How Do Cells Replace Themselves

The Cell Cycle and Mitosis Before You Read How do cells replace themselves? Record your ideas on the lines below. ◆ growth and cell activity ✏ Mark the Text cytokinesis Highlight the text that describes the three stages of the cell cycle. In a different colour, highlight text that describes how cells divide. Use the highlighted text to create a chart about the life of a cell. Inter phase Create a Chart DNA is copied mitosis continued growth and preparation for mitosis What is the cell cycle? The three stages of the life of a cell together are called the cell cycle. These three stages are: ◆ interphase: This stage makes up most of the life of the ✔ ● cell. During interphase, cells grow and carry out their life functions. In cells that will divide, the nucleus makes a copy of its DNA in a process called replication. Reading Check 1. What are the three stages in the life of a cell? ◆ mitosis: During this stage, the nucleus of the cell divides into two equal and identical parts. Each part has a copy of the DNA. ◆ cytokinesis: During this stage, the two equal, identical parts of the cell separate. The result of this stage is two identical cells, each with a nucleus and DNA. ● ✔ What are the phases of mitosis? There are four phases of mitosis. These phases are prophase, metaphase, anaphase, and telophase. Phases of mitosis What happens prophase • the duplicated chromosomes form into an X shape and the nucleolus disappears. • spindle fibres, which are tiny tube-like structures made of protein, begin to form in plant and animal cells metaphase • the duplicated chromosomes line up across the middle of the cell anaphase • the duplicated chromosomes move apart to opposite ends of the cell telophase • a nucleolus forms around the chromosomes at the opposite ends of the dividing cell How can mutagens affect the cell cycle? Mutagens can cause changes in the cell cycle so that cells keep dividing continuously. The cells pile up on top of one another, forming a lump called a tumour. The uncontrolled cell division sometimes results in diseases called cancers. Cancerous cells may grow in one place in the body, or they may spread to other parts of the body where they will continue to divide. ● ✔ ✔ ● Reading Check 2. What is cancer the result of ? Getting to know the cell cycle Vocabulary mitosis nucleolus nucleus prophase telophase three two anaphase cell cycle cytokinesis DNA duplicated chromosomes four interphase metaphase Use the terms in the vocabulary box to fill in the blanks. You can use each term more than once. You will not need to use every term. 1. There are stages in the life of a cell. 2. The stage that makes up most of the cell’s life is . During this stage, cells grow and carry out their life functions. In cells that will divide, the nucleus makes a copy of its . 3. During , the nucleus of the cell divides into two equal and identical parts. Each part has a copy of the DNA. 4. During separate. This stage forms nucleus and DNA. , the two equal, identical parts of the cell identical cells with a 5. There are phases of mitosis. 6. In X shape and the , the duplicated chromosomes contract into an disappears. 7. In middle of the cell. , the line up across the 8. In opposite ends of the cell. , the move apart to 9. In ,a chromosomes at the opposite ends of the dividing cell. forms around the Identifying stages of the cell cycle Vocabulary continued growth and preparation cytokinesis replication growth and preparation interphase mitosis Use the vocabulary words in the box above to label the stages of the cell cycle in the following diagram. 1. 5. 2. 6. 4. 3. Briefly describe what is occurring in each stage of the cell cycle. 1. 2. 3. 4. 5. 6.