Cell Division Chapter 2, Lesson 3 Page 56

What Are the Functions of Cell Division? Read the “My Planet Diary: Cycling On”…p. 56 Comparing Cell Cycles The table below compares the length of different cell cycles.

What are the Functions of Cell Division? Use the data table to help answer the following questions: 1. Which type of cell completes a cell cycle fastest? Frog egg cells 2. With each cell cycle, two cells form from one cell. In three hours, how many cells could form from one frog egg cell? 64 cells

What Are the Functions of Cell Division? Cell division allows organisms to: GROW REPAIR damaged structures REPRODUCE

What Happens During the Cell Cycle? During the Cell Cycle, a cell grows, prepares for division, and divides into two new cells, which are called “daughter cells.”

3 stages of the cell cycle The cell cycle consists of three stages: Interphase Mitosis Cytokinesis “I ‘M Cool”

Interphase – 1st stage of cell cycle more details… G1 - GROWING: Cell grows to full size Produces organelles it needs Makes more enzymes S - COPYING DNA: Makes an exact copy of DNA: REPLICATION At the end of replication, the cell has 2 identical sets of chromosomes G2 - PREPARING FOR DIVISION: Produces structures that will help it to divide centrioles, spindle fibers, etc.

Background of a chromosome p. 59 (stage 2: Mitosis) Chromosomes are made of 2 rod-like parts called chromatids; chromatids are identical to each other w/ the same DNA. Centromere holds the two chromatids together When a cell divides, one chromatid will go to each new cell

The cell’s nucleus divides into two new nuclei STAGE 2: MITOSIS The cell’s nucleus divides into two new nuclei One set of DNA is distributed into each daughter cell Divided into 4 phases:

Prophase Metaphase Anaphase Telophase (Pass My Algebra Test!) MITOSIS HAS 4 PHASES Prophase Metaphase Anaphase Telophase b (Pass My Algebra Test!)

Phases of Mitosis PROPHASE: Chromosomes in the nucleus condense (smash together) Nuclear envelope breaks down pairs of centrioles move to opposite sides of nucleus spindle fibers form a bridge between ends of the cell

Phases of Mitosis How does prophase look different from interphase? Chromosomes condense (the Xs); the nucleus is changing (nuclear envelope goes away)

Phases of Mitosis METAPHASE: Each chromosome attaches to a spindle fiber at its centromere. Chromosomes move to center of the cell Meta = middle

Phases of Mitosis What is missing from the cell in metaphase? Nucleus Prophase What is missing from the cell in metaphase?   Nucleus What happened to the chromosomes? the chromosomes moved to the center of the cell Metaphase

Phases of Mitosis ANAPHASE: Chromatids (now called chromosomes) move to opposite ends of the cell Cell stretches out

Phases of Mitosis TELOPHASE: Nuclei are forming (nuclear envelope reappears) Cell is pinching in at the middle

Stage 3: Cytokinesis Cytokinesis: Cytoplasm divides Each daughter cell has the same number of chromosomes as the parent cell

The cell’s nucleus divides into two new nuclei STAGE 3: Cytokinesis The cell’s nucleus divides into two new nuclei One set of DNA is distributed into each daughter cell Divided into 4 phases:

Length of a Liver Cell Cycle Do the Math – p. 63 Length of a Liver Cell Cycle Human liver cells generally reproduce less than once per year. At other times, they can complete one cell cycle in about 22 hours. The circle graph to the left displays this.

What do the three curved arrows outside of the circle represent? Do the Math – p. 63 What do the three curved arrows outside of the circle represent?

Do the Math – p. 63 What do the three curved arrows outside of the circle represent? Interphase, mitosis and cytokinesis

The wedge representing growth is in which stage of the cell cycle? Do the Math – p. 63 The wedge representing growth is in which stage of the cell cycle?

The wedge representing growth is in which stage of the cell cycle? Do the Math – p. 63 The wedge representing growth is in which stage of the cell cycle? Interphase

About what percentage of the cell cycle is shown for DNA replication? Do the Math – p. 63 About what percentage of the cell cycle is shown for DNA replication?

About what percentage of the cell cycle is shown for DNA replication? Do the Math – p. 63 About what percentage of the cell cycle is shown for DNA replication? About 45%

Do the Math – p. 63 What stage of the cell cycle takes the shortest amount of time? How do you know?

Cytokinesis; it is the smallest section of the graph Do the Math – p. 63 What stage of the cell cycle takes the shortest amount of time? How do you know? Cytokinesis; it is the smallest section of the graph