2. Either flightlessness in these birds evolvedindependently three times (possible, butimprobable) or they arose from acommon, flightless ancestor

3. If the latter explanation is correct, andthey could not fly, how then could theyget to these disparate southerncontinents while being excluded fromthe northern hemisphere?

4. Geological evidence indicates thecontinents were once one large landmass that subsequently broke up intopieces (plate tectonics) that moved(continental drift) first into northernand southern portions, and later into thepresent-day continents

5. This geological concept also explains whymarsupial mammals (e.g., kangaroos)developed only on Australia, as thiscontinent was geographically isolated fromareas where placental mammals evolved

C.Fossils1. Preserved remnants of dead organisms2. Darwin termed evolution “descent with

modification”3. Although the fossil record has gaps (some

structures/organisms do not fossilize well),fossils provide valuable information aboutevolutionary changes or modifications inorganisms (including transitional forms,e.g., horses with toes, whales with hindlimbs, ferns with seeds) that have takenplace over many generations

4. Estimating the age of fossils involves lookingat their physical positions in sedimentaryrocks (relative dating) and radiometricisotope techniques (absolute dating)

A.Artificial selection1. Human-controlled breeding of species

strongly supports the idea that, overtime, nature could also influencechanges in populations

2. Humans have selected for traits toincrease the attractiveness (to us) of theoffspring (e.g., “cute” dogs, chickensthat produce many eggs, wheat thatyields numerous, plump grains)

3. Domesticated species often do poorly inthe wild, as traits (i.e., variations)selected by humans would notnecessarily be advantageous in nature

B.Biogeography: Geographic distributionof species can show organisms arerelated

1. Flightless birds, such as African ostriches,Australian emus, and South Americanrheas are found (naturally) only in thesouthern hemisphere; on separatecontinents

Evidence for Evolution via Natural Selection

A.Definitions1. Concept that all organisms are related by common ancestry2. Fundamental paradigm of biology

B.Natural selection: The mechanism for how evolution occurs1. Species have high potential for rapid reproduction2. Population sizes eventually level off and remain fairly

constant over time3. There is competition for reproduction and survival of

offspring4. Variations (from random mutations and shuffling of

genes via meiosis) exist in behavior, physiology,structure, etc.

5. Nature selects individuals (i.e., the fittest or justfortunate) for survival and reproduction to pass thesefavorable characteristics (adaptations) via their genesto their offspring

6. Over time, natural selection “can” lead to geneticchanges in populations – i.e., evolution

7. Microevolution: Small-scale changes8. Macroevolution: Larger-scale changes; can lead to

evolution of new species and groups

5. Molecular clocks look at changes in portions ofgenomes of organisms; also used to help determinethe age of evolutionary events

D.Homologies1. Anatomical similarities of related life forms2. Provide strong evolutionary evidence of relatedness3. Example: Forelimbs of vertebrates are composed of the

same basic bones in disparate groups, but differ basedon adaptations necessary for the specific environmentalneeds (i.e., walking, swimming, flying)

4. Vestigial structuresa. Those present are usually in a rudimentary, non-

functional formb. Show anatomically-related structures that are likely

to disappear completely in future generationsc. Example: The vestiges of pelvic bones within the

body in some modern-day baleen whales

Cellular/Molecular Evidence for EvolutionA.Cell Theory

1. The cell is the basic unit of life2. Every life form, from bacteria to humans, is made

of/comes from this basic structureB.Organic Molecules

1. 99% of all life consists of carbon, hydrogen, oxygen,nitrogen, phosphorus and sulfur

2. Evolutionary relatedness explains organisms’ common usage ofa small subset of over 90 available elements

C.DNA1. Genetic, informational molecule in every organism, including

viruses (which appear to be molecular fragments ofDNA/RNA capable of “living” in host cells)

2. DNA “language” (genetic code) is essentially universal(slightly different dialects exist in some single-celled organismsand in some mitochondrial/chloroplast genomes)

3. A common genetic language allows for such phenomena asthe insertion of human genes into bacteria, which can thenproduce “human” proteins (see Molecular Biology)

D.ATP (Adenosine triphosphate): The primary energy currencymolecule used by every organism

DNA Double Helix

Wild mustard

Broccoli

Cauliflower

Cabbage

Kohlrabi

Brussel sprouts

Kale

Artificial Selection For Crop Production

Human

Dolphin

Bat

Homologous Forelimb Bones: Evidence for VertebrateEvolution

BarCharts, Inc.® WORLD’S #1 ACADEMIC OUTLINE

1

Featuring: Evolution/origins, molecular biology, cancer biology, human aging and immunology

Evolution

Pig

A.Where do humans fit in the evolutionaryscheme?

B.Some of the greatest evidence forevolution is seen when comparingvertebrate chordates, which includehumans (see Homologies, Evolution &Natural Selection)

C.Comparative anatomy of adults1. Obvious visual similarities in adult

vertebrates (i.e., eyes, ears, mouth,nose, appendages) link humans toother vertebrates, especially thegreat apes

D.Comparative embryology1. Earnst Haeckel coined the phrase

“ontogeny recapitulates phylogeny,”suggesting the false claim humansstart as fish, then progress through aseries of developmental stages thatretrace the lower vertebrate groupsbefore becoming human

2. Early developmental stages ofhumans share remarkably similarvertebrate characteristics that eitherdisappear or become vestigial inadult humans

Human Originsa. Gill (pharyngeal) slits (they occasionally do not

close in infants – cervical (branchial) fistulae –may require surgery)

E. Vestigial structures1. Show clear links to vertebrate ancestry and include

the following non-functional structures:a. Tail bones (coccyx)b. Ear muscles (function in other mammals)c. Nictitating membrane (3rd eyelid in some

vertebrates)d. Pointed canine teeth(continued pg.3)

E. Variations in Life1. In England, the peppered moth shifted from

predominantly light coloring to dark when airpollution darkened the trees on which it lives

2. Predators can easily spot moths that contrastwith their background, limiting the abundanceof these types of moths in the population

3. Subsequent air quality measures havelightened trees and light-colored moths areagain the predominant form

4. Additional examples of selection observed inliving organisms involve increasing drugresistance: e.g., bacteria-antibiotics, insect-insecticides and HIV-drug therapies

Evidence for Evolutionvia Natural Selection cont.

A.The ultimate spark of life may never be knownbut science provides a controversial scenario ofhow life “might” have arisen

B.Universe/Earth origins1. First, the universe had to be formed,

theoretically via the Big Bang about 16-18billion years ago

2. Geologic and other physical evidence date theearth’s origin to about 4.6 billion years ago

3. The crust and biosphere (thin portion ofearth where life exists) would not behabitable (too hot) for nearly a billion years

C.First cells: How did they form?1. Early hypotheses suggest life arose

spontaneously from simple molecules (e.g.,CO, CO2, N2, H2O) that combined into larger,complex macromolecules such as proteins,carbohydrates, lipids and nucleic acids

2. Some rocks from outer space (meteorites)have pre-formed complex organicmolecules, including the five nitrogenousbases that make up DNA/RNA

3. Whether life was seeded from outer space(panspermia), or macromolecules weresynthesized entirely on earth, the next stepwas to incorporate these organics into cells –the basic functional units of life

4. These first life forms were likely heterotrophs,which consumed the abundant food moleculespresent in the “primordial soup”

5. Later, photosynthesis (by autotrophs)developed and oxygen levels beganincreasing in the atmosphere

6. The oldest fossils discovered (aged 3.8billion years) consist of photosynthesizingbacteria called stromatolites, which stillhave representatives in colonies that formlarge, calcareous structures in some shallow,tropical oceans

ii. Mitochondrial DNA is more likepresent-day bacterial DNA than thenuclear DNA of the cell in which itresides

iii. Chloroplasts have their own genomesiv. Today, living organisms provide

numerous examples of symbioticrelationships between single-celledorganisms; sometimes includingbacteria that perform the role ofmitochondria in cells lacking ATP-producing organelles

7. Eukaryotic cells subsequently evolved intoprotists, fungi, plants and animals

8. Prokaryotes continued to thrive and, thoughmicroscopic, are among the most successfulgroups of organisms on earth

FishGenerations of Peppered Moths Changed Colorto Match Habitat

Embryonic Similarities Among Vertebrates

Reptile Bird Human

Gill (pharyngeal) slits

TailTail

Host Prokaryotic Cell

Aerobic bacteriaingested

Plants, certain protists

Evolution of Eukaryotic Cells

Animals, fungi,certain protists

Aerobic bacteriadevelop intomitochondria

Photosyntheticbacteriaingested &developedinto chloroplasts

2

Eukaryotes

D.Oxygen crisis and the endosymbiotichypothesis1. Geologic evidence supports increasing

oxygen levels via photosynthesis-created“rust” zones at similar ages in ancient seabeds worldwide

2. Chemically, oxygen is a corrosive elementto organic molecules as well, and likelycreated a crisis for many of the earliestlife forms

3. Some bacteria evolved a metabolic pathwaythat could neutralize as well as produce ATPenergy from this highly-reactive oxygen

4. Symbioses formed between these oxygen-consuming, energy-producing bacteria andother larger, soft-bodied bacteria that lackedprotection against the effects of oxygen

5. This was the birth of the eukaryotic cell,from prokaryotic ancestors; one of themajor evolutionary events in life

6. This endosymbiotic hypothesis is supportedby the following facts:

i. Mitochondria (use oxygen formetabolism) have their own set of DNA,separate from that of the cell nucleus

Origins of LifeStromatolites Form Aquatic Reefs

e. 3rd molar teethf. Hair (plays major thermoregulation role

in most mammals)g. Nipples in malesh. Appendix (functions as digestive

caecum in many mammals)i. Segmented muscles of abdomenj. Pyramidalis muscle (absent in 20% of

humans; arguably unnecessary; presentin other mammals)

Human Origins3. From this origin in Africa, modern humans, Homo

sapiens, eventually arose 4. Debate exists among paleoanthropologists about how to

arrange the phylogenetic tree of humans based on theavailable fossils

5. Most agree that Neanderthals were the most recent groupof humans to become extinct, and were probably asubspecies called Homo sapiens neanderthalensis

6. From these origins, humans have spread to most landareas on Earth

F. Molecular Comparisons1. Comparison of DNA sequences in

humans and chimpanzees showaverage similarity of 98.5%

2. Comparison of hemoglobin aminoacid sequences (the main carrier ofoxygen in the blood of thousandsof different animals [by itselfevidence for evolution]) betweenhumans and other vertebrates showthe same evolutionary patterns asthose with skeletal/physicalanatomy that is comparative, withthe great apes showing the greatestsimilarity

G.Fossil Record1. Fossils show a transition from ape-

like forms to the first primitivehuman forms that were trulybipedal (walking on the pelvicappendages or legs)

2. Modern apes are not bipedal, but oneof the oldest fossil forms (3.2 millionyears) resembling an ape towalk bipedally was namedAustralopithecus afarenesis or Lucy(named after a famous Beatles song)

A.The discovery that DNA is the informational molecule housinggenes started a revolution in biology

B.Molecular biotechnology is now a pervasive component inmodern societies

CloningA.Gene Cloning

1. Making exact copies of genes2. Involves two major processes:

a. Recombinant DNAi. Restriction enzymes create DNA fragments with the

gene of interestii. DNA fragments are fused with DNA from a bacterium

(plasmid)iii. Newly-created recombinant DNA is placed into bacteriaiv. Bacteria produce protein for which the “cloned” gene codedv. Large quantities of the gene, and thus protein, are

produced as the bacterial cell reproduces

Molecular Biologyb. Polymerase Chain Reaction (PCR)

i. Amplifies (copies) a segment of DNA without using a bacterial (or other)host organism

ii. DNA sample is heated until the double helix denatures (hydrogen bonds arebroken), separating the DNA into two single strands

iii. Heat-resistant, single-stranded DNA primers allow DNA polymerase to addthe appropriate nucleotides to each side of the separated DNA strands

iv. This process results in multiple copies of the original DNAv. Repeating the process on the copies, via automation, can amplify a small DNA

fraction a billion fold in a short period of time

B.Reproductive cloning1. Produces living cells/organisms with exactly the same DNA in the nuclei as that

from a donor cell/organism 2. Specifically, DNA from the nucleus of a somatic cell of the donor is inserted into

an egg cell from which the original nucleus has been removed3. The new egg cell is electrically or chemically stimulated to begin cell division and

embryonic development4. The growing embryo is implanted into a female where development continues until birth

A

TGA

T

ACT

A

TG

C

A

TGA

T

A

TG

C

A

T

G

C

A

T A

T

A

TG

C

A

TA

TG

C

A

T

A

TG

C

A

T

G

C

A

T A

T

A

TG

C

A

T

G

C

A

T A

T

Some Vestigial Structures in Humans

Nictitating membrane

Hair

Nipples onmale

Segmentedmuscles ofabdomen

Gene Cloning using Recombinant DNA

Bacterium

1. Plasmid isolated

Gene of interest

Bacterium with Recombinant DNA

Recombinant DNA in plasmid

DNA containinggene to be cloned

2. DNA is fragmentedby enzymes

4. Plasmid inserted into a bacterial cell

3. Gene inserted intoisolated plasmid

Separate DNA strands by heating

Two new DNA molecules produced

Repeat above processes tomake multiple DNA copies

3

Spine

Gorilla Human

Pelvis

Toes

Anthropoid Skeletal Comparison

Using PCR to Amplify DNA

Primers add base pairs to DNA template strands

4

5. The new individual is not a true clone of the donororganism, as the mitochondrial DNA is from theorganism that donated the egg

6. Survival rates have been low as multiple factors(mostly unknown) influence successful development,such as source of donor cells

C.Therapeutic cloning1. Use of reproductive cloning to

create human embryos to procurestem cells, which have potential todevelop into adult tissues

2. These special cells may hold the keyto treatments for many diseases(heart, cancers, Alzheimer’s,Parkinson’s) and afflictions (injuryto spinal cord, including paralysis)

3. Stem cells can also be retrieved fromhuman embryos produced by regularfertilization processes (in vivo or invitro) or adults (e.g., bone marrow)

4. Stem cell procurement via cloningand embryos is a growing ethicaland political issue

A.Study of the structural and functionalaspects of the entire set of genes in aspecies (i.e., genome)

B.Encompasses many different aspects ofapproach1. Bioinformatics uses computer/statistical

applications to access large databasesconcerning DNA/gene/protein information

2. Proteomics studies the functioning ofthe proteins coded by the genes

C.Several specific applications of genomicswill be discussed further below:1. Restriction Fragment Length

Polymorphisms (RFLP)a. Technique relies on enzymes

discovered that protect bacteria from“foreign” DNA of bacteriophages(viruses specific for bacteria) andother invading bacteria

b. These bacterial restriction enzymescut foreign DNA at specific points orrestriction sites, while protectingtheir own DNA by adding special“buffering” functional groups topotentially susceptible areas

c. Exact positions of restriction pointsare highly individual, reproducibleand measurable

d. DNA samples from the sameindividual will produce the samefragments, but these fragments will bedifferent from others (polymorphic)

e. Fragment patterns can be representedvisually as a DNA fingerprint, by useof special electrophoretic processes

f. RFLP is used frequently in forensic,criminal and paternity applications

g. Because DNA samples may be minutein some of these applications, PCRamplification may be used to createquantities necessary for RFLP analysis

h. A modified DNA fingerprint approachhas been developed usingpolymorphisms of satellite (repetitive)DNA regions called Simple TandemRepeats (STR)

3. Gene therapya. Treating diseases and injury in humans

involves the use of harmless retrovirusvectors (or other entry mechanisms)that possess the enzyme reversetranscriptase, allowing them to insertgenetic information “into” DNA

b. Normal information flow occurs“from” the DNA

c. These treatments raise ethicalquestions, but certainly havetremendous potential

d. Limited success and legal restrictionsusing human subjects have madeprogress in this area challenging

4. Genetic engineeringa. Research involving gene transfer in

non-human organisms has been muchmore extensive

b. Transgenic and genetically-modifiedplants and animals are becoming morecommon

c. Great potential to artificially selectdesirable traits in crops, farm animals, etc.

d. Safety concerns are still high as thisnew technology is incorporated intomodern society

2. Human genome projecta. Monumental, historical effort to determine

the actual sequence of the entire set ofchromosomes in humans - gene mapping

b. Involved over 3 billion base pairs, whichif written, would create a book with ahalf-billion pages and take nearly alifetime to read

c. Several molecular techniques wereemployed, with automated computer-assisted analysis paving the way for arapid conclusion to the project

d. Although the precise number of genes isstill unknown, a priori estimatessuggested there would be nearly 100,000

e. Actual number probably does not exceed40,000, which when compared to simplerorganisms suggests human genomics isextremely concise, but complex

f. Future studies will undoubtedly revealmuch about how genes function, whichshould lead to numerous future benefits

A

C D

B

AT

G C

A T

T A

C G

CloningDonor organismto be cloned

Unfertilizedegg cell

Differentiatedcells from donor

Clone is born

Embryo implantedinto uterus of female

Develop into embryo

Egg cellwithoutnucleus

Removal ofnucleus egg cell

Culturing Stem Cells

DNA fingerprinting using RFLP

Genomic Project-Mapped Human Genes

Using Retroviruses to Insert Healthy Genes

RNA

Healthy gene

Nucleus DNA

Healthy gene

Gene

Nucleus

BloodstainDNA removedfrom blood cells

DNA fragmentedusing restrictionenzymes

RadioactiveDNA probesbind tocertain DNAfragments

Membraneis washed tofree excessprobe

X-ray film isattached tomembrane todetect radioactivepatterns

DNA fragmentsare transferredto a membrane(Southern blot)

DNA fragmentsare separated byelectrophoresis

DNA bondingpattern of sampleis compared toknown subjects

Sheri sample Alicia

1. In vitro fertilized egg

2. Blastocyst stage(5-7 days old)

3. Stem cell frominner mass

4. Cultured,undifferentiated stemcells can be used toproduce many kinds ofcells/tissues

e.g., Blood cells

Molecular Biology cont.

Genomics

Retrovirus

Donor & eggcell fuse

Optional review: “Cell Reproduction” section, p.2 ofQuickstudy® Biology guide

A.Cells reproduce by dividing primarily through two processes:1. Mitosis: Nuclear division2. Cytokinesis: Cytoplasm division

B.Cell division is part of the cell cycle, which is under acontrol system involving internal and external factors

C.Cancer cells have escaped this regulatory process throughtransformation and divide uncontrollably

D.Tumors form, which may progress from a benign to amalignant state and interfere with normal tissue functioning

E. Metastasize: Initial tumor cells can spread and form moremalignant tumors in other tissues in the body

F. Oncogenes stimulate abnormal cell growth and division,which can lead to malignant tumors1. These abnormal genes are converted from normal genes

(proto-oncogenes) that regulate the cell cycle. Virusescan also deliver oncogenes to cells

G.Tumor-suppressor genes normally prevent theuncontrolled growth and division of cells and tissues

H.Mutations are primary factors contributing to cancers1. Mutagens are any factors that can trigger mutations –

those that cause cancer are called carcinogensI. All tissues in the human body are susceptible to tumors,

because mutations (either induced by carcinogens orinherited) can occur in any cell

J. Cancers are prevalent and difficult to cure (in most cases)because of our limited knowledge about:1. Factors controlling the cell cycle2. The genomics of humans

Biology of Cancer

5

A.Most animals in nature die shortlyafter their reproductive years, andin some cases, die immediatelyafter reproduction

B.Humans and most animals keptunder controlled conditions cansurvive many years after fertility haswaned, allowing the phenomenon ofaging to be studied

C.For humans, the potential to live longerhas been realized over our history; inthe last 50 years, average lifespan inwell-developed countries has risenfrom the 60-70s to nearly 80 years

D.Considering the longevity of somerare individuals, human lifespan could be up to 120-130 years in the near future

Biology of Aging

A.What prevents all but a few of us from living to our physiological maximum?B.What are the specific causes for the physical transformations that occur as we age?C.Random events may accumulate and contribute to early senescence; some specific

hypotheses follow:1. Free radical formation typically involves the production of oxidative metabolic

by-products such as molecular variants of oxygen, which may damage the DNA,RNA, proteins and mitochondriaa. Anti-oxidants produced naturally may eventually lose the battle in cells,

causing cell deathb. Proponents of this hypothesis suggest supplemental intake of anti-oxidants

(e.g., found in vitamins) may slow this form of damage2. Cross-linking suggests as cells age, structural molecules such as DNA and

proteins form unsuitable attachments within or between other moleculesa. Skin wrinkling, cataracts of the eye, atherosclerosis in blood vessels, kidney

function and brain functiondecline are all possiblyrelated to cross-linking

b. Some drugs that prevent orslow cross-linking may beimportant future therapies

3. Wear and tear suggests thatthe mere use of cells andconcomitant damage result in aginga. This type of damage occurs at the DNA level, which has its own set of repair proteinsb. Years of exposure to mutagens such as toxins and various forms of radiation

are not always repairedc. At the ends of DNA molecules are protective caps called telomeres, which

are degraded with each cell division eventi. Telomere loss eventually can lead to DNA damageii. Telomerase, an enzyme that repairs these end caps, has been shown to keep

cells in a more “youthful” state4. Somatic mutations, those occurring in tissues outside of the egg or sperm,

could lead to diminished function; skin and connective tissues lose resiliency,muscles become weaker, brain cells become less efficient, etc.

5. Rate of living hypothesis: Suggests those that “live the fastest, die the youngest”a. Theorizes those organisms with the most active metabolisms have the

shortest lifespanb. With mammals, this is usually the case (e.g., an elephant lives longer than a mouse)c. Hypothesis may be broadly linked to those under the pre-programmed events

(see below)D.Pre-programmed events may be a cause of senescence in humans; following is a

discussion of specific hypotheses:1. Genetic theory suggests our lifespan is determined by the inherited genes

a. When food and health issues are maintained at least minimally, humans haveroughly the same lifespan

b. Females in most instances (including other animals) typically live longer than malesc. Offspring of long-lived parents typically live longer than offspring of

shorter-lived parentsd. The above observations strongly suggest at least part of lifespan

determination is related to longevity-assurance genes2. Pacemaker theory suggests there are “biological clocks” or pacemakers that

commence at birth and simply slow and stop, ending in deatha. Specifically, the immune and neuroendocrine systems are thought to be

controlled by pacemakersb. Cessation of these systems could account for body-wide failures,

susceptibility to attack by foreign agents, and increase incidence of cancers

Theories of Aging

1950 1960 1970 1980 1990 2000

80

70

60

50

AGE

YEAR

Human Lifespan Increase

Tumor-Suppressor Gene Deactivation Leading to Cancer

Oncogene Activation Leading to Cancer

Tumor Formation & Spreading

Physical Changes During Aging

Tumor

Glandulartissue

1. Malignant tumorstarts from singlecancerous cell

Normal cell

Lymphvessels

Metastasis

2. Tumor grows,invadingneighboringtissue

3. Lymph and bloodvessels spread cancercells to other areasof the body

Cancer cell

Mutated/damaged proto-oncogenes are convertedinto oncogenes triggeringrapid, uncontrolled cellgrowth

Proto-oncogenes controlnormal cell growth

Normal cell

Cancer cell

Suppressor genesprevent cancer

Mutation or loss ofsuppressor genes allowcancerous cells to divide

All races, male

All races, female

30 years 40 years 60 years 80 years

Mutagen

Mutagen

ISBN-13: 978-142320391-9ISBN-10: 142320391-7

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U.S.$5.95 / CAN.$8.95

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6

Optional review: “Immunology” section, p.5 ofQuickstudy® Physiology guide

A.The body has two main lines of defense against injury andinfection:1. Nonspecific immunity involves a generalized, similar

response to a wide variety of potentially harmfulconditions; a typical component of this response isinflammation, which results in swelling, redness, heatand pain in the affected area

2. Specific immunity is an extremely specific responsetypically involving the production of antibodies, whichare designed with the exact purpose of combining withspecific cell surface markers, or antigens, of foreignagents (microbes, toxins)

B.Selected subjects related to immunity are discussed below:1. Passive immunity involves receiving antibodies or

antiserum from another sourcea. This could involve maternal antibody delivery to the

fetus/child via breast milk from the mother orinjections (also for treatment of venomous bites/stings)

2. Vaccinations contain weakened versions of pathogensinjected into the body to stimulate, among other aspectsof specific immunity, B cells to produce two products:a. Plasma cells, which begin synthesizing antibodies

within 10-17 daysb. Memory cells, which retain the potential (for up to many

years) to develop quickly (within 2-5 days) into antibody-producing plasma cells upon subsequent exposure

c. This quicker response could mean the differencebetween successfully destroying the foreign antigenversus possible death of the individual

i. In this affliction, the virus attacksimmune cells called helper T cells,which are integral in mounting aspecific immune response

ii. Individuals with suchcompromised immunesystems are susceptible tosecondary infections andcancers, which untreated usuallyleads to death

iii. AIDS is still a worldwidehealth issue and the leadingcause of premature death insome countries

b. Severe Combined Immuno-deficiency Syndrome (SCIDS) is arare congenital condition in which Tand B cells are defectivei. In the most severe cases, a person

is born essentially with nospecific immune response andstands little chance of wardingoff infection

ii. Death can occur within the firstyear without a bone marrow orstem-cell transplant

6. Bacterial resistance to antibiotics canoccur when medical drugs are used tosupplement the specific immuneresponse, the latter of which maybe too slow to prevent serious andpossibly fatal symptoms

i. When antibiotics are taken, highlyresistant forms of bacteria maysurvive and reproduce

ii. These new “resistant” strainsmay be extremely difficult, if notimpossible, to treat

iii. Over-prescribing of antibioticsmay be a leading cause ofresistance

iv. As much as half of the roughly100 million prescriptions forantibiotics written each year maybe unnecessary (e.g., colds andflu symptoms are caused by viralinfections; therefore, antibioticsare of limited use)

v. When prescriptions are given,medication should be taken tocompletion - only taking aportion of the pills may allowthe hardiest bacteria to surviveand evolve

3. Allergies are hypersensitive tissue reactionsto part of the specific immune responsea. Specifically, antibodies against specific

antigens called allergens trigger tissueresponse resulting in typical allergicsymptoms (e.g., hay fever, asthma)

b. Severe allergic reactions can lead toanaphylactic shock, which may be life-threatening

4. Autoimmunity is a condition in which cellsof the specific immune response attackhealthy tissuesa. Normally, those antibodies and cells of

the immune response that could harm“self ” tissues are either suppressed ordeleted to prevent such self attacks

b. The following diseases/afflictions aretriggered or related to autoimmunity:i. Rheumatoid arthritisii. Diabetes mellitusiii. Grave’s diseaseiv. Multiple sclerosisv. Lupus

5. Immunodeficiency diseases are those inwhich some aspect of the immune system(usually specific)is defective, thuscompromising theability of the bodyto protect itself

a. One of the bestknown of these is Acquired Im-munodeficiencyS y n d r o m e(AIDS) - adisease which istriggered by theHuman Immun-o d e f i c i e n c yVirus (HIV)

HIVvirus

T-cell

Bone

Autoimmune Disease Leadingto Rheumatoid Arthritis

Synovial membranehypertrophy intonearby bone

Swollen/inflammed joint

Inflammatory cellsattacking joint surfaces

Cartilage and bone worndown narrowing joint cavity

Anti-bodies

Antigen

Oral/injection

Initial milk

Serum injection

Allergic Reaction Events

1. Immune system exposedto pollen through nose,lung or eyes

2. Antibodies specific to thepollen grains are formed

3. Antibodies bind to mastcells in connectivetissues

5. The released chemicalstrigger allergic reaction(runny nose and eyes,itching throat and nose,sneezing, respiratorycongestion, related asthmasymptoms)

4. Pollen again entersthe body, attaching toantibodies, triggeringthe mast cells torelease histamine andother chemicals

Antibodies Injected or Passed to Others

HIV VirusAttacking HelperT-cell Lymphocyte

Active Immunity Passive Immunity

Immunology

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