Exam 2 Flashcards
1
Q
CH6
Energy
A
The capacity to do work
2
Q
CH6
Types of Energy (2)
A
Kinetic: the energy of motion
Potential: stored energy
3
Q
CH6
What is the form of energy that most other forms can be converted to?
A
Heat energy
4
Q
CH6
What is heat energy measured in?
A
Calories
5
Q
CH6
Calories
A
One calorie = heat energy required to raise the temp of 1 g of water 1 degree C
1 kilocalorie (kcal) = 1000 calories = 1 food calorie
6
Q
CH6
How is potential energy, stored in chemical bonds, transferred from one molecule to another?
A
They are transferred by way of electrons
7
Q
CH6
Redox Reactions
A
First, remember that redox comes from reduction-oxidation (reduction-gaining an electron; oxidation-losing an electron)
This is both oxidation and reduction occurring at the same time
These reactions are always coupled to one another
8
Q
CH6
First Law of Thermodynamics
A
Energy cannot be created or destroyed, it can only be converted from one form to another
Ex: sunlight energy –> chemical energy
(through photosynthesis)
9
Q
CH6
Second Law of Thermodynamics
A
Without external energy input, all systems naturally become more disorderly over time
Ex: think of a room becoming messy over time-this seems to require zero energy, whereas cleaning it (making it orderly) requires work
10
Q
CH6
Entropy
A
Disorder
Written as “S”
11
Q
CH6
Free Energy
A
The energy available to do work
Written as “G” (Gibb’s Free Energy)
Free energy = Enthalpy – (Temp X Entropy)
G = H - TS
12
Q
CH6
Enthalpy
A
Energy contained in a molecule’s chemical bonds
13
Q
CH6
What effect do chemical reactions have on free energy?
A
Chemical reactions create changes in free energy
ΔG = ΔH - T ΔS
(Δ is the symbol “delta,” it represents a change)
14
Q
CH6
In a chemical reaction, what happens when the products have MORE free energy than the reactants?
A
ΔG is positive (the change in free energy is a positive change); energy is gained
15
Q
CH6
In a chemical reaction, what happens when the products contain LESS free energy than the reactants?
A
ΔG is negative (the change in free energy is negative); energy is lost
16
Q
CH6
Endergonic Reaction
A
Requires free energy (positive ΔG)
An “energy requiring” reaction
*ender/enter ~ energy enters
17
Q
CH6
Exergonic Reaction
A
releases free energy (negative ΔG)
An “energy yielding” reaction
*exo/exit ~ energy leaves
18
Q
CH6
Activation Energy
A
Energy needed to get a reaction started by destabilizing chemical bonds
*even exergonic reactions require some energy just to get started
19
Q
CH6
Catalysts
A
Substances that lower the activation energy of a reaction
20
Q
CH6
ATP
A
Adenosine triphosphate, the energy currency of the cells
Structure:
ribose (a 5-C sugar)
adenine (a nucleotide)
three phosphates
21
Q
CH6
Where does ATP store energy?
A
In its phosphate bonds
22
Q
CH6
Phosphates are highly _____
A
Phosphates are highly electronegative
23
Q
CH6
What happens because of the electronegativity in phosphates? (What are some characteristics/properties they have due to their electronegativity?) (3)
A
They naturally repel each other
Much energy is required to keep them bound to each other
Much energy is released when the P bonds are broken
24
Q
CH6
What happens when the bond between phosphates is broken by hydrolysis?
A
*First of all, hydrolysis is the chemical breakdown of a compound due to its reaction with water
When this occurs, energy is released
ATP = ADP + Pi
25
CH6
| ATP = ADP + Pi
ATP: adenosine triphosphate
ADP: adenosine diphosphate
Pi: inorganic phosphate
26
CH6
| When ATP is hydrolyzed, energy is released. What can this energy then do?
This energy can fuel endergonic reactions
27
CH6
| Energy released from exergonic reactions can be used to produce ______
ATP from ADP + Pi
28
CH6
| What do enzymes do?
Enzymes catalyse biological reactions
29
CH6
| What are enzymes' properties/characteristics? (4)
Nearly all are proteins (however, not all are proteins; certain reactions involving RNA molecules are catalyzed by the RNA itself)
Lower the activation energy required for a reaction
Are not permanently changed or consumed by the reaction
Temporary enzyme-substrate complexes are formed during reactions
30
CH6
| Enzymes interact with _____
Enzymes interact with substrates
31
CH6
| Substrate
A molecule that will undergo a reaction
Reactants
32
CH6
| Active Site
Region of the enzyme that binds to the substrate
33
CH6
| What does "induced fit" mean?
An "induced fit" is what occurs when the substrate forces the enzyme to change shape in order to bind together
34
CH6
| Ribozymes
RNA with enzymatic abilities
Ex: the ribosome is a ribozyme
35
CH6
| Enzyme function is affected by _______
its environment
36
CH6
| Some changes in an enzyme's environment that may affect its function include: (4)
pH
Temperature
Concentrations of reactants and products
Regulatory molecules (co-enzymes or co-factors)
*the effects of these changes may be positive or negative
37
CH6
| What effect does temperature have on enzymes?
Up to the optimum temperature, enzyme activity increases with rising temperature. Beyond the optimum temperature, the enzymes will become denatured (their function is destroyed).
38
CH6
| What pH do enzymes have their optimal shape and charge at?
The preferred pH is anywhere from 6 to 8
39
CH6
| Inhibitors
Molecules that bind to enzymes and decrease their activity
40
CH6
| Types of Inhibitors
Competitive inhibitors: compete with the substrate for binding to the active site
Noncompetitive inhibitors: bind to sites other than the enzyme’s active site. An example is an allosteric inhibitor
41
CH6
| Allosteric Enzymes
Exist in either an active or inactive state and possess an allosteric site where molecules other than the substrate bind
Allosteric inhibitors bind to the allosteric site to inactivate the enzyme
Allosteric activators bind to the allosteric site to activate the enzyme
42
CH6
| Metabolism
All the chemical reactions occurring inside an organism
43
CH6
| Anabolism
Endergonic reactions use energy to make chemical bonds
44
CH6
| Catabolism
Exergonic reactions break bonds and energy is released
45
CH6
| What are examples of additional molecules that some enzymes may require for proper function?
Co-factors: usually metal ions found in the active site
Co-enzymes: organic molecules, often used to donate or accept electrons in a redox reaction
46
CH6
| Biochemical Pathways
Are a series of reactions in which the product of one reaction becomes the substrate for the next reaction
*often regulated by feedback inhibition in which the end product of the pathway is an allosteric inhibitor of an earlier enzyme in the pathway
47
CH6
| Multienzyme Complexes in Membranes:
1. The product of one reaction is directly delivered to the next enzyme
2. Unwanted side reactions are reduced
3. Reactions can be regulated as a unit
48
CH7
| How do autotrophs obtain their energy?
They capture energy and build organic (C-based) molecules through photosynthesis
49
CH7
| How do heterotrophs obtain their energy?
They use preformed organic molecules for both energy and to build new organic molecules
50
CH7
| How do ALL organisms (regardless of it being an auto/heterotroph) extract energy from organic molecules?
Through cellular respiration
51
CH7
| What is cellular respiration?
A series of redox reactions (transfer of electrons) that are also dehydrogenations (H+ or proton transfers)
1 electron + 1 proton = 1 H atom
e- + H+ = H
Therefore, what is technically transferred is hydrogen atoms
52
CH7
| During redox reactions, what are electrons transferring from molecule to molecule?
Electrons transfer energy from one molecule to another
53
CH7
| Give an example of electrons transferring energy during redox reactions.
NAD+ is an electron carrier.-NAD+ accepts 2 electrons and 1 proton to become NADH (this reaction is reversible)
54
CH7
| What is the goal of cellular respiration?
To generate lots of ATP
55
CH7
| How are electrons moved during respiration?
Electrons are shuttled by electron carriers (e- transport chains) to a final electron acceptor
56
CH7
| What is the final acceptor in aerobic respiration?
The final acceptor is O2 (oxygen)
57
CH7
| What is the final acceptor is anaerobic respiration?
The final acceptor is an inorganic molecule (not O2)
58
CH7
| What is the final acceptor in fermentation?
The final acceptor is an organic molecule
59
CH7
| What is the formula for aerobic respiration?
C6H12O6 + 6O2 --> 6CO2 + 6H2O
Energy is released, this is an exergonic reaction (a large amount of energy is released in small steps)
The electrons use some energy at each level
60
CH7
| What is the change in free energy (ΔG) during aerobic respiration?
ΔG = - 686 kcal per mole of glucose
This can be even higher in a cell
61
CH7
| What is the main outcome in cellular respiration?
The capture of energy in ATP
62
CH7
| Electron energy makes ATP from ___ + ___
ADP+Pi
63
CH7
| What are two ways cells make ATP from ADP+Pi?
Substrate-level phosphorylation
Oxidative phosphorylation
64
CH7
| What is the process of substrate-level phosphorylation?
Pi transferred directly from a molecule (substrate) to ADP
65
CH7
| Describe the process of oxidative phosphorylation.
ATP synthase enzyme uses energy derived from a proton (H+) gradient to make ATP
also called chemiosmosis
66
CH7
| What are the 4 stages of glucose oxidation and where do they occur?
1. Glycolysis– in cytoplasm
2. Pyruvate oxidation– in mitochondrial matrix
3. Krebs cycle – in mitochondrial matrix
4. Electron transport & chemiosmosis – across inner membrane of mitochondrion
67
```
CH7
Explain glycolysis (step 1 of glucose oxidation).
```
Converts glucose to 2 pyruvates
A 10-step biochemical pathway that occurs in the cytoplasm
Net production of 2 ATP molecules by substrate-level phosphorylation and 2 NADH by reduction of NAD+
68
CH7
| What must occur for glycolysis to continue?
NADH must be oxidized back to NAD+ by either:
1. aerobic respiration – NADH oxidized back to NAD+ during electron transport. Final e-/H+ acceptor is O2, producing H2O)
2. fermentation – NADH donates e-/H+ to an organic molecule forming a reduced organic molecule (an alcohol or acid)
69
CH7
| Pyruvate in relation to glycolysis
The fate of pyruvate also depends on O2availability
When O2 is present, each pyruvate is oxidized to acetyl-CoA which enters the Krebs cycle
Without O2, each pyruvate is reduced in order to oxidize NADH back to NAD+
70
CH7
| Explain pyruvate oxidation (step 2 of glucose oxidation).
When O2 is present, each pyruvate is oxidized in the mitochondria in eukaryotes
The enzyme pyruvate dehydrogenase
catalyzes the oxidation of pyruvate
71
CH7
| What are the products of pyruvate oxidation?
1 CO2
1 NADH
1 acetyl-CoA (2 Cs from pyruvate added to coenzyme A)
72
CH7
| Explain the Krebs cycle (step 3 of glucose oxidation)
Oxidizes the acetyl group (carried by acetyl CoA) in the mitochondrial matrix
This is a nine step biochemical pathway; step one is
acetyl group + oxaloacetate --> citrate
(2 carbons)+(4 carbons) --> (6 carbons)
After glycolysis, pyruvate oxidation, and the Krebs cycle, each glucose molecule has been completely oxidized to:
6 CO2
4 ATP
10 NADH
2 FADH2
*last two are carried on to electron transport chain
Also called TCA cycle
73
CH7
| What are the products of the remaining steps of the Krebs cycle?
2 CO2
3 NADH
1 FADH2
1 ATP from ADP + Pi via substrate-level phosphorylation
regenerates oxaloacetate so that cycle can continue
74
CH7
| Explain the connection/relationship between pyruvates, glucose, and acetyl-CoA
Two acetyl-CoAs enter the Krebs cycle for every glucose, and two pyruvates come from every glucose
75
CH7
| Explain electron transport (step 4 of glucose oxidation).
Electrons from NADH and FADH2 are transferred to the ETC carriers
Each carrier transfers electrons to the next carrier in the chain
Each level loses some energy
76
CH7
| What is the electron transport chain (ETC)?
A series of electron carriers embedded in the mitochondrial inner membrane
This energy is used to pump protons (H+) across the membrane from the matrix to the inner membrane space
A proton gradient is established
77
CH7
| Where do electron transport and oxidative phosphorylation (chemiosmosis) occur?
The inner membrane of the mitochondrion
78
CH7
| (In electron transport) what brings the protons back from the intermembrane space to the matrix?
The high negative charge within the matrix
79
CH7
| How does the accumulation of protons in the intermembrane space drive protons from that space into the matrix?
Diffusion (chemiosmosis)
80
CH7
| Some protons diffuse through the membrane, but how are MOST moved to the matrix?
Through the ATP synthase enzyme
81
CH7
| Where does ATP synthase get its energy and how does it function?
Uses the energy of the proton gradient to synthesize ATP from ADP + Pi
Functions similarly to the rotors of bacterial flagella. Whereas flagella rotors “use ATP to spin”, ATP synthase “uses spin to make ATP”
82
CH7
| What do ATP synthase and bacterial flagella rotors have in common?
They may have a common evolutionary origin
83
CH7
| What are the theoretical vs the actual energy yields?
Theoretical energy yields:
38 ATP per glucose for bacteria
36 ATP per glucose for eukaryotes
Actual energy yields:
30 ATP per glucose for eukaryotes
reduced yield is due to “leaky” inner membrane and use of the proton gradient for purposes other than ATP synthesis
84
CH7
| Respiration can occur without O2. How does glycolysis continue this way? (2 ways)
NADH must be oxidized back to NAD+ by either:
Anaerobic respiration - uses inorganic molecules (other than O2) as final electron/H+ acceptor
Fermentation - uses organic molecules as final electron/H+ acceptor
85
CH7
| Anaerobic methanogens use CO2 as the final e- acceptor, producing:
Methane instead of water
CO2 + 4H2 + NADH → CH4 + 2H2O + NAD+
86
CH7
| Anaerobic sulfur bacteria use:
SO4 as the final e- acceptor, regenerating both NAD+ and FAD
Produces H2S instead of H2O
This happens a lot in marshes and swamps
87
CH7
| What does fermentation do?
Reduces organic molecules in order to oxidize NADH to NAD+
88
CH7
| Two types of fermentation:
Ethanol fermentation occurs in yeast; CO2 is released from pyruvate forming acetaldehyde; NADH reduces acetaldehyde to ethanol + NAD+
Lactic acid fermentation occurs in animal cells (especially muscles); NADH reduces pyruvate to lactic acid + NAD+
89
CH7
| Explain the catabolism of proteins.
```
Amino acids (AAs) are deaminated to remove amino group
remainder of the AA is converted to a molecule that can be directly used in glycolysis or the Krebs cycle
```
Ex: alanine is converted to pyruvate
aspartate is converted to oxaloacetate
90
CH7
| Explain the catabolism of fats.
Broken down to fatty acids and glycerol
Fatty acids are converted to acetyl groups by b-oxidation
Acetyl CoAs enter Krebs
A 6-carbon fatty acid yields 20% more energy than the 6-carbon glucose
91
CH7
| How does the regulation of aerobic respiration occur?
By feedback inhibition of key enzymes.
ATP and citrate both allosterically inhibit phosphofructokinase (glycolysis)
NADH inhibits pyruvate dehydrogenase (pyruvate oxidation)
ATP inhibits citrate synthetase enzyme (Krebs cycle)
92
CH7
| What can glucose be used for when feedback inhibition slows down respiration?
For storage or to build organic molecules
93
CH7
| What happens when the cell runs out of ATP and NADH?
ADP builds back up and respiration again begins to “burn” glucose
94
CH8
| Where does energy for nearly all life come from?
Photosynthesis
95
CH8
| What is the formula for photosynthesis?
6CO2 + 12H2O --> C6H12O6 + 6H2O + 6O2
96
CH8
| What carries out oxygenic photosynthesis?
Cyanobacteria, 7 groups of algae, and plants
97
CH8
| What carries out non-oxygenic photosynthesis?
Some bacteria
98
CH8
| In plants, where are chloroplasts abundant?
In the cells of parenchyma
| or mesophyll tissues
99
CH8
| What two types of reactions does photosynthesis include?
Light-dependent and light-independent
100
CH8
| Explain light-dependent reactions.
Capture light energy to make ATP and NADPH
101
CH8
| Explain light-independent reactions.
Use energy from ATP and NADPH to synthesize glucose from CO2
102
CH8
| How are light-dependent and light-independent reactions linked?
Products of LD reactions in the thylakoid membrane “feed” the LI reactions in the stroma
103
CH8
| In chloroplasts, where do LD reactions take place?
In the thylakoid membranes
104
CH8
| Thylakoids contain: (2 things)
Chlorophyll a and accessory pigments
105
CH8
| What is grana?
Stacks of thylakoids
106
CH8
| What is stroma?
Semiliquid substance surrounding thylakoids (this is site of LI reactions)
107
CH8
| What is a photon?
A discrete packet of light energy
108
CH8
| How is energy related to the wavelengths?
Inversely: shorter wavelengths = higher energy
109
CH8
| What is the photoelectric effect?
Removal of an electron from a molecule by light energy
*Occurs when photons energize electrons in molecules
110
CH8
| The electromagnetic spectrum:
Shows the visible light range expanded
111
CH8
| What are pigments?
Molecules that absorb light energy
Pigments have characteristic absorption spectra (range and efficiency of photon absorbance)
112
CH8
| What is chlorophyll a?
The primary photosynthetic pigment in plants and cyanobacteria (absorbs violet-blue and red light, appears yellow-green)
113
CH8
| What is chlorophyll b?
Secondary or accessory pigment (absorbs wavelengths that chlorophyll a does not absorb well; appears blue-green)
114
CH8
| (chlorophyll pigments) Explain the porphyrin ring.
Ring with alternating double and single bonds, with Mg at the center
*Photons excite electrons in the ring, which are then shuttled away from the ring
115
CH8
| What are accessory pigments?
Secondary pigments (e.g., chlorophyll b, carotenoids, phycobilins); absorb wavelengths that are not absorbed well by chlorophyll a
increases the overall range of wavelengths absorbed (carotenoids also act as antioxidants)
116
CH8
| Photosystems (on the thylakoid membranes) consist of: (2 things)
An antenna complex of 100s of accessory pigment molecules
A reaction center of one or more chlorophyll a molecules
*Energy from light is transferred through the electrons of the antenna complex to the reaction center of a photosystem
117
CH8
| What are the two types of photosystems in plants?
Photosystem 2 and photosystem 1 (in that order")
Electrons from PSII are passed to PSI where they are energized again
118
CH8
| Explain the general workings of a photosystem.
Energy from the antenna complex is transferred to the reaction center chlorophyll a, causing an e-to be boosted to a higher energy level and then transferring it to a nearby electron acceptor
119
CH8
| Explain photosystems in oxygenic photosynthesis.
Water donates an e-to replace the e-lost from chlorophyll a. This splits the water, releasing H+ and O2
120
CH8
| Explain photosystems in non-oxygenic photosynthesis.
The e- donor is a molecule other than H2O(e.g., H2S)
121
CH8
| What occurs in photosystems? (3 things)
1) Light energy boosts an e- within the reaction center to a high energy level
2) This e-is transferred to an e-acceptor in a redox reaction
3) The e-is replaced by an e-from H2O, which results in the production of H+ ions and O2. H2O is said to be “split”
122
CH8
| What are the four stages in light-dependent reactions?
1. primary photoevent – absorption of a photon by a pigment molecule
2. charge separation – transfer of energy to the reaction center, followed by the transfer of an excited electron to an acceptor molecule
3. electron transport – transfer of electrons through carriers that pump H+ to the inside of the thylakoid and reduce NADP+ to NADPH
4. chemiosmosis – production of ATP (similar to production of ATP in mitochondrion)
123
CH8
| In eukaryotic chloroplasts, two linked photosystems allow for what?
Noncyclic phosphorylation
124
CH8
| In light-dependent reactions, which photosystem works first? Explain its process.
Photosystem II acts first
accessory pigments shuttle energy to P680
excited electrons from P680 are transferred to b6-f complex (electron carriers)
electrons lost from P680 are replaced by electrons released by splitting water
H+ ions and O2 released; builds up in the thylakoid space
125
CH8
| What is the b6-f complex?
A short electron transport chain in the thylakoid membrane
As electrons are transferred through the complex, they lose energy. Energy released is used to by proton pumps to move H+ into the thylakoid space to establish a proton gradient
126
CH8
| Explain photosystem 1. (4 steps)
receives light energy from its antenna complex and shuttles it to P700
electrons from P700 are excited and transferred to an electron carrier
electrons are passed along transport chain and ultimately reduce NADP+ to NADPH
electrons lost from P700 are replaced by those in the b6-f complex (originally came from PS II)
so, PS2 “feeds” electrons to PS1
127
CH8
| In light-dependent reactions, ATP is produced via chemiosmosis. Explain what goes into this process. (4 things)
ATP synthase enzyme is embedded in the thylakoid membrane
protons (H+) have accumulated in the thylakoid space (establishing a proton gradient)
protons move into the stroma through ATP synthase
proton flow provides energy to produce ATP from ADP + Pi in the stroma (identical to chemiosmosis that occurs in the inner mitochondrial membrane during respiration)
128
CH8
| Cyclic photophosphorylation produces what?
ATP via PSI, but no NADPH
129
CH8
| Light-independent reactions are part of what cycle?
Calvin
130
CH8
| What do cells need to build carbohydrates and where does this occur? (3 things)
1. Energy from ATP (from LD reactions)
2. Reducing power from NADPH (from LD reactions)
3. Source of carbon (CO2 from air or water)
Done by Calvin Cycle in the stroma of chloroplast.
131
CH8
| What are the three phases of the calvin cycle?
1. Carbon fixation (using Rubisco enzyme): RuBP + CO2 2 PGA
2. Reduction: Each PGA is reduced to G3P
3. Regeneration of RuBP: G3P is used to regenerate RuBP
132
CH8
| In the calvin cycle, what is needed for every 6 carbon glucose?
the following “raw materials” are needed:
18 ATP
12 NADPH
6 CO2
133
CH8
| Since glucose is not the immediate product of the Calvin cycle, what is?
3-carbon G3P
134
CH8
| Explain how 3-carbon G3P results in glucose.
For every 6 molecules of CO2 taken in, 2 G3P molecules “leave” the cycle (each contains 3 carbons = 6 carbons total)
Two G3Ps are bonded to produce one glucose in the cytoplasm.
2(G3P)-->glucose
135
CH8
| What is the energy cycle?
Photosynthesis uses the products of respiration as substrates
Respiration uses the products of photosynthesis as substrates
136
CH8
| Rubisco has two enzymatic activities. What are they?
1. Carboxylation (good) – the addition of CO2 to RuBP (normal conditions)
2. Photorespiration (bad) – the oxidation of RuBP by O2 (hot, dry conditions). Causes loss of CO2because it competes with O2for same active site on Rubisco
137
CH9
| What two things does communication between cells require?
Ligand: a signaling molecule
Receptor: a protein to which the ligand binds (may be on the plasma membrane or within the cell)
138
CH9
| There are four basic mechanisms for cellular communication between different cells, what are they?
1. direct contact (e.g., via gap junctions)
2. paracrine signaling
3. endocrine signaling
4. synaptic signaling
139
CH9
| What is direct contact in cell communication?
Ligand molecules on the surface of one cell are recognized by receptor molecules on an adjacent cell
Or they pass through gap junctions
140
CH9
| What is paracrine signaling?
Ligands released from a secretory cell bind to receptors on adjacent cells
141
CH9
| What is endocrine signaling?
Special ligands called hormones are released from secretory cells and bind to receptors on or within cells throughout the body
142
CH9
| What is synaptic signaling?
Nerve cells release the signal ligands (neurotransmitters) which binds to receptors on nearby nerve or muscle cells
143
CH9
| When a ligand binds to a receptor, the cell “responds” chemically. What is a name for this?
Signal transduction: a series of chemical reactions that occur following the binding of a ligand to a receptor.
144
CH9
| Do different types of cells all respond the same way to the same signalling liganing?
No
145
CH9
Signal transduction often involves activating or inactivating proteins (e.g., by phosphorylating or dephosphorylating proteins). What activates/deactivates it?
Kinase – an enzyme that adds a phosphate to a protein, thus activating it.
Phosphatase – an enzyme that removes a phosphate from a protein, thus deactivating it.
146
CH9
| How do kinases activate the protein?
Kinases add a phosphate group (PO4-3 ) to the amino acids serine, threonine or tyrosine in proteins
147
CH9
| Where can cell receptors be located?
Cell surface or membrane receptor: on the plasma membrane
| Intracellular receptor: located inside cell
148
CH9
| What are the three classes of membrane receptors?
1. Channel linked or gated receptors – an ion channel that opens in response to ligand binding
2. Enzymatic receptors – an enzyme that is activated by ligand binding
3. G protein-coupled receptors – a G-protein (protein bound to GTP) that assists in transmitting the signal
149
CH9
| What is the receptor tyrosine kinase?
a special type of receptor that is a kinase enzyme
When the ligand binds, the receptor is dimerized and autophosphorylated
The activated receptor then adds a phosphate to tyrosine on a response protein
An example is the epidermal growth factor receptor
150
CH9
| What is kinase cascade?
a series of protein kinases that phosphorylate each other in succession, amplifying the signal.
So, a few signal ligand molecules can cause a large response.
Example: Mitogen-activated protein (MAP) kinases are activated by kinase cascades (a mitogen is a ligand that encourages cell division)
151
CH9
| What are g-proteins bound to?
GTP
152
CH9
| What are g-protein coupled receptors?
receptors bound to G proteins
G-protein is a switch turned on by the receptor
Signal ligand binds receptor, then G-protein activates an effector protein (usually an enzyme)
can activate effector proteins
153
CH9
| What happens when the effector protein is activated?
The effector protein produces a second messenger, which generates the cellular response
For example – one common effector protein is adenylyl cyclase which converts ATP to cAMP, which then acts as a second messenger (for example, activating protein kinase A).
Other second messengers include inositol phosphates, calcium ions (Ca2+)
154
CH9
| What does the formation of cyclic AMP (cAMP) do?
cAMP serves as a second messenger to activate or inactivate proteins
155
CH9
| Give an example of a G-protein coupled receptor/enzyme complex.
Adenylyl cyclase
156
CH9
| What are steroid hormones?
Nonpolar (lipid-soluble), so can cross the plasma membrane to a steroid receptor
Usually regulate gene expression: an inhibitor blocks the steroid receptor from binding to DNA until the hormone is present.
157
CH9
| What are the three functional domains of steroid receptors?
1. Hormone-binding domain
2. DNA binding domain
3. Domain that interacts with coactivators to affect gene expression (activating or deactivating transcription)
158
CH9
| What are autoinducers?
Small molecules produced by bacteria that regulate gene expression.
Responsible for quorum sensing (Quorum sensing is the regulation of gene expression in response to fluctuations in cell-population density. Quorum sensing bacteria produce and release chemical signal molecules called autoinducers that increase in concentration as a function of cell density)
159
CR
| Overall equation for cellular respiration?
C6H12O6+6O2-->6CO2+6H2O
160
CR
Glycolysis:
Where does it take place? (in eukaryotic cells)
What are the reactants? (Per glucose molecule in eukaryotes)
What are the products? (Per glucose molecule in eukaryotes)
What is the net ATP?
How is the ATP made?
Cytoplasm
Glucose, NAD (2), ATP(2), ADP(4), Pi(4)
Pyruvate(2),NADH(2),ATP(4)
2(2 used, 4 produced)
Substrate-level phosphorylation
161
CR
Pyruvate oxidation:
Where does it take place? (in eukaryotic cells)
What are the reactants? (Per glucose molecule in eukaryotes)
What are the products? (Per glucose molecule in eukaryotes)
What is the net ATP?
How is the ATP made?
Mitochondrial matrix
Pyruvate(2),CoA(2),NAD+(2)
Acetyl CoA(2),NADH(2),CO2(2)
0
Not applicable
162
CR
Krebs (TCA) Cycle:
Where does it take place? (in eukaryotic cells)
What are the reactants? (Per glucose molecule in eukaryotes)
What are the products? (Per glucose molecule in eukaryotes)
What is the net ATP?
How is the ATP made?
Mitochondrial matrix
Acetyl CoA(2), oxaloacetate(2),NAD+(6),FAD(2),ADP(2),Pi(2)
CO2(4),ATP(2),NADH(6),FADH2(2)
2
Substrate-level phosphorylation
163
CR
Electron Transport:
Where does it take place? (in eukaryotic cells)
What are the reactants? (Per glucose molecule in eukaryotes)
What are the products? (Per glucose molecule in eukaryotes)
What is the net ATP?
How is the ATP made?
Inner membrane of the mitochondrion
NADH(10),FADH2(2),O2(6)
NAD+(10),FAD(2),H20(6),H+(34)into intermembrane space
0
Not applicable
164
CR
Chemiosmosis:
Where does it take place? (in eukaryotic cells)
What are the reactants? (Per glucose molecule in eukaryotes)
What are the products? (Per glucose molecule in eukaryotes)
What is the net ATP?
How is the ATP made?
Inner membrane of the mitochondrion
H+(34),ADP(34),Pi(34)
ATP(34)
32(2 used to transport
pyruvates into mitochondrion)
Oxidative phophorylation (chemiosmosis of H+ ions driving ATP Synthase)
165
CR
| What is the net ATP in eukaryotes?
36
166
CR
| What is the net ATP in prokaryotes?
38
167
P
| What is the overall equation for photosynthesis?
6CO2+6H2O-->C6H12O6+6O2
168
P
| What's combined in the cytoplasm to make one glucose molecule?
2 G3P
169
```
P
Light-Dependent(PSII):
Where does it take place?
What are the reactants?
What are the products?
How is the ATP made?
```
Photosystems on Thylakoid Membranes of Chloroplast
Photons, chlorophyll and accessory pigments, H2O, ADP, Pi
ATP, O2, H+
Chemiosmosis of H+ ions drives ATP synthase
170
```
P
Light-Dependent (PS1)
Where does it take place?
What are the reactants?
What are the products?
How is the ATP made?
```
Photosystems on thylakoid membranes of chloroplasts
Photons, electrons from PSII, chlorophyll and accessory pigments, NADP+
NADPH
Not applicable
171
```
P
Light-Independent (Calvin Cycle)
Where does it take place?
What are the reactants?
What are the products?
How is the ATP made?
```
Stroma of chloroplast
CO2 (6), ribulose biphosphate (RuBP), ATP (18), NADPH( 12)
Glyceraldehyde-3-Phosphates (G3P) (2)[2 combined for one glucose], ADP (18), Pi (18), NADP+(12), H+(12)
Not applicable
