Vocabulary Cell cycle Interphase Mitosis Cytokinesis Spindle Centrosome

Eukaryotic Cell Cycle: Discovery Reading Questions 1. The first three phases together are known as ______. Name & describe the phases. a. b. c. The remaining two phases make up _______. Name & describe the phases. d. e. 2. Which stage do most cells (except skin cells) spend most of its time in? 3. Which stage is DNA copied in? 4. What is mitosis? 5. What’s the significant difference between mitosis & cytokinesis?

Get into Groups 2 books per group. Work with books in partners.

Objectives: Cell Division & the Cell Cycle Identify and restate what the phases of the eukaryotic cell cycle are. Restate what happens in each stage of the cycle.

A Cell Divided You know that a cell goes through division for three main reasons: › To replace old or… › To repair damaged tissue or… › To allow an organism to grow. This process of cell division doesn’t happen randomly as you can expect. It is highly regulated and has distinct features. As such, there are five main stages during a cell’s life, during each of which specific things happen.

The Cell Cycle These stages make up what is called the cell cycle. The cell cycle is a repeating sequence of cellular growth and division during the life of a cell. Your job today is to discover what these five stages are and identify the main process that happens during each of these stages.

Cell Cycle Posters 25 pts. Illustrate the cell cycle on a piece of copy paper. These will go into your notebooks but will be for a grade. Check them off with me for credit. Use the drawing on page ______ (Cell Cycle) as your basis for your poster. Use the pages of the book to help describe the steps. Each Step of the cell cycle must be correctly depicted on your poster. For each step you must include at least 3 points and 1 drawing. For Synthesis you must describe the purpose of replication. For Mitosis you must label the goal. Use color and check your grammar. Cell Cycle

The Cell Cycle

Interactive Cell http: //www. exploratorium. edu/traits/cell_expl orer. html

Eukaryotic Cell Cycle Interphase During interphase, the cell is not dividing. It is growing, making proteins, metabolizing sugars and other nutrients, and preparing to divide. Different types of cells spend different amounts of time in interphase dependent upon their roles in the body. Cells that divide often, such as skin cells, spend less time in interphase. › Their job is more for protection & produce a shield, not to produce proteins. Cells that divide seldom, such as nerve cells, spend most of their time in interphase. › Their job is more for relaying information. › Muscle and other tissue cells are in this category.

Eukaryotic Cell Cycle Interphase During the first gap phase (G 1), a cell grows rapidly as the cell builds more organelles and makes proteins. For most organisms, this phase occupies the major portion of the cell’s life as the cell performs most “life” functions here (like transcription & translation… gene expression) During the synthesis phase (S), a cell’s DNA is copied. At the end of the S phase, the cell’s nucleus has twice as much DNA as it did in the G 1 phase. This, as you now know, is replication. During the second gap phase (G 2), the cell continues to grow and prepares to divide. Hollow protein fibers called microtubules are organized in the cytoplasm during G 2.

Interphase Cell Only the nucleolus is visible under a microscope. The DNA is all spread out.

Eukaryotic Cell Cycle Cell Division In addition to duplicated DNA, each new cell requires a complete set of organelles. This is accomplished in G 2. The rest of the cell cycle is dedicated to dividing the cell’s now-duplicated chromosomes and the cytoplasm. The process of dividing the nucleus into two daughter nuclei is called mitosis. The process of separating the organelles and the cytoplasm is called cytokinesis.

Objectives: Mitosis Identify and restate what the four stages of mitosis are. Identify when and why cytokinesis occurs.

Review & Reset Vampire Mitosis You have learned that cells divide for several reasons. You also learned about how DNA is prepared before the cell divides. Today you will learn the process…What happens through the life of a cell.

Interphase Cell Only the nucleolus is visible under a microscope. The DNA is all spread out.

Interphase Remember, interphase is broken down into 3 separate stages. › G 1: Cell Growth accomplished by making new proteins. › S: Replicating the DNA to go from 46 chromatids to 96 chromatids. Basically, doubling all the genes. › G 2: Doubling organelle and prepping the DNA for cell division.

Stages of Mitosis Although mitosis is a continuous process, biologists traditionally divide it into four stages. Mitosis is a continuous process that can be observed in four stages: Prophase Metaphase Anaphase Telophase

Stages of Mitosis Stage 1 Prophase 1. Within the nucleus, chromosomes begin to condense and become visible under a light microscope. 2. The nuclear membrane breaks down. Outside the nucleus, a special structure called 3. the spindle forms. The spindle is made up of several spindle fibers. Each spindle fiber in turn is made up of an individual microtubule—a hollow tube of protein. Microtubules organize into a spindle that runs at a right angle to the cell’s equator.

Stages of Mitosis Stage 1 Prophase Cells have an organelle called the centrosome, which helps assemble the spindle. In animal cells, the centrosome includes a pair of centrioles. Each centriole is made up of nine triplets of microtubules arranged as a short, hollow tube. 4. Before mitosis, the cell’s centrosome is duplicated. During prophase, the centrosomes move to opposite poles of the cell. › This gives 4 centrioles

Prophase Click to animate the image. C B F E D A

Identify the stage of this Cell Prophase Cell

Metaphase Cell

Stages of Mitosis, continued Stage 2 Metaphase During metaphase, the chromosomes are packaged into their most condensed form. 1. The nuclear membrane is fully dissolved, and the condensed chromosomes move to the center of the cell and line up along the cell’s equator. 2. Spindle fibers link to the centromere of each chromosome.

Anaphase Cell

Stages of Mitosis, continued Stage 3 Anaphase Once all of the chromosomes are lined up, 1. the spindle fibers shorten. The spindle fibers shorten by breaking down the microtubules bit by bit. 2. Sister chromatids move toward opposite poles as the spindle fibers that are attached continue to shorten. Each pole now has a full set of n chromosomes.

Telophase Cell

Stages of Mitosis, continued Stage 4 Telophase 1. A nuclear envelope forms around the chromosomes at each pole of the cell. 2. Chromosomes, now at opposite poles, uncoil and change back to their original chromatin form. 3. The spindle dissolves and the spindle fibers break down and disappear. Mitosis is complete.

Cytokinesis

Cytokinesis As mitosis ends, cytokinesis begins. The cytoplasm is separated, and two cells are formed. During cytokinesis, the cell membrane grows into the center of the cell and divides it into two daughter cells of equal size. Each daughter cell has about half of the parent’s cytoplasm and organelles. The end result of mitosis and cytokinesis is two genetically identical cells in place of the original cell.

Cytokinesis Separating the Cytoplasm In animal cells ( and other cells that lack cell walls ), the cell is pinched in half by a belt of protein threads. In plant cells and other cells that have rigid cell walls, the cytoplasm is divided in a different way. In plants, cell division is accomplished by vesicles creating a large, membrane-bound cell wall called the cell plate.

Cytokinesis Continuing the Cell Cycle After cytokinesis is complete, each new daughter cell enters the G 1 stage of interphase. The daughter cells are about equal in size—about half the size of the original cell. The activity of each cell continues because each has its own DNA and organelles. The cell cycle continues for each new cell.

Interphase Animal Cell Plant Cell Photographs from: http: //www. bioweb. uncc. edu/biol 1110/Stages. htm

Prophase Animal Cell Plant Cell Spindle fibers Centrioles Photographs from: http: //www. bioweb. uncc. edu/biol 1110/Stages. htm

Metaphase Animal Cell Plant Cell Photographs from: http: //www. bioweb. uncc. edu/biol 1110/Stages. htm

Anaphase Animal Cell Plant Cell Photographs from: http: //www. bioweb. uncc. edu/biol 1110/Stages. htm

Telophase Animal Cell Plant Cell Photographs from: http: //www. bioweb. uncc. edu/biol 1110/Stages. htm

Animal Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Cytokinesis

Plant Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Cytokinesis

REMEMBER!. . . The Cell Cycle Stages Interphase Prophase Metaphase Anaphase Telophase Cytokinesis IPMATC I Play Music At The Concert

Cell Cycle 41

Mitosis Notes Assignment On the worksheet, complete the mitosis notes. These are not word-for-word so work with your group mates & come up with logical answers. Skip & come back to those you can’t figure out. Use the illustrations on the board to fill in the ovals. Use books!!!

How can you apply this? › Your lab today will allow you to practice identifying cells in each phase. › The question you are trying to answer is how long does a cell stay in each phase of the cell cycle? › What does this mean about the life of a cell? › First, predict how many hours a cell might spend in each phase of the cell cycle. • Onion Root Tip Lab • Turn your sheet to the side with the picture so we can try to determine 1 of each kind of cell

Decide which phase each numbered cell is. IF YOU THINK THE CELL IS IN 1. Anaphase CYTOKINESIS THEN COUNT IT AS 2 CELLS IN INTERPHASE. 2. Interphase 3. Telophase 4. Prophase 5. Metaphase 3 1 5 IF YOU CAN’T TELL IT’S IN INTERPHASE 2 4 THIS IS DUE FRIDAY THE NUCLEOLUS IS THE FEATURE OF A CELL IN INTERPHASE

Summary The life of a eukaryotic cell cycles through phases of growth, DNA replication, preparation for cell division, and division of the nucleus and cytoplasm. Mitosis is a continuous process that can be observed in four stages: prophase, metaphase, and telophase. During cytokinesis, the cell membrane grows into the center of the cell and divides it into two daughter cells of equal size. Each daughter cell has about half of the parent’s cytoplasm and organelles.

Self Test Look at the next 2 slides. Before you advance, try to fill in all the blanks with the most reasonable answer. If you can do this without notes, you are getting close to understanding the stepd of the cell cycle.

Interphase growth synthesis Cell division cytoplasm Interphase G 1 organelle major portion S G 2 copied Divide Mitosis condense membrane spindle centrosomes poles

Metaphase equator chromosomes chromatid centromere opposite Cytokinesis Mitosis Anaphase Spindle fibers chromatid sister Telophase Sister chromatid Nuclear membrane spindle chromosomes chromatin cytokinesis Mitosis protein belt Cytokinesis middle Genetically identical daughter