LECTURE 03 CELLULAR BASIS OF LIFE

LECTURE 03 CELLULAR BASIS OF LIFE - 2:010 Principles of...

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2:010 Principles of Biology 1 LECTURE 3 THE CELLULAR BASIS OF LIFE We have agreed that: Life is composed of physical matter and is governed by the laws of physics and chemistry. Specific properties of life can be included in its metabolic and evolutionary aspects. One of the main topics of biology is the nature of the structure of living matter. The study of biological structure is called anatomy or morphology . It addresses the following questions: How is physical matter organized in things considered to be alive? Are there any patterns to the way living matter is organized? What is the smallest unit of matter that is alive? Historically, the first things considered to be alive were visible to the naked eye and relatively large. Descriptions of structure were based on what could be seen both externally and internally after dissection. How would you determine if these large organisms were made of smaller units that were also alive? You could cut them in half and see if these halves were alive and continue this process until the smallest fragment that retained life was found. If you do this on a human you get 2 pieces that die shortly after the first cut is made. However, other organisms can be cut into many smaller parts and each of these parts will remain alive and regrow into a new entire organism. This is seen in some animals. 1 HYDRA FLATWORM
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And in some plants: These are examples of organisms with great regenerative ability. There are other organisms that can only regenerate parts of the body. Cut off a limb and the limb cannot form a new animal but the body can replace the limb. One of the major questions in human biology is why do we have such a limited ability to regenerate. Are there ways to increase human regenerative abilities? The conclusion from these kinds of studies is that yes there are fragments of whole organisms that are alive and that can regrow into whole bodies or parts of bodies. Further information on the structures of such even smaller parts of organisms required the development of technology like the light microscope to enable the examination of organisms at higher magnification. This was first done by Robert Hooke in 1665 when he examined cork (plant tissue). He detected many small units each of which appeared separate from all the others. Could these “cells” be the structural units of life? 2
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In order to test this on other life forms like animals required the development of histological techniques. In order to examine anything in the transmission light microscope it is necessary that the light pass through the sample. If you place your finger or any small animal on such a microscope stage you will see nothing because insufficient light passes through to the eyepiece. Therefore, it is necessary to cut the sample into very thin slices. If you try to do this
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This note was uploaded on 03/30/2008 for the course BIO 2:010 taught by Professor Denburg during the Spring '08 term at University of Iowa.

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LECTURE 03 CELLULAR BASIS OF LIFE - 2:010 Principles of...

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