Chapter 23
Section 2
Advances in Science
And Medicine
Cell Theory in Biology






Biological Sciences are sciences that deal with living
organisms such as genetics, zoology, botany and
biology
Physical Sciences are sciences that deal with the
properties of nonliving matter and energy such as
chemistry, astronomy, geology and physics
Scientists of the 1800’s were interested in explaining
the nature of life as well as the nature of nonliving
matter
Early observers, with the help of microscopes, saw
what we now know as plant and animal cells.
They noticed that all species cells were different
shapes and sizes
But they did not fully understand or draw any general
conclusions
Cells from an Elodea Plant
Human Brain Cells
Dog Kidney Cells
Continued….
Finally in 1838, a German botanist and a German
biologist clearly expressed cell theory
 They stated that all living things are made up of tiny
living matter and that all cells divide and multiply
causing the organism to grow and mature
 In the 1850’s another German scientist expanded on
the theory by stating that every new cell must come
from some older cell therefore only living matter can
produce new living matter
 Thus accepting the cell as the basic unit of living
matter

Lamarck’s Theory of Inheritance





Many scientists believed that plants and animals that
live today had developed from common ancestors
from long ago
This kind of development through change is called
evolution
French biologist Jean-Baptiste Lamarck suggested his
theory of inheritance and evolution through
adaptation.
Some of Lamarck’s theories were later proved to be
wrong and did not become a part of modern biology
But he did influence other scientists such as a British
naturalist named Charles Darwin
Darwin’s Theory of Evolution
Charles Darwin began his theories with a well-known fact: no
two living things are exactly alike not even a parent and its
offspring
 Darwin combined this fact with the idea that as a result of
natural dangers that there will always be more creatures born
than can survive
 Those that survive will then be the best of the species that can
adapt to the environment around them.
 They will then produce offspring that possess the
characteristics so they can pass them on to future generations
 Darwin thought that in this way he could explain the evolution
of all forms of life from previous forms
 The theory of natural selection was controversial because it
stated that human beings developed from animals.
 However Darwin felt that his theory of evolution did not
challenge the existence of God


“There is grandeur in this
view of life…having been
originally breathed by the
Creator into a few forms
or into one; and
that….from so simple a
beginning endless forms
most beautiful and most
wonderful have been and
are being evolved”
-Charles Darwin
Genetics





An Austrian monk named Gregor Mendel founded
genetics, or the study of how characteristics of plants
and animals are passed and inherited by their
descendants
He began his experiments by crossbreeding tall plants
with short plants. To Mendel’s surprise he got tall
plants and not medium sized plants
From these experiments Mendel concluded that inborn
traits were not blended together. Instead they were all
inherited as if they were separate particles
And in some cases a trait could be carried but not
expressed
For example: the tall plant could pass the “particles”
on to the next generation making one or some of its
offspring short
The Fight Against Disease
Until the late 1800’s as many as 50% of the population born
died within the first five years after birth
 Smallpox was one of the deadliest diseases
 An English physician named Edward Jenner developed a
vaccine for smallpox by the way of exposure to another milder
disease called cowpox
 Jenner did create a vaccine but he did not know exactly why it
worked
 Later a French chemist, {Louis Pasteur, identified



microorganisms called bacteria
In the 1860’s Pasteur developed the process of heating liquids
to kill bacteria and prevent fermentation in a process called
pasteurization}
Pasteur also created a vaccine that prevented animals from
contracting the germ that causes anthrax. Leading him to the
conclusion that when weakened germs enter the body that
your body builds up antibodies to fight them
Advances in Surgery and Medicine
In the 1840’s medicinal purposes for ether and
chloroform were discovered, making longer operations
possible
 However, people still died from infection afterward
 Until a surgeon named {Joseph Lister developed

antisepsis, or the use of chemicals to kill germs}
The use of these antiseptics helped to reduce the
number of infections after surgery
 As people began to realize the sources of diseases
such as malaria and the Bubonic Plague they
discovered ways of preventing them
 During this time Aspirin and Insulin were invented
 Alexander Fleming discovered penicillin in 1928
although penicillin drugs were not widely available
until the 1940’s

The Atom and it’s Structure




Although knowledge of atoms can be traced back to the 1500’s
it had not been proven yet
A school teacher named John Dalton created a way to “weigh”
atoms in 1803
Much later in 1869 a Russian chemist, Dmitry Mendeleyev,
expanded on this and created the first periodic table
It was expanded upon throughout the years by chemists such
as {Pierre and Marie Curie who experimented with radium
and plutonium. They found that these elements constantly
break down and release energy on their own in a process called
radioactivity}


Elements that release energy this way are called radioactive
elements
Later evidence was found about electrons and the nucleus,
protons and neutrons.
Plank and Einstein


Before 1900 scientists believed that energy was a exponential
substance, and it could be divided into any number of smaller
units
In 1900 Max Planck disproved this with his quantum theory
in which he proved that energy could only be released in
“definite packages”

{Albert Einstein in studying Planck’s work developed his
special theory of relativity which states that no particles of
matter can move faster than the speed of light}

Einstein also developed the famous equation, E=mc2. Where
he expressed the relationship between energy and mass
Einstein also declared that this is not just a three dimensional
universe but a fourth dimension (time) existed.
Einstein called his 4-dimensial system the space-time
continuum.


Review Questions





This man identified microorganisms called bacteria
Pasteur developed the process of heating liquids to
kill bacteria what was it called?
Joseph Lister developed ___________, or the use of
chemicals to kill germs
Who found that certain elements constantly break
down and release energy on their own in a process
called radioactivity
Who developed the theory of relativity which states
that no particles of matter can move faster than the
speed of light

"The release of atom
power has changed
everything except our
way of thinking...the
solution to this
problem lies in the
heart of mankind. If
only I had known, I
should have become
a watchmaker."
-Albert Einstein on the bomb