The Scientific Method 02 26 2014 Observations Hypothesis Predictions Experiments or new predictions THEORY Living organism characteristics Complexity Ability to change to environment Ability to reproduce Capacity to evolve Spontaneous Creation Louis Pasteur things created from previously created living things spontaneous creation did not occur with micro organisms Swan neck glasses curve in the neck Microorganisms fall into straight neck flask not into the swan neck flask settle in the bottom of curve Can store and transmit information Has a plasma membrane Can harness energy from the environment sunlight chemical Essentials of a Cell compounds Evolution Genetic variation mutation in DNA Differential reproduction Favored traits can reproduce the most Variation is environmental or genetic Tree of Life Eukaryotes humans animals plants protists fungi Archaea Bacteria prokaryotes lack a nucleus Molecules Hydrophilic 02 26 2014 water loving Readily dissolve in water Molecules that contain ionic and or polar covalent bonds Hydrophobic Do not readily dissolve in water Nonpolar molecules like hydrocarbons only C H water fearing Amphipathic molecule Have both polar ionized and nonpolar regions Hydrophobic Effect polar molecules like water exclude nonpolar ones ORGANIC MOLECULES CARBON most are polymers large molecules Carbons in the sugar numbered with primes 1 2 Carbons in the base numbered 1 2 Proteins composed of amino acids linked covalently thru peptide bonds loss of H2O form a polypeptide chain protein provide structural support act as catalysts cellular proteins are composed of 20 amino acids Nucleic Acids Nucleotides o 5 carbon sugar o base o one or more phosphate groups encode and transmit genetic information thru nucleotide sequence DNA deoxyribonucleic acid o deoxyribose sugar H on 2 RNA ribonucleic acid o Ribose sugar OH on 2 pyridmidine single ring bases T C U purine double ring bases A G phosphodiester bond link nucleotides together loss of H2O Carbohydrates Complex carbohydrates composed of simple sugars Composed of C H O usually 1 2 1 Simplest carbohydrates saccharides o Linear 5 6 C atoms o C6H12O6 Monosaccharide simple sugar o Aldehyde group aldoses o Ketone group ketoses Disaccharide two simple sugars covalently bonded Polysaccharides simple sugars linked together covalently Complex carbohydrates long branched chains of monosaccharides Glycosidic bonds monosaccharides attached to each other covalently loss of H2O Lipids fatty acid long chain of carbons attached to carboxyl group at end o carboxyl COOH o Saturated saturated with H no double bonds straight chains higher MP than unsaturated o Unsaturated C C double bonds unsaturated with H kink at each double bond lower MP than saturated make up cell membranes store energy act as signaling molecules defined by property rather than chemical structure lipids are all hydrophobic Van der Waals forces constant motion of electrons regions of slight positive and negative charge weaker than H bonds act together to stabilize molecules 1 Triacylglycerol o fatty acid glycerol o Used for energy storage o Can be any length 2 Steroids o Ex cholesterol o Core of 20 carbons 4 fused rings o Animal cell membranes 3 Phospholipids o Major component of cell membrane o Glycerol fatty acid molecule w phosphate group o Phosphate head group is hydrophilic o Fatty acid tail is hydrophobic o Create bilayer in aqueous solution DNA 02 26 2014 Griffith Experiment Genetic material Pneumonia virus Killed virulent non virulent bacteria mixed mouse dies Transformation of non virulent cells virulent cells Avery Macleod McCarty Experiement Genetic material 3 enzymes o Destroy RNA o Destroy DNA o Destroy Protein Treated non virulent bacteria with enzymes and tested for non virulent virulent transformation Treated with enzyme that destroys DNA only one that was unable to transform to virulent bacteria DNA is molecule responsible for transforming non virulent virulent Key evidence that DNA is genetic material Prokaryotes transcription and translation in the cytoplasm Eukaryotes transcription in nucleus and translation in the cytoplasm NUCLEOTIDES 5 carbon sugar base one or more phosphate groups Negative charges on 2 O atoms in phosphate groups makes DNA a mild acid Nucleoside base sugar Nucleotide base sugar phosphate group Nucleoside monophosphate base sugar phosphate group Nucleoside diphosphate base sugar 2 phosphate groups Nucleoside triphosphate base sugar 3 phosphate groups o Used to make nucleotide polymers DNA RNA and carriers of chemical energy ATP GTP Phosphodiester bond stable bond in DNA withstand heat changes in pH C O P O C linkage in the actual bond 5 3 read as 5 AGCT 3 Gives DNA strand polarity Double Helix Sugar phosphate backbone Major minor grooves 10 base pairs per complete turn Hydrogen Bonding H bonds hold together base pairs A T 2 hydrogen bonds Individual DNA strands are antiparallel run in opposite directions 3 end of one strand is opposite the 5 end of the other Each base pair purine pyrimidine G C 3 hydrogen bonds Base stacking non polar flat surfaces of bases tend to group together away from water molecules stack on top of each other as tightly as possible important stabilizing force Cellular DNA is coiled and packaged with proteins In prokaryotic cells DNA molecules are circular and form supercoils circular molecule coils upon itself caused by enzymes topoisomerases that put strain on the double helix supercoils relieve the strain In eukaryotic cells DNA molecules in nucleus are linear each individual molecule forms one chromosome o DNA molecules packaged with proteins histones into a 30 nm chromatin fiber o Places where transcription is actively taking place 30 m fiber relaxes 10 nm chromatin fiber o Both fibers Chromatin o Fiber is made of nucleosome core particle bead like repeating unit contains 2 of each histone proteins H2A H2B H3 H4 rich in positively charged amino acids lysine and arginine forms ionic bond with negatively charged sugar phosphate backbone of DNA DNA double helix wraps twice around core particle
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