Transcript Anatomy and Physiology BIO 137

Project Lead The Way
Medical Intervention
Exam 2 Review
Disclaimer
This review is an overview. There is no
possible way to revisit every single item we
have covered thus far. This should be used
as 1 tool in your preparation for the exam.
Major Focus
Key Terms – Crossword Puzzles
Key Concepts – Each Activity/Project
Essential Questions – Each Unit
Conclusion Questions – Each Activity/Project
Knowledge and Skills – Each Unit
Exam 2 Review
Unit 1.4.1 through Unit 2.2.2
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1.4.1.A Vaccinations
1.4.2 Types of Vaccines
1.4.2.A Vaccine Development
1.4.3.A Epidemiologist
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2.1.1.A Genetic Counseling
2.1.3.A Test Genes
2.1.5.A Fetal Health
2.2.1.A Gene Therapy
2.2.2.A Reproductive Tech
Unit 1.4
Vaccinations
Unit 1.4 - Overview
In the first activity of the lesson, you will study the history of vaccination through
the eyes of scientist Edward Jenner. Smallpox, a highly infectious disease
characterized by small lesions on the skin, ravaged society for centuries.
Edward Jenner
• English physician/scientist who pioneered smallpox vaccine - the world's first
vaccine
• In 1796 - Jenner inoculated James Phipps, an 8 year old boy
• He scraped pus from cowpox blisters on the hands of a milkmaid who had
contracted cowpox and injected in both arms of Phipps
• Phipps presented with a fever and some uneasiness, but no full-blown infection
• Testing showed he developed an immunity to smallpox
What is a vaccination and how
does it work?
The body is presented a dead or weakened form of the pathogen
to expose the immune system to the antigen.
This allows the B-cell to produce antibodies and memory cells.
Therefore, when the body is exposed to the antigen again the
immune system will be able to fight off the infection.
How has vaccination impacted
disease trends in our country?
Herd Immunity
• More individuals that are immune
decreases the incidence of the
disease and the occurrence of the
pathogen.
• With greater numbers immunized, it
is less likely that an unimmunized
person will encounter the pathogen.
• Mass vaccination confers indirect
protection for those who do not
receive the vaccine resulting in “herd
immunity”.
Effective Vaccines
• Have low levels of side effects or toxicity.
• Protect against exposure to natural, or wild forms of the
pathogen.
• Should stimulate both an antibody (B-cell) response and
a cell mediated (T-cell) response.
• Have long term, lasting effects that produce
immunological memory.
• Should not require numerous doses or boosters
• Are inexpensive, have a long shelf life and are easy to
administer.
Routes of Administration
• The majority of vaccines are
administered by injection
– Subcutaneous
– Intramuscular
– Intradermal
• Oral vaccines are available
for only a few diseases
Methods Used to Produce
Vaccines in the Laboratory?
1)
2)
3)
4)
5)
6)
Killed
Attenuated
Toxoid
Subunit – recombinant DNA technology
Naked DNA
Similar Pathogen
2 goals for every vaccine
– Contains Antigen so we can produce antibodies
– Pathogen will not be harmful
Types of Vaccines
Killed whole cells or inactivated viruses
– Pathogen is killed due to heat or radiation and inserted into
the body
– Even though they are harmless, they still contain
recognizable antigens on their surface
– Because the microbe does not multiply, larger doses and
more boosters are required.
Types of Vaccines
Live, attenuated (weakened) cells or viruses
– Pathogen is grown under non ideal conditions for several
generations, causing the pathogen to evolve
– Due to natural selection the pathogen is now adapted to the
new environment
– When placed in humans they still have the antigens, but will
be weak in the body’s environment so they do no harm
– Longer-lasting and require fewer boosters
– Disease agent could mutate back to pathogenic strain
Types of Vaccines
Toxoid vaccines
– Grow pathogen and collect the toxins produced by the
antigen
– Purified toxin injected into the person with another vaccine
and the body will elicit immune response
Genetically engineered – Recombinant DNA Tech
– Genes for microbial antigens are inserted into a plasmid
vector and are cloned in appropriate hosts
– The resultant protein product is used to provoke immune
system
DNA vaccines – Naked DNA
– These vaccines contain all or part of the pathogen DNA,
which is used to “infect” a recipient’s cells
Subunit
Vaccine
Gene for antigen-only from
pathogen is put onto a
plasmid and inserted into
another organism. This
organism can produce the
antigen, which is used to
produce the vaccine.
What is recombinant DNA
technology?
joining together of DNA molecules (from two different
species) that are inserted into a host organism to produce
new genetic combinations that are of value to science,
medicine, agriculture, and industry.
What are the molecular tools used
to assemble recombinant DNA?
• Restriction Enzymes cut DNA and open Plasmids
• Ligase connects DNA fragments to a plasmid at the sticky ends
• This forms a recombinant plasmid that has a specific gene in it
recombinant
DNA
technology
Inserting engineered
plasmids into bacterial
cells
• The recombinant plasmid is
made and inserted into the
bacteria via transformation.
• The bacteria can express the
gene that was placed into
the plasmid to produce the
necessary antigen for the
vaccine.
Similar Pathogen
Vaccine
Insert a similar pathogen to what you want to
vaccinate against. This pathogen is not as harmful to
humans as the pathogen you are vaccinating against.
It contains a similar enough antigen that we can
develop antibodies to kill the pathogen.
Small Pox – Cow Pox
Naked DNA
Vaccine
Gene for antigen from
pathogen is put onto a plasmid
and inserted into a bacteria to
replicate (copy) the plasmid.
The plasmid is purified and
placed into the body.
The body cells can uptake the
DNA and begin making the
antigen.
Immune Response
White Blood Cells (WBC) are the primary cells responsible for an immune response
WBC are either (1) myeloid leukocytes or (2) lymphocytes
Cells of the myeloid lineage include neutrophils, monocytes, eosinophils and basophils.
Lymphocytes include T (thymus) cells, B (bone marrow) cells and natural killer cells.
Lymphocytes start out in the bone marrow and either stay there and mature into B cells,
or they leave for the thymus gland, where they mature into T cells.
B lymphocytes and T lymphocytes have separate functions:
• B lymphocytes seek out (recognize) their targets
• T cells destroy the invaders
Memory B cells – float around seeking 1 specific antigen
– concentration varies
B Cell
T Cell
What is epidemiology?
Epidemiology is the study of the spread, cause, and effects of
diseases in certain populations.
How can epidemiologists assist with
the detection, prevention, and
treatment of both chronic and
infectious disease?
• They analyze data, conduct surveys, and perform tests, to
identify the cause and spread of the disease.
• They develop informative tools and use preventative
measures to stop the spread of the disease.
2.1.1
Genetic Disorders and Genetic
Testing
Medical Interventions
© 2010 Project Lead The Way, Inc.
What are Genetic Disorders?
• Both environmental and genetic factors play a role in
the development of disease.
• A genetic disorder is a disease caused by
abnormalities in an individual’s genetic material.
Four different types of genetic disorders:
• Single-gene
• Multifactorial
• Chromosomal
• Mitochondrial
Single Gene Disorders
• Single gene disorders are caused by changes or
mutations that occur in the DNA sequence of one gene.
• Remember that a gene, a segment of DNA, contains
instructions for the production of a protein.
 Mutated DNA = Mutated protein!!
• Diseases and disorders result when a gene is mutated
resulting in a protein product that can no longer carry
out its normal job.
Single Gene Disorders
• Single gene disorders are inherited in
recognizable patterns:
– Autosomal dominant
– Autosomal recessive
– Sex linked
Autosome = any chromosome
other than sex chromosome
• Genetic testing looks at genotype to
determine if someone has a genetic disorder,
will develop one, or is a carrier.
Autosomal dominant means you only need to get the abnormal gene from one parent
in order for you to inherit the disease.
Autosomal recessive disorder means two copies of an abnormal gene must be present in
order for the disease or trait to develop.
Multifactorial Disorders
• Multifactorial disorders are caused by a combination
of environmental factors and mutations in multiple
genes.
– Development of heart disease is associated with multiple
genes, as well as lifestyle and environmental factors.
– Different genes that influence breast cancer development
have been found on chromosomes 6, 11, 13, 14, 15, 17 &
22.
• Many of the most common chronic illnesses are
multifactorial.
Chromosomal Disorders
• Humans have 46 chromosomes in their body cells.
– 44 autosomes (22 pairs)
– 2 sex chromosomes (1 pair)
• Because chromosomes carry genetic information,
problems arise when there are missing or extra copies
of genes, or breaks, deletions or rejoinings of
chromosomes.
• Karyotypes, pictures of the paired chromosomes of an
individual, are important in diagnosing chromosomal
disorders.
Mitochondrial Disorders
• Mitochondria, the organelles in your cells that
convert energy, also contain DNA.
• A mitochondrial disorder, a relatively rare type of
genetic disorder is caused by mutations in
nonchromosomal DNA of mitochondria.
• Mitochondiral DNA is unique in that it is passed
solely from mother to child
Autosomal – both parents Cystic Fibrosis
Autosomal – one parent
Huntington’s Disease
Sex chromosome
Duchenne Muscular Dystrophy
Multiple factors influence
Alzheimer’s Disease
Chromosomal deviations
Down Syndrome
mtDNA deviations
Leber hereditary optic neuropathy
Types of Genetic Testing and
Screening
Carrier Screening
• Carrier screening determines whether an individual
carries a copy of an altered gene for a particular
recessive disease even though they do not show the
trait phenotypically.
• Carrier screening is often used if a particular disease
is common in a couple’s ethnic background or if
there is a family history of the disease.
• Examples of carrier tests include those for Tay-Sachs
disease or sickle cell disease.
Preimplantation Genetic Diagnosis (PGD)
• PGD is used following in vitro fertilization to diagnose a
genetic disease or condition before the embryo is
implanted in the uterus.
• A single cell is removed from an embryo and examined
for chromosome abnormalities or genetic changes.
• Parents and doctors can then choose which embryos
to implant.
The Process of
Preimplantation
Genetic Diagnosis
Fetal Screening/Prenatal Diagnosis
• Prenatal diagnosis allows parents to diagnose
a genetic condition in their developing fetus.
• Techniques such as amniocentesis, chorionic
villi sampling (CVS), and regular scheduled
ultrasound allow parents to monitor the
health of the growing fetus.
Newborn Screening
• The most widespread type of genetic screening,
newborn screening is used to detect genetic or
metabolic conditions for which early diagnosis and
treatment are available.
• State tests for newborns typically screen anywhere
from 4 to over 30 genetic or metabolic disorders.
– Testing protocol and mandates vary from state to state.
• The goal of newborn screening is to identify affected
newborns quickly in order to provide quick treatment
and care.
2.1.3
Test Genes (PTC bitter taste)
PTC Activity
While synthesizing a chemical called phenylthiocarbamide (PTC) in
his lab, scientist Arthur Fox accidentally released some into the air.
Fox’s colleague in the lab complained that the dust had a very
bitter taste. Fox, however, tasted nothing.
After further studies, scientists concluded that the inability to taste
PTC is actually a recessive trait. Bitter-tasting compounds are
recognized by receptor proteins on the surface of taste cells. The
gene for this PTC taste receptor, TAS2R38, was identified in 2003.
Sequencing identified three variations in this gene from person to
person. These base pair differences, or SNPs, correlate to a
person’s ability to taste PTC.
What are SNPs? How can restriction enzymes
and electrophoresis be used to identify SNPs
and determine genotype?
SNP = Single Nucleotide Polymorphism – A
single base pair change.
Step 1: Isolating DNA
• The gene of interest in the experiment,
TAS2R38, is located on chromosome #7. This
gene is associated with our ability to taste a
chemical called PTC.
• In this lab you isolated a DNA sample from
your cheek cells.
Step 2: Amplifying the Gene of Interest
• Using your DNA sample, you amplified a 220
base pair region of the PTC gene using PCR.
– Specific primers attach to either side of the target sequence
• You investigated one of the base pair changes
or single nucleotide polymorphisms (SNPs)
that affects a person’s ability to taste the
chemical PTC.
What is the goal of PCR? What are the
steps of the PCR process?
What is the relationship between
phenotype and genotype?
• Genotype - Homozygous Dominant – RR – Have two
copies of the taster gene = Phenotype – Strong Taster
• Genotype – Heterozygous – Rr – Have one copy of
the taster gene = Phenotype – Weak taster
• Genotype – Homozygous Recessive – rr – Have two
copies of the non-taster gene = Phenotype – No taste
Genetics Review – Question 1
• The inability to taste PTC is a recessive trait.
• If a capital “T” is is used to designate the dominant
allele and a lowercase “t” is used to designate the
recessive allele, what is the genotype of a
“Nontaster”?
Answer
A “Nontaster” carries two recessive alleles and thus
has the genotype “tt”
Genetics Review – Question 2
What are the possible genotypes for a “Taster”?
Answer
A “Taster” may be homozygous dominant with a
genotype of “TT” or heterozygous with a genotype of
“Tt”.
Step 3: Restriction Analysis
• Restriction enzymes, molecular scissors,
recognize specific DNA sequences and cut the
nucleotide strands.
• In this part of the experiment, you will use a
specific restriction enzyme, HaeIII, to identify
a SNP or base pair difference in the amplified
segment of the PTC tasting gene.
Step 4: Gel Electrophoresis
• Gel Electrophoresis separates DNA fragments
based on their molecular weight.
• Once you have digested your DNA sample
with the restriction enzymes, run your product
on a gel to analyze your results.
PCR
The DNA, DNA
polymerase, buffer,
nucleoside
triphosphates, and
primers are placed in a
thin-walled tube and
then these tubes are
placed in the PCR
thermal cycler
PCR Thermocycler
The three main steps of PCR
• The basis of PCR is temperature changes and the effect that these
temperature changes have on the DNA.
• In a PCR reaction, the following series of steps is repeated 20-40 x
(note: 25 cycles usually takes about 2 hours and amplifies the DNA
fragment of interest 100,000 fold)
Step 1: Denature DNA
At 95C, the DNA is denatured (i.e. the two strands are separated)
Step 2: Primers Anneal
At 40C- 65C, the primers anneal (or bind to) their complementary
sequences on the single strands of DNA
Step 3: DNA polymerase Extends the DNA chain
At 72C, DNA Polymerase extends the DNA chain by adding
nucleotides to the 3’ ends of the primers.
Step 1:
Denaturation
dsDNA to ssDNA
Step 2:
Annealing
Primers onto template
Step 3:
Extension
dNTPs extend 2nd strand
Vierstraete 1999
extension products in one cycle serve as template in the next
Heat-stable DNA Polymerase
• Given that PCR involves very high temperatures, it is
imperative that a heat-stable DNA polymerase be
used in the reaction.
• Most DNA polymerases would denature (and thus not function
properly) at the high temperatures of PCR.
• Taq DNA polymerase was purified from the hot
springs bacterium Thermus aquaticus in 1976
• Taq has maximal enzymatic activity at 75 C to 80 C,
and substantially reduced activities at lower
temperatures.
2.1.5
Fetal Health
Amniocentesis versus CVS
Chorionic Villus
chorion is one of the four extraembryonic
membranes that make up the amniotic egg
2.2.1
Gene Therapy