Part 1 Notes
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This 12 page Class Notes was uploaded by Keilly Trujillo on Wednesday September 28, 2016. The Class Notes belongs to BIOL 1361 at University of Houston taught by Ann Oliver Cheek in Fall 2015. Since its upload, it has received 4 views. For similar materials see Intro to biological sciences in Biology at University of Houston.
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Date Created: 09/28/16
Chapter 1 5 Characteristics of Life 1. Membrane bound cells 2. Need energy 3. Process hereditary and environ info 4. Reproduce 5. Pop evolves 3 Major bio theories Theory- explanation supported by lots of evidence (not a guess) 1. Cell theory A. 1660s robert hooke and anton von leeuwenhoek a. All organisms made of cells b. All cells come from preexisting cells 2. Theory of evolution by nat selection A. 1858 charles darwin and alfred rossel wallace a. Species related by common ancestry b. Characteristics of species modiﬁed thru genes B. Conditions for nat selection a. Heritable conditions b. Sp environ = sp traits help reproduce 3. tree of life A. 1&2 imply that... a. All species from existing species b. Single common ancestor (LUCA last universal common ancestor) 4. chromosome theory of inheritance A. How are traits transmitted? B. 1902 theodor boveri and walter sutton a. Gen info enconded in genes b. Genes are units on chromosomes The sci method • Background - observations already recorded • Research question - new idea to test ex. Desert ants path back home 1. Hypothesis - pedometer A. Ants know how far from nest B. Track number of steps C. Know length of stride 2. null hypothesis - observe if hypothesis tested incorrect A. ex. Ants arent navigating home or have another method of navigating 3. Conclusion - inference A. Ants use stride length and number to calc distance to nest B. Supports pedometer hypothesis Chapter 2 - water, chem, and evol Electronegativity - an atoms attraction of shared e- in covalent bond • Most to least - O,N,S • Non polar covalent bond - e shared eq • Polar covalent bond - e pulled toward one atom Ex water - O partial neg • Hydrogen bond weak btw partially charged atoms Properties of water • Solid and liquid water held together by h bonds Hydrophobic coating helps insects walk of water Chem rxns req nrg transfer 1. 1st law of thermodynamics A. Energy neither created nore destroyed • forms of energy Kinetic ‣ Thermal nrg (heat) - nrg of molecular motion ‣ Temp - avg kinetic nrg/ heat for all molecules in compound Potential - nrg due to pos ex gravitational • chem energy Potential nrg stored in chem bonds Amt dep on pos of e shared in covalent bond ‣ Low potential nrg - e close to protons of 1 nucleus ‣ High potential nrg - e far from protons of both nucleus ie eq share 2. 2nd law of thermodynamics A. Every nrg transfer, entropy inc in universe a. Hindenberg blimp explosion when h2 gas combine w o B. Spontaneous rxn - potential nrg stored in reactants higher than products a. Rxn release heat (exothermic) Theory of chem evol • 1920s alexander operin and jbs haldane indep propose Complex carbon containing compounds can form simple molecules in absence of life • prebiotic soup hypothesis Nrg in sunlight drove rxns btw simple molecules and heat stimulated more complexity Nrg source : lightning Rxns ‣ Gasses present in atm ‣ E- nrg to drive amino acid synthesis ‣ Amino acids and other mol accumulate in ocean ‣ 1 st chem evol hypothesis tested Prob w concentration in ocean • Surface metabolism hypothesis Nrg source heat Rxns ‣ Dissolved gasses ‣ Inorganic precipitates form small chambers ‣ Org mol adhere to minerals in pipe ‣ Mineral catalysts accel rxns among small mol Functional groups - determine the behavior of mol in chem rxn Proteins and nucleic acids 1. Criteria for mol that formed 1st life A. Info: store hereditary info and process info from environ B. Self reproducing C. Able to evolve and change in response to changing environ conditions 2. evidence for amino acids A. Found in meteorites B. Can be synthesized in experimental environ somilar to outer space C. Can polymerize to form proteins 3. Proteins A. Functions a. Provide structural support for cell b. Regulate transport across cell membranes c. Catalyze chem rxns d. Cell movement e. Chem signaling f. Defense B. monomer - amino acid 4. theory of chem evolution A. Monomers in prebiotic soup polymerized to form larger more complex mol B. 2nd law of thermodynamics - nrg req 5. polymer - mol made of monomers ( repeated subunits) joined by covalent bonds A. Monomers linked by dehydration/condensation rxn - remove O and 2 H B. Linking amino acids into proteins ‣ Peptide bonds - covalent bond btw amino group of 1 amino acid and carboxyl group of next C. Polymer a. Peptide: <50 amino acids linked by peptide bonds b. Polypeptide: >50 amino acids linked by peptide bonds c. Protein: can be 1 peptide or multiple polypeptides D. Overall polymer shape a. Globular 1. membrane pore as channel 2. Enzyme 3. Signalling proteins 4. Receptors b. ﬁbrous 1. Structural support proteins A. Collagen - 3 subunits twisted like a rope, stronger but twist allows stretch B. Actin C. Myosin D. Keratin 6. Polymer structure A. Primary structure - Amino acid sequence B. Secondary structure a. Hydrogen bonds btw functional groups of amino acid backbone 1. Carbonyl O forms h bonds w amino H b. Alpha helix (coil) or beta pleated sheet (folds in same plane like accordion) C. tertiary structure a. 3D structure of protein b. Folding due to interaxns of functional groups in amino acid side chains 1. H bonds 2. Ionic 3. Van der waals interactions A. Hydrophobic and van der waals 4. Disulﬁde bridges ( covalent bond ) D. Quaternary structure a. Protein with 2 or more polypeptides 1. Ex insulin collagen hemoglobin Evaluating evidence with respect to proteins For 1. Contain info that allows interaction with environment Against 1. Cant self replicate (well... Prions) 2. Cant evolve Nucleic acids A. Monomer - nucleotide B. Linkage phospodiester bond 2 nucleotides linked via phosphate group C. Nucleic acid polymers • Ribonucleis acid - ribose contains 2' OH group Makes ribose more reactive • Deoxyribonucleic acid - no O in 2' 1. Primary structure A. RNA a. A G C U nucleotides B. DNA a. A G C T nucleotides 2. secondary structure A. Rna a. Single stranded can fold on itself b. Hair pinned loop c. H bonds form btw complementary n bases B. dna a. Double stranded b. Antiparallel c. H bonds d. Double helix 3. tertiary structure A. Rna a. Fold into complex shapes b. Ribozymes - rna that catalyzes chem rxns ex ribosome B. dna a. Supercoiling b. Histone proteins (nucleosomes) 1. Dna wraps around exactly twice Rna world hypothesis • Rna ﬁrst self replicating mol • Rna mol experience nat selection Most eﬀective self replicators become most common Eval evidence for rna v dna Rna 1. Info that allows interaxn w environ 2. Self replicate 3. Evolve slowly DNA 1. Info that allows interaxn w environ 2. Cant self replicate (need enzymes) 3. Cant evolve Carbohydrates Energy storage • Starch in plant cells • Glycogen in animal cells structural support • Cellulose in plants • Chitin in arthropods (insects, crustaceans, arachnids) sugar and sugar polymers • Contain C=O (Carbonyl) OH (hydroxyl) C-H (hydrocarbon) • Sugar > 5 c spontaneously form ring glycosidic linkage • Covalent bond btw 2 sugars • Dehydration rxn • Disaccharide - 2 covalently bonded monosaccharides polysaccharide • 3 or more covalently bonded monosaccharides • Starch Glucose polymer produce in chloroplast Stored in chloroplast or in roots • glycogen Glucose polymer made in animal cells ‣ Liver and muscle cells Lipids and cell membranes 1. Lipids A. Deﬁned by physical properties a. Nonpolar hydrophobic b. Contain C B. structure highly variable 2. steroids A. Carbon skeleton w 4 rings B. Side chains vary C. Animal cell membranes contain cholesterol 3. fatty acids A. Carboxyl group linked to hydrocarbon chain B. Saturated a. All c atoms linked by single covalent bonds b. All c bonded to max amt of H c. Solid or semisolid at room temp C. unsaturated a. Some c atoms linked by double bonds b. C skeleton not saturated with h c. Liquid at room temp 4. fats A. Glycerol linked to 3 fatty acids a. Wax ex honey B. Energy storage in plants and animals C. Ester linkage btw glycerol and fatty acid a. Dehyrdation rxn 5. phospholipids A. Glycerol 2 fatty acids and phosphate and choline B. Joined by ester linkage C. Dehydration rxn Phospholipid bilayer • Selectively permeable Some substances can cross bilayer Depends on size, polarity, and charge of substance • cells reg membrane permeability Change amt of cholesterol Change amt of fatty acids in phospholipids Change amt and types of transport proteins • Cells reg membrane ﬂuidity More unsat fatty acids ‣ More ﬂuid ‣ More permeable more sat ‣ Less ﬂuid ‣ Less permeable Diﬀusion- spontaneous process, no cell. Energy required • Random movement if molecules from high to low concentration due to kinetic energy • At equilibrium, mols distributed eq across membrane • Mol continue to move Diﬀusion rate • Depends on physical factors • Fick's law of diﬀusion Osmosis - diﬀusion of water across a membrane that is permeable to water but impermeable to other solutes • Water mol move to high solute concentration Towards dehydrated or thirstier sol Eﬀect of osmosis on membrane bound vesicles Osmolarity - moles solute particles/L • Units mosm/L (miniosmols) • Diﬀ from molarity Calc from tot number of particles when a mol dissoxiates in aq soln 50mM NaCl soln is 100 mOsm ‣ 50 mmol na + 50 mmol cl = 100 mosm sol 50 mM glucose= 50 mosm Fluid mosaic model Cell membrane is a phospholipid bilayer with proteins inserted thru membrane • Lipids and proteins circulate around cell membrane Technique: freeze fracture Proteins • Change permeability of bilayer • Transmembrane proteins - integral proteins span the bilayer • Peripheral proteins attach to inner (cytoplasmic) or outer (extracellular) ends of integral proteins • Passive transport - Facilitated diﬀusion Hydrophilic substances cross cell membranes from high to low concentration by passing thru channel or transport proteins 1. Channel proteins - hydrophilic tunnels through cell membrane ‣ Transport small polar or charged mol: H2O, ions 2. Carrier proteins- integral membrane proteins ‣ Polar mol attaches to one side of protein, protein changes shape, moves substance across cell membrane A. Passive transport by membrane proteins a. Channel protein - pore b. Channel protein - gated channel • Active transport - req atp Cell can selectively pump substances from low to high concentration Result - internal env diﬀ from external Nak pump ‣ Transmembrane protein ‣ Pumps out 3 na+ and pumps in 2 k+ ‣ Creates na+ and k+ gradient ‣ Na+ gradient can provide nrg to transport other mol into cells (ex glucose) Na K ATPase 1. 3 Na+ bind to intracellular side of protein 2. Na+-k+ Atpase removes PO4 group from atp 3. Atpase change shape and adp released into cytosol 4. 3 na+ transferred outside cell 5. 2 K+ enter open extracellular gate 6. K bind to atpase 7. Po4 group released from atpase, extracell gate closes, intracell gate opens 8. 2 K+ enter cell