Transcript Chapter 1 - HCC Learning Web

Chapter 1
Introduction: Themes in
the Study of Life
PowerPoint® Lecture Presentations for
Biology
Eighth Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Overview: Inquiring About the World of Life
• Evolution: process of change transforming life
• Biology: scientific study of life
• Scientific Inquiry: biologists ask questions
– How a single cell develops into an organism?
– How the human mind works?
– How living things interact in communities?
• What defines Life: it’s what we do (next slide)!
Important Properties of Life
Order
Response
to the
environment
Evolutionary
adaptation
Regulation
Energy
processing
Reproduction
Growth and
development
Concept 1.1: Themes connect biological concepts
• Themes help to organize biological information
• Evolution: one heck of a big theme, indeed!
All organisms living on Earth are modified
descendents of common ancestors
Theme 1.1A: New properties emerge at each level
in the biological hierarchy
• The study of life can be divided into different
levels of biological organization (see text p. 4-5)
1. The biosphere
8. Cells
6. Organs and 10 µm
organ systems
Cell
2. Ecosystems
9.Organelles
3. Communities
1 µm
Atoms
7. Tissues
50 µm
10. Molecules
4. Populations
5. Organisms
Emergent Properties
• Emergent properties result from the
arrangement and interaction of parts as
complexity increases within a system
• Example: An Emergent property in Biology
– Photosynthesis (process): involves the specific
interaction of components in a Chloroplast
• Example: A Non-biological Emergent property
– A functioning bicycle emerges only when all of
the necessary parts connect in the correct way
Reductionism
• Reductionism: the reduction of complex
systems to simpler components that are more
manageable to study
– For example, molecular structure of chlorophyll
• An understanding of biology connects
reductionism (study the one) with emergent
properties (integrated function)
– For example, new understanding comes from
studying the interactions of chlorophyll with
other molecules to produce photosynthesis
Systems Biology
• Systems biology constructs models for the
dynamic behavior of whole biological systems
• A system is a combination of components that
function together (i.e. the cell or the earth)
• The systems approach poses questions like:
– How does a drug for blood pressure affect
other organs?
– How does increasing CO2 alter the biosphere?
Theme 1.1B: Organisms interact with their
environments, exchanging matter and energy
• Every organism interacts with its environment
and that interaction affects each other.
• Ecosystem Dynamics & Energy Conversion (see
next slide)
Sunlight (Energy)
Ecosystem Dynamics
Ecosystem
1. Nutrients from the soil
are returned to the soil
2. Energy flows from
Producers to Comsumers
Cycling
of
chemical
nutrients
Energy Conversion
Producers
(plants and other
photosynthetic
organisms)
Heat
Chemical energy
1. Work (life processes)
requires energy
2. Energy is transformed
from kinetic (light) to
metabolic (chemical)
3. Energy flows through an
ecosystem: entering as
light and exiting as heat
Consumers
(such as animals)
Heat
Theme 1.1C: Structure and function are closely
correlated at all levels of biological organization
(a) Wings
(b) Bones
Infoldings of
membrane
Mitochondrion
100 µm
(c) Neurons
0.5 µm
(d) Mitochondria
Theme 1.1D: Cells are an organism’s basic units of
structure and function
• The cell is the lowest level of organization that
can perform all activities required for life
• All cells:
– Are enclosed by a membrane
– Use DNA as their genetic information
• The ability of cells to divide is the basis of all
reproduction, growth, and repair of multicellular
organisms
• A eukaryotic cell (plants, animals, fungi) has
membrane-enclosed organelles, the largest of
which is usually the nucleus
• A prokaryotic cell (bacteria, archaea) is
simpler and usually smaller, and does not
contain a nucleus or other membrane-enclosed
organelles
• Other differences too: main one is organellar
Prokaryotic cell
Eukaryotic cell
Membrane
DNA
(no nucleus)
Membrane
Cytoplasm
Organelles
Nucleus (contains DNA)
1 µm
Theme1.1E: The continuity of life is based on
heritable information in the form of DNA
• Chromosomes contain most of a cell’s genetic
material (genes) as DNA (deoxyribonucleic acid)
• DNA is the substance of genes
• Genes are the units of inheritance that transmit
information from parents to offspring
• Thus an organism’s genome is its entire set of
genetic instructions (about 30,000 genes),
organized on chromosomes (we have 23)
DNA Structure and Function
• Each chromosome has one long DNA molecule
(chain) with hundreds or thousands of genes
• Each link of a chain is one of four kinds of
chemical building blocks called nucleotides
• Each DNA molecule is made up of two long
chains arranged in a double helix
• DNA is transcribed into RNA, RNA then
translated into a protein (functional molecule)
• DNA controls development and maintenance
Nucleus
DNA
Nucleotide
Cell
(a) DNA double helix
(b) Single strand of DNA
Systems Biology at the Levels of Cells and Molecules
Outer membrane
and cell surface
Cytoplasm
Nucleus
Advances are due to:
1. “High-throughput” technology, which
yields enormous amounts of data
2. Bioinformatics, which is the use of
computational tools to process a large
volume of data
3. People: Interdisciplinary research teams
Theme 1.1F: Feedback mechanisms regulate
biological systems
• Feedback mechanisms allow biological
processes to self-regulate
• Negative feedback means that as more of a
product accumulates, the process that creates
it slows and less of the product is produced
• Positive feedback means that as more of a
product accumulates, the process that creates
it speeds up and more of the product is
produced
Negative
feedback –
A
Enzyme 1
B
Excess D
blocks a step
D
D
Enzyme 2
D
C
Enzyme 3
D
(a) Negative feedback
W
Enzyme 4
Positive
feedback +
X
Enzyme 5
Excess Z
stimulates a
step
Z
Y
Z
Z
Enzyme 6
Z
(b) Positive feedback
Concept 1.2: The Core Theme: Evolution accounts
for the unity and diversity of life
• Evolution unifies biology at different scales of
size throughout the history of life on Earth
Organizing the Diversity of Life
• Approximately 1.8 million species have been
identified and named to date, and thousands
more are identified each year
• Estimates of the total number of species that
actually exist range from 10 million to over 100
million
• Most species have gone to extinction
Grouping Species: The Basic Idea
• Taxonomy is the branch of biology that names
and classifies species into groups of increasing
breadth (see next slide)
Species Genus Family Order
Class Phylum Kingdom Domain
Ursus americanus
(American black bear)
Ursus
Ursidae
Taxonomy Tool:
Drunk
King
Philip
Came
Over
From
Greece
Stoned
Carnivora
Mammalia
Chordata
Animalia
Eukarya
(a) DOMAIN BACTERIA (prokaryotic)
The Three Domains of Life
(b) DOMAIN ARCHAEA (prokaryotic)
(c) DOMAIN EUKARYA (eukaryotic)
Several Protist
Kingdoms
Kingdom
Plantae
Kingdom Fungi
Kingdom Animalia
Unity in the Diversity of Life
• A striking unity underlies the diversity of life
15 µm
5 µm
Cilia of
Paramecium
Cilia of
windpipe
cells
0.1 µm
Cross section of a cilium, as viewed
with an electron microscope
Charles Darwin: Theory of Natural Selection
• Fossils and other evidence document the
evolution of life on Earth over billions of years
• Charles Darwin published On the Origin of
Species by Means of Natural Selection in 1859
• Darwin made two main points:
– Species have arisen by “descent with
modification” from common ancestors using
natural selection as the mechanism
• Darwin’s theory explained the duality of unity
and diversity
• Darwin observed that:
– Individuals in a population have heritable,
variable traits. More offspring are produced
than survive. Competition is inevitable.
Species generally suit their environment.
• Darwin inferred that:
– Individuals that are best suited to their
environment are more likely to survive and
reproduce; producing more individuals in the
population with the advantageous traits
• Natural selection is often evident in adaptations
of organisms to their way of life & environment
Example of Natural Selection
1
Population
with varied
inherited traits
(in this case,
color).
2
Elimination
of individuals
with certain
Traits (light
color).
3
Reproduction
of survivors
(dark colored
bugs).
4
Increasing
frequency
of traits that
enhance
survival and
reproductive
success.
The Tree of Life
• “Unity in diversity” arises from “descent with
modification”
– For example, the forelimb of the bat, human,
and flipper share common skeletal architecture
• Darwin proposed that natural selection could
cause an ancestral species to give rise to two
or more descendent species
• Evolutionary relationships are often illustrated
with tree-like diagrams that show ancestors
and their descendents (see next slide)
Fig. 1-22
Insect-eaters
Gray warbler finch
Certhidea fusca
Bud-eater
Seed-eater
Warbler finches
COMMON
ANCESTOR
Green warbler finch
Certhidea olivacea
Sharp-beaked
ground finch
Geospiza difficilis
Vegetarian finch
Platyspiza crassirostris
Mangrove finch
Cactospiza heliobates
Insect-eaters
Tree finches
Woodpecker finch
Cactospiza pallida
Medium tree finch
Camarhynchus pauper
Large tree finch
Camarhynchus
psittacula
Cactus-flowereaters
Seed-eaters
Ground finches
Niche’ driven
modifications
Small tree finch
Camarhynchus
parvulus
Large cactus
ground finch
Geospiza conirostris
Cactus ground finch
Geospiza scandens
Small ground finch
Geospiza fuliginosa
Medium ground finch
Geospiza fortis
Large ground finch
Geospiza
magnirostris
Concept 1.3: Scientists use two main forms of
inquiry in their study of nature
• Inquiry: search for information and explanation
• There are two main types of scientific inquiry:
Discovery science describes nature.
Hypothesis-based science explains nature.
Discovery Science
• Describes natural structures and processes
• Based on observation and analysis of data:
recorded observations or items of information
• Types of Data two categories
Qualitative (descriptive) or Quantitative (measured)
• Inductive reasoning draws conclusions through
the logical process of induction: many repeated
and specific observations lead to important
generalizations. Example: sunrise in the east.
Hypothesis-Based Science
• Observations will lead us to ask questions and
propose hypothetical explanations: hypotheses
• Hypothesis: tentative answer to a well-framed
question. Example: Eastern sunrise because…
• A scientific hypothesis leads to predictions that
can be tested by observation or experimentation
• Deductive reasoning uses general premises to
make specific predictions. “If…Then” Logic (see
next slide)
Example of Scientific Method
Observation
Question
Your flashlight doesn’t work
Why doesn’t your flashlight work?
Hypothesis #1:
Hypothesis #2:
Dead batteries
Burnt-out bulb
Prediction:
Replacing batteries
will fix problem
Test prediction
Prediction:
Replacing bulb
will fix problem
Test prediction
Test falsifies hypothesis Test does not falsify hypothesis
So test it!
A Closer Look at Hypotheses in Scientific Inquiry
• Hypothesis-based science often makes use of
two or more alternative hypotheses (last slide)
• A hypothesis must be testable and falsifiable
• Observations and results must be repeatable
• Experiments must be under controlled conditions
meaning that control groups are used to cancel
the effects of unwanted variables
• Failure to falsify a hypothesis does not prove
that hypothesis (example: a replaced bulb)
Limitations of Science
• In science, observations and experimental
results must be repeatable
• Science cannot support or falsify supernatural
explanations, which are outside the bounds of
science
Theories in Science
• In the context of science, a theory is:
– Broader in scope than a hypothesis
– General, and can lead to new testable
hypotheses
– Supported by a large body of evidence in
comparison to a hypothesis
Model Building in Science
• Models are representations of natural
phenomena and can take the form of:
– Diagrams
– Three-dimensional objects
– Computer programs
– Mathematical equations
From
body
From
lungs
Right
atrium
Left
atrium
Right
ventricle
Left
ventricle
To lungs
To body
The Culture of Science
• Most scientists work in teams, which often
include graduate and undergraduate students
• Good communication is important in order to
share results through seminars, publications,
and websites
Science, Technology, and Society
• The goal of science is to understand natural
phenomena
• The goal of technology is to apply scientific
knowledge for some specific purpose
• Science and technology are interdependent
• Biology is marked by “discoveries,” while
technology is marked by “inventions”
• Ethical issues can arise from new technology
You should now be able to:
1. Briefly describe the unifying themes that
characterize the biological sciences
2. Distinguish among the three domains of life,
and the eukaryotic kingdoms
3. Distinguish between the following pairs of
terms: discovery science and hypothesisbased science, quantitative and qualitative
data, inductive and deductive reasoning,
science and technology
A Case Study in Scientific Inquiry: Investigating
Mimicry in Snake Populations
• Many poisonous species are brightly colored,
which warns potential predators
• Mimics are harmless species that closely
resemble poisonous species
• Henry Bates hypothesized that this mimicry
evolved in harmless species as an evolutionary
adaptation that reduces their chances of being
eaten
• This hypothesis was tested with the poisonous
eastern coral snake and its mimic the
nonpoisonous scarlet kingsnake
• Both species live in the Carolinas, but the
kingsnake is also found in regions without
poisonous coral snakes
• If predators inherit an avoidance of the coral
snake’s coloration, then the colorful kingsnake
will be attacked less often in the regions where
coral snakes are present
Fig. 1-25
Scarlet kingsnake (nonpoisonous)
Key
Range of scarlet
kingsnake only
Overlapping ranges of
scarlet kingsnake and
eastern coral snake
North
Carolina
South
Carolina
Eastern coral snake
(poisonous)
Scarlet kingsnake (nonpoisonous)
Field Experiments with Artificial Snakes
• To test this mimicry hypothesis, researchers
made hundreds of artificial snakes:
– An experimental group resembling kingsnakes
– A control group resembling plain brown snakes
• Equal numbers of both types were placed at
field sites, including areas without poisonous
coral snakes
Fig. 1-26
(a) Artificial kingsnake
(b) Brown artificial snake that has been attacked
• After four weeks, the scientists retrieved the
artificial snakes and counted bite or claw marks
• The data fit the predictions of the mimicry
hypothesis: the ringed snakes were attacked
less frequently in the geographic region where
coral snakes were found
Fig. 1-27
RESULTS
Artificial
kingsnakes
Percent of total attacks
on artificial snakes
100
84%
83%
80
60
40
20
17%
16%
0
Coral snakes
absent
Coral snakes
present
Brown
artificial
snakes