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73 Cards in this Set
- Front
- Back
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• SCIENCE
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method of investigation, involving the mind (logic), body (senses)
o Body of knowledge o Way of knowing (w/ a certain point of view) (assumption) |
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• EXPERIMENTAL METHOD
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• MAKE OBSERVATIONS – measurable sensory experiences
• ASK QUESTIONS – about oberservations • FORMULATE HYPOTHESIS (prediction) – (tentative answers) testable/consistent/predictive • MAKE PREDICTIONS – based on hypothesis • TEST HYPOTHESIS – conclusive/repeatable • ANALYZE RESULTS (data) – tables/graphs/statistics • DRAW CONCLUSIONS – accept/modify/reject hypotheses • CONTRUCT THEORIES – well tested hypotheses |
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• EXPERIMENTAL METHOD IN USE
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• MAKE OBSERVATIONS – some frog species have declined in certain areas around the world, especially in mountains.
• ASK QUESTIONS – why have these species declined in those areas and more so at high elevations? • FORMULATE HYPOTHESES – scientists identified environmental factors that change with elevation, including UV-B radiations. • Hypothesis: Declines in some frog species are due to increased exposure to UV-B radiation. • MAKE PREDICTIONS – prediction: Reducing exposure of developing frogs to UV-B radiation should improve survival. • TEST HYPOTHESIS – Response of tadpoles of two frog species from Australian mountains were tested. Littoria verreauxii had disappeared from high elevations; Crinia signiera had not. Scientists predicted l. verreauxii tadpoles would survive less well than C. signigera tadpoles when exposed to UV-B radiations typical of high elevations. • ANALYZE RESULTS – L. Verreauxii survived less well in tanks exposed in UV-B radiation. Both species survived well in tanks with liters that blocked UV-B radiation. • DRAW CONCLUSIONS - the experiments confirmed the hypothesis. |
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• COMPARITIVE METHOD
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• MAKE OBSERVATIONS ABOUT SITUATION – measurable sensory experiences
• ASK QUESTIONS - about observations • FORMULATE HYPOTHESES ABOUT SITUATION – tentative answers; testable/consistent/predictive • PREDICT PATTERNS – based on hypotheses • TEST HYPOTHESES – conclusive/repeatable • OBSERVE PATTERNS – compare with predicted patterns • ANALYZE RESULTS - tables/graphs/statistics • DRAW CONCLUSIONS – accept/modify/reject/hypotheses • CONSTRUCT THEORIES – well-tested hypotheses |
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• COMPARITIVE METHOD IN USE
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• MAKE OBERSERVATIONS OF SITUATION – there are regional differences in the decline of populations of certain frog species.
• ASK QUESTIONS – why are these declines occurring in some regions and not in others? • FORMULATE HYPOTHESIS ABOUT SITUATION - the frogs are sensitive to urban and agricultural air pollutants and affected adversely by them. • PREDICT PATTERNS – Population declines should be greater in areas exposed to such pollutants than in unexposed areas. • GATHER DATA ABOUT SITUATION – Scientists conducted a census of several amphibian species to determine whether there ere present of absent at hundreds of study sites across California. • OBSERVE PATTERNS – One species, Rana aurora, was more likely to be absent from sites downwind of large urban and agricultural areas but present in sites upwind. • MAKE COMPARISONS – Scientists compared the actual results with those predicted by the hypothesis. • ANALYZE RESULTS – Rana aurora population declines had occurred where expected. • DRAW CONCLUSIONS – the census data confirmed the hypothesis for Rana aurora. |
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• ATOMS
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: the constituent of matter
• Contain: a central nucleus • Protons & Neutrons Peripheral shells (energy levels) • Electrons • Matter: occupies space and has mass • Element- distinctive kind of matter • Atom: smallest unit of an element <~ contains only one kind of atom • P - +1, 1 amu • n- 0, 1 amu • e - -1, 0.0005 amu |
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• PROPERTIES OF ATOMS
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• Atomic number – protons – unique to each element
• Atomic mass – protons + neutrons – varies within each element • Atomic Charge - +charges vs. – charges (what it attracts and repels) – positive, negative, or neutral. • ATOMS • Chemical Symbols: represent elements and their atoms • Elements present in bulk amount in living things ~> CHNOPS • Elements present in small amounts in living things ~> Cl, Na, K, Fe, Mg • The periodic table arranged elements in rows according to atomic number in columns according to similar properties. • Ions that have lost electrons become positive (cations) - Na • Ions that have gained electrons become negative (anions) – Cl • Isotopes with the same atomic number but different atomic mass • Radioisotopes: unstable and radioactive some used in medicine and research |
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• ATOMS
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• Valence(outermost) shell determines chemical reactivity
• Reactive atom: which unfilled valence shell, is unstable, and interacts with other atoms (to fill valence shell0 • Inert Atoms: filled valence shell, stable, does not interact. • Electrons in shells closer to the nucleus have less energy than those further from nucleus. |
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• CHEMICAL BONDS: LINKING ATOMS TOGETHER
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• Molecular Weight: Sum of atomic mass in molecule or compound
• P=E • Tritium – 31H • Covalent Bond – Chemical bond in which two atoms share one or more electron pairs. • Single Covalent – Share one electron pair • Double Covalent – Share two electron pairs • Triple Covalent- share three electron pairs • Chemical Bond – force that stabilizes reactive atoms by linking them together • Molecules – group of atoms linked by chemical bonds • Compound – group of different atoms linked by chemical bonds • Structural Formula: show #/ kinds/arrangement • Empirical Formula: show #/kind of atom |
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• CHEMICAL BONDS LINKING ATOMS TOGETHER
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• Nonpolar covalent: same kind of atoms (same electronegativity) share electron pairs equally.
• Polar Covalent: different kinds (different electronegativities) share electron pairs unequally • Shared electrons move closer to nucleus that has greater electronegativity • Electronegativity – attractive force nucleus exerts on electron • Weak bond that may form within or between polar molecules • Ionic bond- chemical. |
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• CHEMICAL BONDS
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• Nonpolar Covalent
• Hydrophobic • Do not interact with/dissolve in water • Oil/wax • Polar Covalent • Hydrophilic • Do interact with/dissolve in water • Sugar-salt, bc water and these have little charges • Nonpolar molecules interact with one another due to weak van der waals forces (weakest bond) – shifting electron distributions within them. |
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• CHEMICAL BONDS
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• Ionic bond: chemical bond in which an atom of lower electronegativity transfers one or more electrons to an atom of higher electronegativity.
• Electron transfer creates two oppositely charged ions which then attract each other. • Functional group: Charged group of covalently bonded atoms. (PO43-, SO43-, NH4+) |
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• WATER: STRUCTURES & PROPERTIES
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• Chemical reaction: makes/breaks chemical bonds, releases/stores chemical energy
• Reactants -> products: a chemical reaction is written s a balanced equation energy same as energy on other side of atoms. • - • Water has unusual properties due to molecular shape, polarity, and hydrogen bonding. • Cohesion ->capillary & surface tension (hydrogen bonds: hold water together) • High heat capacity -> heat storage • High heat of vaporization -> temperature moderation • Freezing density -> lake insulation • Slight reactivity ->universal solvent • Solute dissolved in solvent ->solution |
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• ACIDS BASES AND PH SCALE
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• Acids dissolved in water ionize release H+
• Strong acid dissolves completely example HCl, irreversible • Weak acid dissolves incompletely example H2CO3, reversible • Organic acids may have a carboxyl group (-COOH) • -COOH -> -COO + H+ |
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• ACIDS BASES AND PH SCALE
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• Molecules vary in size, shape, structure, reactivity, solubility (ability to dissolve in water)
• Bases dissolved in water ionize accept H+ • Strong base: dissolves completely, ex. Na-OH, irreversible • Weak Base: dissolves incompletely NH4-OH, reversible • The hydroxyl ion (OH) then accepts H+ - H2O • Organic bases may have an amino group (-NH2) • -NH2 + H+ -> -NH3 • Buffer: a mixture of a weak acid and a weak base minimize ph change. |
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• PROPERTIES OF MOLECULES
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• Isomers: same molecule different structure
• Structural isomers: molecules with same chemical formula, but atoms linked in different ways • Optical isomers: molecules with same chemical formula but atoms linked as mirror images. • Isomers have different chemical properties. |
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• PROTEINS: polymers of amino acids
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• Atoms: CHON
• Structural Units: Amino Acids • Linkages: Peptide (covalent bond between amino acids) • Functions: Structural, Enzymatic • Special Features: Four Structural Levels • Examples: Hemoglobin, Insulin • - • Polymers: large molecules composed of monomer chains • Monomers: small molecules w/ similar chemical structures linked to form polymers. • Mer=piece • Monomer-shapes/chemical properties determine polymer function • Molecular weight > 1000 • Dehydration (condensation) synthesis – removes h20, stores energy, constructive. • Polymerization-putting monomers together to make polymers • Depolymerization – taking a polymer apart into its monomers • Hydrolysis: add h20 to break apart, release energy, destructive. • #22 |
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• PROTEINS POLYMERS OF AMINO ACIDS
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• Primary structure: polypeptide chain – determined by #, kind, sequence of amino acids
• Secondary Structure: polypeptide chain o Alpha helix – twisted chain o Beta pleated sheet • Tertiary structure o Fold the helix o Determined by Nitrogen group interactions • Quaternary structure- polypeptides determined by subunit interactions • Renaturation – usually impossible • Disulfide bonds and H bonds between amino acids to hold form • denatured- not in natural shape causes pH, salinity, temp, redox conditions • Denaturation – disrupts secondary/tertiary structure destroys function • Peptide-linkages- form between amino acids • Amino groups joins carboxyl groups to produce o Dipeptides – 2 linked amino acids o Tripeptides- 3 linked amino acids o Polypeptides – many linked amino acids • Proteins- very long peptides |
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• CARBOHYDRATES: Sugars and sugar polymers
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• Atoms: CHO
• Structural Units: Monosaccharides • Linkages: Glycosidic • Functions: Structural; immediate energy • Special Features: Skeletons for other molecules • Examples: Glucose (monosaccharide) Sucrose (disaccharide) Starch (polysaccharide) |
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• CARBOHYDRATES
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• Monosaccharide
• Disaccharides – two monosaccharide • Oligosaccharides- few monosaccharide • Polysaccharides- many monosaccharides. • Sugars can be modified by adding functional groups. |
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• LIPIDS
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• Atoms: CHO
• Structural Units: Glycerol; Fatty acids • Linkages: Ester • Functions Structural; Stored Energy • Special Features: insoluble in water • Examples: Phospholipids; fats |
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• LIPIDS
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• Unsaturated – C-C & C=C bonds, flexible, bent in plant oils, liquid @ room temperature -> food processors remove (=) to make more like animal fat - > saturated w/ hydrogen’s: C-C bonds only rigid/straight in animal fats, make fats solid @ room temperature.
• - • Bonds=covalent • Nucleotides are composed of three components • Nitrogen-containing base – the nitrogenous bases fall into two categories o Base Pyrimidines have 1 ring (C,T,U) Pyrines have two rings (A,G) o Ribose or deoxyribose = nucleoside + phosphate = nucleotide • Pentose sugar (ribose or deoxyribose) • Phosphate groups |
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• NUCLEIC ACIDS
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• Atoms: CHONP
• Structural Units: Nucleotides • Linkages: Phoshpdiester • Functions: Information Storage/Transfers • Special Features: Replicate • Examples: DNA/RNA • - • DNA-RNA contain a serried of phosphate groups and pentose that for the backbone of structure • -in RNA, bases are attached to ribose, the bases A, G, C, and U • -in DNA, bases are attached to deoxyribose, the bases are A, G, C, and T; contains deoxyribose sugar • -RNA: single stranded; DNA- double stranded • -The numbering of ribose carbons is the bases for identifying the 5’ &3’ end of DNA&RNA strands • -Strands are anti-parallel • Stands are complementary- C, G- A, T |
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• THE CELL
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• Cell theory – cells are fundamental units of life, all organisms composed of cells, all cells from preexisting cells.
• -Control system: information processing; in all cells nucleus (ei) nucleolus (-li) chromosomes ribosomes • Endomembrane system – materials conversion • Endoplasmic reticulum (ER) • Golgi Apparatus • Vacuaoles • Lysosomes – in plants only • Cytoskeleton system- support movement • Microtubules- in all cells • Immediate filaments- in all cells • Microfilaments all cells • Centrioles-in animals • Flagellum-in animals • Cilium-in animals • Cell wall – in plants only • Metabolic system- energy transformation • Mitochondrion-in all cells • Chloroplasts – in plant cells. • - • PLASMA MEMBRANE • Structure: lipid/protein cell boundary • Functions: cellular integrity • Transport interface • Molecular organizer • Organelles: bodies within cell having: unique structures Specific functions |
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• NUCLEUS
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• Structure: nucleoplasm (interior fluid of nucleus) with lamina (meshwork) nuclear envelope (double membrane) with ports
• Functions: cell control • NUCLEOLUS • Structure: RNA-protein region inside nucleus • Functions: Ribosome synthesis – make proteins. |
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• CHROMOSOMES
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• Structure: DNA/protein threads inside nucleus
• Functions: Information storage • CHROMATIN-mass of indistinguishable chromosomes • RIBOSOMES • Structure: large & small RNA/protein subunits in cytoplasm & on ER • Functions: protein synthesis • ENDOPLASMIC RETICULUM – a network of membrane inside the fluid • Structure: Interconnected membranes in cytoplasm • Functions • Rough (RER): Protein Segregation/modification/transport • Smooth (SER) Protein modification Glycogen hydrolysis Lipid synthesis |
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• GOLGI APPARATUS
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• Structure: flattened membranous
• Cisternae & vesicles • Cis/medial/trans regions • Functions: proteins • Storage/modification/packaging • Cell wall (plants) polysaccharide synthesis • LYSOSOMES • Structure: membranous sacs • Functions: Digestion • - • The Golgi chemically modifies proteins in its lumen and targets them to correct address |
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• VACUOLES
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• Structure: membranous sacs
• Function: food/waste/pigment Storage Support Turgor in plants • MITOCHONDRIA • Structure: outer smooth membrane • Inner wrinkled membrane: cristae • Internal space – matrix • Functions: respiration |
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• CHLOROPLASTS
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• Structure: outer smooth membrane
• Inner wrinkled membrane (thylakoids) • Internal space (stroma) • Functions: Photosynthesis • CHROMOPLASTS • Contain red/orange/yellow pigments • Leucoplasts: store starch/oils • MICROTUBLES • Structure: hollow cylinders or tubulin subunits • Functions: support tracts (for organelle movement) |
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• INTERMEDIATE in size FILIMENTS
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• Structure: tough fibers of keratin subunits
• Functions: suppose (Resist tension) • Found only in multicellular organisms • MICROFILIMENTS • Structure: filaments/bundles/networks of actin subunits • Functions: support contract for cell/organelle movement • - • Long thin fibers of cytoskeleton play three roles: • Maintain cell shape & support • Provide cell movement • Help move things within the cell |
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• CENTRIOLES
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• Structure: paired 9+0 microtubular triplets
• Functions: form spindle during cell division (attach to chromosomes to keep them in order while separating • FLAGELLA • Structure: long & few 9+2 microtubular doublets • Functions: move cell with whip-like undulations |
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• CILIA
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• Structure: Short & numerous 9+2 microtubular doublets
• Functions: Move cell with oar-like strokes • CELL WALL • Structure: rigid cellulose surface covering • Functions: support, protection |
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• FLUID-MOSAIC MODEL OF CELL MEMBRANE
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• Proteins float in phospholipids bilayer
• Integral proteins: have hydrophobic regions can penetrate bilayer • Peripheral proteins: Lack hydrophobic regions cannot penetrate bilayer |
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• CELL RECOGNITION AND ADHESION
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• Allows cells to form tissue-specific and species-specific aggregations
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• TIGHT JUNCTIONS
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• Membrane-protein mesh
• Brings epithelial cells together • Prevents substances moving through intercellular space • Restricts membrane protein. Phospholipids movement from one cell region to another |
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• DESMOSOMES
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• Membrane-plaque (flat structure) anchor intracellular adhesion proteins and cytoplasmic intermediate filaments
• Bind epithelial cells together • Strengthen cells • Allow substances to move through intercellular space. |
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• GAP JUNCTIONS
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• Protein channels (connections) span intercellular space
• Allow molecules/electric signals to move through intercellular space • Facilitate cell communication |
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• PLASMODESMATA – in plants cells
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• ER- lined tubes (desmotubles) span cell walls
• Allow small molecules/ions to move across cell walls • Facilitate cell communication |
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• PROCESS OF MEMBRANE TRANSPORT
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• Biological membranes are selectively permeable (some substance can cross/other substances cannot cross
• Factors affecting passage: Size-small particles cross with ease large particle cross with difficulty Charge- uncharged/nonpolar particles cross with ease charge/polar particles cross with difficulty Phospholipids have a slightly negative charge |
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• DIFFUSION
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• Random movement of particles
• NET DIFFUSION: diffusion down a concentration gradient until uniform particle distribution (or equivalent) results • Factors affecting rate: temperature, particle size, charge, concentration • Solutes distribute themselves by diffusion uniformity and independently of each other |
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• OSMOSIS
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• Diffusion of H20 across a selectively-permeable membrane
• Net osmosis: osmosis draw a concentration gradient until uniform particle distribution or equivalent results • - • Isotonic solution- same [solute] concentration as another solution • Hypotonic solution- lower [solute] concentration than another solution • Hypertonic solution – higher [solute] concentration than another solution |
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• FACILITATED DIFFUSION
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• Diffusion across a selectively-permeable membrane with help of specific proteins [hi->lo]
• Channel proteins- aid passage of polar (have charges and might get stuck in the negative permeable membrane) molecules/ions by forming pores • Carrier proteins – aid passage of polar molecules by binding/releasing them; carrier molecules/ ions to other side • Diffusion rates increases then plateaus because the cell runs out of transporters |
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• ACTIVE TRANSPORT
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• Movement of substances up a concentration gradient across a selectively permeable membrane with the help of specific proteins
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• VESICULAR TRANSPORT – a small vacuole
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• Bulk movement of materials I vesicles into/out of cell without passing through membrane
• ENDOCYTOSIS- membrane invaginates to engulf materials • Phagocytosis- intake solids • Pinocytosis-intake liquids • EXOCYTOSIS- membrane evaginates to secrete materials |
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• ENERGY AND ELECTRONS FROM GLUCOSE
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• Glucose is the most common energy molecule. When oxidized (combined with oxygen) it breaks down releasing energy
• Complete chemical breakdown of glucose • C6H1206 ->602->6C02 + 6H20 + energy • Change in G = -686 kcal/mole • COMBUSTIVE OXIDATION- releases energy in a single burst • METABOLIC OXIDATION – releases energy in several steps –about half is stored in ATP • Three metabolic processes breakdown glucose: • Glycolysis • Cellular respiration • Fermentation • GLYCOLYSIS- ring form in body, hexose • Incomplete oxidation • Anaerobic (does not require O2) • Converts glucose to 2 pyruvate molecules • Stores captured energy in 2 ATP molecules (net) • Begins glucose metabolism in all cells |
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• CELLULAR RESPIRATION
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• Complete oxidation of molecules
• Aerobic (requires o2) • Converts pyruvate to CO2 and H20 • Stores captured energy in 34 ATP molecules (net) |
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• FERMENTATION
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• Incomplete oxidation
• Anaerobic (does not require o2) • Converts pyruvate from glycolysis into lactic acid or ethanol + CO2 • Stores captured energy in 2 ATP molecules (net) |
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• OXIDIZING AGENT
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• Accepts electrons/hydrogen atoms from another substance. It is reduced
• REDUCING AGENT • Donates/electrons/hydrogen atoms to another substance. It is oxidized. • During breakdown of glucose: • Oxygen is oxidizing agent (is reduced) • Glucose is reducing agent (is oxidized) • Redox reactions • Oxidation = loss of e-, H+, & energy • Reduction = gain of e-, H+, and energy • Whenever material is oxidized another is reduced • Oil Rig: Oxidation is loss, reduction is gain. |
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• OXIDIZING AGENT- brings about oxidation
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• Accepts electrons/hydrogen atoms from another substance. It is reduced
• REDUCING AGENT • Donates electrons/hydrogen atoms to another substance. It is oxidized. • During the breakdown of glucose • Oxygen is oxidizing agent (is reduced) • Glucose is reducing agent (is oxidized) |
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• ENERGY AND ELECTRONS FROM GLUCOSE
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• Coenzyme NAD is a redox intermediate during metabolism
• NAD+ is oxidized form. • NAD + H+ is reduced form. • Reduction reaction endergonic: • NAD+ +2H + ENERGY -> NADH + H+ • Oxidation reaction exergonic • NADH + H+ ½ O2 - > NAD+ +H20 +ENERGY |
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• GLYCOLYSIS
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• Energy – transformation in cells occur in interconnected metabolic pathways
• When O2 is present: • Glycolysis, cellular respiration, pyruvate oxidation, citric acid cycle, respiratory chain (electron transport chain) • When o2 absent: o Glycolysis and Fermentation • Inside Mitochondrion on Cristae: • Pyruvate oxidation • Respiratory Chain • In matrix • Citric Acid Cycle • Outside Mitochondrion: • Glycolysis • Fermentation • - • Energy- Investing reactions – use ATP • Glucose destabilized by phophorylation (With 2 ATP’S) – step 1 & 3 • Resulting molecule splits into 2 3-carbon molecules: DAP + G3P <- (2 molecules of G3P for every glucose) – step 4 • DAP converted to G3P- step 5 |
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• ENERY HARVESTING REACTIONS – produce ATP
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• Two G3Ps phosphorylated (with inorganic phosphates and oxidized (gains H+, e-, energy) by NAD+s – step 6
• Succeeding molecules dephosphorylated to produce 4 ATPs (substrate-level phosphorylation) – step 7 & 10 • Two 3-carbon pyruvates formed – step 10 • 1 GLUCOSE NETS: • 2 ATP • 2 NADH + H+ • 2 PYRUVATE |
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• PYRUVATE OXIDATION – in matrix
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• Each pyruvate is oxidized (Take away H+, e-, energy) by NAD+ and splits into acetate +CO2
• Each acetate +coenzyme A -> Acetyl CoA (some energy stored temporarily) • KREBS CYCLE-CITRIC ACID CYCLE – in matrix • Each acetyl CoA enters Citric Acid Cycle • Succeeding molecules oxidized, dephosphorylated, & rearranged • Each turn of cycle (2) generates- will turn twice for each glucose molecule 3NADH + H+ 1 FADH2 1 ATP 2 CO2 • 6-CO2, H20 left over from glucose |
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• ELECTRON TRANSPORT CHAIN-RESPIRATORY CHAIN –last step
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• Glucose energy is lost because of 2nd law of thermodynamics
• It is to react by adding phosphate (2) from ATP • Oxidizing lose- energy, electrons, hydrogen • Put into NAD wagons (2) • Remove phosphate and make ATP (happens twice for each = 4 ATP) dephosphorylation • Which makes pyruvate, which we oxidize – pyruvate oxidation • Pyruvate oxidized in citric acid cycle • - • Electrons flow from NADH + H+ and FADH2 to oxygen through a series of carriers on inner membrane (cristae) • 02 +4H+ + 4e- -> 2 H20 |
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• RESPIRATORY CHAIN
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• Sub-level phosphorylation – ADP -> ATP, energy from redox
• Cellular Respiration • Made 40 ATP – used 2 during glycolysis • 38 ATP – 2 in pyruvate oxidation = 36 ATP • Chemiosmosis • The resulting redox reactions (1st step) actively transport (2nd step) H+ (protons) across membrane (inner membrane of cristae) from matrix to intermembrane space. • An electrochemical gradient (proton-motive force) results • Store ATP • ATP synthase (3rd step) allows H+ to diffuse back across membrane through proton channels and synthesizes ATP (oxidative phosphorylation) – ADP -> ATP, H+ go back through and combine with CO2 • Every 2 e- flowing along chain from NADH + H+ -> 3 ATP • Every 2 e- flowing along chain from FADH2 -> 2 ATP |
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• LACTIC ACID FERMENTATION
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• NADH + H+ reduces pyruvate (from glycolysis) to lactate
• NAD+ replenished for continued glycolysis and ATP production • Occurs in certain bacteria and oxygen-starved muscles. • ALCOHOLIC FERMENTATION • CO2 removed from pyruvate (from glycolysis) • Acetaldehyde forms • NADH + H+ reduces - H+, e-, energy give it to acetaldehyde to form ethanol • NAD+ replenished for continued glycolysis and ATP production • Occurs in certain yeasts |
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• ONE GLUCOSE
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• In glycolysis pyruvate oxidation and citric acid cycle
40 ATP (gross) -2 ATP to activate glucose in glycolysis -2 ATP to shuttle NADH + H+ across inner membrane in glycolysis • In fermentation 2 ATP (net) End products still contain much energy |
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• RELATIONSHIPS BETWEEN METABOLIC PATHWAYS
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• Glucose metabolism is central to other metabolic pathways
• Catabolic interconverstions: macrmolecules hydrolyzed into metabolic intermediates • Anabolic interconversions: Metabolic intermediates synthesized into macromolecules • Cells maintain metabolic homeostasis by regulating enzymes of catabolism and anabolism • The metabolic pool (levels of biochemicals) in remarkably constant |
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• PHOTOSYNTHESIS
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• Plants obtain CO2, H20, and NH4 (for nucleic acids) from environment and ATP from glycolysis/ cellular respiration or fermentation
• 6CO2+12H20 - > C6H12O6 + 6O2 + 6H20 – photosynthesis reaction |
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• THER INTERACTIONS OF LIGHT AND PIGMENTS
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• Photosynthesis occurs in two sets of chemical reactions: light and CO2 fixation reactions (Calvin Benson cycle)
• Light is a part of electromagnetic spectrum. It manifests as photons (units of light) or waves • Wave energy inversely proportional to wavelength (color) • Wavelengths (colors of light) measured in nanometers (nm) |
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• INTERACTIONS OF LIGHT AND PIGMENTS
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• Photons can be biologically active when sufficiently energetic and absorbed by molecules.
• In photon-molecule interactions, photons may be scattered (bounce off), transmitted (pass through) or absorbed • A pigment absorbs certain wavelength of light, and is raised from ground state to excited state • Electrons jump to higher energy levels • An absorption spectrum plots light absorption as functions of wavelength • An action spectrum plots biological activity of function of wavelength • Chlorophyll pigments – absorb blue and red wavelengths • Accessing pigments – absorb intervening wavelengths |
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• INTERACTIONS OF LIGHT AND PIGMENTS
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• Antenna system – set of pigments packed on thylakoid membranes
• Reaction Center – are of antenna system where pigments transform (absorbed light energy to usable chemical (electron) energy • An excited pigment may release the energy (fluoresce) or pass it along to reaction center • Excited – energy moving from lower to higher energy levels • Energized electrons jump from excited chlorophylls (chlorophyll alpha in plants) in reaction center and enter redox reactions (electron acceptor) • Light reactions in thylakoid membrane |
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• LIGHT REACTIONS
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• Photosystem 1 (P700nm)
Antenna system whose reaction center best absorbs light of wavelength 700nm and donates electrons to an electron transport chain, replacing them with electrons from photosystem II • Photosystem II – P680nm Antenna system whose reaction center best absorbs light of wavelength 680nm and donates electrons to an electron transport chain, replacing them with electrons from H20 |
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• LIGHT REACTIONS
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• Electrons released from photosystem flow through electron transport chain on thylakoid membranes
• Non-cyclic transport -> ATP +NADPH+ H+ 02 using water and photosystems I and II. • Cyclic electron transport -> ATP using photosystem I |
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• CHEMIOSMOSIS
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• Redox energy released in cyclic and non cyclic electron flow actively transports H+ (protons) across thylakolid membrane from stroma to thylakoid (intermembrane) space
• An electrochemical gradient (proton-motor forces) results • ATP synthase allows H+ to diffuse back across membrane through proton channels and synthesize ATP – phosphorylation • Energy 2 e- flowing along chain from photosystems -> 1 ATP • ATP synthase couples fermentation of ATP |
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• CALVIN-BENSON CYCLE- in stroma
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• CO2 fixation – attach CO2 to a molecule by the enzyme rubisco
• Reduction and production of G3 ( using ATP and NADHPH + H+) from light reactions on thylakoids • Regeneration of RuBP using ATP |
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• CALVIN-BENSON CYCLE- through holes in stromata
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• As CO2 molecules enter Calvin-Benson cycle, rubisco (enzyme) fixes each to RuBP (ribose 1, 5-biphosphate)
• Succeeding molecules reduced, phosphorylated, & rearranged • - • Each turn: • Uses 2 NAPH + H+ 3 ATP • Generates 2 G3P (glyceraldehydes 3-phophate) |
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• ENERGY AND ENERGY CONVERSIONS
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• First law of thermodynamics – during energy transformations energy quantity (amount) is unchanged
• ENERGY INPUT = ENERGY OUTPUT • Second law of thermodynamics – during energy transformations, energy quality (usefulness) is decreased • USED ENERGY = USELESS ENERGY |
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• ENERGY AND ENERGY CONVERSIONS
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• Entropy- tendency toward disorder due lack of useable energy. Ex. A road, a messy kid room.
• CLOSED SYSTEM- thermos bottle, no system-environment energy exchange Entropic (disorder overwhelms system) change stops • OPEN SYSTEM –living cell, system-environment energy exchange Negentropic (system resists disorder) change continues. |
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• ENERGY AND ENERGY CONVERSIONS
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• Free energy (G) - useable energy (Can do work) in a chemical reaction
• Entropy (S) – unusable energy (cannot do work) in a chemical • Enthalpy (H) – total energy (usable & unusable) in a chemical reaction • Absolute Temp (T) – Temperature scale based on absolute 0 (-273.15 degrees Celsius) • Change in G = Change in H – Tchange in S |
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• ENERGY AND ENERGY CONVERSIONS
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• Endergonic (nonspontaneous) reaction
Change in G > 0(net free energy input) = positive Dehydration Syntehsis • Exergonic (spontaneous) reaction Change in G <0 (net free energy output) |
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• ENZYMES: BIOLOGICAL CATALYSTS
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• Energy barrier: thermodynamic resistance to reaction
• Activation Energy (Ea) – energy needed to overcome energy barrier • Transition state- unstable intermediate condition following activation |
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• ENZYMES: BIOLOGICAL CATALYSTS
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• Cofactors – inorganic/ bind temporarily to enzyme
• Coenzymes – organic/bind temporarily to enzyme • Prosthetic group- organic/ bind permanently to enzyme • Catalyst- lowers energy barrier speeds up chemical reaction does not change equilibrium point/change in G not altered by reaction • Enzyme- protein catalyst combines with specific substrate • Substrate binds specifically to active site or enzyme (lock and key) • Enzyme changes shape (induced fit) • Reaction occurs product released enzyme unaltered. |
