Lecture1: What is biology?
Young Frankenstein, Mel Brooks & Gene Wilder, 1974
Lecture 1: What is biology?
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Lecture 01.1: What makes something alive?
Lecture 01.2: How do scientists learn?
Lecture 01.3: Is it really “just a theory?”
Module 01.1: What makes something
alive?
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Biology is the study of living things.
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Bio = life
-logy = study of
Things function and interact with each other on many
levels.
Cells is the most basic thing of life
The organization of life is a hierarchy of levels of
increasing complexity.
Cellular
 Organismal
 Populational
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Levels of organization: cellular level
Tissue = a bunch of cells stuck together
Cells talk to one another
Levels of organization: organismal level
Levels of organization: populational level
• Population is a group of a life form around
together
• Species is different kinds of life forms
together
• Community is an expand of life forms
• Ecosystem is everything dead or alive
The Diversity of Life
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Living things are diverse.
Therefore, we divide them into
groups:
Kinky People Come Over For Great Sex
sapiens
Homo
Hominidae
Primates
Mammalia
Chordata
Animalia
Eukarya
Biology Hierarchy
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Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Properties of Life
 Cells
 Organization
 Metabolism
 Homeostasis
 Growth
 Reproduction
 Responsiveness
 Heredity
Properties of Life: Cells
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All living things are
comprised of at least
one cell.
Properties of Life: Organization
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Both molecular and cellular organization.
Living things must be able to organize simple
substances into complex ones.
Properties of Life: Metabolism
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Living things take in energy and use it for
maintenance and growth.
Metabolism = All chemical reactions in an organism
Properties of Life: Homeostasis
Maintaining a stable state of conditions
 Body temperature
 Blood volume
 pH balance
 Water balance
Properties of Life: Growth
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Cell division - the orderly formation of new cells.
Cell enlargement - the increase in size of a cell. Cells grow
to a certain size and then divide.
An organism gets larger as the number of its cells
increases.
Properties of Life: Reproduction
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Reproduction is not
essential for the survival
of individual organisms,
but must occur for a
species to survive.
Properties of Life: Responsiveness
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Living things will make changes in response to a
stimulus in their environment.
 Light
 Temperature
 Gravity
 Odor
 Sound
 Water
Properties of Life: Heredity
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Traits are passed on to
the next generation in
Nucleic Acid.
Properties of Life
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Is a virus alive?
Cells
 Organization
 Metabolism
 Homeostasis
 Growth
 Reproduction
 Responsiveness
 Heredity
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NO! Well its
in the grey
area,
depending
Properties of Life
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Is a machine alive?
Cells
 Organization
 Metabolism
 Homeostasis
 Growth
 Reproduction
 Responsiveness
 Heredity
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Properties of Life
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Is a city alive?
Cells
 Organization
 Metabolism
 Homeostasis
 Growth
 Reproduction
 Responsiveness
 Heredity
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Properties of Life
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Is fire alive?
Cells
 Organization
 Metabolism
 Homeostasis
 Growth
 Reproduction
 Responsiveness
 Heredity
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Module 01.2: How do scientists learn?
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Latin scientia = knowledge
A systematic enterprise that builds
and organizes knowledge in the
form of testable explanations and
predictions about the universe.
Science is a process
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Scientific Method
What is Science?
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Latin scientia = knowledge
A systematic enterprise that builds
and organizes knowledge in the form
of testable explanations and
predictions about the universe.
Science is a process
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Scientific Method
Stages of a Scientific Investigation
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Biology is a dynamic science with new ideas
appearing and replacing old ones.
Scientific Method
Scientific Method
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Observation
 Senses / Lit search
Hypothesis
 Testable and Repeatable
 H0: Null hypothesis – No significant difference
 HA: Alternative hypothesis – significant difference
Prediction
 If a hypothesis is correct, then specific consequences can be expected
Experiment
 Sample Size = 30
 Control, change one variable
Analysis of Results
 Quantitative (Statistical testing)
Conclusion
Scientific Method
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Control
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Parallel design to
minimize effect of
variables other than
the independent
variable being tested.
Placebo
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“Blind study”
Trans fats in adipose tissue
(g trans fat per 100 g total fat)
2.0
1.77
1.5
1.48
1.0
0.5
0
Heart attack
patients
Control
group
Louis Pasteur
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Experimentation
disproved the widelyheld notion that life
could arise from nothing
19th century France
He discovered at the
time that people didn’t
just get sick,
Louis Pasteur
Observation: Broth contaminated with microbes
Question: Do microbes spontaneously appear?
Hypothesis: Microbes come from the air
Experiment:
Collect results:
Conclusion:
Louis Pasteur
Louis Pasteur
Observation: Broth contaminated with microbes
Question: Do microbes spontaneously appear?
Hypothesis: Microbes come from the air
Experiment:
Broth left exposed or unexposed
Collect results:
S-neck flask remains sterile
Conclusion:
Microbes come from the air. Life does
not arise from nothing.
Correlation v Causation
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A correlation between two variables does not
necessarily imply that one causes the other.
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Are Mexican
lemons making
our roads
safer?
Is Internet
Explorer
responsible for
murder?
Do vaccines cause autism?
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http://www.jennymccarthybodycount.com/
Module 01.3: Is it really “just a
theory?”
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The term “theory” means different things to
different audiences
 To
scientists
A
theory represents certainty and is a unifying explanation
for a broad range of observations.
 To
the general public
A
theory implies a lack of knowledge or guess.
Theory and Certainty
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A Theory is a complicated result of many separate
experiments that all suggest a similar thing.
Scientists’ acceptance of theory is provisional.
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The possibility always remains that future evidence will
cause a theory to be revised.
The process of science is not just trial-and-error but
involves judgment and intuition.
Four Theories Unify Biology as a Science
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1. The Cell Theory
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2. The Gene Theory
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3. The Theory of Heredity
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4. The Theory of Evolution
The Cell Theory
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All organisms are
composed of at least one
cell.
The cell is the most basic
unit of life.
All cells come from preexisting cells.
The Gene Theory
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Genetic information is encoded in molecules of
deoxyribonucleic acid (DNA).
Genes encode specific proteins or RNA or act to
regulate other genes.
The proteins and RNA encoded by an organism’s
genes determine what it will be like in terms of form
and function.
The Theory of Heredity
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Genes are passed down from generation to
generation.
 Mendel’s
theory of heredity gave rise to the field of
genetics.
 Chromosomal
theory of inheritance located Mendelian
genes on chromosomes.
The Theory of Evolution
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All living organisms are related to one another in a
common tree of descent.
Charles Darwin’s theory of evolution explains the
unity and diversity of life as “descent with
modification.”
 Scientists
have been able to identify changes in
individual genes that are responsible for differences
among individuals.
Evolution