Transcript Document

LECTURE PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
Chapter 1
Introduction: Themes in the
Study of Life
Lectures by
Erin Barley
Kathleen Fitzpatrick
© 2011 Pearson Education, Inc.
Overview: Inquiring About Life
• An organism’s adaptations to its
environment are the result of evolution
– the mother of pearl plant’s thick,
succulent leaves are adaptations
to conserving water; this helps it to
survive in the crevices of rock
walls
• Evolution is the process of change that
has transformed life on Earth
• but many questions remain about these
changes
• asking these questions and finding the
science-based answers is BIOLOGY
• Biology is the scientific study of life
• Biologists ask questions such as
– How does a single cell develop into an organism?
– How does the human mind work?
– How do living things interact in communities?
• Life defies a simple, one-sentence definition
What is Life?
1. movement: internal & external
2. responsiveness & adaptation
to environment
3. growth
4. reproduction
5. digestion & energy
processing
6. absorption
7. secretion
8. circulation
9. order
10. regulation
Order
Response to
the environment
Evolutionary adaptation
Reproduction
Regulation
Energy processing
Growth and
development
Requirements for Life:
1. water
2. food
3. oxygen
4. heat
5. pressure
Concept: The themes of this book make
connections across different areas of biology
• Biology consists of more than memorizing factual
details
• Themes help to organize biological information
Theme #1: New Properties Emerge at Each Level in the
Biological Hierarchy
• Life can be studied at different levels, from molecules to the
entire living planet
• The study of life can be divided into different levels of biological
organization
• starting with the biosphere and ending with the atom
• as we proceed through these levels – different properties
emerge
7. Tissues – group of cells
that work together to perform
specific functions
1. The biosphere – all life on Earth
2. Ecosystems – all living things
in a particular area +
all non-living components
e.g. soil, water, atmosphere
mesophyll
leaf
epidermis
6. Organs and organ
systems – a part that carries
out a specific function within
an organism
8. Cells – life’s fundamental
unit of structure &
function
3. Communities –
the entire array
of organisms
living within an
ecosystem
9. Organelles – the
functional components
of a cell
5. Organisms – individual
living things
4. Populations – all the living individuals of a
species living within the bounds of an area
e.g. population of sugar maple tress within a forest
11. Atoms
10. Molecules – a chemical
structure consisting of two
or more atoms
Emergent Properties
• novel properties emerge at each step along this hierarchy
– the properties at each step are unique
• known as emergent properties
– result from the arrangement and interaction of parts within a system
– due to the arrangement and interaction of parts as complexity increases
– e.g. human brain – memories and thoughts are emergent properties of a
complex network of nerve cells
– e.g. photosynthesis occurs in chloroplasts – will not take place in a test
tube containing a disorganized mixture of chlorophyll and other
chloroplast molecules
Emergent Properties
• emergent properties are not unique to life
• they can characterize nonbiological entities as well
– for example, a functioning bicycle emerges only when all of
the necessary parts connect in the correct way
– the lead of a pencil and a diamond are both carbon – but
the arrangement of their carbon atoms are different –
leads to different properties
The Power and Limitations of Reductionism
• the complexity of emergent properties make them
challenging to study
– so we try to reduce them into something simpler
• reductionism is the reduction of complex systems to simpler
components that are more manageable to study
• but you need to observe the interactions of these systems
with others in order to fully understand them
– e.g. studying the molecular structure of DNA helps us to
understand the chemical basis of inheritance
– but you need to study how DNA interacts with the
proteins of the nuclear matrix
Systems Biology
• you must balance reductionism with a larger, more holistic
approach to emergent systems
• how cells, organisms and higher levels of order work together =
goal of Systems Biology
• a system = is a combination of components that function
together
• Systems biology constructs models for the dynamic behavior of
whole biological systems
– based on a study of the interactions among the system’s parts
– the model allows for predictions when one variable changes
• systems biology poses questions such as
– how does a drug for blood pressure affect other organs? (physiological
models)
– how does increasing CO2 alter the biosphere? (ecosystem models)
Theme #2: Organisms Interact with Other
Organisms and the Physical Environment
• in an ecosystem - every organism interacts with its environment,
including nonliving factors and other organisms
– e.g. leaves of a tree take up CO2 and release O2 to the air
– humans utilize this O2
Sunlight
• both organisms and their
environments are affected
by the interactions
between them
– some of these interactions
can be harmful
– e.g. greenhouse gases
Leaves absorb
light energy from
the sun.
CO2
Leaves take in
carbon dioxide
from the air
and release
oxygen.
O2
Cycling
of
chemical
nutrients
Leaves fall to
the ground and
are decomposed
by organisms
that return
minerals to the
soil.
Water and
minerals in
the soil are
taken up by
the tree
through
its roots.
Animals eat
leaves and fruit
from the tree.
Theme #3: Life Requires Energy Transfer and
Transformation
•
•
•
•
a fundamental characteristic of living organisms is their use of energy to carry out life’s
activities
work, including moving, growing, and reproducing, requires a source of energy
living organisms transform energy from one form to another
– e.g. light energy is converted to chemical energy (i.e. sugar), chemical energy
becomes kinetic energy (e.g. growth, reproduction, movement)
energy flows through an ecosystem, usually entering as light and exiting as heat
Sunlight
Heat
When energy is used
to do work, some
energy is converted to
thermal energy, which
is lost as heat.
Producers absorb light
energy and transform it into
chemical energy.
Chemical
energy
Chemical energy in
food is transferred
from plants to
consumers.
(a) Energy flow from sunlight to
producers to consumers
An animal’s muscle
cells convert
chemical energy
from food to kinetic
energy, the energy
of motion.
(b) Using energy to do work
A plant’s cells use
chemical energy to do
work such as growing
new leaves.
Theme #4: Structure and Function Are Correlated
at All Levels of Biological Organization
• form fits function
• so analyzing a biological structure gives us clues as to its function
• structure and function of living organisms are closely related
– e.g. a leaf is thin and flat, maximizing the capture of light by chloroplasts
– e.g. the structure of a bird’s wing is adapted to flight
(a) Wings
(b) Wing bones
Theme #5: The Cell Is an Organism’s Basic Unit 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
• a eukaryotic cell has membrane-enclosed organelles, the largest of which is
Prokaryotic cell
usually the nucleus
Eukaryotic cell
Membrane
• by comparison, a prokaryotic cell is
simpler and usually smaller, and does
not contain a nucleus or other
membrane-enclosed organelles
DNA
(no nucleus)
Membrane
Cytoplasm
Membraneenclosed organelles
Nucleus
(membraneenclosed)
DNA (throughout
1 m
nucleus)
Theme #6: The Continuity of Life Is Based on Heritable
Information in the Form of DNA
• the ability of cells to divide is the basis of all reproduction, growth, and repair of
multicellular organisms
• the dividing cell contains a specific form of genetic material = chromosomes
– chromosomes contain most of a cell’s genetic material in the form of DNA
(deoxyribonucleic acid)
• DNA is the substance of genes
• genes are the units of inheritance that transmit information from parents to
offspring
25 m
DNA Structure and Function
• each chromosome is made up of one long DNA molecule with hundreds or
thousands of genes
– genes encode information for building proteins
• DNA is inherited by offspring from their parents
– one chromosome from each parent
• DNA controls the development and maintenance of organisms
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 and are
nicknamed A, G, C, and T for the
bases they carry
• genes control protein
production indirectly
– DNA is transcribed into RNA then
translated into a protein
– known as a process called gene
expression
Nucleus
A
C
DNA
Nucleotide
T
A
T
Cell
A
C
C
G
T
A
G
T
A
(a) DNA double helix (b) Single strand of DNA
Theme #7: Feedback Mechanisms Regulate
Biological Systems
Negative
feedback
• 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
A
Enzyme 1
B
Excess D
blocks a step. D
D
Enzyme 2
D
C
Enzyme 3
D
(a) Negative feedback
Theme #7: Feedback Mechanisms Regulate
Biological Systems
Enzyme 4
• Positive feedback means that as more
of a product accumulates, the process
that creates it speeds up and more of
the product is produced
Positive
feedback 
Excess Z
stimulates a
step.
Z
X
Enzyme 5
Y
Z
Z
Enzyme 6
Z
(b) Positive feedback
Evolution, the Overarching Theme of Biology
• there is consensus among biologists as to the core theme of biology
= Evolution
– “Nothing in biology makes sense except in the light of evolution”—Theodosius
Dobzhansky
• evolution unifies biology at different scales of size throughout the
history of life on Earth
– evolution makes sense of everything we know about biology
• organisms are modified descendants of common ancestors
• evolution explains patterns of unity and diversity in living organisms
• similar traits among organisms are explained by descent from
common ancestors
• differences among organisms are explained by the accumulation of
heritable changes
Classifying the Diversity of Life
• diversity is a hallmark of life
• approximately 1.8 million species have been identified and named
to date, and thousands more are identified each year
–
–
–
–
–
100,000 species of fungi
290,000 plant species
52,000 vertebrate species
1 million insect species
untold numbers of single-cells species
• estimates of the total number of species that actually exist range
from 10 million to over 100 million
• thousands of new species identified each year
Grouping Species: The Basic Idea
• taxonomy is the branch of biology that names and classifies
species into groups of increasing breadth
• domains, followed by kingdoms, are the broadest units of
classification
Species Genus Family Order Class Phylum Kingdom Domain
Ursus americanus
(American black bear)
Ursus
Ursidae
Carnivora
Mammalia
Chordata
Animalia
Eukarya
• in 1969: five-kingdom classification system – Robert
Whittaker
– recognized the existence of two fundamental cell types:
prokaryotes and eukaryotes
– created a separate kingdom for prokaryotes and divided up
the eukaryotes
– 1. Monera - prokaryotic
– 2. Protista – unicellular organisms including algae
– 3. Fungi
– 4. Plantae
– 5. Animalia
– based on the nutritional requirements and methods of
these domains
•
•
•
•
plants = autotrophs
fungus and animals = heterotrophs
fungus = decomposers
animals = digestors within the body
• recently the application of
molecular analysis to this
classification has resulted in a
reclassification
1
Billion years ago
– some prokaryotes can differ
dramatically from each other –
as much as they differ from
plants and animals
– reorganization based on
molecular data
0
Bacteria
Eukarya
gene transfer
2
3
common ancestor
of all life
4
Origin of life
Archaea
• adoption of a three domain system of superkingdoms
– 1. Bacteria – most of the currently known prokaryotes (or
Eubacteria)
– 2. Archaea – prokaryotes that inhabit a wide variety of
environments
– 3. Eukarya - eukaryotes
• contains the “old” kingdoms of protists, fungi, plants and animals
2 m
(b) Domain Archaea
2 m
(a) Domain Bacteria
(c) Domain Eukarya
Kingdom Animalia
100 m
Kingdom Plantae
Protists
Kingdom Fungi
Unity in the Diversity of Life
• as diverse as life is – there is a striking unity
• unity is evident in many features of cells
– e.g. cilia of a paramecium and a respiratory mucous cell
• REASON: DNA is the universal genetic language common to all
organisms
– unity is evident in many features of cell structure
15 m
5 m
Cilia of
Paramecium
Cilia of
windpipe
cells
0.1 m
Cross section of a cilium, as viewed
with an electron microscope
• how do you account for the unity and diversity
found in nature = Evolution
• Evolution!!!!
Evolution
• three key observations about life
– 1. organisms are suited for life in their
environments
– 2. many forms of life share characteristics
– 3. life is diverse
• 150 yrs ago – Charles Darwin developed
a scientific explanation for these
observations
• published his theory in 1859 as the
Origin of Species by Means of Natural
Selection
– from his work categorizing species as a
member of the HMS Beagle
Evolution
• evolution = descent with modification
• can also be defined as a change in the genetic
composition of a population from generation to
generation
• pattern of evolutionary change is revealed by data
taken from biology, geology, physics and chemistry
Evolution is Descent with Modification
• Darwin never used the term evolution
• used the term descent with modification
• proposed that similarities between organisms was due to descent
from a common ancestor in the remote past
• the descendants lived in various habitats developing adaptations to
fit them to their habitat
• called the mechanism of this evolutionary adaptation = Natural
Selection
three orchids showing
variations on a common
floral theme
Artificial & Natural Selection
• Natural selection was proposed as the mechanism
explaining evolution
• used artificial selection used by humans in breeding to
explain his theory
• made two observations:
– 1. members of a population often vary in their inherited
traits
• SO: individuals whose inherited traits give them a higher probability
of surviving and reproducing will leave more offspring
– 2. all species can produce more offspring than their
environment can support – many fail to survive
• SO: the ability to survive and reproduce will lead to an accumulation
of favorable inheritable traits
• if these traits make your offspring more successful at coping with its
environment = traits will persist over time = NATURAL SELECTION
Natural Selection: a recap
• 1. NS is a process in which individuals with certain heritable traits survive and
reproduce at a higher rate than other individuals who don’t have those traits
• 2. over time, NS can increase the match between organisms and their
environment
• 3. if an environment changes (or if an individual moves to a new environment),
NS may result in adaptations
• These new adaptations sometime give rise to new species.
1 Population with
varied inherited
traits
2 Elimination of
individuals with
certain traits
3 Reproduction of
survivors
4 Increasing
frequency of
traits that
enhance
survival and
reproductive
success
The Tree of Life
• “Unity in diversity” arises from “descent with
modification”
– e.g. the forelimb of the bat, human, and horse and
the whale flipper all share a common skeletal
architecture
• evolutionary relationships are often illustrated with
treelike diagrams that show ancestors and their
descendants
– fossils provide additional evidence of anatomical unity from
descent with modification
Insect-eaters
Green warbler finch
Certhidea olivacea
Gray warbler finch
Certhidea fusca
Bud-eater
Seed-eater
COMMON
ANCESTOR
Warbler finches
Figure 1.22
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
Small tree finch
Camarhynchus parvulus
Cactus-flowereaters
Seed-eaters
Ground finches
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: In studying nature, scientists make
observations and then form and test hypotheses
• The word science is derived from Latin and means “to know”
• at the heart of science is inquiry
– the search for information and explanation
• in the search for answers, scientists use the scientific process
• scientific process includes:
–
–
–
–
–
1. making observations
2. forming logical hypotheses – that are testable and falsifiable
3. testing them
4. analysis of results
5. verification of hypothesis
Types of Data
• biologists use data to describe
natural structures and processes
• Data = recorded observations or
items of information that fall into
two categories
– Qualitative data =
descriptions rather than
measurements
• e.g. Jane Goodall’s observations
of chimpanzee behavior
– Quantitative data = recorded
measurements
• which are sometimes organized
into tables and graphs
Inductive Reasoning
• collection of data leads to conclusions based on a type of
logic called inductive reasoning
• inductive reasoning draws conclusions through the
logical process of induction
• proper induction can lead to important generalizations
• but these generalizations must be tested through testing
or experimentation
• an experiment requires two components:
– 1. controls – something known you can compare your
experimental results to
– 2. repeatability - repeating specific observations
Forming and Testing Hypotheses
• observations and inductive reasoning can lead us to ask
questions and propose hypothetical explanations called
hypotheses
• a hypothesis is a tentative answer to a well-framed
question
• a scientific hypothesis leads to predictions that can be
tested by observation or experimentation
• a scientific hypothesis must be falsifiable
© 2011 Pearson Education, Inc.
Observation: Your flashlight doesn’t work
– Inquiry: Why doesn’t your flashlight work?
– Inductive reasoning leads to two possible
hypotheses:
– Hypothesis 1: The batteries are dead
– Hypothesis 2: The bulb is burnt out
• Both these hypotheses are testable
• good experimentation requires two
components
Observations
– 1. controls – something known you can
compare your experimental results to
•
•
•
•
•
•
put in batteries that you KNOW are good
did it work? NO
then it might be the bulb
put in a bulb that you KNOW is good
did it work? YES
THEN: it was the bulb
– 2. repeatability – eliminates the
possibility that your results are due to
chance
Question
Hypothesis #1:
Dead batteries
Hypothesis #2:
Burnt-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test of prediction
Test of prediction
Test falsifies hypothesis
Test does not falsify hypothesis
• hypothesis-based science often makes use of two
or more alternative hypotheses
• failure to prove one hypothesis does not prove
another hypothesis
– e.g. you replace your batteries and it still doesn’t
work
– this doesn’t mean it is the bulb
– maybe you put your batteries in the wrong way
Deductive Reasoning and Hypothesis Testing
• inductive reasoning uses observations to make a
hypothesis
• deductive reasoning uses general premises to make
specific predictions and test the hypothesis
– used after the hypothesis has been developed
– involves the use of IF/THEN statements
– e.g. IF I put working batteries in my flashlight and it works
(premise) THEN it was the batteries that were the
problem (deductive prediction)
– e.g. IF organisms are made of cells (premise 1), and
humans are organisms (premise 2), THEN humans are
composed of cells (deductive prediction)
Questions That Can and Cannot Be
Addressed by Science
• A hypothesis must be: testable and falsifiable
– for example, a hypothesis that ghosts fooled with the
flashlight cannot be tested
• Supernatural and religious explanations are outside
the bounds of science
© 2011 Pearson Education, Inc.
Concept: Science benefits from a cooperative
approach and diverse viewpoints
• 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
© 2011 Pearson Education, Inc.
Building on the Work of Others
• scientists check each others’ claims by performing
similar experiments
• it is not unusual for different scientists to work on the
same research question
• scientists cooperate by sharing data about model
organisms and by sharing their results and conclusions
• this course will discuss what we know using data that
had been accumulated by numerous scientists all
working together and building upon one another