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Chapter 1

BIL 255 Chapter Notes - Chapter 1: Robert Hooke, Paramecium, Neuron

Course Code
BIL 255
Baker James

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Unity and Diversity of Cells
A. Cells vary enormously in appearance and function
a. Size
b. Shape
i. Ex: nerve cell is long and extended
ii. Ex: paramecium is shaped like a submarine and is covered with cilia
c. Chemical requirements
i. Some require oxygen, and some do not
d. Functions
i. Some cells are specialized factories for the production of particular
substances, such as hormones, fats, starch, latex, or pigments
ii. Others, like muscle cells, burn fuel to do mechanical work
iii. Others are electric generators
B. Living Cells All Have a Similar Basic Chemistry
a. Carry genetic information in DNA molecules, which are made of the same set of
four nucleotides
b. DNA is transcribed into chemically related polymers called RNA
c. Subset of RNA is translated into protein
d. Proteins are built from the same set of 20 amino acids
C. All Present-Day Cells Have Apparently Evolved from the Same Ancestral Cell
a. Evolution is the process by which living organisms become gradually modified
and adapted to their environment in more and more sophisticated way
i. Occurs through genetic mutation and natural selection
D. Genes Provide the Instructions for Cell Form, Function, and Complex Behavior
a. Genome: the entire sequence of nucleotides in an organism’s DNA that provides
the genetic program that instructs the cell how to behave
Cells Under the Microscope
A. Discovered in the seventeenth century
B. Light microscopes allowed biologists to see for the first time the structures in cells
C. Electron microscopes, invented in the 1930s, allowed us to see the finer details of the cell
and make large molecules visible individually
a. Uses beam of electrons instead of beam of lights
D. The Invention of the Light Microscope Led to the Discovery of Cells
a. Robert Hooke discovered cells
b. Named them “cells” because of their resemblance to monk chambers
c. In the 1800s, Schleiden and Schwann discovered that cells were the building
blocks of all living tissues; found cell biology
E. Light Microscopes Allow Examination of Cells and Some of Their Components
a. Cells have defined boundaries, indicating presence of membrane
b. Nucleus is prominent in middle of cell
c. Around the nucleus and filling the cell’s interior is the cytoplasm
d. Organelles cannot be seen with a regular light microscope
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