Lecture 9: Energy and Enzymes (start of final exam material) Flashcards Preview

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Flashcards in Lecture 9: Energy and Enzymes (start of final exam material) Deck (31)
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1
Q

What are the 5 important functions energy is used for?

A
  • movement
  • chemical reactions
  • temperature control
  • nerve signals
  • cell division/ reproduction
2
Q

What is the difference between kinetic energy and potential energy

A
  • kinetic: active motion energy

- potential: stored energy

3
Q

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?
A
  • highest PE: non polar bonds (equal sharing of electrons and long weak bonds) vs lowest PE: polar bonds
  • the products have a lower PE
4
Q

Explain the first law in thermodynamics

A
  • energy in = energy out
5
Q

Write out the chemical breakdown of glucose

A
  • C6H12O6 + 6O2 6CO2 + 6H2O + 2800kJ
6
Q

What is enthalpy (H)?

A
  • the total energy in a molecule; most of it is stored potential energy
7
Q

Explain the change in enthalpy in an:

  • exothermic reaction
  • endothermic reaction
A
  • exothermic: change in enthalpy is NEGATIVE

- endothermic: change in enthalpy is POSITIVE

8
Q

Define: entropy (s)

A
  • amount of disorder
9
Q

What is the Gibbs free energy equation? State the whole equation.

A

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

10
Q

Explain the change in entropy in the chemical breakdown of glucose

A
  • entropy increases because more disorder occurs
11
Q

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?
A
  • delta G is negative and the reaction is exergonic and spontaneous
  • delta G is positive and the reaction is endergonic and non spontaneous
12
Q

define: exergonic and endergonic reactions;

- what drives endergonic reactions?

A

exergonic: reaction that releases energy
endergonic: reaction that absorbs energy; driven by ATP

13
Q

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
A
  • 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
14
Q

Draw the hydrolysis reaction of ATP and the coupled reaction diagram

A
  • see google doc
15
Q

explain the metabolic pathway

A
  • reactions are sequential (A–>B–>C–>D)
16
Q

define: oxidation and reduction

A
  • oxidation: loss of electrons

- reduction: gain of electrons

17
Q

write out the oxidation of glucose reaction

A
  • see google doc
18
Q

Fill in the blank: redox reactions often involve electron _____ such as _____ and ______. Both of these transfer __ electrons

A
  • carriers
  • F. A. D.
  • NAD+
  • 2
19
Q

Glucose

  • stored as? (3)
  • function
  • what is glycolysis?
A
  • 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))
20
Q

define: catabolism and anabolism

A

catabolism: breakdown of complex molecules
anabolism: creation of complex molecules (ex: making glucose)

21
Q

Give the photosynthesis equation

A
  • see google doc
22
Q

Write out the metabolic pathway

A
  • see google doc
23
Q

what process produces ATP? How is this accomplished?

A
  • cellular respiration; transfer of electrons
24
Q

What are the 4 steps/stages of cellular respiration?

A
  • glycolysis
  • pyruvate processing
  • citric acid cycle
  • electron transport and oxidative phosphorylation
25
Q

Explain step 1 of cellular respiration: glycolysis

  • location
  • what is oxidized and reduced
  • what goes in
  • what comes out
  • equation
  • anaerobic or aerobic?
A
  • 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
26
Q

Explain step 2 of cellular respiration: pyruvate processing

  • location
  • what goes in
  • what comes out
  • equation
A
  • 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
27
Q

Explain step 3 of cellular respiration: citric acid cycle

  • location
  • for every glucose molecule, how many times does the cycle run?
  • equation
A
  • matrix
  • twice
    2 acetyl-CoA + 6NAD+ + 2FAD + 2ADP –> 4CO2 + 6NADH + 2FADH2 + 2ATP + 2CoA
28
Q

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?
A
  • 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
29
Q

Explain step 4 part 2 of cellular respiration: oxidative phosphorlyation
- define: chemiosmosis

A
  • proton gradient drives the synthesis of ATP
  • see google doc
  • chemiosmosis: movement of ions across a semipermeable membrane according to electrochemical gradient
30
Q

Why is oxygen the final electron acceptor? What happens in cellular respiration if no oxygen is available?

A
  • larger change in PE than other substrates

- only substrate level phosphorylation occurs and we need to regenerate NAD+

31
Q

Explain fermentation and how it occurs in humans and yeast

A
  • 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