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Chapter 8 – Study Guide 1. What is the role of histones in the cell? Proteins that DNA wraps around in order to allow the genetic code to fit into the nucleus. 2. Explain the difference between chromatids and chromosomes. Chromatids are two identical halves of a chromosome. 3. What is the difference between prokaryotes and eukaryotes chromosomes? Prokaryotic DNA is circular. They only have 1 chromosome and no nucleus. Eukaryotic DNA is linear and have many chromosomes. 4. What is binary fission? Cell reproduction in bacteria. 5. What are the stages of the cell cycle in order? G1 S G2 M C 6. What occurs during crossing over in prophase I? Genetic material is swapped between tetrads of chromosomes. This increases the variability within offspring. 7. What is a tetrad? Homologus chromosomes that are next to each other and part during anaphase I. 8. What are the end products of the cell cycle? Meiosis? 4 non-idential haploid cells. 9. What is the advantage of sexual reproduction over asexual reproduction? Sexual reproduction increases the advances of evolution as well as the variation among offspring. 10. What happens during the three stages of interphase? The cell first grows, doubles the organelles, duplicates the DNA, and grows some more. Throughout this time the cell is being regulated with cyclins. 11. What do cyclins do? Keep time of cell cycle as well as check/repair for any signs of mutation or change. 12. Why are stem cells important? They have the ability to become any type of cell in the body. 13. What is the importance of chromosomes during cell division? During mitosis, the nucleus of a cell divides into two nuclei, each containing a complete set of the cell’s chromosomes. Thus, each new cell formed during cell division contains identical DNA. 14. What do cancer cells look like? What can they develop into? Cancer cells typically do not have a circular round shape like normal cells. They have much less cytoplasm, and their nuclei are dark and dense. If cancer cells are not stopped and regulated, they can become a tumor. 15. Fill in the follow tables. Stage of cell cycle What’s happening? Cell growth Interphase Duplication of organelles Duplication of DNA Regulation Chromatin Chromosomes Prophase Nucleus disappears Centrioles begin to make sprindle fibers and move to opposite poles Metaphase Chromsomes line up at the equator of the cell Anaphase Chromosomes split at the centromere and break into sister chromatids Plant: Nuclei reappear, Chromosomes Chromatin, cell plate forms in center of two cells Telophase Cytokinesis Animal: Nuclei reappear, Chromosomes Chromatin, cleavage furrow forms in center of two cells Cytoplasm splits into two separate cells What cell looks like Stage of Meiosis Prophase I What’s happening? Nucleus disappears Chromatin Chromosomes Spindle fibers from centrioles Centrioles move to opposite poles Tetrads form, crossing over Metaphase I Tetrads line up randomly along equator of the cell Anaphase I Tetrads separate randomly to opposite poles of the cell Telophase/ Chromosomes reach opposite poles Cytokinesis I Cleavage furrow appears Nucleus disappears Prophase II Chromosomes move Spindle fibers from centrioles Metaphase II Chromosomes line up randomly along equator of the cell Anaphase II Chromosomes separate randomly to opposite poles of the cell Telophase/ Chromosomes reach opposite poles Cytokinesis II Cleavage furrow appears What cell looks like