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Invitation to Biology
Chapter 1
1.1 Molecules of Life
• All things are made up of the same units
of matter
• Living things are made up of a certain
subset of molecules:
– Nucleic acids
– Proteins
– Carbohydrates
– Lipids
DNA (deoxyribonucleic acid)
• Signature molecule of life
• Molecule of inheritance
• Directs assembly of amino acids
DNA and Inheritance
• Inheritance
– Acquisition of traits by way of
transmission of DNA from parent to
offspring
• Reproduction
– Mechanism by which an organism
produces offspring
– Governed by instructions in DNA
DNA Guides Development
• Multicelled organisms develop
• Series of stages
• Instructions for each stage in DNA
Nothing Lives without Energy
Energy = Capacity to do work
Metabolism = Reactions by which
cells acquire and use energy to
grow, survive, and reproduce
Sensing and Responding
• Organisms sense changes in their
environment and make responses to
them
• Receptors detect specific forms of
energy (stimuli)
• Allows maintenance of homeostasis
1.2 Levels of Organization
Cell
Multicelled Organism
Population
Community
Ecosystem
Biosphere
Interdependencies among
Organisms
Producers
Make their own food
Consumers
Depend on energy stored in tissues
of producers
Decomposers
Break down remains and wastes
Energy Flow
• Usually starts with energy from sun
• Transfer from one organism to
another
• Energy flows in one direction
• Eventually, all energy flows back to
the environment
ENERGY FROM
SUN
Producers
NUTRIENT
CYCLING
Consumers,
Decomposers
ONE-WAY FLOW
OF ENERGY
In time, all energy
flows back to the
environment.
Unity of Life
All organisms:
– Are composed of the same substances
– Engage in metabolism
– Sense and respond to the environment
– Have the capacity to reproduce based
on instructions in DNA
1.3 Diversity of Life
• Millions of living species
• Millions more now extinct
• Classification schemes attempt to
organize diversity
Scientific Names
• Devised by Carolus Linnaeus
• First name is genus (plural, genera)
– Homo sapiens - genus is Homo
• Second name is species within genus
3 Domains
Eubacteria
(Bacteria)
Archaebacteria
(Archaea)
Eukaryota
(Eukaryotes)
6 Kingdoms
Protistans
Plants
Fungi
Animals
Eukaryotes
Archaebacteria
Eubacteria
Origin of life
Prokaryotic
Organisms
• Single cells
• No nucleus or
organelles
• Smaller, less
complex
Eukaryotic
Organisms
• Single- or multicelled
• Nucleus and other
organelles
• Larger, more
complex
1.4 Mutation: Source of Variation
• Mutation = change in structure of DNA
• Basis for the variation in heritable traits
• Most are harmful
Adaptive Trait
A trait that gives the individual an
advantage in survival or reproduction,
under a given set of circumstances
Evolution
• Genetically based change in a line of
descent over time
• Population changes, not individuals
Artificial Selection
• Breeders are selective agents
• Individuals exhibiting favored traits are
bred
• Favored traits become more common in
population
Natural Selection
• Individuals vary in some heritable traits
• Some forms of heritable traits are more
adaptive
• Natural selection is differences in
survival and reproduction among
individuals that vary in their traits
• Adaptive forms of traits become more
common than other forms
Antibiotic Resistance
• Antibiotics are used to kill bacteria
• Mutations for antibiotic resistance exist
or arise
• Antibiotic-resistant bacteria survive and
reproduce better than nonresistant
• Over time, proportion of antibioticresistant bacteria increases
1.5 Scientific Method
• Observe phenomenon
• Develop hypotheses
• Make predictions
• Devise test of predictions
• Carry out test and analyze results
Inductive Logic
• Using observations and facts to arrive at
generalizations or hypotheses
• Observation: Eagles, swallows, and
robins have feathers
• Hypothesis: All birds have feathers
Deductive Logic
• Drawing a specific conclusion based on
a generalization
– Generalization - Birds have feathers
– Example - Eagles are birds
– Conclusion - Eagles have feathers
Role of Experiments
• Used to study a phenomenon under
known conditions
• Allows you to predict what will happen if
a hypothesis is not wrong
• Can never prove a hypothesis 100%
correct
Experimental Design
• Control group
– A standard for comparison
– Identical to experimental group except for
variable being studied
• Sampling error
– Nonrepresentative sample skews results
– Minimize by using large samples
Scientific Theory
• A hypothesis that has been tested for its
predictive power many times and has
not yet been found incorrect
• Has wide-ranging explanatory power
– Darwin’s theory of evolution by natural
selection
1.7 Limits of Science
• Scientific approach cannot provide
answers to subjective questions
• Cannot provide moral, aesthetic, or
philosophical standards
• Conflict with supernatural beliefs
– Copernicus
– Darwin
Scientists Raise Questions
The external world, not internal
conviction, must be the testing ground
for scientific beliefs