Wednesday, November 5, 2008

Inroduction to Chapter 12

Today we took the Unit 2 Test on Chapters 2, 4, 5, and 8. Hope it went OK for everyone. Ch 12 vocab cards were checked today as well, and the Ch 12 vocab quiz is TOMORROW so study up! Ms Lyon asked me to just introduce you into Chapter 12 and get a feel for it. So:

Chapter 12: The Cell Cycle

Everyone should have some knowledge of this from 10th grade Bio! This chapter will, of course, be a bit more in depth than we have previously learned.

Overview: The Key Roles of Cell Division

Cell division is the reproduction of cells.

The ability of organisms to reproduce their own kind is the one characteristic that best distinguishes living things from nonliving matter.

Rudolf Virchow said, "When a cell exists, there must have been some preexisting cell, just as the animal arises from an animal and the plant only from a plant."

When a unicellular organism, such as an amoeba, divides and forms offspring,
the division of one cell reproduces an entire organism.

Cell division on a larger scale can produce progeny (offspring) from some multicellular organisms (such as plants that grow from cuttings).

Cell division also enables sexually reproducing organisms to develop from a single cell--the fertilized egg, or zygote.

Cell division continues to function in repair and renewal after an organism is fully grown, replacing cells that die from normal wear and tear accidents
--E.g. dividing cells in your bone marrow continuously make new blood cells

Cell division is an integral process in the cell cycle.

The cell cycle is an ordered sequence of events in the life of a eukaryotic cell, from its origin in the division of a parent cell until its own division into two: composed of the M, G1, S, and G2 phases.

Passing identical genetic material to cellular offspring is a crucial function of cell division.

There is a molecular control system that regulates the cell cycle. Lack of regulation plays a major role in cancer development.

Here is an activity off of that will perhaps help you to better understand the roles of cell division

Key Concepts:
12.1 Cell divison results in genetically identical daughter cells.
12.2 The mitotic phase alternates with interphase in the cell cycle
12.3 The cell cycle is regulated by a molecular control system

Multiple Choice Questions
1. Which of the following is NOT a direct function of cell division?
A. health and well-being
B. tissue renewal
C. growth and development
D. reproduction

2. The person credited with first recognizing (in the 1860's) that living cells cannot arise spontaneously, but arise only from previously existing cells is __________.
A. Louis Pasteur
B. Robert Hooke
C. Rudolf Virchow
D. Anton van Leeuwenhoek

3. True or false:
The cell cycle is unregulated.

That's it for tonight; you might want to start reading Chapter 12 if you haven't already.

Answers: A, C, False

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