Lecture 9: Energy and Enzymes (start of final exam material) Flashcards
What are the 5 important functions energy is used for?
- movement
- chemical reactions
- temperature control
- nerve signals
- cell division/ reproduction
What is the difference between kinetic energy and potential energy
- kinetic: active motion energy
- potential: stored energy
Explain the potential energy in bonds:
- which bonds have the highest PE and the lowest; why?
- what happens to the PE of the products if a chemical reaction creates more polar bonds?
- highest PE: non polar bonds (equal sharing of electrons and long weak bonds) vs lowest PE: polar bonds
- the products have a lower PE
Explain the first law in thermodynamics
- energy in = energy out
Write out the chemical breakdown of glucose
- C6H12O6 + 6O2 6CO2 + 6H2O + 2800kJ
What is enthalpy (H)?
- the total energy in a molecule; most of it is stored potential energy
Explain the change in enthalpy in an:
- exothermic reaction
- endothermic reaction
- exothermic: change in enthalpy is NEGATIVE
- endothermic: change in enthalpy is POSITIVE
Define: entropy (s)
- amount of disorder
What is the Gibbs free energy equation? State the whole equation.
Calculates the energy associated with a chemical reaction that can be used to do work.
delta G = delta H + T(deltaS)
- H is enthalphy, T is temp, S is entropy
Explain the change in entropy in the chemical breakdown of glucose
- entropy increases because more disorder occurs
Explain delta G/ the change in free energy if:
- the products have less free energy than the reactants
- the products have more free energy than the reactants
- what does this mean about the reactions?
- delta G is negative and the reaction is exergonic and spontaneous
- delta G is positive and the reaction is endergonic and non spontaneous
define: exergonic and endergonic reactions;
- what drives endergonic reactions?
exergonic: reaction that releases energy
endergonic: reaction that absorbs energy; driven by ATP
Draw a diagram of the free energy overtime of a spontaneous reaction. Also:
- explain and label delta G, Ea, transition state.
- explain the speed of the reaction and what it is dependent on.
- how can you accelerate the reaction?
- what stabilises the transition state
- see google doc
- speed of reaction may be fast or slow depending on activation energy required
- to accelerate the reaction you must lower the activation energy (with a catalyst)
- enzymes stabilize the transition state
Draw the hydrolysis reaction of ATP and the coupled reaction diagram
- see google doc
explain the metabolic pathway
- reactions are sequential (A–>B–>C–>D)
define: oxidation and reduction
- oxidation: loss of electrons
- reduction: gain of electrons
write out the oxidation of glucose reaction
- see google doc
Fill in the blank: redox reactions often involve electron _____ such as _____ and ______. Both of these transfer __ electrons
- carriers
- F. A. D.
- NAD+
- 2
Glucose
- stored as? (3)
- function
- what is glycolysis?
- glycogen, fats, and starch
- function: energy
- glycolysis: cellular respiration (set of metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into (ATP))
define: catabolism and anabolism
catabolism: breakdown of complex molecules
anabolism: creation of complex molecules (ex: making glucose)
Give the photosynthesis equation
- see google doc
Write out the metabolic pathway
- see google doc
what process produces ATP? How is this accomplished?
- cellular respiration; transfer of electrons
What are the 4 steps/stages of cellular respiration?
- glycolysis
- pyruvate processing
- citric acid cycle
- electron transport and oxidative phosphorylation
Explain step 1 of cellular respiration: glycolysis
- location
- what is oxidized and reduced
- what goes in
- what comes out
- equation
- anaerobic or aerobic?
- cytosol
- oxidized: carbon; reduced: oxygen
- what goes in: 2 ADP, 2 NAD+
- what comes out: 2 new ATP (4 total) , 2 NADH
- glucose + 2NAD+ + 2ATP –> 2 pyruvate + 2NADH + 4 ATP
- anaerobic
Explain step 2 of cellular respiration: pyruvate processing
- location
- what goes in
- what comes out
- equation
- matrix
- oxidized: carbon and pyruvate; reduced: oxygen
- what goes in: 2NAD+
- what comes out: 2NADH
- 2 pyruvate + 2 NAD+ + 2 CoA -> 2 acetyl-CoA + 2 NADH + 2 H+ +2CO2
Explain step 3 of cellular respiration: citric acid cycle
- location
- for every glucose molecule, how many times does the cycle run?
- equation
- matrix
- twice
2 acetyl-CoA + 6NAD+ + 2FAD + 2ADP –> 4CO2 + 6NADH + 2FADH2 + 2ATP + 2CoA
Explain step 4 part 1 of cellular respiration: electron transport
- location
- how does it occur?
- what is the role of ubiquinone and cytochrome c?
- how much ATP is created?
- cristae (inner membrane of mitochondria) or prokaryote plasma membrane
- transfer of electrons from soluble redox coenzymes
(NADH or FADH2) onto membrane-bound electron acceptors; electrons move down “chain” until it reaches the final acceptor: O2; creates a proton gradient (PE) - ubiquinone and cytochrome c: shuffle electrons between molecular complexes
- 25
Explain step 4 part 2 of cellular respiration: oxidative phosphorlyation
- define: chemiosmosis
- proton gradient drives the synthesis of ATP
- see google doc
- chemiosmosis: movement of ions across a semipermeable membrane according to electrochemical gradient
Why is oxygen the final electron acceptor? What happens in cellular respiration if no oxygen is available?
- larger change in PE than other substrates
- only substrate level phosphorylation occurs and we need to regenerate NAD+
Explain fermentation and how it occurs in humans and yeast
- extraction of energy from carbs in the absence of respiration (anaerobic)
- humans: glycolysis ends at pyruvate and is reduced to lactate to regenerate NAD+
- yeast: glycolysis ends at pyruvate which is decarboxylated and reduced to alcohol
