Unit 3: Cycling of Matter in Living
Systems
Contents:
Chapter 7: The Basis of Life
Chapter 8: Dynamic Cells
Chapter 9: Focus on Plants
Chapter 7: The Basis of Life
5 Characteristics of Living Things
1.
2.
3.
4.
5.
Need Energy
Produces waste
Responds and adapts to environment
Reproduce
Grow
How do maggots form on
rotting meat?
Spontaneous generation?
(abiogenesis)
Abiogenesis
• Abiogenesis (spontaneous
generation)– believed for
2000 years – the idea that
living things can appear from
non-living things
• Maggots on meat and
mushrooms on logs were 2
examples commonly cited
Francesco Redi(1627 – 1697)
• Placed meat in an uncovered jar
•
•
Placed meat in jar covered with cheesecloth
(air but not flies could pass through)
A few days later…….
Francesco Redi(1627 – 1697)
• Maggots were found in uncovered jars only!
• Redi was convinced that maggots are not
reproduced by abiogenesis.
Louis Pasteur (1822 – 1895)
• Was convinced
spontaneous generation
did NOT occur
• He studied
FERMENTATION and knew
that living organisms were
responsible for the
process
• Developed the “Swan
neck Flask” Experiment
Swan Neck Flask Experiment
1. Filled 2 flasks with
nutrient-rich broth and
boiled them to force out air
and kill microbes.
2. Pasteur broke the neck of
one of the flasks thereby
exposing the broth to
microbes in the air.
3. The other flask had its
neck intact and Pasteur
hypothesized that microbes
would not be able to reach
the broth.
4. The broth in the unbroken
flask remained clear after
several days, but the broth
in the broken flask became
cloudy, indicating the
presence of microbes.
Biogenesis
• Biogenesis is the idea that living organisms
can only come from other living things.
DISCOVERING CELLS
Cells: The smallest functional Unit of
Life
Cell Theory:
Robert Hooke (1635-1703)
• Looked at thin slices of
cork from a tree
• Using a compound light
microscope saw
hundreds of empty
boxes
• Names them “cells”
after monks’ small
rooms
Antony Von Leeuwenhoek (1632-1723)
• First person to discover
single celled micro
organisms
• Studied pond water,
blood and skin cells
• Called them
“animalcules”
Schleiden and Schwann (1804-1882)
Schleiden:
• Concluded all PLANTS
are composed of cells
• Each new cell has a
nucleus
Schwann:
• Concluded all ANIMALS
are composed of cells
• All organisms are made
up of one or more cells
Rudolf Virchow
• He performed experiments to
test Schleiden and Schwann’s
hypotheses
• Virchow sees cells dividing
under the microscope, and
finds that bone cells develop
from cartilage cells. He
concludes that cells can only
arise from other cells and the
cell theory is born.
Current Cell Theory
1. All organisms are made of one or more cells
2. The cell is the smallest functional unit of life
3. All cells are produced from other cells