Mr. Fuchigami Wednesday, April 11th, 2018 THE CELL CYCLE Mr. Fuchigami Wednesday, April 11th, 2018

Review: Unicellular vs. Multicellular Organisms

What is the cell cycle? A repeating series of events that occur as a cell grows and divides. Cells need to make new copies of themselves in order to: Grow and replace damaged or dead cells (multicellular organisms). Form a new unicellular organism.

Cell Cycle Rates FAST: Cells are constantly dividing throughout their lifespan. SLOW: Cells very rarely or never divide. Examples: -Fast: skin cell, nail cell, hair follicle cell -Slow: brain cell, eye cell Skin cell Brain cell

2 Main Phases of Cell Cycle Interphase: Cell grows and duplicates its DNA to prepare for cell division. DNA exists in the form of chromatin. Mitosis & Cytokinesis: Cell divides to produce 2 identical cells called daughter cells. DNA exists in the form of chromosomes.

Different Steps of the Cell Cycle G1 (Gap 1): Cell grows in size. Cell organelles (excluding the DNA) are duplicated. S (Synthesis): Each of the 46 chromosomes are duplicated = DNA synthesis.

Different Steps of the Cell Cycle G2 (Gap 2): Cell continues to grow and prepares for cell division. M (Mitosis): Nuclear division. Genetic material is separated equally into 2. Cytokinesis: Cell divides the cytoplasm and organelles to produce 2 identical daughter cells.

Cell Cycle - Overview

Cell Cycle Checkpoints Specific points during the cell cycle where we check for mistakes in or damages to the cell and/or DNA. The cell cycle must be stopped so that the cell can be repaired or killed.

Different Cell Cycle Checkpoints G1 checkpoint: Check the cells for DNA damage. Cell must grow to an appropriate size and have enough energy to prepare for cell division. G2 checkpoint: Check to make sure DNA has been correctly duplicated. There should be no damages or mistakes. M checkpoint: Check to make sure chromosomes will be separated into two cells equally. *Indicate on the diagram of the handout.

Textbook Terms Please read pages 105-107 and define the bolded terms: Chromosome Chromatin Gene Somatic cell Mitosis Sister chromatid Centromere Spindle fibres