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Unit 4 modified portfolio Comparing Mitosis and Meiosis (18 points total are possible) Review the comparison of mitosis and meiosis, below, and use the information to help you fill in the chart. Cell Division Smaller cells are more efficient at transporting materials in/out of the cell, than larger cells. When cells grow too big, they divide. They also divide for repair (healing) Before cells can divide, they must copy all of their DNA, first, to ensure the new cells get the correct number of chromosomes. This process is called DNA replication (copies) and occurs during the “S” (synthesis) phase. 2 types of cell division: Mitosis produces diploid cells (2 of each chromosome) and they are exact copies of parent cell. Some organisms, can reproduced by mitosis. Hydra can form buds, which are genetic clones of the parent but will eventually become a new hydra. Meiosis produces haploid cells (1 of each chromosome –half) and they are genetically different than the parent cell. 4 phases of cell division Prophase: prepare to divide nucleus dissolves, temporarily to allow chromosomes to move around (“pro” means before) Metaphase: chromosomes line up in the middle of the cell (“meta” means middle). While lined up in the middle, spindle fibers attach to pull sister chromatids apart Anaphase: chromosomes get pulled apart (with the help of centrioles “cowboys” in animal cells) Telophase: the nucleus begins to reappear after chromosomes are separated to each new cell Cytokinesis: the cytoplasm divides. In plants it occurs with a cell plate and in animals cells it occurs with a cleavage furrow (like a drawstring bag). Chart is worth 6 points Mitosis Define the process What is the purpose of this type of division? (growth and repair or production of gametes) Where in the body, does it occur? (ex. all body cells or reproductive organs) Type of cell produced? (Ex. an exact copy or genetically diverse cells) Are daughter cells haploid or diploid? (ex. n or 2n) Involves crossing over and recombination of genes? (yes or no) Number of divisions? (1x or 2x) Number of cells produced (2 or 4) In human cells, the final chromosome number produced (23 or 46) Meiosis Analysis Questions (2 points each) 1. Crossing over, between non-sister chromatids during meiosis is significant in heredity. This process most likely leads to an increase in which of the following? a. The expression of dominant traits b. Number of gametes c. The occurrence of polyploidy d. Genetic variation 2. Which of these must occur during S phase, of the cell cycle, so that two daughter cells can be produced during M phase? a. The DNA must be replicated b. The chromosomes must be joined c. The cytoplasm must be separated d. The cell membrane must be expanded 3. The leaf cells of the white oak (Quercus alba) contain 24 chromosomes. After meiosis is complete, how many chromosomes are in the new cells? a. 12 b. 20 c. 24 d. 48 4. A cut on a frog’s foot will repair itself using the process of – a. Mitosis b. Meiosis c. Phagocytosis d. Pinocytosis