Cell Cycle and Mitosis

Why do cells divide rather than grow bigger? Have you ever been in a traffic jam in a small town? Where are major traffic jams found? As a city’s population grows, more people are moving in an out which causes traffic. Cells are like cities: The bigger they are, the more food, water, and waste that must move in and out to keep the cell alive.

Why do cells divide rather than grow bigger? To prevent traffic jams, they will divide Cells divide for 4 major reasons: 1. 2. 3. 4.

Why do cells divide rather than grow bigger? To prevent traffic jams, they will divide Cells divide for 4 major reasons: 1. Prevent the cell from becoming too big (prevent traffic jam) 2. To heal injuries 3. To allow the organism to grow (up) 4. To reproduce (new individuals)

Before we get started with the cell cycle… Before we get started with the cell cycle…. Let’s talk about chromosomes Chromosome: DNA - containing structure that carries genetic material from one generation to another.

What happens during the cell cycle? Cell Cycle - Process of cellular reproduction, occurring in the main stages Interphase (_______) Mitosis (____________) Cytokinesis (_________________)

What happens during the cell cycle? Cell Cycle - Process of cellular reproduction, occurring in the main stages Interphase (growth) Mitosis (nuclear division) Cytokinesis (cytoplasmic division)

What occurs during Interphase (the 1st step in cell cycle) There are 3 stages during interphase: 1st Grows 2nd Duplicates DNA 46 Chromosomes 92 Chromosomes 3rd Prepares to divide

Interphase Up Close First Gap phase (G1): cell growth, non-dividing cells remain in this phase Synthesis phase (S): DNA is copied (duplicated); each chromosome now consists of 2 identical chromatids Second Gap phase (G2): cell continues to grow and prepare to divide; microtubules are formed in the cytoplasm

Question 1: Which of the following is NOT a reason cells divide? To heal injuries To allow the organism to grow To reproduce To maintain homeostasis

Question 2: What will happen if the cell continued to grow rather than divide? The organism would get too big. Food & wastes would not be able to move in & out as easily. The surface area would increase and allow more materials into and out of the cell. Nothing would happen.

What are the 3 stages of the cell cycle? Question 3: What are the 3 stages of the cell cycle? Prophase, Metaphase, & Anaphase Mitosis, Telophase, & Cytokinesis Interphase, Metaphase, & Prophase Interphase, Mitosis, & Cytokinesis

Question 4: Which of the following is NOT a stage during Interphase? Growth (G1) DNA replicates (S) Prepares to divide (G2) Mitosis (M)

What is Mitosis? Mitosis: 2nd main stage of the cell cycle during which the cell’s replicated DNA divides and 2 genetically identical diploid daughter cells are produced.

What occurs during mitosis? (the 2nd step in cell cycle) There are 4 stages during mitosis: 1st Prophase (pro = 1st) 2nd Metaphase 3rd Anaphase 4th Telophase (telo = end)

What occurs during mitosis? (the 2nd step in cell cycle) There are 4 stages during mitosis: 1st Prophase (pro = 1st) Nucleus disappears Centrioles separate

What occurs during mitosis? (the 2nd step in cell cycle) There are 4 stages during mitosis: 2nd Metaphase Chromosomes line up in the middle

What occurs during mitosis? (the 2nd step in cell cycle) There are 4 stages during mitosis: 3rd Anaphase Chromosomes move apart

What occurs during mitosis? (the 2nd step in cell cycle) There are 4 stages during mitosis: 4th Telophase (telo = end) Nucleus reappears Cytoplasm starts to separate

What occurs during cytokinesis? (the 3rd step (LAST) in cell cycle) Cytokinesis: The last stage of the cell cycle, during which the cell’s cytoplasm divides, creating a new cell. Daughter Cells

Question 5: Mitosis creates 4 genetically identical cells. 4 genetically different cells. 2 genetically different cells.

What are the 4 stages of mitosis in order? Question 6: What are the 4 stages of mitosis in order? Interphase, prophase, metaphase, anaphase Interphase, prophase, metaphase, telophase Prophase, metaphase, telophase, cytokinesis Prophase, metaphase, anaphase, telophase

Question 7: Cytokinesis Interphase Telophase Metaphase This is the last phase of the cell cycle where the cell’s cytoplasm divides to create 2 daughter cells: Cytokinesis Interphase Telophase Metaphase