Download DNA Day research - DNA model construction

DNA DAY MODEL CONSTRUCTION RESEARCH
1.) History of discovery of DNA
* 1928 Fredrick Griffith; studied rough strain & smooth strain of bacteria
~ concluded transformation occurred from live R to live S.
* 1944 Oswald Avery; suggests DNA is changing substance from R strain of bacteria to S strain
* 1952 Alfred Hershey & Martha Chase; give definite evidence to conclude DNA is transforming
substance
*Chargaff; discovers the amount of cytosine always = guanine & the amount of adenine always =
thymine
*1951 Rosalind Franklin; use x-ray diffraction to capture picture of DNA, which indicated double helix
shape
* 1953 Watson & Crick pinpoint structure of DNA
~double helix
~sides of 5 carbon sugars and phosphate groups
~ connected by bases (adenine, thymine, guanine, cytosine)
2.) Scientific breakthroughs due to knowledge on structure of DNA
*Replication method of DNA found : semiconservative replication. Process of replication discovered
*opened doors to explore with genetic engineering
~ genes could be cut out of one organism and placed in the DNA of another
~transgenic organisms created in this way
~selection of traits in this way beneficial to humans agriculturally, medically, and with
research (high yield crops created, etc.)
*locations of some genes can be identified
~makes GE possible
~helps with understanding of certain genetic diseases
3.) DNA replication
* form of semiconservative replication ( strands separate & used as template to produce new strands w/
1 parental strand & 1 new)
* occurs during interphase
* 3 stages: Unwinding, base pairing, joining
* UNWINDING
~ DNA helicase (enzyme) unzips (breaks hydrogen bonds holding strands) DNA
~single-strand binding proteins keep strands separate
~ RNA primase adds RNA primer to DNA strands
* BASE PAIRING
~DNA polymerase adds appropriate nucleotides to new strand of DNA
~leading strand elongates as DNA unwinds, lagging strand elongates away from
replication
* JOINING
~DNA polymerase replaces RNA primer with nucleotides.
~DNA ligase links 2 sections
4.) How mutations cause disease
* Mutation- permanent change in DNA sequence, inherited (in gametes) or acquired ( somatic cells)
*altering important protein can cause condition/ genetic disorder
* prevent proteins from working properly
* changing instructions changes protein so malfunction may occur or protein may be missing
* Some proteins more important than others
* GENES DON’T CAUSE DISEASE! MUTATIONS IN GENES DO! (everyone has a CFTR gene, not everyone
has a mutation on that gene (cystic fibrosis) ).
* Types of mutations : missense (1 amino sub for another)
nonsense ( early stop)
insertion (add piece)
deletion (delete piece)
duplication ( piece copied)
frameshift ( reading frame & rest of amino acid sequence changed)
5.) Disease model illustrates and type of mutation that causes disease
*Cystic Fibrosis
~ salt movement in and out of cell blocked; results in mucus covered cells
~ mainly affects lung cells
~ducts in pancreas & airways in lungs blocked
~too much salt lost through sweat
~recessive disorder
*chromosome 7; CFTR gene; most from deletion of 3 base pairs ( causes loss of phenylalanine at
position 508 in protein)