Week of Aug 21 - genetics
Week of Aug 21 - genetics BIOL 3000
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This 5 page Class Notes was uploaded by Emma Shoupe on Friday August 26, 2016. The Class Notes belongs to BIOL 3000 at Auburn University taught by Seibenhener in Fall 2016. Since its upload, it has received 5 views. For similar materials see Genetics in Biology at Auburn University.
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Date Created: 08/26/16
Genetics Dr. Seibenhener Week of August 21, 2016 Introduction to Molecular Biology What is life? Ability to grow, change, etc. that separates plants and animals from things like water or rocks o Consume = eating; changing nourishment into metabolites o Grow = reproduce o Information content = blueprint o Living organisms = complex o Ability to take energy from the environment and transform it for growth o Living organisms tend toward equilibrium with their environment o Respond to stimuli o Biological requirement = structural system Macromolecules of Life Found in all living organisms Building blocks Comprised of a combo of 6 atoms: carbon, nitrogen, oxygen, hydrogen, sulfur, phosphorus 1. Carbohydrates: sugar, C, H, O; provide energy and support to cell 2. Lipids: fatty acid; C, H, O; provide energy, structure, prevent loss of heat 3. Nucleic acid: nucleotide; DNA, RNA; directs and controls cells 4. Proteins: amino acids; C, H, O, N and S; provide vast array of functions – metabolism, transport, stimulus response All in a cell – phospholipid bilayer, DNA in nucleus, protein; cell wall, carbs in cell or cell wall 17 /18 Centuries Fourcroy – recognized distinct class of macromolecules distinguished by ability to coagulate under heat Mulder – carried out elemental analysis and first described a protein; recognized elements Meischer – first identified DNA inside nuclei of white blood cells – nuclein Kossel – isolated non-protein component of nuclein, the nucleic acid; isolated 5 nucleobases Levene – identified 3 major components of nucleotide (Phosphate, sugar, base); proposed a polynucleotide model of nucleic acid; DNA and RNA Griffith – “transforming principle” ; discovered that there were two types (R-type – rough, s-type – smooth) from bacteria in pneumonia after the war. This suggested some type of transformation Avery, MacLeod, and McCarty – transformation cannot occur unless DNA is present o Removed lipids and carbs from solution of heat kill smooth cells o Subjected solution to enzymes that destroy either DNA, RNA or protein o Added samples to rough cultures and observed transformation o DNA is material of heredity Hershey and Chase – confirmed DNA, not protein, was in fact the source of genetic material o Bacteria phage DNA was the most important o Protein is made from DNA o Heredity – genes = DNA o Gene interactions/chromosomes o Modern genetic research DNA and Biotechnology Base recombinant DNA technology revolves around DNA making protein o E. Coli o Restriction enzymes o DNA libraries DNA and Pharmaceuticals Insulin HGH Hepatitis B vaccine DNA and Diagnostics PCR (polymerase chain reaction) Disease detection – HIV, cancer, Lyme, cystic fibrosis DNA and Agriculture GMOs o Soybean – herbicide tolerance o Corn – insect tolerance o Plum – virus tolerance August 24, 2016 DNA structure and properties Levene – differentiated DNA and RNA; Identified phosphate, sugar, and base; Tetranucleotide hypothesis Astbury – x-ray diffraction studies on nucleic acids; DNA had a regular structure, DNA repeated every 2.7 nm; base in DNA laid flat, stacked and at regular (0.34 nm) intervals from each other Chargraff – RULES: o The number of guanine equals the number of cytosine units and the number of adenine units equals the number of thymine units o Composition of DNA varies from one species to another, in particular in relative amounts of individual bases (molecular diversity) Pauling – proposed the TRIPLE HELIX STRUCTURE of deoxyribonucleic acid Wilkens and Gosling – x-ray diffraction technique; crystalline structure; overall helix shape Watson and Crick – tried to figure the shape Rosalind Franklin – dry (A) v. wet (B) x-ray diffraction; structure of DNA changed when water was there; DNA attracts water molecules (phosphate groups outside of DNA molecules) Watson and Crick got this wrong because Watson didn’t take notes after hearing Franklin speak. Found dry structure symmetry (DNA- A) Image B-51 absorbed water – turned into DNA- B o Confirmed helix, bases per twist, base position o Diameter o 3:4 atoms August 26, 2016 DNA Structure and Properties chemical composition of DNA o DNA = deoxyribose nucleic acid o Composed of nucleotides o Consists of 2 polynucleotide chains – complementary o Double helix Nucleotides o Nitrogenous bases – 6 or 9 Purine: 2 ringed heterocyclic nitrogenous base (9 atom ring structure) A, G Pyrimidine: single ringed nitrogenous base (6 atom ring structure) C, T, U (RNA) o Deoxyribose sugar – H, lack of Oxygen on 2’ carbon. Ribose sugar: OH on 2’ carbon DNA contains deoxyribose, RNA contains ribose o Phosphoric acid Nucleoside – nitrogenous base + deoxyribose sugar Nucleotide – nitrogenous base + deoxyribose sugar + phosphoric acid N- glycosidic bond: between base and 1’ sugar of carbon; covalent bond Phosphate: phosphodiester bond: attaches each nucleotide to another; 5’ to 3’; covalent bond Two Polynucleotide Chains o Anti-parallel (3’ to 5’ phosphodiester bonds are in opposite directions) o Phosphate molecules are on the outside o Bases point inward, perpendicular to the helical axis Base Pairing o Bases linked by hydrogen bonds between oxygen and nitrogen atoms o Purines pair with pyrimidines (A-T base pair- 2 H bonds, G-C base pair- 3 H bonds) Physical Structure o 2 complimentary chains in opposite polarity o twist around a central axis and form a double helix o right handed helix (B-DNA) o bases are NOT co-planar o are projected at right angles to the phosphate- sugar backbone (perpendicular) o shift in planes when stacked caused by energetically non- compatible hydrophobic interactions, cause partial overlap helping to cause twisting of DNA o because of base pairing, shift in the backbone structure as well as results in twisting of DNA o IF deoxyribose sugars attached 180 degrees to each other, they would have similar sized grooves Major grooves and minor grooves B-DNA o Hydrated form – water molecules o Double stranded o Right handed o Anti- parallel and complimentary o Specific base interactions o Stacked and pointed inside molecule o Anti – configuration A- DNA – replication start sites o Dehydrated form of DNA o Double stranded o Anti- parallel and complimentary o Base interactions o Right handed o Bases are TILTED not stacked, still pointed inside o Anti- configuration o Wider and shorter Z- DNA – protein binding – transcription factors o Double stranded o Left handed with zig-zag pattern o Anti-parallel and complimentary o Repeating purine – pyrimidine sequences o Bases are syn and anti configurations o Alternate conformation, still pointed inside o Molecule is more compact o Typically more dehydrated because of the crazy shape There are plenty of images and diagrams on google, or on Dr. Seibenhener’s notes, that can help make sense of some of these terms.
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