Presentation on theme: "Could you please insert Genes and Diseases intro slide here?"— Presentation transcript:
Could you please insert Genes and Diseases intro slide here?
2 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.
4 A change in gene result in a change in protein SAM AND TOM ATE THE HAM Possible Change: SAM AND TOM ATE THE HIM ThrProGlu LysLeu ACT | CCT | GAG | GAG | AAG | CTG ACT | CCT | GAG | GAG | AAG | CGG ThrProGlu LysMet Result: 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 cant roll tongue into U shape (homozygous recessive) T can roll tongue into U shape (heterozygous or homozygous dominant )
Single-gene Traits Crossing 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) Widows peak ww no widows peak (homozygous recessive) W has a widows peak (heterozygous or homozygous dominant)
Single-gene Traits Bending thumbs (Hitch-hikers thumb) bb thumb bends at 90 degree angle (homozygous recessive) B thumb is straight (heterozygous or homozygous dominant)
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 cant see!
Variations in the DNA of different individuals can cause varying traits in individuals
15 These traits can be inherited!
16 Traits are inherited through genes Genes are on chromosomes One chromosome inherited from each parent We have two copies of each gene
17 Different versions of genes are alleles For each gene, you might have… 2 different alleles2 of same allele OR Combinations of alleles determine what traits you have
18 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! or If you inherit both alleles, the dominant one is expressed.
19 Each parent contributes 1 allele to offspring Fathers alleles Mothers 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 Mucus gland Cilia Dust Mucus gland Mucus Dirt Out to mouth
Cilia Mucous These special cells clear mucus
Healthy AirwayCF Airway Cystic Fibrosis patients airways are dehydrated and cannot clear mucus. Thick, dry mucus Normal 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 TGC DNA RNA UCC AGC CCA GUU GUU ACG *Convert the DNA sequence into the RNA intermediate. DNA A T C G RNA U A G C DNA RNA Protein
Now convert the mRNA message to a protein. mRNA UCC AGC CCA GUU GUU ACG Ser ProVal Thr Protein 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.
38 environment gene family history Genes & environment can work together to cause disease Disease gene yes Will you have the disease? maybe What diseases have both a genetic and an environmental component? Cancer lack of exercise smoking bad diet
39 mutation Cancer Your own cells dividing out of control –tumor cells behave abnormally, invade tissues Why? mutations in DNA many mutations tumor
40 What causes these mutations? Environment (carcinogens) Can inherit mutations in certain genes
41 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
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