Unit 3: Cellular Energetics Flashcards

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1
Q

enzymes

A

biological catalysts made of proteins with 3D tertiary structure specific to their function

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2
Q

ribozymes

A

biological catalysts made of RNA

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3
Q

active site

A

interacts with substrate; shape and charge of active site must match substrate to interact

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4
Q

substrate

A

reactant of enzyme; specific to shape and charge of active site

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5
Q

enzymes catalyze reactions most efficiently at…

A

optimum temperatures and pHs that are specific to the enzyme

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6
Q

if the temperature in the environment is too low…

A

the rate of collisions between the enzyme and its substrate will be reduced, slowing the reaction

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7
Q

if the temperature in the environment is too high…

A

bonds that hold the enzyme together may be disrupted, and the enzyme’s shape can be altered

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8
Q

a pH too far from optimum can…

A

disrupt bonds in the enzyme and result in a change in its tertiary structure

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9
Q

denaturation

A

change to an enzyme’s structure, which can limit the enzyme’s ability to catalyze chemical reactions; this can sometimes be reversed when optimum conditions are reached

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10
Q

competitive inhibitors

A
  • similar in shape to substrates and compete with them for the active site of an enzyme
  • competition lowers the rate of enzyme-catalyzed reactions
  • the effect of competitive inhibitors can be diluted by adding higher concentrations of substrate so that the substrates can outcompete the inhibitors
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11
Q

noncompetitive (allosteric) inhibitors

A
  • bind to the allosteric site of an enzyme
  • binding changes the shape of the enzyme, affecting its function
  • adding higher concentrations of substrate does not affect the actions of a noncompetitive inhibitor
  • function in feedback mechanisms, adjusting the rate of chemical reactions in the cell to suit changing environmental conditions
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12
Q

cofactors

A

inorganic molecules that increase the efficiency of enzyme-catalyzed reactions by binding to active site or substrate to enhance the binding of the substrate to the active site

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13
Q

coenzymes

A

organic molecules that increase the efficiency of enzyme-catalyzed reactions by binding to active site or substrate to enhance the binding of the substrate to the active site

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14
Q

endergonic reactions

A

products with higher free energy level than its reactants; considered energetically unfavorable

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15
Q

exergonic reactions

A

products with lower free energy level than its reactants; considered energetically favorable

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16
Q

activation energy

A

energy used to start a reaction; difference between energy level of the reactants and the transition state of the reaction

17
Q

higher activation energies result in….

A

slower chemical reactions

18
Q

lower activation energies allow chemical reactions to…

A

proceed at a faster rate

19
Q

enzymes speed up chemical reactions by…

A

lowering the activation energy of the reaction

20
Q

how do enzymes lower the activation energy of a reaction?

A

1) bringing substrates together in the proper orientation for a reaction to occur
2) destabilizing chemical bonds in the substrate by bending the substrate
3) forming temporary ionic or covalent bonds with the substreate

21
Q

enzymes cannot…

A

change an endergonic (energetically unfavorable) reaction into an exergonic (energetically favorable) reaction

22
Q

energy input into the cell must be _________ than the energy requirements of the cell to maintain life

A

greater

23
Q

energy coupling

A

combination of endergonic and exergonic reactions that occur in multiple steps to allow for controlled transfer of energy between molecules to increase efficiency; coupling allows energy released in exergonic reaction to “drive” the endergonic reaction; ex. exergonic breakdown of ATP into ADP releases more than enough energy to power formation of sucrose from glucose and fructose

24
Q

photosynthesis

A

carbon atoms from carbon dioxide gain hydrogen atoms and the oxygen atoms in water lose hydrogen atoms; consists of light-dependent and light-independent reactions

25
Q

light-dependent reactions

A

use energy from sunlight to split water, producing oxygen gas, protons, and high-energy electrons; the oxygen gas is released into the atmosphere and the protons and high-energy elections are used to power the production of ATP and NADPH, which are then sent to the light-independent reactions

26
Q

light-independent reactions

A

use ATP and NADPH from light-dependent reactions, along with carbon dioxide, to produce sugars; then, they send ADP, P, and NADP+ back to the light-dependent reactions so photosynthesis can continue

27
Q

in plants, light-independent reactions take place in the…

A

stroma

28
Q

in plants, light-dependent reactions take place in the…

A

thylakoid membrane

29
Q

in prokaryotes, light-dependent reactions take place in the…

A

plasma membrane

30
Q

in prokaryotes, light-independent reactions take place in the…

A

cytosol

31
Q

phosphorylation

A
  • in light-dependent reactions, light energy is used to drive ATP production
  • light energy excites electrons in the chloroplast to higher energy levels, releasing energy
  • at the end of the light-dependent reactions, NADP+ accepts these electrons, forming NADPH, which reduces power for the light-independent rections
32
Q

chlorophyll

A

light-absorbing pigment that captures the energy of photons from the sun; primary light-absorbing pigment in photosynthesis; found in PSI and PSII

33
Q

photosystems

A

composed of proteins, chlorophyll, and other light-absorbing pigments called accessory pigments; PSI and PSII contain different types of chlorophyll that absorb the most light energy at different wavelengths; located in the thylakoid membrane of the chloroplast and are connected by an electron transport chain

34
Q

photolysis

A