Transcript lecture 1, introduction to biology, 021009c

Introduction to Biology
Lecture 1
Much of the text material in the lecture notes is from our textbook,
“Essential Biology with Physiology” by Neil A. Campbell, Jane B.
Reece, and Eric J. Simon (2004 and 2008). I don’t claim authorship.
Other sources were sometimes used, and are noted.
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Outline
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Life sciences—a few current areas
Approaches to understanding life
The beginning of our journey
Ecology and ecosystems
Cells and their DNA
The diversity of life
Natural selection and evolution
The processes and culture of science
Words and terms to know
Possible test items
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A Few Current Areas
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Ecosystems and ecology
Human genome project
Reproductive and therapeutic cloning
DNA fingerprinting for legal purposes
Nutrition and physical activity
Medicines derived from plants
Human development and aging
Neurosciences and behavior
Infectious disease spread
Aircraft and spacecraft design
Understanding of the origin of life
Are we alone in the universe?
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Human Genome Project
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The entire set of genetic instructions an
organism inherits is called its genome.
• A human genome map was published in
2001 after several years of work at many
laboratories.
• The map gives biologists a powerful tool
to explore the functions of thousands of
genes.
• Genome have many applications in the
biological and medical sciences such as
the early identification of genetic diseases
and the production of new pharmaceutical
drugs.
http://www.bioinfo.mbb.yale.edu
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DNA Fingerprinting
Each person has a unique DNA ‘fingerprint’
based on genetic material common to each
of the trillions of cells in the human body.
• DNA patterns are more similar—the closer
people are genetically related to each other.
• The probability that two or more people have
an identical DNA fingerprint is very small.
• DNA fingerprinting has been used to obtain
criminal convictions and exonerations, and
establish identity and paternity.
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http://www.ubermorgen.com
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http://www.mypyramid.gov
Nutrition and Physical Activity
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Good nutrition and physical activity are critical to child development,
and life-long healthy living.
• They are critical to weight management (obesity and overweight rates
are very high in the United States).
• They can also help in disease prevention (for example, two-thirds of
cancer cases are related to lifestyle choices).
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Periwinkle, Madagascar
Vinblastine is used in some
leukemia drugs.
http://upload.wikimedia.org
http://sataic.howstuffworks.com
Medicines Derived From Plants
Eucalyptus, Australia
Menthol is an ingredient in
some cough medicines.
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Medicines Derived from Plants
Belladonna, Europe,
western Asia, Africa, and
North America
Atropine is used as an
pupil dilator in eye exams.
http://upload.wikimedia.org
Pacific Yew, Pacific Northwest
and British Columbia
Taxol is an ovarian cancer
drug.
http://www.ubcbotanicalgarden.org
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http://milavia.cjb.net
Aircraft Design
The design of the B-2 aircraft included life support, ozone effects, rapid
decompression effects, ejection systems and survivability, NBC
protection, acoustic noise cancellation, workload assessment, physical
and mental fatigue, anthropometry, visual and acoustic processing,
situational awareness, vibration effects, and biodynamic modeling.
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First Steps Beyond Our Planet
http://www.nasa.gov
Ed White, first U.S. spacewalk, Gemini program, 1965
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Bioastronomy and SETI
Andromeda Galaxy (M31)
http:// www.spacepix.net
With billions of stars in a galaxy and billions of galaxies in our universe,
is life unique to our planet?
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Understanding Life
Science, Philosophy, Theology, Art
Public domain
Paul Gauguin, Where Do We Come From? Where Are We Going To? (1897-98)
This course is based on the scientific method—I’m not sufficiently
knowledgeable to teach other approaches.
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Our Journey Begins Here
We will soon get started…
http://www.thebestlinks.com
Human brain—the left cerebral
hemisphere, cerebellum, and
brainstem are visible.
http://www.afacereamea.ro
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… And Here
A neuron has one axon, some as long as one
meter, and typically many more dendrites than
shown here.
• The human brain has over 10 billion neurons,
each with potentially thousands of connections
known as synapses.
• Neurons are the basic cellular unit of information processing.
• Much research is being performed on neurons
and their synaptic connections as they relate
to:
– Sensations and perceptions
– Thoughts and emotions
– Fine motor skills and other motor actions
– Sleep and altered states of consciousness
– Neurological and other medical conditions
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http://www.dez3d.com
An artist’s conception
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Ecology
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Life does not exist in a vacuum—all life forms interact continuously with
other living organisms and non-living components in their environments.
• Consider plants:
– Roots absorb water (H20) and minerals from the soil.
– Fungi (mycorrhizae) help the roots absorb nitrogen from the soil.
– Leaves absorb carbon dioxide (CO2) from the air.
– Chloroplasts absorb sunlight and produce sugars from H20 and CO2.
– Leaves release oxygen (O2) into the air.
– Roots break-up rocks to help form soil to promote more plant growth.
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Mycorrhizae
http://extension.lastate.edu
Fungi living in mutual association with roots are essential
to many plants.
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Ecology
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Ecology is the biological study of the relationship between organisms and
their environments.
• As a scientific discipline, ecology helps us understand the impact of human
activities on our planet.
http://www.birdforum.net
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Ecosystems
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An ecosystem refers to all organisms and nonliving factors affecting life
in an specific area.
• Southern California’s ecosystems includes:
– Foothills and mountains
– High and low deserts
– Rivers, streams, and lakes
– Marshes, estuaries, and other wetlands
– Channel Islands and Pacific Ocean
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Dynamics
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The dynamics of a ecosystem depend on:
– Cycling and recycling of nutrients
– The flow of energy from sunlight to food producers, and then to
consumers
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The biosphere is the sum of the dynamic processes in all ecosystems
on our planet.
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Grasslands
http://www.bcgrasslands.org
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Kelp Forest
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The kelp forests off our coast are one of
many ecosystems in Southern California.
• Kelp is rich in nutrients such as plankton.
• The underwater forest provides food and
protection to many fish and other marine
species.
• Biologists study marine life to understand
each species and interdependence among
species in the oceans.
http://www.underwaterplanet.com
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Eaton Canyon Falls
http://natureathand.com
Near Altadena, California
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Bolsa Chica Wetlands
http://api.ning.com
Just south of Seal Beach, California.
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Life’s Basic Unit
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Cells are the lowest level of structure that can perform all activities of
life.
All life is composed of cells.
Many forms of life are single-cell organisms such as bacteria, amoeba,
and protozoa.
Plants and animals are composed of many cells (trillions in humans).
The ability of cells to divide is the basis of reproduction, and for growth
and repair of multi-cellular organisms.
All cells use DNA for transmitting information from parents to offspring.
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Cell Types
http://www.visualsunlimited.com
Prokaryotic cell
Bacteria
Not to scale: A prokaryotic cell is
about 1000 times smaller in volume
than a eukaryotic cell.
http://www.visualsunlimited.com
Eukaryotic cell
Plants, animals, and fungi
(animal cell shown)
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DNA
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DNA is found in the nuclei of eukaryotic
cells, and central region of prokaryotic
cells.
DNA consists of four chemical ‘letters’
(A, G, C, and T).
Human DNA contains about 3.2 billion
chemical letters.
DNA is the universal genetic language
that serves as the chemical material of
genes.
Genes are units of inheritance that
transmit information from parents to
offspring.
Double helix
http://www.ks.uiuc.edu
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Diversity of Life
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Biological diversity can be overwhelming with so many plants and animal
species.
• Species are grouped into smaller numbers of groups to aid in comparison
of similarities and differences.
• Taxonomy is a branch of biology that names and classifies species into a
hierarchical ordering.
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Domains and Kingdoms
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For now, we consider only domains and kingdoms, the broadest units of
classification.
• New methods such as comparative analysis of DNA have led to ongoing
reassessment of the number of kingdoms.
• Although debate continues, the general consensus is that the kingdoms
belong to three domains of life.
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Course Focus
Green represents the primary
focus of this course
Life
Domain
Archaea
Four kingdoms
of eukarya
Domain
Eukarya
Domain
Bacteria
Kingdom
Protista
Kingdom
Fungi
Three domains
of life
Kingdom
Plantae
Kingdom
Animalia
The domains bacteria and archaea consist of prokaryotic cells;
the domain eukarya consists of eukaryotic cells
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History of Life
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The history of life on our planet, which is about 4.5 billion years old, is a
changing cast of life forms.
• Each species that exists now is one ‘twig’ on a branching tree extending
to earlier species and a more remote time.
• Similar species sharing a common ancestor represent a recent branch
point (for example, brown bears and polar bears).
• Less similar species, for example, represent a branch point further back
in time (for example, bears and squirrels).
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Evolution
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http://picasaweb.google.com
Mammals, birds, reptiles share a common ancestor even further back in
time.
• Evidence of this interconnectedness can be found in cell features, DNA,
and anatomy.
• All life is connected, and the basis for this kinship is known as evolution.
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H.M.S. Beagle
Public domain
Exploration of Tierra Del Fuego
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Voyage of Discovery
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As a young man, Charles Darwin was invited to be the ship’s naturalist
on a hydrographic survey of South America.
The around-the-world expedition lasted almost five years, from 1831 to
1836.
Darwin spent 18 months at sea and over three years on land, much of it
in South America.
He kept detailed notes and collected many animal and plant species that
were shipped home to England.
Darwin had time to read including books some that anticipated aspects
of the theory of evolution.
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Then and Now
Queen Mary 2, 2006
http://upload.wikiemdia.org
H.M.S. Beagle, 1831
Both ships have circumnavigated the globe, but only one journey
led to a profound change in science and worldview.
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Discovery
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Darwin’s later microscope that he
used to study plant and barnacle
specimens.
http://www.hps.cam.ac.uk
Although Darwin spent just six weeks in the Galapagos Islands, his visit
would change biological thinking.
• In 1859, Darwin published “On the Origin of the Species” his first work on
natural selection and evolution.
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Environmental Adaptation
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Darwin regarded adaptation to the environment and origin of new species
as closely related processes.
For example, populations of a species separated by a geographical barrier
diverge in appearance over many generations as they adapt to different
local conditions.
Finches arrived in the Galapagos Islands from South America 2-3 million
years ago.
Fourteen finch species were found on individual islands in the island chain.
Darwin noted major differences in beak structures.
The beaks evolved as adaptations to the types of foods available on each
island.
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Finch Beaks
Public domain
Finches in the Galapagos Islands have vastly varying beaks.
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Darwin’s Finches
Large ground finch
Medium ground finch
Small ground finch
Large cactus ground finch
Cactus ground finch
Vegetarian finch
Thin beak
Large, powerful beak
Seed-eaters
Small tree finch
Medium tree finch
Large tree finch
Mangrove finch
Woodpecker finch
Cactus-flowereaters
Bud-eater
Insect-eaters
Green warbler finch
Gray warbler finch
Thin beak
Sharp-beaked ground finch
Ground Finches
Tree Finches
Warbler Finches
Common Ancestor,
South American
Mainland
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Natural Selection
Natural selection is based on two principals and a conclusion
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Principal 1: Overproduction and struggle for existence—any population of a
species can produce many more offspring than the environment can support.
• Principal 2: Individual variation—individuals in a population vary in heritable
traits, and no two individuals are exactly alike.
• Conclusion: Unequal reproductive success—in the struggle for existence
individuals with traits best adapted to the environment will have the greatest
reproductive success.
Traits that enhance survival and reproduction will be more highly
represented in the next generations.
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Meet the Beetles
2. Birds eliminate individual
beetles (usually white shells)
1. Beetle population has a specific
inherited trait (white or dark gray shells)
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Insect-Eating
Birds
These imaginary beetles typically
live on a dark-colored tree bark
3. The survivors reproduce
4. Traits that enhance survival and
reproductive success predominate
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Descriptive Science
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Science seeks natural causes for natural phenomena based on observation
and measurement.
Science cannot prove or disprove the existence of the supernatural and if
they have any effect on natural phenomena.
The goal of descriptive, or discovery, science is to understand the structure
of nature.
Darwin’s study of the plants and animals on the Beagle was descriptive
science.
Descriptive science can lead to important conclusions based on inductive
reasoning.
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Inductive Reasoning
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Inductive reasoning flows in the direction of specifics to the general, or from
observations to conclusions.
• A conclusion is a generalization summarizing many observations, such as
“all organisms consist of cells.”
• Inductive reasoning has played an important in the accumulation of biology
knowledge.
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http://www.digitastar.net
Classification
A scientist’s sketch of diatoms.
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Hypothesis-Based Science
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Hypothesis-based science is based on deductive reasoning that flows from
the general to the specific.
• Results (predictions) are extrapolated if the premises are found to be true.
Premise 1: If all organisms are made of cells
Premise 2: And humans are living organisms
Deductive prediction: Then humans are composed of cells
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The approach is known as hypothesis testing, the cornerstone of scientific
experimentation.
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Hypothesis Testing
Observations
Questions
Hypothesis
Prediction
Test does not support hypothesis;
revise or reject hypothesis, or
develop a new one.
Test
(Experiment or study)
Test supports hypothesis;
make additional predictions
and test them.
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A Tale of Two Snakes
Eastern Coral Snake
http://www.sciencemore.com
Scarlet Kingsnake
Both species of snake live in the
eastern Carolinas
http://fwie.fw.vt.edu
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Experiment
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Observation: The venomous eastern coral snakes and non-venomous
scarlet kingsnake both have red, yellow, and black rings.
Question: Why do scarlet kingsnakes look similar to eastern coral
snakes?
Hypothesis: Mimicry helps protect scarlet kingsnakes from predators.
Prediction: Predators will confuse scarlet kingsnakes with eastern coral
snakes.
Test: Compare the number of animal attacks on ringed versus brown
artificial snakes.
Test outcome: The brown artificial snakes are attacked by birds and
other animals about five times more often than ringed artificial snakes.
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Percentage of Total Attacks
Results
100%
84%
50%
16%
0%
Artificial Snakes Artificial Snakes
In Plain Brown With Colored Rings
Details of the experiment are
described in the textbook.
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Culture of Science
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Science is dependent on observations and measurements.
Ideas or hypotheses are testable by experiments that others can repeat.
Scientists focus on evidence, and often have a high level of inquiry and
skepticism.
Information is shared in many ways including in meetings, publications,
and the internet.
This sharing contributes to the progressive and self-correcting qualities
of science.
The theories that scientists develop consolidate observations and have
predictive power.
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Science Is International
Basic science is international, and often knows no political boundaries.
• Some of the giants of science are:
– Isaac Newton, Great Britain
– Charles Darwin, Great Britain
– Ramón y Cajal, Spain
– Marie Curie, Poland and France
– Albert Einstein, Germany and United States
Galileo Galilei,
Italy
Public domain
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Words and Terms to Know
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Biosphere
Deductive reasoning
DNA
Domains of life
Ecology
Ecosystem
Eukaryotic cell
Evolution
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Genome
Hypothesis testing
Inductive reasoning
Kingdoms
Natural selection
Organism
Prokaryotic cell
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Possible Test Items
1. Describe two current areas of general interest in the life sciences.
2. How can ecology help us understand the interconnectedness of our
world?
3. What are the characteristics of an ecosystem? Describe an ecosystem
you visited.
4. Describe the basic elements of adaptation and natural selection, and
give an example.
5. Describe two differences between inductive reasoning and deductive
reasoning.
6. Outline an experiment to answer a simple question of your choosing.
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