Chapter 12 - Cell Division

Chapter 12 - Cell Division - Chapter 12 - The Cell Cycle...

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Chapter 12 - The Cell Cycle Cell division functions in reproduction, growth, and tissue renewal o Cell division is the process in which the genome of a cell is faithfully passed along to the next generation of cells. o Genome is the total endowment of genetic material unique to each species (uniqueness doesn’t pertain to clones and our cells are clones) Some characteristics of cell division o Replication of DNA – In order to make 2 cells, the DNA must be copied faithfully o Equal distribution of DNA to opposite ends of the dividing cell – Must be separated into two piles that are identical (bulk of process happen here o Separation into two daughter cells – cytoplasm is separated The Eukaryotic Cell Cycle Each species has a characteristic number of chromosomes in the somatic cells , which are cells that make up the body of the organism (except for the reproductive cells). Somatic Cells are usually diploid. Diploid is the condition where cells have two sets of chromosomes. Usually, each set is derived from a different parent. Gametes, also called sex cells or germ cells, are the cells that take part in sexual reproduction. Haploid is the condition where cells have only one set of chromosomes. The genome of a eukaryotic cell is organized into multiple chromosomes o Chromosomes – a structure made up of a material called chromatin Can be linear or have an “X” shape structure. When DNA is duplicated, the chromosome is taken from a long linear structure to an “X” structure. o The chromosome is made up of chromatin Chromatin – a composite made of long DNA molecule and protein in eukaryotic cells. DNA + Protein build chromosomes The aggregate mass of dispersed genetic material formed of DNA and protein DNA is formed from a skinny molecule to a short condensed package The DNA is packaged right before it is moved during the cell cycle. It is constructed into a structure that is highly organized and ready to move. Now that it is packed, the genes are inaccessible. So the DNA is only packed as long as it takes to move it and separate it into the 2 equal piles.
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The Cell Cycle Mitosis alternates with interphase during the cell cycle . Mitosis is a very small part of the cell cycle, where you can see the chromosomes. The replication of each chromosome results in a pair of chromosomes called sister chromatids. When the DNA goes from being linear to “X” shaped, the chromosome in the “X” configuration represents a pair of sister chromatids. But this statement is wrong in terms of what it tells you. It is NOT a pair of chromosomes yet, it is A chromosome. To keep track of how many chromosomes you have is to count the centromeres, which are located in the center of the chromatids. The replication of each chromosome actually results in A chromosome made up of sister chromatids. The replication occurs during S-phase interphase. It is NOT part of mitosis. It happens well in advance of when mitosis happens. S-phase of interphase stands for synthesis of DNA
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Chapter 12 - Cell Division - Chapter 12 - The Cell Cycle...

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