Chapter 11 The Continuity of Life

Chapter 11 The Continuity of Life - Chapter 11 The...

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Chapter 11 The Continuity of Life I. Cellular Reproduction a. The cell cycle is the sequence of activities that occurs between one cell division and the next. b. Cell Division i. Growth ii. Renewal and repair iii. Reproduction c. Cell division is the process in which the genetic information of a cell is passed along to the next generation of cells. d. Involves the division of a parent cell into 2 daughter cells. e. Characteristics of cell division i. Replication of DNA ii. Equal distribution of DNA to opposite ends of the dividing cell iii. Separation into two daughter cells II. Asexual Reproduction a. Reproduction in which offspring are formed from a single parent, rather than through a fusion of gametes (sperm and egg) as in sexual reproduction. b. Asexual reproduction involves only one parent. Produces genetically identical offspring. III.Bacteria reproduce by binary fission a. Binary fission is a prokaryotic cell division, which literally means “splitting in two”. i. The circular DNA double helix is attached to the plasma membrane at one point. ii. The DNA replicates and the two DNA double helices attach to the plasma membrane at nearby points. iii. The plasma membrane between the attachment points enlarges, pushing them farther apart. iv. Once the cell has doubled in size, the plasma membrane rapidly grows inward between the 2 DNA attachment sites.
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v. The parent cell divides into two daughter cells, each containing a complete chromosome. IV. If the organism is single-celled then a cell cycle can be the same as the life cycle. a. The cell cycle is a well-ordered sequence of events during which the cell divides, grows and prepares to divide again. b. During the cell cycle interphase alternates with mitosis (a.k.a. M phase) c. Interphase is the period of the cell cycle when the cell is not dividing V. Interphase a. Non-dividing phase b. During this time, the cell is acquiring nutrients from its environment, growing, and replicating its DNA. c. Interphase makes up about 90% of the cell cycle d. High metabolic activity e. Chromosomes and organelles are duplicated f. Human skin cells divide about once a day. g. These skin cells spend about 22 hours in interphase. h. Consists of 3 phases: G1 phase, S phase, and G2 phase. VI. G 1 to G 0 phase a. Some cells can exit the G 1 phase and enter the G o phase. b. During G 0 , cells do not replicate their DNA and do not divide. c. Many cells undergo a process called differentiation in G 0 where the external signals that it receives will determine what type of cell it becomes. d. Many differentiated cells, including most of those in your heart, eye, and brain will stay in G 0 for the rest of your life. e. Most of these cells do not divide. VII.
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This note was uploaded on 05/04/2010 for the course BIOL 1001 taught by Professor Minor during the Fall '08 term at LSU.

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Chapter 11 The Continuity of Life - Chapter 11 The...

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