Chapter 12 - Copy - BIOLOGY 51 Dovala 1 The Key Roles of...

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BIOLOGY 51 Dovala 1 The Key Roles of Cell Division 1. Explain how cell division functions in reproduction, growth, and repair. Larger organisms do not have larger cells than smaller organisms, they just have more cells. Cell division (mitosis and cytokinesis) provide these extra cells. Also, when something is damaged, signals are sent to neighboring cells to start dividing, allowing for repairs to take place. A scab is a good example of this process. In reproduction, the fertilized zygote undergoes mitosis to grow a full multicellular organism. Meiosis, a similar process to mitosis, is used for the production of gametes in reproduction. 2. Describe the structural organization of a prokaryotic and eukaryotic genome. In prokaryotes, the genome is circular and resting in a region known as the nucleoid. Eukaryotes have linear DNA that is coiled many times into chromosomes. 3. Describe the major events of cell division that enable the genome of one cell to be passed on to two daughter cells. Interphase : The cell grows during the G1 phase and produces more organelles. Then the DNA is duplicated in the S phase. Final checkpoints and growth takes place in the G2 phase. Prophase : The chromosomes condense and the nuclear envelope breaks apart. Metaphase : The chromosomes, sets of two sister chromatids connected at the centromere, line up on the metaphase plate and are attached to spindles emanating from the poles of the cells. Anaphase : The spindles pull the sister chromatids apart and start pulling them to their respective poles. Telophase : The chromatids are at the poles. New nuclei begin to form. Cytokinesis begins. Cytokinesis : The cell physically divides in two. Two daughter cells are produced each genetically identical to the parent cell. 4. Describe how the chromosome number changes throughout the human life cycle. The human starts as a zygote, a fertilized egg. This stage is diploid. The zygote undergoes mitosis until a multicellular organisms (human) is produced. This stage is also diploid. The mature human produces gametes which are haploid. The gametes come together to form the zygote. All diploid stages have 2n = 46 chromosomes, and all haploid stages have n = 23 chromosomes.
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This note was uploaded on 05/22/2011 for the course BIO 6 taught by Professor Lalala during the Spring '11 term at East Los Angeles College.

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Chapter 12 - Copy - BIOLOGY 51 Dovala 1 The Key Roles of...

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