could you please insert ‘genes and diseases’ intro slide here?
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Could you please insert ‘Genes and Diseases’ intro slide here?
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On April 25, 1953
Drs. James Watson and Francis Crick determined the structure of DNA
In April 2003,
Human Genome Project determined the entire DNA sequence of a human (3 billion letters)
What is DNA Day?
Protein
RNA copy
Information is stored in DNA
Genes contain instructions to make proteins
Proteins do most of the
work in a cell and provide much of its structure.
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A change in gene result in a change in protein
SAM AND TOM ATE THE HAMPossible Change:
SAM AND TOM ATE THE HIM
Thr Pro GluGlu Lys Leu
ACT|CCT|GAG|GAG|AAG|CTG
ACT|CCT|GAG|GAG|AAG|CGG
Thr Pro GluGlu Lys MetResult: Changed meaning or function
Change in DNA is called a mutation
Variations in the DNA of different individuals can cause phenotypic changes in individuals
• Just by looking around the room, we can see many examples of genetic variation.
• Some genetic traits, such as skin color and eye color, are controlled by multiple genes
• Others are controlled by only one gene
• We are going to look at 7 traits that are each determined by one gene with two possible alleles.
Variations in the DNA of different individuals can cause visible changes
in individuals
Single-gene Traits
Laugh dimples• ll no dimples (homozygous
recessive)• L dimples (heterozygous or
homozygous dominant)Tongue roll• tt can’t roll tongue into “U”
shape (homozygous recessive)
• T can roll tongue into “U” shape (heterozygous or homozygous dominant )
Single-gene TraitsCrossing Thumbs• cc right thumb on top of
clasped hands (homozygous recessive)
• C left thumb on top of clasped hands (heterozygous or homozygous dominant )
Pinkies• pp pinkies are straight when
pressed side by side (homozygous recessive)
• P pinkies bend away from each other, toward the ring fingers, when pressed side by side (heterozygous or homozygous dominant)
Single-gene Traits
Ear lobes• ee attached ear lobe
(homozygous recessive)• E free ear lobe
(heterozygous or homozygous dominant)
Widow’s peak• ww no widow’s peak
(homozygous recessive)• W has a widow’s peak
(heterozygous or homozygous dominant)
Single-gene Traits
Bending thumbs (Hitch-hiker’s thumb)
• bb thumb bends at 90 degree angle (homozygous recessive)
• B thumb is straight (heterozygous or homozygous dominant)
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Genetic Wheel Results
• There are 128 possible combinations from the 7 traits illustrated on the genetic wheel.
• Are you the same as anyone else?
• If this much genetic variation exists in traits that are visible, imagine how different we all are in ways that we can’t see!
Variations in the DNA of different individuals can cause varying traits
in individuals
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These traits can be inherited!
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Traits are inherited through genes
• Genes are on chromosomes
• One chromosome inherited from each parent
• We have two copies of each gene
http://www.biotechnologyonline.gov.au
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Different versions of genes are alleles
• For each gene, you might have…
2 different alleles 2 of same allele
ORCombinations of alleles determine what traits you have
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Can you roll your tongue?
Yes! You carry a copy of the dominant allele.
No! You have two copies of the recessive allele.
Dominant does NOT mean more common!
orIf you inherit both
alleles, the dominant one is expressed.
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Each parent contributes 1 allele to offspring
Father’s alleles
Mother’s alleles
r
r
r
R
r
Rr
r
r
r
r
R
r = No-roll allele
(Recessive)
R = Roll allele
(Dominant)
Inheriting Traits- Tongue Rolling
Disease alleles can be inherited just like a “tongue rolling” allele...
Some diseases are caused by genetic factors and can be inherited
A good example of genetically inherited disease is Cystic Fibrosis
Symptoms of Cystic Fibrosis
• Thick mucus in airways and lungs
• Chronic Lung infections– can cause permanent
lung-cell damage.
• Digestive problems– Lack of nutrient
absorption
What is the cause of Cystic Fibrosis?
The lungs are lined with specialized cells.
Dust
Dust
Mucus gland
Cilia
DustMucus gland
Mucus
Dirt
Out to mouth
Cilia Mucous
These special cells clear mucus
Healthy Airway CF Airway
Cystic Fibrosis patients’ airways are dehydrated and cannot clear mucus.
Thick, dry mucusNormal mucus
As a result, CF airways accumulate bacteria and inflammatory cells.
Pseudomonas aeruginosa
Too many inflammatory cells can cause permanent lung-cell damage.
CFTR protein hydrates and allows mucus clearance
=
Cilia
The CFTR in Lung Cells
CFTR protein
Cell nuclei
Cystic Fibrosis Transmembrane Regulator(CFTR)
Chromosome 7
CFTR protein
RNA
DNA
Protein
transcription
translation
DNA
RNA
Mutations in the CFTR gene blocks CFTR protein function
CFTR
Mutant CFTR
Healthy cell
Cystic fibrosis cell
Changes in the DNA sequence lead to a protein that cannot reach the plasma membrane.
Cystic Fibrosis Activity
You be the investigator…Find a cystic fibrosis patient
Investigate the BALF
A
1. Do not open the tubes!!2. Analyze the contents of each tube for:• Mucus consistency• Presence of inflammatory cells• Evidence of infection with Pseudomonas
aeruginosa (bacterial cells)3. Record your findings on the worksheet
provided.
= inflammatory cell (macrophage)
= bacterium (Pseudomonas)
Who do think has Cystic Fibrosis?
What would you do next to confirm the diagnosis?
Sequence the DNA and look for mutations in the cftr gene.
• There are ~900 different mutations that have been found in the cftr gene.• To save time, we have printed the DNA sequences from the sequencing reactions for you.
Remember the Central Dogma?
DNA RNA Protein
How do mutations in the DNA sequence lead to defective proteins?
AGG TCG GGT CAA CAA TGCDNA
RNA UCC AGC CCA GUU GUU ACG*Convert the DNA sequence into the RNA intermediate.
DNAATCG
RNAUAGC
DNA RNA Protein
Now convert the mRNA message to a protein.
mRNA UCC AGC CCA GUU GUU ACG
Ser Ser Pro Val Val ThrProtein
DNA RNA Protein
Which patient has the defective CFTR protein?
Now you know that mutations in the genes (or DNA) can lead to changes in the protein.
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environmentenvironment
environment
gene
gene
genegene
“family history”
Genes & environment can work together to cause disease
Disease
Diseasegene yes
Will you have the disease?
maybe
What diseases have both a genetic and an environmental component?
Cancer
lack of exercise
smoking bad diet
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mutation
Cancer
• Your own cells dividing out of control– tumor cells behave abnormally, invade tissues
• Why? mutations in DNA
many mutations
tumor
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What causes these mutations?• Environment (carcinogens)
• Can inherit mutations in certain genes
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How does knowing the genetics of diseases help us?
Better understanding of disease can lead to better or safer treatments:
– Better, more specific drugs – Gene replacement therapy– Personalized medicine
Does this mean we can cure everything?
No
END OF PRESENTAION
FEEL FREE TO DISCUSS YOUR RESEARCH AND CAREERS
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