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Life 102|107 Exam 2
(Arthun,CSU)Questions With Answers
Light Reactions - when light energy is captured in thylakoid membrane, during these reactions oxygen is released, NADPH produced from NADP+, ATP is produced.
How are the light reactions coupled to the Calvin cycle? - Light reactions are coupled with the calvin cycle because light reactions are the photo part and the calvin cycle is the synthesis part. Calvin cycle uses NADPH and ATP to breakdown CO2.
Calvin Cycle - When CO2 is "fixed" and reduced to sugars in the stroma, forms a sugar from CO2 using ATP and NADPH.
How is the calvin cycle coupled to light reactions? - uses the NADPH and ATP that were produced in the light reactions
Photosynthetic pigments - Molecules that can absorb light, more specifically chlorophyll. They are located in the chloroplast. Plants are green from the chlorophyll.
How does light absorption work? - When a photon hits any molecule it can push an electron into a higher energy level.
What happens to the excited electrons from chlorophyll? - doesn't fall back, but is captured by another molecule
Primary electron acceptor - molecule that accepts excited electrons from the reaction center
Photosystem - cluster of pigment molecules working together
Reaction Center - central chlorophyll molecule that receives all the captured light energy
How is the electron transport system in chloroplasts coupled to ATP synthesis? - the electrons of the NADPH are available for the reactions of the calvin cycle.
Carbon Dioxide Fixation - conversion process of inorganic carbon to organic carbon bound molecules. CO2 is fixed and reduced to sugar (CHO).
What light reaction products are required for CO2 fixation? - NADPH and ATP
How many molecules of CO2 are needed to make one C3 sugar? What else is needed? - 3 molecules of CO2 are needed as well as 9 ATP and 6 NADPH to reduce CO2 to sugar.
Does photosynthesis proceed in the dark? - No, photosynthesis needs to have light in order to energize electrons.
Where do H+ go in photosynthesis? - goes to reducing p680+ to P
Where does O2 go in photosynthesis? - released as a by-product of this reaction
What is Anabolism? - any process that results in the synthesis or assembly of larger molecules from smaller ones, usually at the expense of energy (synthesis of proteins to amino acids)
What is Catabolism? - breakdown of large molecules into smaller ones, involving the breakdown of chemical bonds typically releasing energy (cellular respiration)
Enzyme - protein that speeds up a reaction
Active Site - actual site on the enzyme where substrate binds for the reaction to proceed
What effect does an enzyme have on the activation energy needed for a chemical reaction? - lowered by enzymes, enzymes promote reactions by serving as a physical site upon which the reactant molecules (subtstrates) can be positioned for various interaction.
What affects enzyme activity? - environmental conditions such as temperature, pH, concentration as well as activation/inhibitors by other molecules such as cofactors which are non protein molecule/atom required for enzymatic activity (many are metals).
What happens to an enzyme during the course of a chemical reaction? - The substrate binds to the enzyme. The enzyme converts the substrate to a product. The product leaves the active site and the enzyme is now ready for anew substrate.
Are the enzymes premaritally altered in a chemical reaction - No
Co-factor - non-protein molecule/atom required for enzymatic activity (many are metals)
Coenzyme - organic non-protein molecules that binds to the protein to form the active enzyme
Competitive Inhibitor - binds in the active site
Non competitive inhibitor - binds in the allosteric site
Allosteric site - place on the enzyme that is not the active site, a non substrate molecule can bind to the enzyme altering its shape
Feed-back "end product" inhibition - when an enzyme is inhibited by its product; supply and demand
Effect of an increase in product in a multi-enzyme pathway - result in feedback inhibition
Effect on a decrease in product in a multi-enzyme pathway - multi enzyme pathway will lift the feedback inhibition so it can produce more products again
What is allosteric regulation of a multimeric/multi-subunit protein? - the regulation of a protein when an effector molecule binds to the allosteric site.
Reaction of glucose (sugar) with molecular oxygen - C6H12O6+O2—-
CO2+H2O+energy
Is the reaction of glucose with molecular oxygen endergonic or exergonic? - Exergonic (breakdown of molecules)
Electronegative - atoms attract electrons and pulls them closer to its nucleus
What happens when a molecule is oxidized? - Lose electrons
What happens when a molecule is reduced? - Gain electrons
Redox Reaction - chemical reaction that transfers electrons between reactants
Why doesn't the temperature of a cell increase when glucose is catabolized? - Heat is lost to the environment
Where does the energy from glucose metabolism go? - To drive the production of ATP. Energy is released to make ATP.
How is electron transport coupled to ATP synthesis? - during oxidative phosphorylation chemiosmosis couples Electron transport to ATP synthesis.
What are the functions of membranes? - to create boundaries (inside vs. outside and cellular compartments) and to control traffic (selective permeability, some cross easily some don't).
What are the major structural components of membranes? - The structure of a membrane is polar phosphate heads and non polar fatty acid tails.
Why is the plasma membrane a selectively-permeable membrane? - because some will be able to crosss it, others will not.
Membrane viscosity is influenced by what factors? - Membrane viscosity is influenced by temperature, type of phospholipids and cholesterol content
What is the role of cholesterol? - The role of cholesterol is to keep membrane fluidity optimal at different temperatures.
What are integral membrane proteins? - proteins that float freely in the phospholipid bilayer.
What are peripheral membrane proteins? - Peripheral membrane proteins are proteins on the peripheral of the membrane.
How are small, non-polar molecules transported across membranes? - Through diffusion, from a high concentration to a low concentration
What are the properties of diffusion? Does it require energy? - the distribution of molecules from a high concentration to a low
concentration usually through osmosis (diffusion by water). Diffusion does not require energy
What kind of molecules require a transport system? - Larger molecules that cannot diffuse down their own concentration gradient.
How do passive and active transport differ? - Active transport requires energy from ATP, passive transport does not require additional energy
What is osmosis? - passive diffusion of water across a semi-permeable membrane.
What drives osmosis? - solutes that don't cross membranes, Water diffuses towards highest solute concentration (water follows salt), towards lowest free water concentration.
What is a Hypertonic solution? - higher concentration of solute outside of the cell rather than inside, water flows out of cell causing cell to shrivel
What is a hypotonic solution? - higher concentration of water inside of the cell rather than outside of the cell, water flows into the cell; animal cells will swell up and burst, plant cells vacuoles will expand until cell want cannot any longer
What is an isotonic solution? - Equal amount of solute inside and outside of the cell. Causing water to flow in and out of the cell at the same rate because it is at equilibrium
How are larger molecules moved across membranes? - vesicle transport
What is exocytosis? - secretion of vesicle content via the membrane; vesicle moves and fuses with the membrane
Anaerobic Metabolism - respiration using an electron transport chain with a final electron acceptor other than O2 (i.e. sulfate); respiration without the presence of oxygen.
Products of Glycolysis - 2 pyruvates and a net of 2 ATP produced
Products of Citric Acid Cycle - 1 ATP, 3 NADH, and 1 FADH2 per turn ( turns=1 molecule of glucose)
Products of Electron Transport - H2O and H+ ions
How is ATP synthesized by the mitochondria? - ATP synthase
What molecules are produced in the Citric Acid Cycle and then used during electron transport in the mitochondria? - NADH and FADH
Fermentation - an extension of glycolysis, breakdown of glucose in the absence of oxygen
Products derived from fermentation - NAD+ and ATP
What happens to oxygen molecules during electron transport? - Oxygen molecules breakdown to H2O
Final product of electron transport - H2O and H+ ions
Is glucose the only food that can provide energy to form ATP? - No. Fats, proteins and carbohydrates can also provide food.
How is cellular respiration regulated? - through feedback inhibition; if ATP concentration begins to drop, respiration speeds up. When there is plenty of ATP respiration slows down. The control of catabolism is based mainly on regulating the activity of enzymes.
Structure of a chloroplast - The site of photosynthesis in plants. The chlorophyll is in the membranes of thylakoids (stacks). Chloroplasts also contain stroma, a dense interior fluid.
