The Cell Cycle LN #14

The Cell Theory All cells come from preexisting cells. Cell division has two major roles in the life cycle of multicellular organisms. Allows organisms to develop from a fertilized egg to an embryo and then to an adult. Allows life to continue through the production of sperm and eggs.

Eukaryotes have chromosomes Chromosomes are made of DNA and protein. They are located in the nucleus. Chromosomes are visible under the microscope only when the cell is dividing. When a cell is not dividing they are in a tangled mass called chromatin.

Number of Chromosomes The somatic cells (all the body cells except sperm or eggs) contain a characteristic number of chromosomes. Human somatic cells have 46 chromosomes. Human sperm and egg cells have 23 chromosomes. Every somatic cell (body cell) in your body has the same DNA. Cells are specialized and only use part of the DNA for their specific job.

The Cell Cycle Interphase Mitosis Cytokinesis cell grows chromosomes duplicate cell parts are made 90% of cell cycle time Mitosis cell division Cytokinesis cytoplasm divides in two

Chromosomes Duplicate and Split Before the cell begins to divide the cell makes a copy of its chromosomes. Duplication results in two identical structures called sister chromatids. When cell divides sister chromatids are separated. Sister chromatids

Interphase is a period of cell growth and DNA replication Prophase Chromatid coils to form chromosomes. Nuclear envelope is gone. Spindle fibers move chromosomes to the center.

I Pee Mondays And Tuesdays Metaphase Chromosomes line up in the Middle. Anaphase Chromosomes are pulled Apart. Telophase Two cells are formed. I Pee Mondays And Tuesdays

Summary What are chromosomes made of Where are chromosomes located? What are the different parts of the cell cycle? What is mitosis? What are the different phases of mitosis?