01 lectures ppt
TRANSCRIPT
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
PowerPoint Lectures for Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
Chapter 1
Exploring Life
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• 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
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• Life’s basic characteristic is a high degree of order
• Each level of biological organization has emergent properties
Video: Seahorse CamouflageVideo: Seahorse Camouflage
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• 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
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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
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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
Ecosystems
The biosphere
Organisms
Populations
Communities
Cells
Organelles
Molecules
Tissues
Organs and organ systems
Cell1 µm
Atoms
10 µm
50 µm
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A Closer Look at Ecosystems
• Each organism interacts with its environment
• Both organism and environment affect each other
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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
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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
Chemicalenergy
Consumers(including animals)
Producers(plants and otherphotosynthetic
organisms)
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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
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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
NucleicontainingDNA
Egg cell
Fertilized eggwith DNA fromboth parents
Embryo’s cells With copies of inherited DNA
Offspring with traits inherited from both parents
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• 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
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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
Membrane
Cytoplasm
EUKARYOTIC CELL PROKARYOTIC CELL
DNA(no nucleus)
Membrane
1 µm
Organelles
Nucleus (contains DNA)
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• 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
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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
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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
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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
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• 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
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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
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• 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: Negative FeedbackAnimation: Negative Feedback Animation: Positive FeedbackAnimation: Positive Feedback
LE 1-12
W
Enzyme 4
W
XX
Y Y
ZZ
ZZ
Z ZZ
ZZ Z
Enzyme 5
Enzyme 6
Positivefeedback
Enzyme 4
Enzyme 6
Enzyme 5
Z
Z Z Z
Z
Z
Z
ZZ
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• 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
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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
Ursidae
Ursus
Carnivora
Mammalia
Chordata
Animalia
Eukarya
Species Genus Family Order Class Phylum Kingdom DomainUrsusamericanus(Americanblack bear)
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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
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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 1-16b
Cilia of windpipe cellsCilia of Paramecium
Cross section of cilium,as viewed with anelectron microscope
0.1 µm
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• 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
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• 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
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• 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
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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
Evolution of adaptationsin the population
Differences inreproductive success
Overproductionand competition
Populationof organisms
Hereditaryvariations
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• 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 enhancesurvival and reproductive success
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• Natural selection is often evident in adaptations of organisms to their way of life and environment
• Bat wings are an example of adaptation
Video: Soaring HawkVideo: Soaring Hawk
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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 1-23Largeground finch
Large cactusground finch
Sharp-beakedground finch
Geospizamagnirostris
Geospizaconirostris
Mediumground finch
Geospizafuliginosa
Smallground finch
Woodpecker finch
Camarhynchuspsittacula
Large tree finch
Medium tree finch
Cactusground finch
Geospizadifficilis
Cactus flowereaters
Geospizascandens
Seed eater
Ground finches
Seed eaters
Tree finches
Common ancestor fromSouth American mainland
Insect eaters Bud eater
Warbler finches
Mangrove finchGeospiza
fortis
Cactospizapallida Small
tree finch
Camarhynchuspauper
Camarhynchusparvulus
Greenwarblerfinch
Graywarblerfinch
Certhideaolivacea
Certhideafusca
Vegetarianfinch
Platyspizacrassirostris
Cactospizaheliobates
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Video: Albatross Courtship RitualVideo: Albatross Courtship Ritual
Video: Blue-footed Boobies Courtship RitualVideo: Blue-footed Boobies Courtship Ritual
Video: GalapVideo: Galapáágos Islands Overviewgos Islands Overview
Video Galapágos Marine IguanaVideo Galapágos Marine Iguana
Video: Galapágos Sea LionVideo: Galapágos Sea Lion
Video: Galapágos TortoiseVideo: Galapágos Tortoise
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• 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
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Discovery Science
• Discovery science describes nature through careful observation and data analysis
• Examples of discovery science:
– understanding cell structure
– expanding databases of genomes
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Types of Data
• Data are recorded observations
• Two types of data:
– Quantitative data: numerical measurements
– Qualitative data: recorded descriptions
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Induction in Discovery Science
• Inductive reasoning involves generalizing based on many specific observations
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Hypothesis-Based Science
• In science, inquiry usually involves proposing and testing hypotheses
• Hypotheses are hypothetical explanations
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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 1-25b
Hypothesis #1:Dead batteries
Hypothesis #2:Burnt-out bulb
Test prediction
Test falsifies hypothesis
Prediction:Replacing batterieswill fix problem
Prediction:Replacing bulbwill fix problem
Test prediction
Test does not falsify hypothesis
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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
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A Closer Look at Hypotheses in Scientific Inquiry
• A scientific hypothesis must have two important qualities:
– It must be testable
– It must be falsifiable
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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
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• In mimicry, a harmless species resembles a harmful species
• An example of mimicry is a stinging honeybee and a nonstinging mimic, a flower fly
A Case Study in Scientific Inquiry: Investigating Mimicry in Snake Populations
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• 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 coralsnake
Scarlet king snake
Key
Range of scarlet king snake
NorthCarolina
Range of easterncoral snake
SouthCarolina
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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
In areas where coral snakes were present, most attacks were on brown artificial snakes.
In areas where coral snakeswere absent, most attacks
were on artificial king snakes.
LE 1-29
% of attacks onartificial king snakes
% of attacks onbrown artificial snakes
Field site withartificial snakes
83%
NorthCarolina
SouthCarolina
17%
16%
84%
Key
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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
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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
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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
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Model Building in Science
• Models are representations of ideas, structures, or processes
• Models may range from lifelike representations to symbolic schematics
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The Culture of Science
• Science is an intensely social activity
• Both cooperation and competition characterize scientific culture
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Science, Technology, and Society
• The goal of science is to understand natural phenomena
• Technology applies scientific knowledge for some specific purpose
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• 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