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Chapter 4 Cell Reproduction Section 1: Cell Division and Mitosis A. Cell division—increases the number of cells and causes many-celled ____________________to grow B. The Cell Cycle—series of events that takes place from one ____________________ to the next 1. Cells have periods of formation, growth and development, and death called ________________________________. 2. Interphase—most of the life of any eukaryotic cell, or cell with a nucleus, is spent in a period of _________________and ________________. a. During interphase, a cell duplicates its ____________________ and prepares for cell division. b. After interphase, the nucleus divides, and then the ______________________separates to form two new cells. C. Mitosis—process in which the nucleus divides to form two identical __________________ 1. Chromosome—structure in the nucleus that contains ___________________ material 2. Prophase a. Nucleolus and ______________________________ disintegrate. b. ________________________ move to opposite ends of the cell. c. __________________________ begin to stretch across the cell. 3. Metaphase—pairs of ___________________ line up across the center of the cell. 4. Anaphase a. Each _____________________ divides. b. Each pair of chromatids __________________ and moves to opposite ends of the cell. 5. ________________—spindle fibers disappear and a new nucleus forms. D. Division of the Cytoplasm—for most cells, the _______________ separates after the nucleus divides. 1. In ___________________ cells, the cell membrane pinches in the middle and the cytoplasm divides. 2. In ______________________ cells, a cell plate forms. E. Results of mitosis 1. Each cell in your body, except sex cells, has a nucleus with _____ chromosomes. 2. Allows growth and__________________ worn out or damaged cells F. __________________________—a new organism is produced from one parent organism. 1. An organism with no nucleus divides into two identical organisms by ______________. 2. ____________________—a small, exact copy of the adult grows from the body of the parent. 3. In ________________________, a whole new organism grows from each piece of the parent. Discussion Question Why is cell division important? __________________________________________ _________________________________________________________________ ______________________________________________________________ Section 2: Sexual Reproduction and Meiosis A. ___________________ reproduction—two sex cells, usually an egg and a sperm, come together. 1. Fertilization—the joining of an __________ and a ____________, generally from two different organisms of the same species a. Sperm are formed in the ___________ reproductive organs. b. Eggs are formed in the ___________________ reproductive organs. c. A cell that forms from fertilization is a ____________________. 2. Following fertilization, ______________________ begins and a new organism develops. 3. Human body cells are ________________, because they have 23 pairs of similar chromosomes. 4. Human sex cells are ________________, because they have 23 single chromosomes. B. ___________________—a process that produces haploid sex cells and ensures that offspring have the same diploid number as its parent 1. In meiosis I, the nucleus divides and produces two new cells with one duplicated ______________________ each. 2. In meiosis II, the nuclei divide and the chromatids separate, producing _______ cells with half the number of chromosomes of the original nucleus. Discussion Question Why do you think sex cells must be haploid? _______________________________ _______________________________________________________________ _______________________________________________________________ Section 3: DNA A. DNA—a ____________________ that contains information that an organism needs to grow and function 1.Watson and ________________ made an accurate model of DNA in 1953. 2. The structure of DNA is similar to a ______________________________. a. The sides of the ladder are made up of _________________________. b. The rungs of the ladder are made up of ________________________. 3. Before a cell divides, its DNA duplicates itself by unwinding and separating its sides, then each side becomes a pattern on which a ________________- forms. B. Genes—sections of _________ on a chromosome 1. Contain instructions for making specific _______________ 2. RNA carries the ___________ for making proteins from the nucleus to the ribosomes in the cytoplasm. a. Messenger RNA carries the code that directs the order in which the ___________________________ bond. b. Ribosomal RNA makes up ________________, where proteins are built. c. _______________RNA brings amino acids to the ribosomes to build the protein. 3. Cells use only the _____________ that direct the making of proteins needed by that cell. C. Mutations—any permanent _____________ in the DNA sequence of a cell’s gene or chromosome 1. Can be caused by outside factors like X rays, _________________, and some chemicals 2. A change in a gene or chromosome can change the ____________ of an organism.