Chapter 5: Cell Metabolism Flashcards
(105 cards)
1
Q
Fuels
A
Carbon-based molecules whose stored energy can be released for use
2
Q
What is the most common fuel in organisms?
A
Glucose
3
Q
How are metabolic pathways regulated?
A
allosteric mechanisms
4
Q
Cellular Respiration Equation
A
C6H12O6 + 6O2 -> 6CO2 + 6H2O + free energy
5
Q
How much free energy is involved in cellular respiration
A
-686 kcal/mol
6
Q
Where is free energy from cellular respiration involved?
A
32ADP +32Pi + free energy -> 32 ATP
7
Q
Synthesis of ATP is ________
A
endergonic
8
Q
In synthesis of ATP, ________ provides the energy
A
glucose oxidation
9
Q
Energy released by exergonic reactions is stored in the bonds of _____
A
ATP
10
Q
Synthesis of ATP from ADP and Pi _______ energy
A
requires
11
Q
Hydrolysis of ATP to ADP and Pi _____ energy
A
releases
12
Q
what is the energy currency of the cell?
A
ATP
13
Q
Glycolysis
A
glucose is converted to pyruvate
14
Q
Cellular respiration
A
aerobic and converts pyruvate into H20 and CO2; leads to synthesis of a lot of ATP
15
Q
Fermentation
A
anaerobic and converts pyruvate into lactic acid or ethanol + CO2; produces a little ATP
16
Q
Cellular respiration occurs ______ oxygen present and is ______; Fermentation occurs ______ oxygen present and is _____
A
with, aerobic
without, anaerobic
17
Q
Cellular respiration has ___ oxidation; fermentation has _____ oxidation
A
complete
incomplete
18
Q
Waste products of Cellular Respiration
A
H2O, CO2
19
Q
Waste products of Fermentation
A
lactic acid or ethanol, CO2
20
Q
Cellular Respiration Net Energy Trapped per glucose
A
32 ATP
21
Q
Fermentation Net Energy Trapped per glucose
A
2 ATP
22
Q
All glucose oxidation reactions involve _________ reactions
A
electron transfer
23
Q
Reduction
A
gain of one or more electrons by an atom, ion, or molecule
24
Q
Oxidation
A
Loss of one or more electrons
25
oxidizing agent
the reactant that becomes reduced
26
reducing agent
the reactant that becomes oxidized
27
Redox: glucose is _____ and oxygen is _____. Explain?
oxidized
reduced
All the electrons in glucose are transferred to molecules of oxygen to form water
28
why does the oxidation of glucose occur in steps?
Energy from bonds of glucose is transferred, and it was all released in one step it would fry the cells
29
What are the functions of the two forms of NAD+
NAD+ (oxidized) revieves e- from glucose
NADH (reduced) carries e- from glucose to other molecules in the mitochondria, ultimately on to O2
30
Reaction Equation of the oxidation of NADH
NADH + H+ + (1/2)O2 -> NAD+ + H2O
31
Reaction Equation of the oxidation of NADH
NADH + H+ + (1/2)O2 -> NAD+ + H2O
32
Steps in Glycolysis and Cellular Respiration
Glucose to Pyruvate which is oxidized and enters the citric acid cycle, leaves through electron transport/ATP synthesis, expells waste of CO2 and H2O
33
Steps in Glycolysis and Fermentation
Glucose to pyruvate which goes through fermentation and expells lactate or alcohol
34
CH bonds have higher/lower free energy than CO bonds. Why?
Higher
CH bonds are weaker than CO bonds
35
Most oxidized/reduced has the highest free energy
reduced
36
Inputs and outputs of glycolysis
Inputs: glucose, 2 NAD+, 2 ADP + 2Pi
Outputs: 2 molecules of pyruvate, 2 NADH, 2 ATP
37
How many reactions are in glycolysis? Which require energy and which create energy?
10; 1-5 are energy investment, 6-10 are energy payout
38
Steps for glucose to pyruvate
A six-carbon sugar is cleaved into 2 three carbon sugars (glyceraldehyde 3-phosphate) which is then converted to pyruvate through substrate-level phosphorylation
39
What does pyruvate oxidation (decarboxylation) do? Where does it occur?
links glycolysis (in the cytoplasm) and the citric acid cycle (in mitochondria); occurs in the liquid mitochondrial matrix
40
Chemical formula for pyruvate breaking down
Pyruvate (3C) -> acetate (2C) + CO2
41
Characteristics of pyruvate breaking down to acetate
CO2 released as waste, NAD+ is reduced to NADH which captures the energy, some energy is stored by combining acetate and Coenzyme A (CoA) to form acetyl CoA
42
What is the citric acid cycle?
Eight reactions that begin with acetyl CoA; in a steady state, so the concentrations of the intermediates don't change
43
Inputs and Outputs of the Citric Acid cycle
Inputs: acetyl CoA, electron carriers NAD+ & FAD, GDP
Output: CO2, reduced electron carriers (NADH, FADH2), and GTP (which converts ADP to ATP)
44
Each glucose yields:
6 CO2
10 NADH
2 FADH2
4 ATP
45
Reduce electron carriers must be ______ to take part in the glycolysis and citric acid cycle again
reoxidized
46
What does oxidative phosphorylation involve
proteins and electron carrier molecules imbedded in the mitochondrial inner membrane
47
Electron Transport Chain (ETC)
e- from NADH & FADH2 pass through a respiratory chain of inner membrane carriers
48
What is the ETC made of
4 protein complexes, Ubiquinone, cytochrome
49
What is the final electron acceptor in the ETC
oxygen
50
T/F ETC (complexes I-IV) makes ATP
F
51
Chemiosmosis
Protons (H+) diffuse back into the mitochondria through ATP synthase, a channel protein
52
Where do protons accumulate? What does that create?
Protons accumulate in the intermembrane space which creates a charge difference across the membrane -- potential energy!
53
What does proton-motive force do?
drives protons back across the membrane where they move through the AATP synthase channel, providing energy to phosphorylate ADP
54
T/F ATP leaves the mitochondria once it is made, keeping the concentration high
F; ATP leaves the mitochondria once it is made, keeping the concentration LOW
55
How does ATP synthase work?
H+ flows from intermembrane space through synthase to matrix; this flow rotates the rotor, driving conformation changes in catalytic knob subunits; shape changes force condensation of ADP + Pi to create ATP
56
Lactic Acid Fermentation
-occurs in microorganisms, some muscle cells
-pyruvate is the electron acceptor and becomes reduced
-oxidizes NADH back to NAD+ so more glycolysis can occur
-2 lactate is the product, and no additional ATP is made
57
Reactants and products of lactic acid fermentation
reactants: glucose, 2 ADP, 2 Pi
products: 2 lactate, 2 ATP
58
Alcoholic Fermentation
-yeasts are some plant cells
-requires two enzymes to metabolize pyruvate to ethanol
-CO2 is a waste product
-The intermediate, acetaldehyde is reduced by NADH and H+ producing NAD+ and glycolysis continues
59
Reactants and Products of alcoholic fermentation
reactants: glucose, 2 ADP, 2Pi
products: 2 ethanol, 2 CO2, 2 ATP
60
T/F aerobic respiration captures all of the energy released by glucose oxidation but fermentation does not
F; neither aerobic respiration or fermentation capture all of the energy released by glucose oxidation
61
In catabolism/anabolism, breakdown products eventually enter the aerobic respiration pathways
catabolism
62
T/F Glucose is the only molecule that can be catabolized
F
63
What are catabolic pathways
Carbohydrates, lipids, proteins, nucleic acids
64
Carbohydrate catabolic pathway
polysaccharides --> monosaccharides
65
Lipid catabolic pathway
triglycerides --> glycerol and fatty acids --> acetyl CoA
66
Protein catabolic pathway
protiens --> amino acids --> molecules that enter glycolysis
67
nucleic acids catabolic pathway
nucelic acids --> nucleotides --> phosphate groups, bases, sugars
68
Anabolic pathways are often ____ of catabolic pathways
reversals
69
Gluconeogenesis
citric acid cycle and glycolysis intermediates are reduced to form glucose
70
Autotroph
an organism that is capable of living exclusively on inorganic materials, water, and some energy source such as sunlight
71
Heterotroph
organism that requires preformed organic molecules as food
72
Photosynthesis equation
6CO2 + 6H20 --> C6H12O6 +6O2
73
Is photosynthesis exergonic/endergonic? anabolic/catabolic?
endergonic, anabolic
74
What are two redox reactions in photosynthesis
CO2 is reduced to form carbohydrates
Water is oxidized to form oxygen
75
What is a light reaction?
Convert light energy to chemical energy as ATP and NADPH
76
Light-independent reactions
Use ATP and NADPH (from light reactions) plus CO2 to produce carbohydrates
77
The energy of light is ______ proportional to it's wavelength
inversely
78
Photons
Particles of light
79
What are the three things that can happen to a photon when it meets a molecules
scattered (bounces off)
transmitted (passed through)
absorbed (acquires the energy of the photon, the molecule goes from ground state to excited state)
80
T/F The color that we see is the light than an object does not absorb
T
81
What colors do plants absorb?
red and blue
82
What happens after a molecule is excited?
energy can be converted to heat, light, or passed to a nearby molecule by resonance energy transfer
83
Absorption spectrum
plot of wavelengths absorbed by a pigment
84
Action spectrum
a plot of biological activity as a function of exposure to varied wavelengths of light
85
T/F multiple pigments are used during photosynthesis
T; the use of several pigments to absorb light of different wavelengths will broaden the action spectrum
86
What are the main two pigments absorbing light for photosynthesis
Chlorophylls and carotenoids; are both quite nonpolar
87
Accessory pigments
absorb in red and blue regions, transfer the energy to chlorophyll -- cartenoids and phycobilins
88
What do Cilia and Flagella do?
move the cell
89
Antenna systems
light-harvesting systems in which pigments are arranged
90
What does a photosystem consist of
multiple antenna systems and their pigments; surrounds a reaction center
91
How does energy end up in the reaction center?
excitation energy passes from pigments that absorb short wavelengths to those that absorb longer wavelengths and end up in the reaction center
92
Key events of light reactions
- photosystem reaction center (Chl) absorbs a photon and becomes excited
-Chl donates an e- to an acceptor molecule (A)
-A is the first in a chain of electron carriers in the thylakoid membrane
- A final electron acceptor is NADP+ and becomes NADPH
93
Photosystem I
-light energy reduces NADP+ to NADPH
- Reaction center has P700 chlorophyll a molecules (absorb in the 700 nm range)
94
Photosystem II
-light energy oxidizes water --> O2, H+ and electrons
- reaction center has P680 chlorophyll a molecules (Absorb at 680 nm
95
Noncyclic electron transport
produces NADPH and ATP; light energy is used to oxidize water --> O2, H+, and electrons
96
Cyclic electron transport
produces ATP only
97
What is the process of noncyclic electron transport?
light energy oxidizes water, CHI+ is unstable due to excitation by light and takes electrons from water, splitting the water molecule
98
Process of cyclic electron transport
An e- from an excited chlorophyll molecule cycles back to the same chlorophyll molecule; begins and ends in PS 1
99
What do non-cyclic and cyclic electron transport drive?
photophosphorylation
100
Use of light reaction products to synthesize carbohydrates Steps
- CO2 fixation & Calvin Cycle
- CO2 is reduced to carbohydrates
- Enzymes in the stroma use the energy in ATP and NADPH to reduce CO2
101
Steps of the Calvin Cycle
- CO2 is first added to an acceptor molecule
- the 6C compound breaks into two molecules of 3PG
102
What enzyme catalyzes the intermediate formation in the calvin cycle?
rubisco
103
here does the Calvin cycle take place?
the stroma
104
What are the two parts of photosynthesis and their roles
Light reactions: collect light energy, oxidize water and store energy as ATP and NADPH
105
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