Introduction to BiologyLecture 1

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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

• 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

• 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

http://www.bioinfo.mbb.yale.edu

• 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.

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DNA Fingerprinting

http://www.ubermorgen.com

• 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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Nutrition and Physical Activity

• 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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Medicines Derived From Plants

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Periwinkle, Madagascar

Vinblastine is used in some leukemia drugs.

Eucalyptus, Australia

Menthol is an ingredient in some cough medicines.

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Medicines Derived from Plants

http://upload.wikimedia.org

Pacific Yew, Pacific Northwest and British Columbia

Taxol is an ovarian cancer drug.

http://www.ubcbotanicalgarden.org

Belladonna, Europe, western Asia, Africa, and

North America

Atropine is used as an pupil dilator in eye exams.

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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.

http

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First Steps Beyond Our Planet

Ed White, first U.S. spacewalk, Gemini program, 1965

http://www.nasa.gov

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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?

Bioastronomy and SETI

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Understanding Life

This course is based on the scientific method—I’m not sufficiently knowledgeable to teach other approaches.

Paul Gauguin, Where Do We Come From? Where Are We Going To? (1897-98)

Science, Philosophy, Theology, Art

Public domain

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Our Journey Begins Here

http://www.thebestlinks.com

Human brain—the left cerebral hemisphere, cerebellum, and

brainstem are visible.

http://www.afacereamea.ro

We will soon get started…

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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 informa-tion 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

http://www.dez3d.com

An artist’s conception

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Ecology

• 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

• 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

• 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

• 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

• 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

http://www.underwaterplanet.com

• 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.

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Eaton Canyon Falls

http://natureathand.com

Near Altadena, California

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Bolsa Chica Wetlands

Just south of Seal Beach, California.

http://api.ning.com

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Life’s Basic Unit

• 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

Eukaryotic cellPlants, animals, and fungi

(animal cell shown)

http://www.visualsunlimited.com

Prokaryotic cellBacteria

Not to scale: A prokaryotic cell is about 1000 times smaller in volume

than a eukaryotic cell.

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DNA

• 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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• 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.

Diversity of Life

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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.

Domains and Kingdoms

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Course Focus

The domains bacteria and archaea consist of prokaryotic cells; the domain eukarya consists of eukaryotic cells

Domain Archaea

DomainBacteria

Domain Eukarya

Kingdom Protista

Kingdom Fungi

Kingdom Animalia

Kingdom Plantae

Three domains of life

Four kingdomsof eukarya

Life Green represents the primary focus of this course

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History of Life

• 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

• 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.

http

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H.M.S. Beagle

Public domain

Exploration of Tierra Del Fuego

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Voyage of Discovery

• 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, 2006http://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

• 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.

Darwin’s later microscope that he used to study plant and barnacle

specimens.

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Environmental Adaptation

• 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

Common Ancestor,South American

Mainland

Ground Finches Tree Finches Warbler Finches

Seed-eatersCactus-flower-

eaters Bud-eater Insect-eaters

Sharp-beaked ground finch

Large ground finchMedium ground finchSmall ground finch

Large cactus ground finchCactus ground finch Vegetarian finch

Small tree finchMedium tree finchLarge tree finchMangrove finchWoodpecker finch

Green warbler finchGray warbler finch

Large, powerful beak Thin beak

Thin beak

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Natural Selection

Natural selection is based on two principals and a conclusion

• 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

1. Beetle population has a specificinherited trait (white or dark gray shells)

2. Birds eliminate individualbeetles (usually white shells)

3. The survivors reproduce4. Traits that enhance survival and reproductive success predominate

+Insect-Eating

Birds

These imaginary beetles typically live on a dark-colored tree bark

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Descriptive Science

• 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

• 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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Classification

A scientist’s sketch of diatoms.ht

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Hypothesis-Based Science

• 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 cellsPremise 2: And humans are living organismsDeductive prediction: Then humans are composed of cells

• The approach is known as hypothesis testing, the cornerstone of scientific experimentation.

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Test supports hypothesis; make additional predictions

and test them.

Questions

Prediction

Observations

Hypothesis

Test(Experiment or study)

Test does not support hypothesis; revise or reject hypothesis, or

develop a new one.

Hypothesis Testing

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A Tale of Two Snakes

Eastern Coral Snake

http://fwie.fw.vt.edu

Scarlet Kingsnake

http://www.sciencemore.com

Both species of snake live in the eastern Carolinas

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Experiment

• 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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Results

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Artificial SnakesIn Plain Brown

Artificial SnakesWith Colored Rings

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Details of the experiment are described in the textbook.

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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.

Culture of Science

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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

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Words and Terms to Know

• Biosphere• Deductive reasoning• DNA• Domains of life• Ecology• Ecosystem• Eukaryotic cell• Evolution

• 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.