Exam 2 (Ch 7-8) Flashcards
the two laws of Thermodynamics
- Energy cannot be created or destroyed, but can change forms
- When energy changes forms, there is a loss of energy that is available to do work (free energy)
reaction where the products have less energy than the reactants (release energy)
- occur spontaneously
Exergonic Reactions
reaction where the products have more energy than the reactants (require energy input)
- do not occur spontaneously
Endergonic Reactions
what is an example of a coupled reaction?
energy released by an exergonic reaction is captured in ATP, and then ATP is used to drive an endergonic reaction
reasons why ATP is the energy currency of the cell
- It donates its phosphoryl groups to release energy
- during hydrolysis, it releases free energy which can be used to drive many reactions in metabolic pathways
how do enzymes operate?
- by lowering the energy of activation (enabling a reaction)
factors that affect enzymatic rate
- Substrate concentration (increases with substrate concentration bc of more frequent collisions)
- Most enzymes have an optimal pH (most neutral)
- Temperature (activity increases with temperature, but too hot can cause enzymes to denature)
what is oxidation?
when a substance loses an electron and loses hydrogen atoms
what is reduction?
when a substance gains an electron and gains hydrogen atoms
where does the calvin cycle reaction take place?
in the stroma of the thylakoid
what do light reactions produce that Calvin cycle reactions use?
NADPH and ATP
what does the Calvin cycle produce using NADPH and ATP?
NADP+ and ADP+P
what is the pigment in plants that absorbs reds and blues of white light and reflects green?
- captures solar energy to start the light reactions of photosynthesis
Chlorophyll
what are the accessory pigments that absorb light in the violet-blue-green range and reflect yellow and orange light?
- protects plants from UV damage
Carotenoids
what is the three-step process of the Calvin cycle that uses atmospheric carbon dioxide to produce carbohydrates?
- carbon dioxide fixation
- carbon dioxide reduction
- regeneration of RuBP
why is the Calvin cycle important?
The reduction of carbon dioxide (the second step) forms G3P, which can make many other molecules - glucose (from that, fructose, sucrose, starch and cellulose), amino acids, and fatty acids/glycerol
reactants and products of photosynthesis
carbon dioxide + water + energy = glucose + oxygen
reactants and products of cellular respiration
glucose + oxygen = carbon dioxide + water + energy
what is oxidized and reduced during cellular respiration?
glucose is oxidized and oxygen is reduced
the phases of cellular respiration
- Glycolysis (occurs in the cytoplasm, ATP is formed)
- Preparatory Reaction (pyruvate is oxidized and enter the matrix of the mitochondria)
- Citric Acid cycle/Krebs Cycle (occurs in the matrix and produces NADH and FADH2)
- Electron Transport chain (carriers on the cristae of the mitochondria that extract energy from the products of the citric acid cycle)
what process takes place in the cytoplasm if oxygen is not available?
Fermentation
- anaerobic process that reduces pyruvate to either lactate or alcohol and carbon dioxide
advantages and disadvantages of Fermentation
advantages: provides a quick burst of ATP energy for muscular activity
disadvantages: lactate and alcohol are toxic to cells
- lactate changes pH and causes muscles to fatigue (oxygen debt)
- yeast die from the alcohol they produce from fermentation
what is the process called where the flow of hydrogen atoms drives the synthesis of ATP from ADP and inorganic phosphate by ATP synthase
- establishment of the H+ gradient
Chemiosmosis
net yield of energy from glucose metabolism (cellular respiration) from each step
- from glycolysis - 2 ATP
- from citric acid cycle - 2 ATP
- from electron transport chain - 32 or 34 ATP
