LIFE 102 Exam 2 (Ch5-9) PDF

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Life 102 notes for exam 2. Includes brief summary of notes for chapters 5-9...

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LIFE 102 Exam 2 Ch5-9 Ch5 - Membranes ●

Cell membrane four components: ○ Phospholipid bilayer ■ Flexible matrix, barrier to permeability, helps retain moisture ■ Fluid mosaic model - mosaic of proteins float in/on the fluid lipid bilayer like boats on a pond ■ Phospholipids made up of glycerol, 2 fatty acids (tails), phosphate group (head) ● Nonpolar hydrophobic tails ● Polar hydrophilic heads

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Transmembrane proteins ■ Move material in/out of cell; corridor ■ Nonpolar regions can create pore through membrane Interior protein network ■ Not embedded, in one side; move around and carry stuff Cell surface markers ■ Glycoproteins (sugar protein) and glycolipids (sugar lipids); send message well

Transport across membranes

Major ISSUE to crossing membrane is the hydrophobic interior that repels polar molecules, not nonpolar molecules (diffusion) ○ Facilitated diffusion ■ Molecules cannot cross membrane → go through proteins; higher to lower concentration ■ Channel Proteins ● Ion channel, hydrophilic when open; open/close in response to stimulus (chemical/electrical) ● Concentration, voltage, channels open/closed all determine direction ■ Carrier Proteins ● Transport ions, solutes, sugars, amino acids ● REQUIRES concentration difference ● Bind specifically to molecules they assist Osmosis ○ Hypertonic=higher solute, cell in hypersolute shrivels ○ Hypotonic=lower solute, cell in hypotonic swells ○ Isotonic=same osmotic concentration ○ Aquaporins facilitate osmosis; only let water molecules through ○ Plant cells use turgor pressure to push cell membrane against cell wall, rigid (doesnt burst/shrink) Active Transport ○ Carrier proteins: ■ Uniporters - move 1 molecule at a time ■ Symporters - move 2 molecules at a time ■ Antiporters - move 2 molecules opposite directions ○ Endocytosis - movement of substances into cell ○ Exocytosis - movement of substances out of cell ○

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Ch 6 Energy and Metabolism ● ●

Kinetic energy - energy of motion Potential energy - stored energy

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Redox reactions ○ Oxidation - atom/molecule loses electron

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○ Reduction - atom/molecule gains electron ○ Reactions always paired Free energy ○ G = H - TS ■ G=energy available to do work ■ H=enthalpy, energy in molecules chemical bonds (energy that's there) ■ T = absolute temperature ■ S= entropy, unavailable energy (energy that's not there) ○ ΔG = ΔH –  TS ■ ΔG = change in free energy ■ Positive ΔG - products have more free energy than reactants; (endergonic) needs energy added ■ Negative ΔG - products have less energy than reactants; spontaneous; (exergonic) gives off energy when reaction ATP (Adenosine triphosphate) ○ Ribose, adenine, 3 phosphates (2 ADP, 1 AMP) ○ Not suitable for long term energy storage, it is for speed and convenience Enzymes ○ Most are protein (Pacman) ○ Substrate fits into active site (enzyme-substrate complex)- lowers activation energy ○ Ribozymes (not protein) ■ Intramolecular catalysis - catalyze reaction on RNA molecule itself ■ Intermolecular catalysis - RNA acts on another molecules ○ Inhibitor - substance that binds to enzyme to decrease its activity ■ Competitive inhibitor - compete w/ substrate for active site ■ Noncompetitive inhibitor - binds to enzyme at other site (allosteric site); causes shape change so enzyme cannot bind substrate ○ Allosteric enzymes - enzymes exist in active (turn on) and inactive (turn off) forms ■ Allosteric inhibitor - binds to allosteric site, reduces enzyme activity ■ Allosteric activator - binds to allosteric site, increases enzyme activity Metabolism - total of all chemical reactions carried out by an organism ○ Anabolic reaction = expend energy, build up molecules (small-->big) ○ Catabolic reaction = harvests energy, break down molecules (big-->small)

Ch 7 How Cells Harvest Energy ●

Cellular respiration - series of reactions ○ Oxidized = loss of electrons ○ Reduced = gain of electrons ○ Dehydrogenation - lost electrons accompanied by protons (hydrogen atom is lost - lose 1 electron, lose 1 proton) ○ Autotrophs - able to produce own organic molecules through photosynthesis ○ Heterotrophs - live on organic compounds produced by other organisms

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Redox reactions - electrons carry energy from 1 molecule to another ○ NAD+ (big dead battery) ■ Accepts 2 electrons, 1 proton = NADH (big charged battery) Electron acceptors ○ Aerobic respiration = final electron acceptor is oxygen (makes lots of ATP) ○ Anaerobic respiration = final electron acceptor is inorganic molecule ○ Fermentation = final electron acceptor is organic molecule (very wasteful) ■ Lactic acid fermentation Aerobic respiration ○ C6H1 2O6  + 6O2  → 6CO2  + 6H2 O  ○ Free energy = -686 kcal/mol of glucose ○ Energy released in small steps ATP ○ ΔG = -7.3kcal/mol ○ 2 mechanisms for synthesis ■ Substrate level phosphorylation - transfer phosphate group to ADP ■ Oxidative phosphorylation - ATP synthase use energy from proton gradient Oxidation of glucose ○ Glycolysis ■ Converts 1 glucose → 2 pyruvate ■ Uses 2 ATP, makes  4 ATP (2 profit) + 2 NADH ○ Pyruvate oxidation ■ Oxygen is present - pyruvate → acetyl-CoA, enters krebs cycle, aerobic respiration ■ Oxygen is not present - pyruvate oxidized NADH to NAD+, fermentation ○ Krebs cycle ■ Happens in matrix of the mitochondria ■ Oxidized acetyl group from pyruvate ● acetyl-CoA + oxaloacetate → citrate ● Citrate rearrangement + decarboxylation ● Regeneration of oxaloacetate ■ Releases 6 CO2 , 4  ATP ■ Reduces 10 NAD+ to 10 NADH, 2 FAD to 2 FADH2 ○ Electron transport chain ■ Membrane bound electron carrier, embedded in inner mitochondrial membrane, operate as proton pump to shoot protons into intermembrane space ○ Chemiosmosis ■ 10:1 ratio proton in intermembrane space drives protons into matrix via diffusion ○ ATP Synthase ■ Carried out by tiny rotary motor driven by proton gradient ■ F0 membrane bound complex ■ F1 complex (stalk and knob) ■ Protons go through F0, rotates, makes 1 ATP ○ 32 ATP per glucose for bacteria

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30 ATP per glucose for eukaryotes Allosteric = change in shape/activity of protein because it combines w/other substance at a site other than active site

Ch 8 Photosynthesis ● ● ● ● ●

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6CO2  + 12H2 O → C6H12O6 + 6O2 + 6H2O  Chloroplasts take energy from protons, store it in sugars (starch) Photons add energy to electrons in chlorophyll Chlorophyll uses blue and red wavelengths Chlorophyll is embedded in reaction center (protein) ○ Photosystem II ■ First photon adds energy to electron, makes  ATP ○ Photosystem I ■ Next photon adds energy to electron, makes NADH Calvin cycle - ATP and NADPH are used to make sugars ○ Carbon fixation; makes 6ADP, 6NADP+ ○ Reduction; makes  a sugar ○ Regeneration of the CO2  acceptor; makes 3 ADP

Ch9 Cell Communication ● ●

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Signal transduction - events within cell respond to signal; ligand binds to receptor protein; cell responds Phosphorylation - change activity of a protein ○ Protein kinase - enzyme adds a phosphate to a protein ○ Phosphatase - enzyme removes a phosphate from a protein 3 classes of membrane receptors ○ Chemically gated ion channels - channel-linked receptors that open to let specific ion pass in response to a ligand ■ Lock able to recognize key ○ Enzymatic receptors - receptor is enzyme that’s activated by ligand ■ Almost all are protein kinases ■ Lock with key somewhere that fits it ○ G protein-coupled receptor - G protein assists in transmitting signal from receptor to enzyme ■ G protein = service dog ■ GDP is dog collar ■ GTP is electric dog collar that trained dog to open ● G Protein is activated by receptor, activate enzymes ○ Active when bound to GTP ○ Inactive when bound to GDP Steroid receptors ○ Cross plasma membrane ○ Bind intracellular steroid receptor ○ Regulator of gene expression Receptor tyrosine kinases ○ Dimerization - have 2 diff molecules that come together to do job

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○ Two proteins must link together Kinase (protein) cascade ○ Phosphorylate more kinases ○ Very rapid activation Scaffold protein ○ Organize components of kinase cascade into single protein complex ○ Like a tool belt - holds kinases close (kinases=tools) Second messengers ○ Adenylyl cyclase activated by G protein, activates protein kinase A ■ G protein = first messenger ■ cAMP = second messenger ○ Phospholipase C is activated by G protein ■ G protein = first messenger ■ Many second messengers ● IP3 ● DAG ● Ca2+

5 FREEBIES 1) For the mathematical expression : A) ∆S is the change in enthalpy, a measure of randomness B) ∆H is the change in entropy, the energy available to do work C) ∆G is the change in free energy D) T is the temperature in degrees Celsius E) This equation proves that the free energy of the universe is constantly increasing  2) Compound A binds to an enzyme at a position far away from its active site, and this binding decreases the activity of the enzyme. Compound A is called: A) a polyphosphate B) an allosteric inhibitor C) the substrate D) a flux capacitor E) a competitive inhibitor  3) What is the reducing agent in the following reaction?

 A) oxygen B) NADH C) NAD+ D) lactate E) pyruvate 4) Which of the following statements best represents the relationships between the light reactions and the Calvin cycle? A) The light reactions provide ATP and NADPH to the Calvin cycle, and the Calvin cycle returns ADP, Pi, and NADP+ to the light reactions B) The light reactions provide ATP and NADPH to the Calvin cycle, and the Calvin cycle provides water and electrons to the light reactions

C) The light reactions supply the Calvin cycle with CO2 to produce sugars, and the Calvin cycle supplies the light reactions with sugars to produce ATP D) The light reactions provide the Calvin cycle with oxygen for electron flow, and the Calvin cycle provides the light reactions with water molecules to split apart for energy E) The light reactions and the Calvin cycle operate completely independently of one another 5) Consider the pathway: What is the second messenger?

 A) cAMP B) G protein C) GTP D) adenylyl cyclase E) G protein-coupled receptor ...