Transcript Hypothesis

Introduction to Biology
Studying Life’s Diversity and
Intricate Processes
Biological Inquiry
 Bio = of living things
 What Are the Characteristics of Living
Things?
 What are the Themes that Connect Biological
Concepts?
 How Do Biologists Study Living Things?
What are common
characteristics of living things?
Properties of Life
order (organization)
energy processing
regulation
growth and development
reproduction
response to the environment
evolutionary adaptation
Theme: New Properties Emerge at Each
Level in the Biological Hierarchy
Principle of Emergent Properties
New characteristics arise out
of the arrangement and
interactions of the components
of a complex system
(whole > sum of the parts)
order
Organizational Hierarchy of Life
Most
Complex biosphere
inhabitable regions of earth
ecosystem
coral reef (living + nonliving)
community
coral reef populations
population
school of fish
organism
fish
organ system
nervous system
organ
brain
tissue
nervous tissue
cell
neuron
organelle
nucleus
macromolecule
DNA
molecule
nucleotide
Least
atom
nitrogen
Complex sub-atomic particles protons, neutrons, electrons
Theme: Cells are an Organism’s Basic
Units of Structure and Function.
Two types of cells
Prokaryotic
 Archaea and Bacteria
 few internal membranes
 no membrane-bound nucleus
Eukaryotic
 Protists, Fungi, Animals, Plants
 extensive internal membranes
 membrane-bound nucleus
order
Theme: Structure and Function are Correlated
at all Levels of Biological Organization.
How is red blood cell structure suited
to its function of carrying oxygen?
order
Theme: Organisms Interact with Their
Environments, Exchanging Matter and Energy
Processes occurring in ecosystems
Cycling of nutrients, such as minerals
One-way flow of energy from sunlight to
Producers who synthesize organic
(carbon-containing) molecules
Consumers who obtain organic
molecules from producers or other
consumers
energy processing
response to environment
Energy
Processing
 Energy = ability to do work
 Energy conversion = change
of one form of energy to
another
 Metabolism = sum of
chemical reactions in an
organism
 Heterotrophic: other feeder
 taking in organic molecules
produced by other organisms
 Autotrophic: self-feeder
 photosynthesis = using the
energy of the sun to produce
organic molecules
Theme: The Continuity of Life is Based
on Heritable Information in DNA.
The molecule of heredity =
DNA = deoxyribonucleic acid
reproduction
regulation
Per 23
chromosomes
Now estimated
at 30,000
genes
Theme: The Continuity of Life is Based
Nuclear
on Heritable Information in DNA.
division
retaining the
original
chromosome
number
Nuclear division
reducing the
chromosome
number, leading to
sperm or eggs
Theme: The Continuity of Life is Based
on Heritable Information in DNA.
Growth = increase in size
Development = change in characteristics
growth and development
Theme: Feedback mechanisms
regulate biological systems.
Theme: Feedback mechanisms
regulate biological systems.
Living things maintain homeostasis
= a relatively stable internal condition
regulation
response to environment
Theme: Evolution Accounts for
the Unity and Diversity of Life
Two components of Darwin’s Theory of
Evolution
Descent with modification: current
species arose from a succession of
ancestors
Natural Selection: individuals with traits
that provide an advantage in the
current environment are more likely to
survive and reproduce
response to environment
evolution
Theme: Evolution Accounts for
the Unity and Diversity of Life
Descent with modification
Theme: Evolution Accounts for
the Unity and Diversity of Life
Natural Selection leads to a change
in the genetic characteristics of a
population  evolution
Adaptation = characteristic that
promotes survival and reproduction
The Unity and Diversity of Living Things
An Evolutionary Tree of Life
The Three Domains of Life Represent the Earliest
Branches in Evolutionary History
Contains
multiple
kingdoms
How Do Biologists Study Living Things?
Discovery Science
 Make Observations = objective
notations of a phenomenon
 Inductive Reasoning
 many specific observations 
generalizations
 eg. E. coli has DNA, plant leaves
have DNA, humans have DNA 
All organisms have DNA
How Do Biologists Study Living Things?
Hypothesis-based Science
 Ask Questions
 Formulate an Hypothesis: tentative answer
to well-framed question
 Deductive Reasoning
 general specific
 If…then statements
 If all living things maintain homeostasis and
Paramecium is a living thing, then Paramecium
regulates its internal fluid balance.
 Make Predictions based on hypothesis
 Test Predictions by Conducting Experiments
How Do Biologists Study Living Things?
Biology 21 Definition
•An Hypothesis will have
– Two measurable variables
– Precise relationship between them
(relationship = prediction)
The relationship between
DNA content and length of
the cell cycle is a direct
proportion.
How Do Biologists Study Living Things?
A good hypothesis is
 Testable
 experiments can be designed to test
predictions from the hypothesis
 experimental results must be
repeatable
 Falsifiable
 allows scientists to eliminate
alternative hypotheses
How Do Biologists Study Living Things?
•Testing hypotheses
– Controlled Experiment
• test designed to determine the effect of
one factor while keeping all other factors
constant
• experimental = sample treated to test for
effect of the factor being studied
• control = sample treated like experimental
in all ways EXCEPT for the factor being
studied
Use of a Controlled Experiment
Increasing dose of almonds on subjects with hyperlipidemia.
Full almond = 73 grams/day
Control = whole wheat muffins (>5% saturated fat)
Half almond = half dose almond + half dose muffins
All supplements provided equal amounts of energy in the diet.
Jenkins, et al., 2002, Circulation 106:1327
How Do Biologists Study Living Things?
• Supported Hypothesis
•Theory = hypothesis supported by
repeated testing
•Principle or Law = theory that has been
supported over a long period of time
– Cell Principle
– Principle of Evolution
– Principle of Emergent Properties