01 lectures ppt

Chapter 1
Exploring Life
PowerPoint Lectures for
Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• Overview: Biology’s Most Exciting Era
• Biology is the scientific study of life
• Biologists are moving closer to understanding:
– How a single cell develops into an organism
– How plants convert sunlight to chemical
energy
– How the human mind works
– How living things interact in communities
– How life’s diversity evolved from the first
microbes

• Life’s basic characteristic is a high degree of order
• Each level of biological organization has emergent
properties
Video: SSeeaahhoorrssee CCaammoouuffllaaggee

• Concept 1.1: Biologists explore life from the
microscopic to the global scale
• The study of life extends from molecules and cells
to the entire living planet
• Biological organization is based on a hierarchy of
structural levels

A Hierarchy of Biological Organization
1. Biosphere: all environments on Earth
2. Ecosystem: all living and nonliving things
in a particular area
3. Community: all organisms in an ecosystem
4. Population: all individuals of a species
in a particular area
5. Organism: an individual living thing

A Hierarchy of Biological Organization (continued)
6. Organ and organ systems: specialized body
parts made up of tissues
7. Tissue: a group of similar cells
8. Cell: life’s fundamental unit of structure and
function
9. Organelle: a structural component of a cell
10. Molecule: a chemical structure consisting of
atoms

The biosphere
Ecosystems
Populations
Organisms
Communities
Cells
Organelles
Cell 1 μm
Atoms
Molecules
10 μm
Tissues
50 μm
Organs and organ systems

A Closer Look at Ecosystems
• Each organism interacts with its environment
• Both organism and environment affect each other

Ecosystem Dynamics
• The dynamics of an ecosystem include two major
processes:
– Cycling of nutrients, in which materials
acquired by plants eventually return to the soil
– The flow of energy from sunlight to producers
to consumers

Energy Conversion
• Activities of life require work
• Work depends on sources of energy
• Energy exchange between an organism and
environment often involves energy transformations
• In transformations, some energy is lost as heat
• Energy flows through an ecosystem, usually
entering as light and exiting as heat

LE 1-4
Sunlight
Ecosystem
Heat
Heat
Producers
(plants and other
photosynthetic
organisms)
Chemical
energy
Consumers
(including animals)

A Closer Look at Cells
• The cell is the lowest level of organization that can
perform all activities of life
• The ability of cells to divide is the basis of all
reproduction, growth, and repair of multicellular
organisms

The Cell’s Heritable Information
• Cells contain DNA, the heritable information that
directs the cell’s activities
• DNA is the substance of genes
• Genes are the units of inheritance that transmit
information from parents to offspring

LE 1-6
Sperm cell
Nuclei
containing
DNA
Egg cell
Fertilized egg
with DNA from
both parents
Embryo’s cells
With copies of
inherited DNA
Offspring with traits
inherited from both parents

• Each DNA molecule is made up of two long chains
arranged in a double helix
• Each link of a chain is one of four kinds of
chemical building blocks called nucleotides

LE 1-7
Nucleotide
DNA double helix Single strand of DNA
Nucleus DNA
Cell

Two Main Forms of Cells
• Characteristics shared by all cells:
– Enclosed by a membrane
– Use DNA as genetic information
• Two main forms of cells:
– Eukaryotic: divided into organelles; DNA in
nucleus
– Prokaryotic: lack organelles; DNA not
separated in a nucleus

LE 1-8
EUKARYOTIC CELL PROKARYOTIC CELL
Membrane
Cytoplasm
DNA
(no nucleus)
Membrane
1 μm
Organelles
Nucleus (contains DNA)

• Concept 1.2: Biological systems are much
more than the sum of their parts
• A system is a combination of components that
form a more complex organization
• Cells, organisms, and ecosystems are some
examples of biological systems

The Emergent Properties of Systems
• Emergent properties result from arrangements
and interactions within systems
• New properties emerge with each step upward in
the hierarchy of biological order

The Power and Limitations of Reductionism
• Reductionism is reducing complex systems to
simpler components that are easier to study
• The studies of DNA structure and the Human
Genome Project are examples of reductionism

Systems Biology
• Systems biology seeks to create models of the
dynamic behavior of whole biological systems
• An example is a systems map of interactions
between proteins in a fruit fly cell
• Such models may predict how a change in one
part of a system will affect the rest of the system

LE 1-10
CELL
Nucleus
Outer membrane
and cell surface
Cytoplasm

• Systems biology uses three key research
developments:
– High-throughput technology: methods to
generate large data sets rapidly
– Bioinformatics: using computers and software
to process and integrate large data sets
– Interdisciplinary research teams

Feedback Regulation in Biological Systems
• Regulatory systems ensure a dynamic balance in
living systems
• Chemical processes are catalyzed (accelerated)
by enzymes
• Many biological processes are self-regulating: the
product regulates the process itself

• In negative feedback, the accumulation of a
product slows down the process itself
• In positive feedback (less common), the product
speeds up its own production
Animation: NNeeggaattiivvee FFeeeeddbbaacckk AAnniimmaattiioonn:: PPoossiittiivvee FFeeeeddbbaacckk

LE 1-11
A A
Enzyme 1
B B
Enzyme 2
C C
Enzyme 3
D D
D D
D
D
D
D
D
D D
Negative
feedback
Enzyme 1

LE 1-12
W
Enzyme 4
W
X X
Enzyme 5
Positive
feedback
Y Y
Enzyme 6
Z Z
Z
Z
Z Z Z
Z Z Z
Enzyme 4
Enzyme 5
Enzyme 6
Z
Z Z Z
Z
Z
Z
Z
Z

• Concept 1.3: Biologists explore life across its
great diversity of species
• Biologists have named about 1.8 million species
• Estimates of total species range from 10 million to
over 200 million

Grouping Species: The Basic Idea
• Taxonomy is the branch of biology that names and
classifies species into a hierarchical order
• Kingdoms and domains are the broadest units of
classification

LE 1-14
Species Genus Family Order Class Phylum Kingdom Domain
Ursus
Ursidae
Carnivora
Mammalia
Chordata
Animalia
Eukarya
Ursus
americanus
(American
black bear)

The Three Domains of Life
• At the highest level, life is classified into three
domains:
– Bacteria (prokaryotes)
– Archaea (prokaryotes)
– Eukarya (eukaryotes)
Eukaryotes include protists and the kingdoms
Plantae, Fungi, and Animalia

LE 1-15
Bacteria 4 μm 100 μm
0.5 μm
Protists Kingdom Plantae
Archaea Kingdom Fungi Kingdom Animalia

Unity in the Diversity of Life
• Underlying life’s diversity is a striking unity,
especially at lower levels of organization
• In eukaryotes, unity is evident in details of cell
structure

LE 1-16a
15 μm 5 μm
Cilia of Paramecium Cilia of windpipe cells

LE 1-16b
0.1 μm
Cross section of cilium,
as viewed with an
electron microscope
Cilia Cilia of Paramecium of windpipe cells

• Concept 1.4: Evolution accounts for life’s unity
and diversity
• The history of life is a saga of a changing Earth
billions of years old

• The evolutionary view of life came into sharp focus
in 1859, when Charles Darwin published On the
Origin of Species by Natural Selection
• “Darwinism” became almost synonymous with the
concept of evolution

• The Origin of Species articulated two main points:
– Descent with modification (the view that
contemporary species arose from a
succession of ancestors)
– Natural selection (a proposed mechanism for
descent with modification)
• Some examples of descent with modification are
unity and diversity in the orchid family

Natural Selection
• Darwin inferred natural selection by connecting
two observations:
– Observation: Individual variation in heritable
traits
– Observation: Overpopulation and competition
– Inference: Unequal reproductive success
– Inference: Evolutionary adaptation

LE 1-20
Differences in
reproductive success
Evolution of adaptations
in the population
Overproduction
and competition
Population
of organisms
Hereditary
variations

• Natural selection can “edit” a population’s
heritable variations
• An example is the effect of birds preying on a
beetle population

LE 1-21
Population with varied inherited traits
Elimination of individuals with certain traits
Reproduction of survivors
Increasing frequency of traits that enhance
survival and reproductive success

• Natural selection is often evident in adaptations of
organisms to their way of life and environment
• Bat wings are an example of adaptation
VViiddeeoo:: SSooaarriinngg HHaawwkk

The Tree of Life
• Many related organisms have similar features
adapted for specific ways of life
• Such kinships connect life’s unity and diversity to
descent with modification
• Natural selection eventually produces new species
from ancestral species
• Biologists often show evolutionary relationships in
a treelike diagram
[Videos on slide following the figure]

LE 1-23
Large
ground finch
Large cactus
ground finch
Geospiza
magnirostris
Sharp-beaked
ground finch
Small
ground
finch
Geospiza
fuliginosa
Geospiza
conirostris Medium
ground
finch
Large
tree finch
Camarhynchus
psittacula
Woodpecker
finch
Medium
tree finch
Cactus
ground finch
Geospiza
difficilis
Geospiza
scandens
Cactus flower
eaters
Seed eater
Seed eaters
Ground finches
Camarhynchus
pauper
Green
warbler
finch
Insect eaters Bud eater
Tree finches
Warbler finches
Common ancestor from
South American mainland
Mangrove
Geospiza finch
fortis
Cactospiza
pallida Small
tree finch
Camarhynchus
parvulus
Gray
warbler
finch
Certhidea
olivacea
Certhidea
fusca
Vegetarian
finch
Platyspiza
crassirostris
Cactospiza
heliobates

Video: Albatross CCoouurrttsshhiipp RRiittuuaall
VViiddeeoo:: BBlluuee--ffooootteedd BBoooobbiieess CCoouurrttsshhiipp RRiittuuaall
VViiddeeoo:: GGaallaappáággooss IIssllaannddss OOvveerrvviieeww
VViiddeeoo GGaallaappáággooss MMaarriinnee IIgguuaannaa
VViiddeeoo:: GGaallaappáággooss SSeeaa LLiioonn
VViiddeeoo:: GGaallaappáággooss TToorrttooiissee

• Concept 1.5: Biologists use various forms of
inquiry to explore life
• Inquiry is a search for information and explanation,
often focusing on specific questions
• The process of science blends two main
processes of scientific inquiry:
– Discovery science: describing nature
– Hypothesis-based science: explaining nature

Discovery Science
• Discovery science describes nature through
careful observation and data analysis
• Examples of discovery science:
– understanding cell structure
– expanding databases of genomes

Types of Data
• Data are recorded observations
• Two types of data:
– Quantitative data: numerical measurements
– Qualitative data: recorded descriptions

Induction in Discovery Science
• Inductive reasoning involves generalizing based
on many specific observations

Hypothesis-Based Science
• In science, inquiry usually involves proposing and
testing hypotheses
• Hypotheses are hypothetical explanations

The Role of Hypotheses in Inquiry
• In science, a hypothesis is a tentative answer to a
well-framed question
• A hypothesis is an explanation on trial, making a
prediction that can be tested

LE 1-25a
Hypothesis #1:
Dead batteries
Hypothesis #2:
Burnt-out bulb
Observations
Question

LE 1-25b
Hypothesis #1:
Dead batteries
Hypothesis #2:
Burnt-out bulb
Prediction:
Replacing batteries
will fix problem
Test prediction
Test falsifies hypothesis
Prediction:
Replacing bulb
will fix problem
Test prediction
Test does not falsify hypothesis

Deduction: The “If…then” Logic of Hypothesis-Based Science
• In deductive reasoning, the logic flows from the
general to the specific
• If a hypothesis is correct, then we can expect a
particular outcome

A Closer Look at Hypotheses in Scientific Inquiry
• A scientific hypothesis must have two important
qualities:
– It must be testable
– It must be falsifiable

The Myth of the Scientific Method
• The scientific method is an idealized process of
inquiry
• Very few scientific inquiries adhere rigidly to the
“textbook” scientific method

A Case Study in Scientific Inquiry: Investigating
Mimicry in Snake Populations
• In mimicry, a harmless species resembles a
harmful species
• An example of mimicry is a stinging honeybee and
a nonstinging mimic, a flower fly

LE 1-26
Flower fly (nonstinging)
Honeybee (stinging)

• This case study examines king snakes’ mimicry of
poisonous coral snakes
• The hypothesis states that mimics benefit when
predators mistake them for harmful species
• The mimicry hypothesis predicts that predators in
non–coral snake areas will attack king snakes
more frequently than will predators that live where
coral snakes are present

LE 1-27
Scarlet king snake
Eastern coral
snake
Scarlet king snake
Key
Range of scarlet
king snake
North
Carolina
Range of eastern
coral snake
South
Carolina

Field Experiments with Artificial Snakes
• To test this mimicry hypothesis, researchers made
hundreds of artificial snakes:
– An experimental group resembling king snakes
– A control group resembling plain brown snakes
• Equal numbers of both types were placed at field
sites, including areas without coral snakes
• After four weeks, the scientists retrieved the artificial
snakes and counted bite or claw marks
• The data fit the predictions of the mimicry hypothesis

LE 1-28
(a) Artificial king snake
(b) Artificial brown snake that has been attacked

In areas where coral snakes
were absent, most attacks
were on artificial king snakes.
In areas where coral
snakes were present,
most attacks were on
brown artificial snakes.
LE 1-29
% of attacks on
artificial king snakes
% of attacks on
brown artificial snakes
Field site with
artificial snakes
83%
North
Carolina
South
Carolina
17%
16%
84%
Key

Designing Controlled Experiments
• Scientists do not control the experimental
environment by keeping all variables constant
• Researchers usually “control” unwanted variables
by using control groups to cancel their effects

Limitations of Science
• The limitations of science are set by its naturalism
– Science seeks natural causes for natural
phenomena
– Science cannot support or falsify supernatural
explanations, which are outside the bounds of
science

Theories in Science
• A scientific theory is much broader than a
hypothesis
• A scientific theory is:
– broad in scope
– general enough to generate new hypotheses
– supported by a large body of evidence

Model Building in Science
• Models are representations of ideas, structures, or
processes
• Models may range from lifelike representations to
symbolic schematics

LE 1-30 From
body
From
lungs
Right
atrium
Left
atrium
Right
ventricle
Left
ventricle
To lungs To body

The Culture of Science
• Science is an intensely social activity
• Both cooperation and competition characterize
scientific culture

Science, Technology, and Society
• The goal of science is to understand natural
phenomena
• Technology applies scientific knowledge for some
specific purpose

• Concept 1.6: A set of themes connects the
concepts of biology
• Biology is the science most connected to the
humanities and social sciences
• Underlying themes provide a framework for
understanding biology

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