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BIOL 107 > Chapter 4: How Cells Obtain Energy > Flashcards

Chapter 4: How Cells Obtain Energy Flashcards

1
Q

define energy

A
  • the capacity to cause change
  • ability to do work
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2
Q

define bioenergetics

A

the concept of energy flow through living systems

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3
Q

define metabolism

A
  • all chemical reactions that take place in cells
  • includes reactions using energy and reactions releasing energy
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4
Q

define anabolic pathways

A
  • require energy
  • synthesize complex molecules
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5
Q

define catabolic pathways

A
  • release energy
  • break down complex molecules
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6
Q

define potential energy

A
  • stored energy
  • energy matter has because of its structure
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7
Q

define kinetic energy

A
  • energy of objects in motion
  • movement of objects
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8
Q

define chemical energy

A
  • energy in the bonds that hold atoms of molecules together
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9
Q

define free energy

A
  • G
  • usable energy
  • energy from a chemical reaction that is available to do work AFTER we account for entropy
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10
Q

define entropy

A
  • energy lost to an unusable form such as heat
  • measure of disorder or randomness of the universe
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11
Q

define exergonic

A
  • energy is released; bonds are broken
  • tied to catabolic reactions
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12
Q

define endergonic

A
  • energy is required; bonds are made
  • tied to anabolic reactions
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13
Q

define system

A

matter under study

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14
Q

define surroundings

A

everything outside of the system

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15
Q

define open system/closed system

A
  • open: matter and energy can be exchanged with surroundings
  • closed: energy can be exchanged but not matter
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16
Q

define activation energy

A

initial energy required for a reaction to start

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17
Q

define enzyme

A

molecules (typically proteins) that catalyze (speed up) biochemical reactions

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18
Q

define active site

A
  • location on an enzyme where the substrates bind
  • highly specific so only certain substrates can attach
  • influenced by environment (temp, pH, salt concentration)
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19
Q

define allosteric site

A
  • location on enzyme where substrate doesn’t bind
  • any site that is not active site
  • where cofactors or coenzymes bind
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20
Q

define coenzymes

A
  • organic
  • molecules that promote or inhibit enzyme function
  • can bind to active site or other site
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21
Q

define cofactors

A
  • inorganic
  • molecules that promote or inhibit enzyme function
  • can bind to active site or other site
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22
Q

define competitive inhibition

A
  • molecules similar to substrate bind to the active site
  • block substrate from binding
  • “competes” with substrate for active site
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23
Q

define non-competitive inhibition

A
  • aka allosteric inhibition
  • molecule binds to allosteric site
  • changes shape of enzyme so substrate can’t attach
  • inhibits substrate binding
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24
Q

define feedback inhibition

A
  • enzymes activity inhibited by enzyme’s end product
  • end product attached to enzyme and inhibits more reactions from occurring
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25
what requires energy
- everything - every task performed by living organisms needs energy - every living cell constantly uses energy
26
where does energy come from
sun
27
what energy source sustains most of earth's life forms
sun
28
chemical formula for photosynthesis
6CO2 + 6H2O + energy --> C6H12O6 + 6O2
29
chemical formula for cellular respiration
C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy
30
how do cells use energy
building and breaking molecules
31
what does an organisms metabolism do
transforms matter and energy
32
what is an organisms metabolism subject to
the laws of physics
33
define metabolic pathways
- many biochemical reactions that all require energy transformations - includes many steps in each pathway - very complex - every step is related
34
what is each step in a metabolic pathway
- separate chemical reaction - catalyzed by a specific enzyme
35
what are the two types of metabolic pathways
- anabolic - catabolic
36
examples of anabolic pathways
- photosynthesis - gluconeogenesis - protein synthesis
37
example of catabolic pathways
- glycolysis
38
what is fundamental to all metabolic processes
energy
39
what are the two main types of energy
- potential energy - kinetic energy
40
what type of energy is chemical energy
potential energy
41
examples of potential energy
- membrane potential (sodium potassium pump) - chemical energy stored in molecular structures (bonds of glucose)
42
examples of kinetic energy
- thermal energy: random movement of atoms or molecules
43
can energy be converted from one form to another
- yes - potential and kinetic converted both ways
44
what type of energy do living cells depend on
- chemical energy - structural energy stored in bonds
45
what happens when chemical reactions break energy-storing bonds
- release of energy - catabolic pathway
46
what is ^G (triangle G; change in G) and what does it determine
- free energy change of a reaction - determines whether a reaction happens spontaneously or non-spontaneously - total energy - energy lost - energy of products - energy of reactants
47
what are the two major types of reaction
- exergonic - endergonic
48
are exergonic reactions spontaneous or non-spontaneous and why
- spontaneous - no additional energy is required
49
are endergonic reactions spontaneous or non-spontaneous and why
- non-spontaneous - additional energy is required
50
what happens to free energy during exergonic reactions
- free energy decreases - products have less free energy than the reactants - ^G is negative (low energy products - high energy reactants)
51
what happens to free energy during endergonic reactions
- free energy increases - products have more free energy than the reactants - ^G is positive (high energy products - low energy reactants)
52
which type of reaction increases the stability of the system
exergonic
53
in which type of reaction is the energy of the reactants greater than the energy of the products
- exergonic - energy exits as bonds are broken
54
in which type of reaction is the energy of the reactants less than the energy of the products
- endergonic - energy enters as bonds are created
55
define isolated system
cannot exchange energy or matter with surroundings
56
define thermodynamics
- study of energy and energy transformations between a system and its surroundings - governed by the laws of thermodynamics
57
what is the 1st law of thermodynamics
- total amount of energy in the universe does not change - energy cannot be created or destroyed, only transferred or transformed
58
what is the 2nd law of thermodynamics
- all energy transfers or transformations are never completely efficient; some energy is always lost - conversion of some energy to an unusable form, usually heat
59
what two things does every energy transfer do
- increases entropy of the universe - reduces amount of usable energy available to do work
60
what is a system with high entropy
- disorganized - low available energy
61
what is a system with low entropy
- organized - high available energy
62
what happens when entropy in a system is decreased
entropy in the surroundings is increased
63
how do living organisms increase entropy in the universe
- high ordered/organized - require constant energy input to maintain order within the system
64
review of catabolic process
- breaks down molecules - exergonic: releases energy - ^G is negative - spontaneous - more stable than anabolic - ex: glycolysis
65
review of anabolic process
- builds up molecules - endergonic: requires energy - ^G is positive - non-spontaneous - less stable than catabolic - ex: photosynthesis
66
what reactions require energy to begin
- every single reaction - exergonic and endergonic
67
what helps reactants reach their transition state
activation energy
68
why is the transition state important
- causes reactions to becomes unstable - allows bonds to be broken or made
69
what is the main source of activation energy in the cell
heat energy from surroundings of the system
70
what do enzymes do
- lower activation energy; makes it easier for reaction to take place - bind to reactant molecules and hold them in a way that makes it easier to break or form bonds
71
do enzymes change the overall energy released during a reaction
- no - energy released in the same with or without the enzyme
72
do enzymes change whether a reaction is exergonic or endergonic
no
73
do enzymes get used up
- no - remain unchanged - can catalyze multiple of the same reactions
74
what differentiates enzymes from reactants
enzymes don't get used up like reactants
75
define substrate
- chemical reactants to which an enzyme binds - single substrate broken down or two substrates joined
76
how do enzymes lower activation energy
- bring multiple substrates together in optimal orientation for reaction - optimal environment within active site for reaction to occur - compromise bond structures
77
what is enzyme activity controlled by
- environmental factors (temp, pH, salt concentration) - coenzymes and cofactors
78
what is the difference between coenzymes and cofactors
- coenzymes are organic molecules - cofactors are inorganic molecules
79
can substrates react without enzymes
- yes - less efficiently
80
define allosteric activation
- molecule binds to allosteric site - changes shape of enzyme (activates) so substrate can attach
81
what are the benefits of feedback inhibition
- stops cell from continuing reaction when enough of the end product has been made (more end product = more binding to enzymes = less enzymes catalyzing reactions) - uses less resources when not needed - conserves space in cell
82
define adenosine triphosphate (ATP)
- composed of adenosine, one ribose sugar, and 3 phosphate groups - primary energy supplying molecule of the cell
83
define cellular respiration
process within a cell where energy is made
84
define glycolysis
- breakdown of glucose - creates pyruvate, energy, and NADH
85
define NAD+/NADH
- coenzymes that act as electron carriers to the electron transport chain - NAD+: oxidized form, fewest electrons - NADH: reduced form, most electrons
86
define glucose
- 6 C simple sugar - used for energy
87
define pyruvate
- 3 C sugar - product of glycolysis (2 for each glucose molecule) - go to the citric acid cycle
88
where is energy stored in ATP
bonds between phosphate groups
89
chemical formula for glycolysis
- glucose + oxygen --> carbon dioxide + water + energy - C6H12O6 +6O2 --> 6CO2 + 6H2O + energy
90
what happens when an H2O molecule is added to ATP
- hydrolysis - breaks bond; becomes ADP - releases energy - catabolic/exergonic
91
what happens when an H2O molecule is removed from ADP
- creates bond; becomes ATP - requires energy - anabolic/endergonic
92
what are the two phases of glycolysis
- 1st: energy investment phase - 2nd: energy payoff phase
93
explain the energy investment phase of glycolysis
- start with glucose (6 C sugar) - glucose phosphorylated twice using ATP - fructose-1 6-biphosphate is made (6 C and 2 P) - converted into two glyceraldehyde-3-P (3 C and 1 P)
94
what is the purpose of phosphorylating glucose in the energy investment phase of glycolysis
provides activation energy
95
what is the cost of the energy investment phase of glycolysis
2 ATP
96
explain the energy payoff phase of glycolysis
- glyceraldehyde-3-P gets electron removed with NAD+ which creates NADH - 2 ATP are made from 2 ADP - ends with pyruvate (3 C sugar)
97
how many times does the energy payoff phase of glycolysis happen for each glucose molecule
twice
98
how many ATP are created from the energy payoff phase of glycolysis
4 ATP
99
what is the yield/products of glycolysis
- 4 ATP (net yield 2) - 2 pyruvate - 2 NADH
100
what is the net yield of ATP in glycolysis and why
- net yield is 2 ATP - 2 ATP are used in the energy investment phase - 4 ATP are made in the energy payoff phase - 4-2=2 ATP net yield
101
what is a waste product of glycolysis
H2O
102
what coenzymes are similar to NAD+ and NADH
- FAD+ - FADH2
103
what does NAD stand for
nicotinamide adenine dinucleotide
104
where does glycolysis take place in the cell
cytosol
105
define citric acid cycle/krebs cycle
- occurs after glycolysis - gathers electrons for the electron transport chain
106
define oxidation of pyruvate
- pyruvate oxidized to acetyl CoA - pyruvate attaches to CoA and NAD+ takes an electron - prepares pyruvate for citric acid cycle
107
define acetyl CoA
- 2 C attached to coenzyme A (CoA) - made from pyruvate during oxidation of pyruvate
108
define oxaloacetate
- anchor of the citric acid cycle - 4 C - combines with acetyl CoA to create citrate at the beginning of the cycle
109
define citrate
- 6 C - created from acetyl CoA and oxaloacetate at the beginning of the citric acid cycle
110
define FAD/FADH2
- similar to NAD+/NADH - FAD: few electrons, can accept - FADH2: most electrons, carries electrons
111
define oxidative phosphorylation
- final step of cellular respiration - when oxygen is used - composed of electron transport chain and chemiosmosis
112
define electron transport chain
- electrons passed from one molecule to another - releases energy that is used to form electrochemical gradient; H+ gradient
113
define chemiosmosis
- energy stored in electrochemical gradient is used to generate ATP - process where ATP is actually made
114
define ATP synthase
- protein/enzyme in inner mitochondrial membrane - used in chemiosmosis to make ATP - rotates
115
what happens to the pyruvate produced from glycolysis
- enters the citric acid cycle - converted to acetyl CoA by being oxidized and attached to coenzyme A (CoA)
116
what are the products of oxidation of pyruvate
- acetyl CoA - carbon dioxide (waste product) - NADH
117
where does oxidation of pyruvate take palce
- mitochondria in eukaryotes - cytosol in prokaryotes
118
how many times does the citric acid cycle happen for 1 glucose molecule
- twice - 2 pyruvate made from glycolysis and each undergoes citric acid cycle
119
where does the citric acid cycle take place
- matrix of mitochondria in eukaryotes - cytosol in prokaryotes
120
does the citric acid cycle produce a lot of ATP directly
- no - purpose is to gather electrons for electron transport chain where ATP is mostly made
121
does the citric acid cycle require oxygen
- requires oxygen - doesn't directly consume it
122
what happens to all of the organic carbon from acetyl CoA in the citric acid cycle
- given off as CO2
123
what is the input of the citric acid cycle (for 2 turns, 1 glucose molecule)
- 2 acetyl CoA - 2 oxaloacetate - 6 NAD+ - 2 FAD
124
what is the output/product of the citric acid cycle (for 2 turns, 1 glucose molecule)
- 4 CO2 - 6 NADH - 2 FADH2 - 2 ATP/GTP - H2O
125
when do cells use oxygen in cellular respiration
oxidative phosphorylation
126
why is oxygen important in the electron transport chain
- accepts electrons from NADH - replenishes NAD+ for cellular respiration to continue
127
where does the electron transport chain take place
- embedded proteins in the inner mitochondrial membrane in eukaryotes - plasma membrane in prokaryotes
128
how many proteins are in the inner mitochondrial membrane for the electron transport chain
4
129
explain the steps of the electron transport chain
- NADH from the citric acid cycle drops of electron at first embedded protein (C1) - H+ moves across C1 into the intermembrane space of mitochondria - electron moves through embedded protein (C1 to C2 to C3 to C4) - electron moves back to mitochondrial matrix and is accepted by O2 - H+ attaches and H2O is formed
130
which embedded proteins does H+ move from the matrix to the intermembrane space during the electron transport chain
C1, C3, C4
131
explain the steps of chemiosmosis
- H+ moves from intermembrane space through ATP synthase and into the mitochondrial matrix - energy from H+ combines ADP and P to make ATP
132
why is the electron transport chain important
- regenerates electron carriers: NADH and FADH2 turn into NAD+ and FAD which can go back to glycolysis and the citric acid cycle - creates proton gradient: stored form of energy used to make ATP
133
how much ATP is generated by cellular respiration for 1 glucose molecule and what stages does it come from
- 36-38 total - 2 from glycolysis - 2 from citric acid cycle - 32-34 (majority) from oxidative phosphorylation (ETC and chemiosmosis)
134
glycolysis: purpose, location, input, products, waste
- purpose: reduce glucose to pyruvate, produce NADH for ETC - location: cytosol - input: glucose - products: 2 ATP, 2 pyruvate, 2 NADH - waste: H2O
135
pyruvate oxidation: purpose, location, input, products, waste
- purpose: produce acetyl CoA for CAC, produce NADH for ETC - location: mitochondrial matrix - input: pyruvate - products: 1 NADH, 1 H+, Acetyl CoA - waste: CO2
136
citric acid cycle: purpose, location, input, products, waste
- purpose: NADH and FADH2 for ETC - location: mitochondrial matrix - input: acetyl CoA - products: 6 NADH, 2 FADH2, 2 ATP - waste: 2 CO2
137
oxidative phosphorylation: purpose, location, input, products, waste
- purpose: ATP production - location: mitochondrial inner membrane - input: NADH and FADH2 - products: 36-38 ATP, heat - waste: H2O, heat
138
define aerobic cellular respiration
- electrons transported by NADH or FADH2 to ETC - oxygen accepts electrons - replenishes NAD+ and FAD for use in glycolysis
139
define anaerobic cellular respiration
- use of inorganic molecules as final electron receptor - sulfate, nitrate, sulfur, etc
140
define fermentation
- use of organic molecules as final electron receptor - form of anaerobic cellular respiration - consists of glycolysis and NAD+ regeneration pathway - catabolic pathway
141
define lactic acid fermentation
- pyruvate converted to lactate to regenerate NAD+ - directly regenerates NAD+ - no CO2 released
142
define alcohol fermentation
- pyruvate converted to ethanol (EtOH) - releases CO2 - 2 steps: pyruvate to acetaldehyde to ethanol
143
why is oxygen a good final electron acceptor
highly electronegative
144
what kinds of organisms use anaerobic cellular respiration
prokaryotes (bacteria and archaea) that live in low-oxygen environments
145
why is glycolysis known as the universal pathway
all cells undergo glycolysis whether they use aerobic or anaerobic cellular respiration
146
what point of cellular respiration is the fork in the road
- pyruvate - right after glycolysis
147
is fermentation complete or partial breakdown of glucose
partial
148
where does fermentation take place
cytoplasm
149
does fermentation produce a large or small amount of ATP
small amount
150
what organisms undergo lactic acid fermentation
- animals - bacteria - fungi - protists
151
what type of animal cells perform lactic acid fermentation
- muscle cells: when O2 is limited (exercising) - mammalian RBCs: have no mitochondria for aerobic respiration
152
what is the final electron acceptor in lactic acid fermentation
pyruvate
153
does alcohol fermentation occur in human cells
no
154
where does alcohol fermentation mainly occur
yeast
155
what is the final electron acceptor in alcohol fermentation
acetaldehyde
156
what are the main differences between lactic acid and alcohol fermentation
- lactic acid: in human cells, 1 step, pyruvate in final electron acceptor, no CO2 released - alcohol: not in human cells, 2 steps, acetaldehyde is final electron receptor, CO2 released
157
does increased temperature lower activation energy required for a reaction
- no - heat is the source of activation energy
158
in what type of reaction is free energy increased, stability decreased, and has a positive ^G
- endergonic - non-spontaneous
159
in what type of reaction is free energy decreased, stability increased, and has a negative ^G
- exergonic - spontaneous
160
how will a healthy individual’s ATP production change during an eight-hour fast
- no significant change - respiration continues to function - body stores glycogen and fats for energy
161
which state of matter has the lowest entropy
- solid - less movement of molecules
162
ATP drives endergonic reactions by the process of _________, which is the _________________
phosphorylation, transferring a phosphate to other molecules
163
what organisms undergo aerobic cellular respiration
- animals - plants - fungi - bacteria
164
during cellular respiration, what happens to the 6 carbons in glucose
all are completely oxidized to CO2
165
which is oxidized and which is reduced: NAD+, NADH
- NAD+ is oxidized - NADH is reduced

BIOL 107 (18 decks)

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