LAB 5 - DNA Flashcards
DNA components
-double stranded, complementary strands
-made of nucleotides containing (deoxyribose sugar, phosphate and 1/4 nitrogenous bases)
-humans have genetic info in dna (nucleus of cells in form of chromosomes)
Transcription and Translation
-transcription, nucleas rna polymerase connects complimerary DNA RNA bases to DNA = mrna, mrna goes to cytoplams to ribosome and ribsome builds prtoeins,
translation, trna brings 3 codons as directed by mrna, chain is built
Single gene disorders
-change in dna of one genes leads to genetic disorder
-tay-sachs disease:mutation on 15, the absence of an enzyme that helps break down fatty substances. These fatty substances, called gangliosides, build up to toxic levels in the brain and spinal cord and affect the function of the nerve cells.
-cystic fibrosis: mutation in 7. The mutated gene results in changes in proteins that regulate sodium endocytosis and exocytosis.
multi gene disorders
-complex changes in dna between multiple genes
Chromosomes
-where dna exists
-chromosome = dna molecules weapped around histones (proteins) so DNA is small enough to fit in cell
-we have 23 pairs of chromosmes (one from each parent = 46)
-1-22 then XY
Chromsome issues
-errors can happen when cells replicate and divide chromsomes, leading to too many or little chromosomes
-too few or little = aneuploidy
-chromosome has mixed up parts = translocation, inversion, deletion
Edwards syndrome/trisomy 18
-aneuploidy of chromosomes –> 3 copies of chromosome 18
-most die in utero of before 1st bday
-could use cytogenetics to loook at chromosomes to see if issues like this have happened
Polymerase Chain Reaction PCR
-not all genetic conditions can be found with cytogenetics such as a nueclotide change in on gene on a chromosme
-pcr amplifies small segments of DNA, and to identify infectious disease or antibiotic resistance in a bacteria you are colonized with (both of you have unique genetic info not normally in human genome)
PCR Continued
-in pcr, you must know what youre looking for
-primer is desinged to target abnormal gene youre looking for (primer needs complementary base pairs)
-primer wont bind if dna is normal
Taq DNA
-taq dna is an enzyme (polymerase) to make copies of the abnormal gene so we can visually see it
PCR process
-1st need all components to make new dna:
free nuceloties dNTPS, DNA from patient, DNA polymerase, and primers
- dneture dna double strand with high heat
- keep at that heat so primer will bind (slightly lower temp but not too much or dna will stick together)
4.around 37degrees C, primers bund and DNA polymerase works - repeated multiple times so you have gene of interest to visualize
Gel electrophoresis
-technique to separate DNA fragments based on size and charge
-we make a gel that we load our pcr samples into
-we apply a current –> dna is -ve so it moves from -ve pole to positive, smaller fragments move faster than large
-then weve amplified a small portion of DNA from primers that is +ve for dna were looking for
-dna ladders then tell us the size of fragment and we can use control genes that should be present naturally in our samples to make sure process worked
PCR interpration
-in lab, band at 206 base pairs (bp) of dna as the size, and 2nd band at 271 bp
+ve = double strand
-ve = single strand
Light and dark areas of chromosomes
light bands on a karyotype = euchromatin, (areas that have higher transcription becauseit contains active genes)
dark bands on a karyotype are composed of heterochromatin (tightly packed inactive genes (this part of the DNA is not transcribed).
Trisomy 21
Trisomy 21: symptoms include a flattened face, small head, short neck and poor muscle tone
