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Transcript
Welcome to Biology 101 (RCGC)
Dr. Robert Anderson
Rowan College of Gloucester County
What Rules Do You Follow?
Physics – gravity, electricity, time, forces, etc.
Chemistry (Physiology) – diffusion, chemical
reactions, protein synthesis
Biology – cells, organs, photosynthesis,
organisms, healing, ecology, evolution, etc.
What is BIOLOGY?
• 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
Outline
• 1) Biological Organization
• 2) DNA and Cells
• The human genome project
• 3) Systems Biology and putting together information
• Feedback systems in living cells
• 4) Taxonomy – naming all of the organisms
• 5) Diversity of species
• The theory of evolution
• The theory of natural selection
• 6) The scientific method
• 7) Examples of field studies employing the scientific method
• 8) Theories in science
Biologists study the properties of life!
Life’s Basic Characteristic is Order
• Biologists explore life from the microscopic (Microbiology) to the global scale
(Ecology and Evolution)
• The study of life extends from molecules and cells to the entire living planet
(biosphere)
• Biological organization is based on a hierarchy of structural levels from simple
to complex
• Each level of biological organization has its own set of properties
A Hierarchy of Biological Organization
1.
2.
3.
4.
5.
Biosphere: all environments on Earth – basically
encompasses the entire planet.
Ecosystem: all living and nonliving things in a
particular area.
Community: all living organisms present in an
ecosystem. Each identical life form is known as a
species.
Population: an isolated group of individuals of the
same species living within a particular area.
Organism: an individual living thing.
Largest
Level
Smaller
Levels
A Hierarchy of Biological Organization
(continued)
6.
Organ and organ systems: specialized body parts
made up of tissues comprise an organ. Several
organs come together to form an organ system.
7. Tissue: a group of similar cells.
8. Cell: life’s fundamental unit of structure and
function. Some organisms consist of single cells
(unicellular organisms), while others contain
billions of cells (multicellular organisms).
9. Organelle: a functional or structural component of
a cell.
10. Molecule: a chemical structure consisting of two
or more atoms.
Larger
Levels
Smallest
Levels
An Example of the Hierarchy
of Biological Organization
The biosphere
Ecosystems
Organelles
1 µm
Cell
Cells
Atoms
10 µm
Communities
Molecules
Tissues
50 µm
Populations
Organs and organ systems
Organisms
Important Underlying Themes:
The Fundamentals of Biology
1. New properties emerge at each level of biological
organization
2. Organisms react with each other and the physical
environment
3. Life requires energy transfer and transformation
4. Structure dictates function (like number 1)
5. The cell is the basic unit of life
6. DNA allows species to pass information down through the
generations
7. Feedback mechanisms regulate biological systems
8. Evolution accounts for biodiversity
Theme 1:
New properties emerge at each level of biological
organization
• Structure dictates function!
• Evolution has allowed living
organisms to accomplish many
complex actions through organization
• This organization allows the whole
organism to function in its
environment, but it also allows the
body to function internally giving it
emergent properties
• Should the structure of a living thing
be disrupted, life processes will be
affected (usually in a bad way!)
Making Sense of Complex Organization
• Reductionism – a system can be studied at any level or organization
by breaking it down into its component parts
• However, individual parts do not act the same as the complete
system, and may not provide a good explanation for how living things
work
• Systems biology is an approach that tries to model what happens in a
complete system by adding, subtracting or changing the variables
know to affect the system
• This is the fundamental philosophy of working in SCIENCE!!!
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
Outer membrane
and cell surface
Cytoplasm
CELL
Nucleus
Example - Sequencing the Human Genome
•In 1990 our government launched the Human
Genome Project (HGP)
•it was expected to take 15 years and cost over 3
billion dollars
•goals of the project:
1. map all of the human genes
2. construct a detailed physical map of the entire
human genome
3. determine the nucleotide sequences of all 24
human chromosomes
Results
• By 2004 (14 years later) we sequenced 2.85 BILLION base pairs which translated
to roughly 22,287 genes
•Does this allow us to understand how the whole human body works?
Other Examples?
• What happens to an ecosystem if a species goes extinct?
• Is a newly approved drug safe for people that have immune
problems?
•
•
•
Theme 2: Organisms react with each other and
the physical environment
• Each organism interacts with its environment
• Both organisms and environment affect each other
• Examples
• Cycling of nutrients occurs when plants make sugar and oxygen from
sunlight, carbon dioxide and water
• Animals then eat the plants, breaking down sugar and breathing in the
plants oxygen to make CO2 and water, thus feeding the plant and
completing the cycle
• Other examples? What is happening on the larger scale?
Climate Change – Fact or Fiction?
Theme 3: Life requires energy transfer and
transformation
Sunlight
• Activities of life require the living
organism to do some type of
work
Ecosystem
• Work depends on sources of
energy
• Energy exchange between an
organism and environment often
involves energy transformations
i.e. from sunlight to chemical
energy
• In transformations, some energy
is lost as heat
• Energy flows through an
ecosystem, usually entering as
light and exiting as heat
Producers
(e.g. plants)
Cycling
of
chemical
nutrients
Heat
Chemical energy
Consumers
(such as
animals)
Heat
Theme 4: Structure Dictates Function
• What can you say about the diet of these animals?
Theme 4: Structure Dictates Function
• Other Examples?
Theme 5: The cell is the basic unit of life
• The cell is the smallest level of biological 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
25 µm
Theme 6: DNA allows species to pass
information down through the generations
• Cells contain DNA, (deoxyribonucleic acid), the heritable
information that directs the cell’s activities
• DNA is what makes up our genes
• Genes are the units of inheritance that transmit genetic
information from parents to offspring
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
In 1953, Watson and Crick suggested a 3D structure for DNA
What is DNA?
• 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
More (much more) on this later…..
Structure of DNA
Nucleus
DNA
Nucleotide
Cell
DNA double helix
Single strand of DNA
How do Living Things Work?
• Why do children look like their parents?
• Why can’t different species breed and make
offspring?
• What causes predictable change in an organism over
time?
• What determines behavior?
• So many questions! – best to start with a simple
organism…..
Griffith’s Experiment
Frederick Griffith (1928) observed that virulent (deadly) Streptococcus bacteria,
when heat-inactivated and mixed with a nonvirulent strain, could “transform” the
nonvirulent strain and make it virulent.
What Happened?
Group Hypothesis
1.
2.
3.
4.
Griffith’s Experiment
Frederick Griffith (1928) observed that virulent (deadly) Streptococcus bacteria,
when heat-inactivated and mixed with a nonvirulent strain, could “transform” the
nonvirulent strain and make it virulent.
This showed
that DNA was
the inheritable
material
Implications?
Theme 7: Feedback mechanisms regulate
biological systems
• Many biological processes are self-regulating: the product
regulates the process itself. The end product of a specific reaction
works to feed-back on the process.
• 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
• Regulatory systems ensure a dynamic balance in living systems
• Chemical processes are catalyzed (accelerated) by enzymes
• Examples?
Negative Feedback
A
A
Enzyme 1
Enzyme 1
B
B
Enzyme 2
C
C
Enzyme 3
D
D
D
D
D
D
• Increasing
amounts of
product “D”
shuts off
enzyme 1.
D
D
D
D
D
• This turns off
the production
of product
• The product
limits its own
production
Positive Feedback
W
W
Enzyme 4
Enzyme 4
X
• Increasing
amounts of
product “D”
activates
enzyme 1.
X
Enzyme 5
Enzyme 5
Y
Y
Enzyme 6
Enzyme 6
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
• This increases
the production
of product
Z
Z
Z
Z
Z
Z
Z
• The product
increases its
own production
Evolution Drives Change in Living
Things
• The sum of living things on the planet is called the Earth’s
biodiversity
• The theory of evolution operates on the hypothesis that all life
originated from a common ancestor (LUCA – the Last Universal
Common Ancestor)
• All of the different living things that have appeared since then are the
results of 3 forces:
• Mutation – genetic change
• Time – time is needed for minute changes to accumulate and cause physical
change – thereby leading to diversity
• Selection – an organisms environment leads to “survival of the fittest”,
allowing the best suited individuals to reproduce and forward their genes to
the next generation
Biologists Explore Life in MANY Species
• Biologists have named about 1.8 million species
• Estimates of total species living in the biosphere range from 10 million to over
200 million
• How do we organize species within the framework of biological organization?
Within the biosphere, how do we organize the naming of the individual
species?
• Taxonomy is the branch of biology that names and classifies species into a
hierarchical order
• Kingdoms and domains are the broadest units of classification
• Levels of Taxonomic organization (ordered largest to smallest):
• Domain, Kingdom, Phylum or Division , Class , Order, Family, Genus, Species
Taxonomic organization of a Black bear
Species Genus Family
Order
Class Phylum Kingdom Domain
Ursus
americanus
(American
black bear)
Ursus
Ursidae
Carnivora
Mammalia
Chordata
Humans full name is: Eukarya
anamalia chordata mammalia
Animalia
primates hominoidea homo sapiens
Eukarya
The Three Domains of Life
• At the highest level, life is classified into three domains:
• Archaea – prokaryotes, odd bacteria that live in extreme
environments, high salt, heat, etc
• Eubacteria – prokaryotes, true bacteria
• Eukarya – eukaryotes that have a nucleus, & organelles, Eukaryotes
include protists and the kingdoms Plantae, Fungi, and Animalia
Archaea
Eubacteria
Eukarya
Nomenclature we will use, and is most commonly used in science
•
Binomial (scientific) nomenclature
•
Genus – Homo, first letter is uppercase
•
species - sapiens, lowercase
•
Both italicized or underlined
–
Homo sapiens (H. sapiens)
–
Tyrannosaurus rex (T. rex)
–
Others?
Where Does Diversity Between
Species Come From?
• The theory of evolution has been proposed by biologists to explain the
diversity that arises between species
• 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)
• Darwin inferred natural selection by connecting two observations:
• Observation: Individual variation in heritable traits – inference: unequal
reproductive success
• Observation: Overpopulation and competition - inference: Evolutionary
adaptation
• Natural selection can “edit” a population’s heritable variations
Factors Driving Change
Population
of organisms
Hereditary
variations
Overproduction
and competition
Environmental
factors
Differences in
reproductive success
of individuals
Evolution of adaptations
in the population
The Theory of Natural Selection
Each island in the Galapagos
had different food types
This “selected” for finches that
had bills that were suited to
handle each food type
This is called Adaptive
Radiation
Methods Used to Study 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 – slowly finding things that describe
data that you obtain when doing observations – this leads to a hypothesis
• Hypotheses are formed to test variable that may explain what has been observed
• Hypothesis-based science: explaining nature – slowly finding out and trying
to explain what you see in nature, discrete testing
Discovery Science
• Discovery science describes nature through careful observation and data
analysis
• Examples of discovery science:
• understanding cell structure
• expanding databases of genomes
• Two types of data, or recorded observations generated during the course of an
experiment:
• Quantitative data: numerical measurements
• Qualitative data: recorded descriptions
• Inductive reasoning involves generating ideas to explain many specific
observations or data
Deductive Reasoning vs. Inductive Reasoning
https://www.youtube.com/watch?v=VXW5mLE5Y2g
Hypothesis-Based Science
• In science, inquiry usually involves proposing and testing hypotheses
• Hypotheses are hypothetical explanations that you try to experimentally test
to show that the explanation describes nature
• In science, a hypothesis is a tentative answer to a well-framed question
• A role of a hypothesis is that it is an explanation on trial, making a prediction
that can be tested
Step 1: Formulating hypotheses
Observations
(Flashlight doesn’t work)
Question
Hypothesis #1:
Dead batteries
Hypothesis #2:
Burnt-out bulb
Step 2: Testing your hypotheses
Hypothesis #1:
Dead batteries
Hypothesis #2:
Burnt-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test prediction
Test prediction
Test falsifies hypothesis
Test does not falsify hypothesis
What needs to be answered?
What is already known?
Pose an explanation in the
form of a question.
How to address the
questions/get answers?
Collect/analyze data from the
experiment.
Explain the in terms of your
hypothesis
Example - Explaining Mimicry
• In mimicry, a harmless species resembles a harmful species
• An example of mimicry is a stinging honeybee and a nonstinging mimic, a
flower fly
Flower fly (nonstinging)
Honeybee (stinging)
Field study: Researching mimicry in the wild
• 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
Scarlet king snake
Key
Range of scarlet
king snake
Range of eastern
coral snake
Eastern coral
snake
North
Carolina
South
Carolina
Scarlet king snake
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
(a) Artificial king snake
(b) Artificial brown snake that has been attacked
Making the Case – Descriptive Data
17%
In areas where coral snakes
were absent, most attacks
were on artificial king snakes.
83%
Key
% of attacks on
artificial king snakes
% of attacks on
brown artificial snakes
Field site with
artificial snakes
North
Carolina
South
Carolina
16%
84%
In areas where coral
snakes were present,
most attacks were on
brown artificial snakes.
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
• 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
• Models are often used to explain and simplify observations. Models are
representations of ideas, structures, or processes
• Models may range from lifelike representations to symbolic schematics
Examples?
What Can You Say About
Your Classmates (in general)?
• Is there something you can say in general about your class? Or
groups of people in your class?
• How do you get people to believe you?
• Let’s Experiment! (see handout)
The Culture of Science and Technology
• Science is an intensely social activity
• Individuals in science work together towards a common goal, and MUST be
able to communicate very effectively
• Both cooperation and competition characterize scientific culture
• The goal of science is to understand natural phenomena