Lecture_5,_2008

Lecture_5,_2008 - BIO 187; FALL 2008 LECTURE 5, SEPTEMBER...

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B IO 187; F ALL 2008 L ECTURE 5, S EPTEMBER 11 M ITOSIS Read Chapter 9; go through the lab book exercises, and use the text’s online website. Know the mechanics of mitosis, use the terminology correctly and pay attention to what happens to the chromosomes, DNA and apparatus (eg centrosomes) relevant to mitosis. Don’t worry about the more detailed discussion of protein regulation in the book that goes beyond what we discussed in lecture. Both mitosis and meiosis are associated with cell division , in which two daughter cells are produced from a single parent cell. In each case, the chromosomes replicate, the cell divides, and DNA is partitioned between those two new cells: half moving into each one. Thus, mitosis, meiosis I, and meiosis II all involve the division of the number of pieces of DNA in half . However, they do it in different ways and with different goals. The function of mitosis: is to provide identical genetic information for two daughter cells. In organisms that reproduce sexually, mitosis is used as part of somatic cell division (not gamete production) – it is part of organismal growth and development. Some protists use mitosis to reproduce . They produce identical offspring (clones). Mitosis always occurs after the cell has replicated its chromosomes (no replication-no mitosis). Replication produces two identical pieces of DNA that are attached to each other at a point called the centromere . While they remain attached, these pieces of DNA are called chromatids , or sister chromatids . These chromatids will be separated during mitosis. The cell cycle Mitosis is part of a larger cell cycle, that has 4 phases: Gap 1 Synthesis Gap 2 Mitosis Gap 1, Synthesis and Gap 2 collectively make up interphase Why have a cell cycle? All living cells grow and also must carry out metabolic functions. Because they cannot grow infinitely large, cells must divide. However, the new cells need the same genetic information as the original cell. Therefore the genetic information must be duplicated (DNA replication ) and passed into the new cells.
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Lecture_5,_2008 - BIO 187; FALL 2008 LECTURE 5, SEPTEMBER...

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