2, and takes up 90% of the time of the cell cycle G1 (gap 1) Period of growth, DNA = chromatin S (synthesis) Chromosomes replicate Lesson 1

Part 1-Interphase G2 (gap 2) Cell creates organelles The cell’s DNA is copied during the S stage and is arranged as pairs of identical chromosomes called sister chromatids. Sister chromatids are held together by a structure called the centromere. G2 (gap 2) Cell creates organelles Lesson 1

The Mitotic Phase During mitosis, the contents of the nucleus divide, forming two identical nuclei. Lesson 1

The Mitotic Phase (cont.) Lesson 1

The Mitotic Phase (cont.) Lesson 1

The Mitotic Phase (cont.) Lesson 1

The Mitotic Phase (cont.) Lesson 1

The Mitotic Phase (cont.) In cytokinesis, the cytoplasm divides (cell membrane folds in) and forms two new daughter cells. Lesson 1

Mitosis

Metaphase Hint: Chromosomes are aligned in middle of cell Name that Stage! Metaphase Hint: Chromosomes are aligned in middle of cell

Name that Stage! Telophase Hint: Cell plate is splitting the cell

Name that Stage! Interphase Hint: Two normal looking nuclei of two cells

Name that Stage! Prophase Hint: Chromosomes are forming and the nucleus is gone

Name that Stage! Anaphase Hint: Chromatids are being pulled apart

Lesson 1

Review In order, name the 5 stages of the cell cycle. During which interphase stage do organelles replicate? What do you call the division of the cell’s cytoplasm ? During which interphase stage is DNA created? During which stage do spindle fibers form? During which stage are chromosomes aligned in the middle? During which stage are chromatids separated? During which stage does the nucleus dissolve? What is the result of mitosis? http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/36m.html

In order, name the 5 stages of the cell cycle. Interphase, Prophase, Metaphase, Anaphase, Telophase During which interphase stage do organelles replicate? G1 What do you call the division of the cell’s cytoplasm? Cytokineses During which interphase stage is DNA created? S During which stage do spindle fibers form? Prophase During which stage are chromosomes aligned in the middle? Metaphase During which stage are chromatids separated? Anaphase During which stage does the nucleus dissolve? What is the result of mitosis? 2 identical (daughter) diploid cells