Transcript You Light Up My Life

Chapter 1
Invitation to Biology
Objectives

List the levels of organization in the living world.
 List the distinguishing characteristics of living
organisms.
 Describe the general pattern of energy flow
through Earth’s life forms, and explain how
Earth’s resources are used again and again
(cycled).
 Explain what is meant by the term diversity, and
speculate about what caused the great diversity
of life forms on Earth.
Objectives (cont.)

Explain how people came to believe that the
populations of organisms inhabiting Earth have
changed through time.

List as many steps of the scientific approach to
understanding a problem as you can.

Understand as well as you can what limitations
are imposed on science and scientists.
What am I doing here?
 Current
world events seem chaotic.
Oil spills that threaten aquatic life.
 Diseases such as AIDS destroy lives.
 Even the global temperatures seem to be
unstable. (Global warming?)
 But
past world events also have been
destructive too. (Bioterrorism, Spanish flu)
Section 1.1 Biology
 Biology
 Biology
is the scientific study of life
lays the foundation for asking
basic questions about life and the natural
world
Why Study Biology?
 To
learn how organisms are constructed,
how they function, where they live, and
what they do
 To
help develop, modify, and refine ideas
about life
Levels of Organization
A
general pattern of organization in nature
begins with atoms and molecules.
 Each kind of organism, or species,
consists of one or more cells.
 The
cell, composed of “biological
molecules,” is the smallest unit of life.
Levels of Organization

Multicelled organisms have increasingly
complex levels of organization:
 tissues
 organs
 organ systems
 organisms
 populations
 communities
 ecosystems
 biosphere
Emergent Properties
 Emergent
properties- a new property that
emerges through interactions of entities at
lower levels, none of which displays the
property.
 (ex. Living cells that emerge from “lifeless”
molecules)
1.2 Nothing Lives without
Energy
Energy = Capacity to do work
All cells need energy to stay alive
Metabolism = Reactions by which
cells acquire and use energy to
grow, survive, and reproduce
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 the sun

Transfer from one organism to another
(lose energy in the form of heat)

Energy flows in one direction from
producers to consumers

Eventually, 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
Sensing and Responding
 Organisms
sense changes in their
environment and make responses to them
 Receptors
detect specific forms of energy
(stimuli)
maintenance of homeostasis –
internal environment conditions are
tolerable
 Allows
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
 Directs
molecule of life
of inheritance
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
 Series
organisms develop
of stages
 Instructions
for each stage in DNA
1.3 Diversity of Life
 Our
world possesses abundant
diversity, with an estimate as high
as 100 million species existing
today.
 Millions
more are now extinct
 Classification
schemes attempt to
organize diversity
Scientific Names
 Devised
 First

by Carolus Linnaeus
name is genus (plural, genera)
Homo sapiens - genus is Homo
 Second
name is species within genus
Groupings were added
 genera
– least inclusive
 family
 order
 class
 phylum
 kingdom
 Domain
– most inclusive
Comparison of Life’s Three
Domains
6 Kingdoms
Protistans
Plants
Fungi
Animals
Eukaryotes
Archaebacteria
Eubacteria
Origin of life
Prokaryotic
Organisms
 Single
 No
Eukaryotic
Organisms
cells
 Single-
nucleus or
celled
organelles
 Smaller,
complex
less
or multi-
 Nucleus
and other
organelles
 Larger,
more
complex
1.4 Mutation: Source of
Diversity
 Mutation
 Basis
 Most
= change in structure of DNA
for the variation in heritable traits
are harmful, some are beneficial
Charles Darwin

First, members of a natural population will
compete for limited resources, such as food and
shelter, as their size increases.
 Second, some varieties of the individuals’
heritable traits will improve survival and
reproductive chances.
 Third, those with the adaptive forms of these
traits will be more likely to reproduce and pass
the adaptive traits on with greater frequency in
future generations (natural selection).

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 antibiotic-resistant
bacteria increases
1.5 Scientific Method
 Observe
phenomenon
 Develop
hypotheses
 Make
predictions
 Devise
 Carry
test of predictions
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
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
1.6 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
Example of field experiment
 Durrell
Kapan confirmed Mullerian mimicry
(look alike) with an experiment in the
forests of Ecuador.
 He was able to show that birds that had
“learned” to associate yellow markings
with unpalatability of one species of
butterfly
Fig. 1-11, p.13
Biological Therapy Experiments
Can we use viruses that attack bacteria
(bacteriophages) to fight infections?
See pages 208-209 in textbook.
Experiment 1
 Hypothesis
- Bacteriophages can protect
mice against infectious bacteria
 Prediction
- Mice injected with
bacteriophages will not die as a result of
bacterial injection
Experiment 2
 Prediction
- Bacteriophage injections will
be more effective treatment than single
dose of the antibiotic streptomycin
 Test
- Mice injected with bacteria, then
with saline, streptomycin, or bacteriophage
Minimizing Variables
 All
mice were same age and sex, reared
under same conditions
 Each mouse in each test group received
exact same treatment
 All mice in control group received same
amount of saline
 Variable tested was antibiotic treatment
versus bacteriophage treatment
1.7 Limits of Science
 Science
is limited to questions that can be
tested.

1.Subjective questions cannot be
tested.

2.All of human society must participate
in moral, aesthetic, and other such
judgments.
Limits of Science
 Science
may be considered controversial
when it offers explanations for an aspect
of nature previously considered
supernatural
 Supernatural explanations cannot be
tested
 Conflict with supernatural beliefs- heresy


Copernicus
Darwin
Scientists Raise Questions
The external world, not internal conviction,
must be the testing ground for scientific
beliefs