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DNA marker analysis

DNA marker analysis . Mrs. Stewart Medical Interventions Central Magnet School. Standard:. Marker analysis is a technique used to determine the presence of genetic mutations associated with cancer. Objective :.

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DNA marker analysis

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  1. DNA marker analysis Mrs. Stewart Medical Interventions Central Magnet School

  2. Standard: • Marker analysis is a technique used to determine the presence of genetic mutations associated with cancer. Objective: • Investigate the marker analysis technique and analyze results to determine the presence of a BRCA 2 mutation

  3. BRCA 1 and BRCA 2 • Tumor suppressor genes • Repair DNA damage and control cell growth • Proto-oncogenes

  4. BRCA 2 • 80,000 nucleotides (larger than average gene) • 600+ mutations identified and linked to increased risk of cancer • Most mutations are insertion or deletion mutations (frameshift) of more than one base • Results in a protein that is unable to help repair damaged DNA or fix mutations

  5. Marker Analysis Technique • A technique where a gene mutation is analyzed by using a genetic marker instead of directly analyzing the gene itself. • Genetic marker: Alteration in DNA that may indicate an increased risk of developing a specific disease or disorder

  6. STRs • Genetic markers used in marker analysis are short DNA sequences called Short Tandem Repeats (STRs) • STRs – region of DNA composed of a short sequence of nucleotides repeated many times. • # of repeated sequences vary • Alternate forms of STRs correspond with different alleles.

  7. STRs • Most STRs occur in gene introns (non-coding regions of DNA) • Does not usually affect gene function • Can use as “markers” to differentiate between different alleles for certain genes • (because genes located next to each other are inherited together.)

  8. PCR • The region of the DNA that is the known STR marker is amplified (and the BRCA unknown gene version with it) • The amplified DNA is then run on a gel.

  9. Gel Electrophoresis • Because different alleles have a different number of repeats present in the STR, gel electrophoresis will separate different alleles based on the number of repeats present. • The more repeats present = the longer the DNA fragment • Shorter DNA fragments migrate farther down the gel • So, the fragments that migrate the farthest, have the fewest STRs

  10. Smith Family Analysis • We will determine different alleles for each family member tested by determining the band lengths for each family member. • Who was tested? • Diana –Judy’s sister • Jennifer – Judy’s sister • Laura – Judy’s mom • Judy – Sue, Mike and Tucker’s mom

  11. Who has the BRCA 2 mutation? • Each person has 2 chromosomes #13, so each person will have 2 alleles for the BRCA 2 gene. • You will have to identify which allele is linked to the “mutant” gene by determining which alleles Jennifer and Laura have in common • Since both of them are known to carry that allele. • Analyze Judy and Diana’s results to determine if they also carry the mutated gene allele.

  12. Analysis • DNA size markers are loaded in the first well. • Use the size markers to determine the sizes of your unknown fragments. • The known molecular size markers (weights in base pairs) are written beside each band. • Measure the distance each unknown band migrated

  13. Table One: Data • Distance Migrated (mm)- Measure the distance in mm from the sample well to each fragment in the standard lane. Record in Table One • Distance to Reference Point - Measure the distance from the sample well to the end of the gel. Record in Table One. • This number will be the same for each size marker fragment. • Calculate the Rfof each fragment and record in Table One. • Round values to the nearest one hundredth.

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