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BIO 1510 > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q

flow of energy

A
  • thermodynamics

- Cells are governed by the laws of physics and chemistry

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2
Q

thermodynamics

A

Branch of chemistry concerned with energy changes

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3
Q

energy

A

Capacity to do work

  • 2 states: kinetic & potential
  • Many forms (mechanical, heat, sound, electric current, light, or radioactivity)
  • Heat is the most convenient way of measuring energy
    a) calories
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4
Q

2 states of energy

A

1) kinetic

2) potential

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5
Q

kinetic energy

A

energy of motion

ex: going down the slide

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6
Q

potential energy

A

stored energy

ex: climbing up the slide

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7
Q

what are some of the many forms of energy?

A 
mechanical
heat
sound
electric current
light
radioactivity
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8
Q

__ is the most convenient way of measuring energy

A

heat

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9
Q

1 calorie =

A

heat required to raise 1 g of water 1ºC

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10
Q

calorie of food labels is actually a __

A

kilocalorie

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11
Q

energy flow

A
  • flows into the biological world thru the sun
  • photosynthetic organisms capture this e
  • stored as PE in chem bonds
  • breaking bonds requires e
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12
Q

energy flows into the biological world through the __

A

sun

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13
Q

__ __ capture the energy flow to the world

A

photosynthetic organisms

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14
Q

e in chemical bonds is __ __

A

potential e

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15
Q

redox rxns

A
  • oxidation (atoms or molecules LOSE an e-)
  • reduction (atoms or molecules GAIN an e-)
  • higher level of e than oxidized form
  • oxidation reduction rxn (AKA redox rxn)
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16
Q

oxidation

A

atoms or molecules LOSE an e-

*BECOMES POSITIVE

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17
Q

reduction

A

atoms or molecules GAIN an e-

*BECOMES NEGATIVE

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18
Q

1st law of thermodynamics

A

e cannot be created nor destroyed

  • e can only change from 1 form to another
  • total amnt of e in universe remains constant
  • during each conversion, some e is lost at heat
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19
Q

2nd law of thermodynamics

A

entropy (disorder) is continuously increasing
- Energy transformations proceed spontaneously to convert matter from a more ordered/less stable form to a less ordered/ more stable form

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20
Q

organization requires __

A

energy

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21
Q

disorder happens __

A

spontaneously

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22
Q

free energy

A 
G = H – TS
G = Energy available to do work (free e)
H = enthalpy, energy in a molecule’s chemical bonds
T = absolute temp 
S = entropy, unavailable energy
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23
Q

ΔG = ΔH – TS

A

ΔG = change in free energy

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24
Q

positive ΔG

A
  • Products have more free energy than reactants
  • H is higher or S is lower
  • Not spontaneous, requires input of energy
  • Endergonic
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25
Q

negative ΔG

A
  • Products have less free energy than reactants
  • H is lower or S is higher or both
  • Spontaneous (may not be instantaneous)
  • Exergonic
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26
Q

endergonic rxn

A

energy in products > energy in reactants

*e is absorbed

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27
Q

exergonic rxn

A

energy in reactants > energy in products

*e is released

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28
Q

activation e

A
  • Extra energy required to destabilize existing bonds and initiate a chemical reaction
  • Exergonic reaction’s rate depends on the activation energy required
    a) Larger activation energy proceeds more slowly
  • Rate can be increased 2 ways
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29
Q

a larger activation e proceeds more __

A

slowly

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30
Q

2 ways reaction rate can be increased

A
  1. Increasing energy of reacting molecules (heating)

2. Lowering activation energy

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31
Q

catalysts

A
  • Substances that influence chemical bonds in a way that lowers activation energy
  • Cannot violate laws of thermodynamics
    a) Cannot make an endergonic reaction spontaneous
  • Do not alter the proportion of reactant turned into product
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32
Q

ATP

A

Adenosine triphosphate

  • Chief “currency” all cells use
  • Composed of:
    a) Ribose (5 carbon sugar)
    b) Adenine
    c) Chain of 3 phosphates*
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33
Q

what is ATP composed of?

A
  • Ribose (5 carbon sugar)
  • Adenine
  • Chain of 3 phosphates
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34
Q

in ATP, what is the key to e storage?

A

chain of 3 phosphates

  • Bonds are unstable (meaning they break off easily bc they want to repel each other)
  • ADP: 2 phosphates
  • AMP: 1 phosphate (lowest e form)
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35
Q

ATP cycle

A
  • ATP hydrolysis drives endergonic reactions
    a) Coupled reaction results in net –ΔG (exergonic and spontaneous)
  • ATP not suitable for long-term energy storage
    a) Fats and carbohydrates better
    b) Cells store only a few seconds worth of ATP
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36
Q

enzymes: biological catalysts

A
  • most enzymes are protein
    a) some are RNA (called ribozymes)
  • shape of enzyme stabilizes a temporary association between substrates
  • enzyme not changed or consumed in rxn
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37
Q

Carbonic anhydrase ex

A
  • 200 molecules of carbonic acid per hour made without enzyme
  • 600,000 molecules formed per second with enzyme
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38
Q

active site

A
  • Pockets or clefts for substrate binding
  • Forms enzyme–substrate complex
  • Precise fit of substrate into active site
  • Applies stress (energy/pressure) on bonds to distort particular bond to lower activation energy
    a) induced fit
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39
Q

forms of enzymes

A
  • Enzymes may be 1) suspended in the cytoplasm (inter-) or 2) attached to cell membranes and organelles (intra-)
  • multi enzyme complexes
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40
Q

multi enzyme complexes

A

subunits work together to form molecular machine

  • Product can be delivered easily to next enzyme
  • Unwanted side reactions prevented
  • All rxns can be controlled as a unit
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41
Q

nonprotein enzymes

A
  • ribozymes
  • 1981 discovery that certain reactions catalyzed in cells by RNA molecule itself
  • 2 kinds
    1) Intramolecular catalysis
    2) Intermolecular catalysis
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42
Q

Intramolecular catalysis

A

catalyze reaction on RNA molecule itself

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43
Q

intermolecular catalysis

A

RNA acts on another molecule

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44
Q

enzyme function

A
  • Rate of enzyme-catalyzed reaction depends on concentrations of substrate and enzyme
  • Any chemical or physical condition that affects the enzyme’s 3D shape can change rate
    a) optimum temp
    b) optimum pH
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45
Q

inhibitor

A

substance that binds to enzyme and decreases its activity

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46
Q

competitive inhibitor

A

Competes with substrate for active site

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47
Q

noncompetitive inhibitor

A
  • Binds to enzyme at a site other than active site

- Causes shape change that makes enzyme unable to bind substrate

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48
Q

allosteric enzymes

A

enzymes exist in active and inactive forms

  • Most noncompetitive inhibitors bind to allosteric site (chemical on/off switch)
  • allosteric inhibitor
  • allosteric activator
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49
Q

allosteric inhibitor

A

binds to allosteric site and reduces enzyme activity

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50
Q

allosteric activator

A

binds to allosteric site and increases enzyme activity

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51
Q

metabolism

A

Total of all chemical reactions carried out by an organism

  • anabolism
  • catabolism
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52
Q

Anabolic reactions/anabolism

A

Expend energy to build up molecules

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53
Q

Catabolic reactions/catabolism

A

Harvest energy by breaking down molecules

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54
Q

biochemical pathways

A
  • rxns occur in a sequence
  • Product of one rxn is the substrate for the next
  • Many steps take place in specific organelles
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55
Q

feedback inhibition

A
  • End-product of pathway binds to an allosteric site on enzyme that catalyzes first reaction in pathway
  • Shuts down pathway so raw materials and energy are not wasted
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56
Q

Most noncompetitive inhibitors bind to __ __

A

allosteric site

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57
Q

allosteric site

A

chemical on/off switch

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58
Q

2 kinds of nonprotein enzymes

A

1) Intramolecular catalysis

2) Intermolecular catalysis

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59
Q

what chemical/physical condition(s) can change rate of enzyme-catalyzed rxn?

A

a) optimum temp

b) optimum pH

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60
Q

A covalent bond between two atoms represents what kind of energy?

A

Potential energy

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61
Q

During a redox reaction the molecule that gains an electron has been

A

reduced and now has a higher energy level

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62
Q

An endergonic reaction has the following properties

A

+∆G and the reaction is not spontaneous.

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63
Q

A spontaneous reaction is one in which

A

the reactants have a higher free energy than the products

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64
Q

What is activation energy?

A

The energy required to initiate a chemical reaction

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65
Q

Which of the following is NOT a property of a catalyst?

A

A catalyst lowers the free energy of the reactants.

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66
Q

Where is the energy stored in a molecule of ATP?

A

In the bonds connecting the two terminal phosphate groups

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67
Q

Cells use ATP to drive endergonic reactions because

A

energy released by ATP hydrolysis makes ∆G for coupled reactions more negative.

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68
Q

Which of the following statements is NOT true about enzymes?

A

Enzymes make ∆G for a reaction more negative.

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69
Q

ATP hydrolysis has a ∆G of–7.4kcal/mol. Can an endergonic reaction with a ∆G of 12 kcal/mol be “driven” by ATP hydrolysis?

A

No, the overall ∆G is still positive.

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70
Q

An online auction site offers a perpetual-motion machine. You decide not to bid on this because

A

the Second Law says that energy loss due to entropy will not allow for perpetual motion.

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71
Q

Enzymes have similar responses to both changes in temperature and pH. The effect of both is on the

A

three-dimensional shape of the enzyme.

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72
Q

Feedback inhibition is an efficient way to control a metabolic pathway because the

A

first enzyme in a pathway is inhibited by the end-product of the pathway.

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73
Q

respiration

A

organisms can be classified based on how they obtain e

  • autotrophs
  • heterotrophs
  • all organisms use cell reps to extract e from organic molecules
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74
Q

autotrophs

A

able to produce their own organic molecules thru psyn

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75
Q

heterotrophs

A

live on organic compounds produced by other organisms

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76
Q

all organisms use __ __ to extract energy from organic molecules

A

cellular respiration

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77
Q

cellular respiration

A
  • a series of rxns
  • oxidized
  • reduced
  • dehydrogenation
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78
Q

oxidized rxns

A

loss of e-

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79
Q

reduced rxns

A

gain of e-

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80
Q

dehydrogenation

A

lost e- are accompanied by protons

- a H+ atom is lost (1 e-, 1 proton)

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81
Q

redox rxns

A
  • e- cary e from one molecule to another
  • NAD+
  • dozens of these rxns take place
  • number of e- acceptors including NAD+
  • in the end, high e e- from initial chm bonds have lost much of their e
  • transferred to a final e- acceptor
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82
Q

NAD+

A

nicotinamide adenosine dinucleotide

  • an e- carrier
  • accepts 2 e- and 1 proton to become NADH
  • rxn is reversible
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83
Q

oxidation-reduction rxn

A

2 e- and 1 proton are transferred to NAD+ to form NADH

- a second proton is donated to the solution

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84
Q

e- acceptors

A

final e- acceptors are…

  • aerobic resp: oxygen (O2)
  • anaerobic resp: inorganic molecule (not O2)
  • fermentation: organic molecule
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85
Q

aerobic resp

A

C6H12O6 + 6 O2 -> 6 CO2 + 6 H2O

  • free e: -686 kcal/mol of glucose
    a) can be even higher than this in a cell
    b) amnt of e must be released in small steps rather than all at once
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86
Q

e- carriers

A
  • many types of carriers used
    a) soluble, membrane-bound, move within membrane
  • all carriers can be reversibly oxidized and reduced
  • some carry just e-, some e- and protons
  • NAD+ acquires 2 e- and a proton to become NADH
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87
Q

ATP

A
  • cells use ATP to drive endergonic rxns
    a) ∆G (free energy) of hydrolyzing terminal phosphate = -7.3 kcal/mol
  • 2 mechanisms for synthesis
    a) substrate-level phosphorylation
    b) oxidative phosphorylation
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88
Q

substrate-level phosphorylation

A
  • transfers phosphate group directly to ADP

- during glycolysis

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89
Q

oxidative phosphorylation

A
  • ATP synthase uses e from a proton gradient
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90
Q

oxidation of glucose

A

the complete oxidation of glucose proceeds in stages:

1) glycolysis
2) pyruvate oxidation
3) Krebs cycle
4) ETC & chemiosmosis

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91
Q

glycolysis

A
  • converts 1 glucose (6-C) to 2 pyruvate (3-C)
  • 10 step biochemical pathway
  • occurs in cytoplasm
  • net production of 2 ATP molecules by substrate-level phosphorylation
  • 2 NADH produced by reduction of NAD+
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92
Q

NADH must be __

A

recycled

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93
Q

for glycolysis to continue, NADH must be recycled to NAD+ by either __ __ or __

A

aerobic resp; fermentation

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94
Q

aerobic resp

A
  • oxygen is available as the final e- acceptor

- produces significant amnt of ATP

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95
Q

fermentation

A
  • occurs when oxygen is not available

- organic molecule is the final e- acceptor

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96
Q

fate of pyruvate

A
  • when O2 is present: pyruvate is oxidized to acetyl-CoA which enters the Krebs cycle
  • aerobic resp
  • no O2: pyruvate is reduced in order to oxidize NADH back to NAD+
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97
Q

the fate of pyruvate depends on __ availability

A

oxygen

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98
Q

pyruvate oxidation

A
  • in the presence of oxygen, pyruvate is oxidized
  • occurs in the mitochondria in eukaryotes
    a) pyruvate dehydrogenase catalyzes the rxn
  • occurs at the plasma membrane in prokaryotes
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99
Q

products of pyruvate oxidation

A
  • for each 3-C pyruvate molecule:
    a) 1 CO2
    • decarboxylation by pyruvate dehydrogenase
      b) 1 NADH
      c) 1 acetyl-CoA
    • consists of 2-C from pyruvate attached to CoA
    • proceeds to Krebs Cycle
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100
Q

Krebs cycle

A
  • oxidized acetyl group from pyruvate
  • occurs in mitochondrial matrix
  • biochemical pathway of 9 steps in 3 segments
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101
Q

3 segments of Krebs Cycle

A

1) acetyl-CoA + oxaloacetate -> citrate
2) citrate rearrangement and decarboxylation
3) regeneration of oxaloacetate

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102
Q

Krebs cycle yield

A
  • for each Acetyl-CoA entering:
    1) releases 2 molecules of CO2
    2) reduce 3 NAD+ to 3 NADH
    3) reduce 1 FAD (e- carrier) to FADH2
    4) produce 1 ATP
    5) regenerate oxaloacetate
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103
Q

glucose yield after Krebs cycle

A

Glucose has been oxidized to:

  • 6 CO2
  • 4 ATP
  • 10 NADH
  • 2 FADH2
    a) NADH and FADH2 proceed to ETC
    b) e- transfer has released 53 kcal/mol of e by gradual e extraction
    c) e will be put to use to manufacture ATP
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104
Q

electron transport chain (ETC)

A

a series of membrane-bound e- carriers

  • Embedded in the inner mitochondrial membrane
  • E- from NADH and FADH2 are transferred to complexes of the ETC
  • Each complex in the chain operates as a proton pump, driving protons to the intermembrane space
  • E- move from protein complex to protein complex
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105
Q

chemiosmosis

A

Accumulation of protons in the intermembrane space drives protons into the matrix via diffusion, but this occurs slowly since the membrane is relatively impermeable to ions

  • most protons can only reenter matrix thru ATP synthase
    a) uses e of gradient to make ATP from ADP + Pi
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106
Q

ATP synthase

A

ATP synthesis carried out by a tiny rotary motor driven by proton gradient

  • F0 membrane-bound complex
  • F1 complex (stalk and knob) has enzymatic activity
  • Protons travel through F0 channel, which causes F0 to rotate
  • Mechanical e changes confirmation of catalytic domain in F1
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107
Q

energy yield of resp

A
  • theoretical e yield
    a) 32 ATP per glucose for bacteria
    b) 30 ATP per glucose for eukaryotes
  • P/O ratio (phosphate-to-oxygen ratio) is the amnt of ATP synthesized per O2 molecule
  • theoretical and direct calc of P/O has been contentious and has changed over time
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108
Q

regulation of resp

A
  • ex of feedback inhibition
  • 2 key control points
    1) in glycolysis
  • Phosphofructokinase is allosterically inhibited by ATP and/or citrate
    2) in pyruvate oxidation/ Krebs cycle
  • Pyruvate dehydrogenase inhibited by high levels of NADH
  • Citrate synthetase inhibited by high levels of ATP
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109
Q

oxidation without O2

A

1) anaerobic resp
- Use of inorganic molecules (other than O2) as final e- acceptor
- Many prokaryotes use sulfur, nitrate, carbon dioxide or even inorganic metals
2) fermentation
- use of organic molecules as final e- acceptor

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110
Q

anaerobic resp

A
  • methanogens

- sulfur bacteria

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111
Q

methanogens

A
  • CO2 is reduced to CH4 (methane)

- Found in diverse organisms including cows

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112
Q

sulfur bacteria

A
  • Inorganic sulfate (SO4) is reduced to hydrogen sulfide (H2S)
  • Early sulfate reducers set the stage for evolution of photosynthesis
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113
Q

fermentation

A

reduces organic molecules in order to regenerate NAD+

  • ethanol fermentation
  • lactic acid fermentation
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114
Q

ethanol fermentation

A
  • occurs in yeast

- CO2, ethanol and NAD+ are produced

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115
Q

lactic acid fermentation

A
  • occurs in animal cells (especially muscles)

- e- are transferred from NADH to pyruvate to produce lactic acid

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116
Q

catabolism of protein

A
  • amino acids undergo deamination to remove amino group
  • remainder of amino acid is converted to a molecule that enters glycolysis or the Krebs cycle
    a) alanine is converted to pyruvate
    b) aspartate is converted to oxaloacetate
    c) glutamate is converted to Ketoglutarate
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117
Q

in catabolism of protein, alanine is converted to __

A

pyruvate

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118
Q

in catabolism of protein, aspartate is converted to __

A

oxaloacetate

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119
Q

catabolism of fat

A
  • fats are broken down to fatty acids and glycerol
    a) fatty acids are converted to acetyl groups by ß-oxidation
  • resp of a 6-C fatty acid yield 20% more e than 6-C glucose
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120
Q

The respiration of a 6-carbon fatty acid yields __ more energy than 6-carbon glucose.

A

20%

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121
Q

evolution of metabolism

A
  • hypothetical timeline
    1) Ability to store chm e in ATP
    2) Evolution of glycolysis
  • Pathway found in all living organisms
    3) Anoxygenic psyn (using H2S)
    4) Use of H2O in psyn (not H2S)
  • Begins permanent change in Earth’s atmosphere
    5) Evolution of nitrogen fixation
    6) Aerobic resp evolved most recently
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122
Q

An autotroph is an organism that

A

does both a and b

a. extracts energy from organic sources.
b. converts energy from sunlight into chemical energy

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123
Q

Which of the following processes is (are) required for the complete oxidation of glucose?

A

all of the choices are correct

a. The Krebs cycle
b. Glycolysis
c. Pyruvate oxidation

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124
Q

Which of the following is NOT a product of glycolysis?

A

CO2

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125
Q

Glycolysis produces ATP by

A

substrate-level phosphorylation

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126
Q

What is the role of NAD+ in the process of cellular respiration?

A

It functions as an electron carrier

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127
Q

The reactions of the Krebs cycle occur in the

A

matrix of the mitochondria

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128
Q

The electrons carried by NADH and FADH2 can be

A

moved between proteins in the inner membrane of

the mitochondrion

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129
Q

Which of the following is NOT a true statement regarding cellular respiration?

A

Electrons have a higher potential energy at the end

of the process.

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130
Q

The direct source of energy for the ATP produced by ATP synthase comes from

A

a proton gradient

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131
Q

Anaerobic respiration

A

yields less energy than aerobic respiration because other final
electron acceptors have lower affinity for electrons than O2

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132
Q

What is the importance of fermentation to cellular metabolism?

A

It oxidizes NADH to NAD+ in the absence of O2

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133
Q

The link between electron transport and ATP synthesis

A

is a proton gradient.

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134
Q

A chemical agent that makes holes in the inner membrane of the mitochondria would

A

stop ATP synthesis.

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135
Q

Yeast cells that have mutations in genes that encode enzymes in glycosides can still grow on glycerol. They are able to utilize glycerol because it

A

can feed into the Krebs cycle and generate ATP via e- transport and chemiosmosis.

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136
Q

Energy for all life on Earth ultimately comes from __

A

photosynthesis

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137
Q

formula for psyn

A

6CO2 + 12H2O -> C6H12O6 + 6H2O + 6O2

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138
Q

Oxygenic photosynthesis is carried out by

A
  • Cyanobacteria
  • 7 groups of algae
  • All land plants
  • chloroplasts
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139
Q

stages: light-dependent rxns

A

Require light

  1. Capture energy from sunlight
  2. Make ATP and reduce NADP+ to NADPH
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140
Q

stages: light-independent rxns/ carbon fixation rxns

A

–Does not require light

3.Use ATP and NADPH to synthesize organic molecules from CO2

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141
Q

chloroplast

A
  • thylakoid membrane
  • grana
  • stroma lamella
  • stroma
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142
Q

thylakoid membrane

A

internal membrane

  • Contains chlorophyll and other photosynthetic pigments
  • Pigments clustered into photosystems
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143
Q

grana

A

stacks of flattened sacs of thylakoid membrane

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144
Q

stroma lamella

A

connect grana

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145
Q

stroma

A

semiliquid surrounding thylakoid membranes

146
Q

Jan Baptista van Helmont (1580–1644)

A

Demonstrated that the substance of the plant was not produced only from the soil

147
Q

Joseph Priestly (1733–1804)

A

Living vegetation adds something to the air

148
Q

Jan Ingenhousz (1730–1799)

A

Proposed plants carry out a process that uses sunlight to split carbon dioxide into carbon and oxygen (O2 gas)

149
Q

F.F. Blackman (1866–1947)

A
  • Came to the startling conclusion that psyn is in fact a multistage process, only one portion of which uses light directly
  • Light vs dark reactions
  • Enzymes involved
150
Q

C. B. van Niel (1897–1985)

A

Found purple sulfur bacteria do not release O2 but accumulate sulfur
- Proposed general formula for psyn
•CO2 + 2 H2A + light energy → (CH2O) + H2O + 2 A
- Later researchers found O2 produced comes from water

151
Q

Robin Hill (1899–1991)

A

demonstrated Niel was right that light energy could be harvested and used in a reduction reaction

152
Q

pigments

A

Molecules that absorb light energy in the visible range
•Light is a form of energy
•Photon
•Photoelectric effect

153
Q

photon

A

particle of light

  • Acts as a discrete bundle of energy
  • Energy content of a photon is inversely proportional to the wavelength of the light
154
Q

light is a form of __

A

energy

155
Q

photoelectric effect

A

removal of an electron from a molecule by light

156
Q

Absorption spectrum

A

range and efficiency of photons molecule is capable of absorbing

157
Q

When a photon strikes a molecule, its energy is either

A
  • Lost as heat
  • Absorbed by the e- of the molecule
    •Boosts electrons into higher energy level
158
Q

pigments in psyn

A
  • Organisms have evolved a variety of different pigments
  • Only two general types are used in green plant photosynthesis
    a) Chlorophylls
    b) Carotenoids
  • In some organisms, other molecules also absorb light energy
159
Q

Chlorophyll a

A
  • Main pigment in plants and cyanobacteria
  • Only pigment that can act directly to convert light energy to chemical energy
  • Absorbs violet-blue and red light
160
Q

chlorophyll b

A

Accessory pigment or secondary pigment absorbing light wavelengths that chlorophyll a does not absorb

161
Q

structure of chlorophyll

A
  • Porphyrin ring
  • Photons excite electrons in the ring
  • Electrons are shuttled away from the ring
162
Q

Porphyrin ring

A
  • Complex ring structure with alternating double and single bonds
  • Magnesium ion at the center of the ring
163
Q

action spectrum

A
  • Relative effectiveness of different wavelengths of light in promoting photosynthesis
  • corresponds to the absorption spectrum for chlorophylls
164
Q

Carotenoids

A

Carbon rings linked to chains with alternating single and double bonds
- Can absorb photons with a wide range of energies
- Also scavenge free radicals- antioxidant
•Protective role

165
Q

Phycobiloproteins

A

Important in low-light ocean areas

166
Q

Photosystem organization

A

Light is captured by photosystems, each of which consists of two components

1) Antenna complex
2) Reaction center

167
Q

antenna complex

A
  • Hundreds of accessory pigment molecules
  • Gather photons and feed the captured light e to the rxn center
  • aka light-harvesting complex
  • Captures photons from sunlight & channels them to the rxn center chlorophylls
  • In chloroplasts, light-harvesting complexes consist of a web of chlorophyll molecules linked together & held tightly in the thylakoid membrane by a matrix of proteins
168
Q

reaction center

A
  • 1 or more chlorophyll a molecules
  • Passes excited electrons out of the photosystem
  • transmembrane protein–pigment complex
    •When a chlorophyll in the rxn center absorbs a photon of light, an e- is excited to a higher e level
    •Light-energized e- can be transferred to the primary electron acceptor, reducing it
    •Oxidized chlorophyll then fills its electron “hole” by oxidizing a donor molecule
169
Q

light-dependent rxns

A
  1. Primary photoevent
  2. Charge separation
  3. Electron transport
  4. Chemiosmosis
170
Q

Primary photoevent

A

Photon of light is captured by a pigment molecule

171
Q

charge separation

A

Energy is transferred to the reaction center; an excited electron is transferred to an acceptor molecule

172
Q

Electron transport

A

Electrons move through carriers to reduce NADP+

173
Q

chemiosmosis

A

produces ATP

174
Q

cyclic photophosphorylation

A
  • In sulfur bacteria, only one photosystem is used
  • Generates ATP via electron transport
  • Anoxygenic photosynthesis
  • Excited electron passed to electron transport chain
  • Generates a proton gradient for ATP synthesis
175
Q

chloroplasts have 2 connected photosystems

A
  • Oxygenic photosynthesis
  • Photosystem I (P700): Functions like sulfur bacteria
  • Photosystem II (P680): Can generate an oxidation potential high enough to oxidize water
  • Working together, the two photosystems carry out a noncyclic transfer of e- that is used to generate both ATP and NADPH
176
Q

photosystem I and II

A
  • Photosystem I transfers e- ultimately to NADP+, producing NADPH
  • E- lost from photosystem I are replaced by e- from photosystem II
  • Photosystem II oxidizes water to replace the e- transferred to photosystem I
  • 2 photosystems connected by cytochrome/ b6-f complex
177
Q

noncyclic phosphorylation

A
  • Plants use photosystems II and I in series to produce both ATP and NADPH
  • Path of electrons not a circle
  • Photosystems replenished with e- obtained by splitting water
  • Z diagram
178
Q

photosystem II

A
  • Resembles the reaction center of purple bacteria
    •Core of 10 transmembrane protein subunits with e- transfer components & two P680 chlorophyll molecules
  • Reaction center differs from purple bacteria in that it also contains four manganese atoms
    a) Essential for the oxidation of water
  • b6-f complex
    a) Proton pump embedded in thylakoid membrane
179
Q

photosystem I

A
  • Rxn center consists of a core transmembrane complex consisting of 12 to 14 protein subunits with two bound P700 chlorophyll molecules
  • Photosystem I accepts an e- from plastocyanin into the “hole” created by the exit of a light-energized e-
  • Passes electrons to NADP+ to form NADPH
180
Q

chemiosmosis

A
  • Electrochemical gradient can be used to synthesize ATP
  • Chloroplast has ATP synthase enzymes in the thylakoid membrane
    a) Allows protons back into stroma
  • Stroma also contains enzymes that catalyze the reactions of carbon fixation-the Calvin cycle reactions
181
Q

production of additional ATP

A

•Noncyclic photophosphorylation generates NADPH and ATP
•Building organic molecules takes more energy than that alone
•Cyclic photophosphorylation used to produce additional ATP
–Short-circuit photosystem I to make a larger proton gradient to make more ATP

182
Q

carbon fixation- calvin cycle

A 
To build carbohydrates cells use:
– Energy
•ATP from light-dependent reactions
•Cyclic and noncyclic photophosphorylation
•Drives endergonic reaction
– Reduction potential
•NADPH from photosystem I
•Source of protons and energetic electrons
183
Q

calvin cycle

A

Named after Melvin Calvin (1911–1997)
•Also called C3 psyn
•Key step is attachment of CO2 to RuBP to form PGA
•Uses enzyme ribulose bisphosphate carboxylase/oxygenase or rubisco

184
Q

3 phases of the calvin cycle

A
  1. Carbon fixation
  2. Reduction
  3. Regeneration of RuBP
185
Q

calvin cycle: carbon fixation

A

RuBP + CO2 → PGA

186
Q

calvin cycle: reduction

A

PGA is reduced to G3P

187
Q

calvin cycle: regeneration of RuBP

A

–PGA is used to regenerate RuBP
•3 turns incorporate enough carbon to produce a new G3P
•6 turns incorporate enough carbon for 1 glucose

188
Q

output of calvin cycle

A 
Glucose is not a direct product of the Calvin cycle
 •G3P is a 3 carbon sugar
–Used to form sucrose
 •Major transport sugar in plants
 •Disaccharide made of fructose and glucose
–Used to make starch
 •Insoluble glucose polymer
 •Stored for later use
189
Q

energy cycle

A

Psyn uses the products of respiration as starting substrates
•Resp uses the products of psyn as starting substrates
•Production of glucose from G3P even uses part of the ancient glycolytic pathway, run in reverse
•Principal proteins involved in e- transport & ATP production in plants are evolutionarily related to those in mitochondria

190
Q

photorespiration

A

Rubisco has 2 enzymatic activities
–Carboxylation
–Photorespiration
•CO2 and O2 compete for the active site on RuBP

191
Q

carboxylation

A
  • Addition of CO2 to RuBP

* Favored under normal conditions

192
Q

photorespiration

A
  • Oxidation of RuBP by the addition of O2

* Favored when stoma are closed in hot conditions •Creates low-CO2 and high-O2

193
Q

types of psyn

A

• C3
–Plants that fix carbon using only C3 photosynthesis (the Calvin cycle)
• C4 and CAM
–Add CO2 to PEP to form 4 carbon molecule
–Use PEP carboxylase
–Greater affinity for CO2, no oxidase activity
–C4: spatial solution
–CAM: temporal solution (time difference)

194
Q

C4 plants

A
  • Corn, sugarcane, sorghum, and a number of other grasses
  • Initially fix carbon using PEP carboxylase in mesophyll cells
  • Produces oxaloacetate, converted to malate, transported to bundle-sheath cells
  • Within the bundle-sheath cells, malate is decarboxylated to produce pyruvate and CO2
  • Carbon fixation then by rubisco and the Calvin cycle
195
Q

C4 pathway

A
  • it overcomes the problems of photorespiration
  • does have a cost
  • To produce a single glucose requires 12 additional ATP compared with the Calvin cycle alone
  • C4 psyn is advantageous in hot dry climates where photorespiration would remove more than half of the carbon fixed by the usual C3 pathway alone
196
Q

CAM plants

A

•Many succulent (water-storing) plants, such as cacti, pineapples, and some members of about two dozen other plant groups
•Stomata open during the night & close during the day
– Reverse of that in most plants
•Fix CO2 using PEP carboxylase during the night and store in vacuole
•When stomata closed during the day, organic acids are decarboxylated to yield high levels of CO2
•High levels of CO2 drive the Calvin cycle and minimize photorespiration

197
Q

C4 and CAM

A
  • Both use both C3 and C4 pathways
    •C4: two pathways occur in different cells
    •CAM: C4 pathway at night and the C3 pathway during the day
198
Q

the light-dependent rxns of psyn are responsible for the production of

A

ATP and NADPH

199
Q

Which region of a chloroplast is associated with the capture of light energy?

A

Thylakoid membrane

200
Q

The colors of light that are most effective for photosynthesis are

A

red, blue, and violet

201
Q

During noncyclic photosynthesis, photosystem I functions to ___________, and photosystem II functions to ______________.

A

reduce NADP+; oxidize H2O

202
Q

How is a reaction center pigment in a photosystem different from a pigment in the antenna complex?

A

The reaction center pigment loses an electron when it absorbs light energy.

203
Q

The ATP and NADPH from the light reactions are used

A

during the reactions of the Calvin cycle to produce glucose.

204
Q

The carbon fixation reaction converts

A

inorganic carbon into an organic acid.

205
Q

C4 plants initially fix carbon by

A

incorporating CO2 into oxaloacetate, which is converted to malate.

206
Q

The overall flow of electrons in the light reactions is from

A

H2O to NADPH.

207
Q

If you could measure pH within a chloroplast, where would it be lowest?

A

In the lumen of the thylakoid

208
Q

The excited electron from photosystem I

A

Both a and c are correct.

a. can be returned to the reaction center to generate ATP by cyclic photophosphorylation.
c. is replaced by an electron from photosystem II.

209
Q

If the Calvin cycle runs through six turns

A

enough carbon will be fixed to make one glucose, but they will not all be in the same molecule.

210
Q

Which of the following are similarities between the structure and function of mitochondria and chloroplasts?

A

Both a and c are correct.

a. They both create internal proton gradients by electron transport.
reactions.
c. They both have a double membrane system.

211
Q

Given that the C4 pathway gets around the problems of photorespiration, why don’t all plants use it?

A

It also has an energetic cost.

212
Q

if the thylakoid membrane became leaky to ions, what would you predict to be the result on the light reactions?

A

It would stop ATP production.

213
Q

the overall process of photosynthesis

A

results in the reduction of CO2 and the oxidation of H2O.

214
Q

the optimum temp for human enzyme is at __

A

42ºC

215
Q

at 50ºC, the enzyme will be __

A

degraded

216
Q

optimal temp for humans

A

37ºC

217
Q

optimum temp for enzyme from hot springs prokaryote

A

72ºC

218
Q

competitve inhibition

A

substrate binds to block

219
Q

allosteric inhibition (noncompetitive)

A

allosteric binds somewhere else to give off a lock to block it

220
Q

anaerobic vs aerobic

A

anaerobic: no oxygen, undergoes fermentation
aerobic: oxygen present, undergoes cell resp in the mitochondria

221
Q

the longer the wavelength the __ the energy; the shorter the wavelength the __ the energy

A

lower; higher

222
Q

plants use the visible wavelengths of light to…

A

capture e

223
Q

colors on the wavelength spectrum: ROYGBIV

A 
red
orange
yellow 
green
blue 
indigo
violet
224
Q

chlorophyll __ green light

A

reflects

225
Q

carotenoids absorb __ lights

A

green, yellow, orange, red

226
Q

the Calvin cycle is also known as __

A

light independent reactions

227
Q

Communication between cells requires

A
  • Ligand
  • Receptor protein
  • Interaction of these two components initiates the process of signal transduction, which converts the information in the signal into a cellular response
228
Q

ligand

A

signaling molecule

229
Q

receptor protein

A

molecule to which the receptor binds

230
Q

types of cell signaling

A

four basic mechanisms for cellular communication:

1) Direct contact
2) Paracrine signaling
3) Endocrine signaling
4) Synaptic signaling
- Some cells send signals to themselves (autocrine signaling)

231
Q

direct contact

A
  • Molecules on the surface of one cell are recognized by receptors on the adjacent cell
    Important in early development
  • Gap junctions
232
Q

paracrine signaling

A
  • Signal released from a cell has an effect on neighboring cells
  • Important in early development
  • Coordinates clusters of neighboring cells
  • Signaling between immune cells
233
Q

endocrine signaling

A
  • Hormones released from a cell travel through circulatory system to affect other cells throughout the body
  • Both animals and plants use this mechanism extensively
234
Q

synaptic signaling

A
  • Occurs in animals
  • Nerve cells release the signal (neurotransmitter) which binds to receptors on nearby cells
  • Association of neuron and target cell is a chemical synapse
235
Q

signal transduction

A
  • Events within the cell that occur in response to a signal
  • When a ligand binds to a receptor protein, the cell has a response
  • Different cell types can have similar response to the same signal
    a) Glucagon example
  • Different cell types can respond differently to the same signal
    a) Epinephrine example
236
Q

phosphorylation

A
  • Addition of phosphate group
  • A cell’s response to a signal often involves activating or inactivating proteins
  • Phosphorylation is a common way to change the activity of a protein
  • Protein kinase
  • Phosphatase
237
Q

protein kinase

A

an enzyme that adds a phosphate to a protein

238
Q

phosphatase

A

an enzyme that removes a phosphate from a protein

239
Q

receptor types

A
  • Receptors can be defined by their location
    1) Intracellular receptor
    2) Cell surface receptor or membrane receptor
240
Q

intracellular receptor

A

located within the cell

  • bind to hydrophobic ligands
  • bind non polar ligands
  • steroid hormones
241
Q

Cell surface receptor or membrane receptor

A
  • located on the plasma membrane to bind a ligand outside the cell
  • bind polar ligands
    a) Transmembrane protein in contact with both the cytoplasm and the extracellular environment
242
Q

3 Subclasses of membrane receptors

A

1) Chemically gated ion channels
2) Enzymatic receptors
3) G protein-coupled receptor

243
Q

Chemically gated ion channels

A

channel-linked receptors that open to let a specific ion pass in response to a ligand

244
Q

enzymatic receptors

A

receptor is an enzyme that is activated by the ligand

a) almost all are protein kinases

245
Q

G protein-coupled receptor

A

a G-protein (bound to GTP) assists in transmitting the signal from receptor to enzyme (effector)

246
Q

steroid hormones

A
  • Common nonpolar, lipid-soluble structure
  • Can cross the plasma membrane to an intracellular steroid receptor
  • Binding of the hormone to the receptor causes the complex to shift from the cytoplasm to the nucleus
  • Act as regulators of gene expression
247
Q

steroid hormone receptors

A
  • 3 functional domains
    1) Hormone-binding domain
    2) DNA-binding domain
    3) Domain that interacts with coactivators to affect level of gene transcription
  • In its inactive state, the receptor typically cannot bind to DNA because an inhibitor protein occupies the DNA binding site
  • Binding of ligand changes conformation
248
Q

coactivators

A
  • Target cell’s response to a lipid-soluble cell signal can vary enormously, depending on the nature of the cell
  • Even the same type of cell may have different responses
  • Depends on coactivators present
  • Estrogen has different effects in uterine tissue than mammary tissue
    a) Regulation is not by presence or absence of receptor
    b) Instead presence or absence of coactivator
249
Q

intracellular receptors as enzymes

A
  • Intracellular receptors can act as enzymes
  • Nitric oxide (NO) is a small gas molecule that can diffuse in and out of cells
  • NO binds to guanylyl cyclase, enabling it to catalyze the synthesis of cyclic guanosine monophosphate (cGMP)
  • cGMP is an intracellular messenger molecule that relaxes smooth muscle cells
250
Q

Paracrine signaling is characterized by ligands that are

A

secreted by neighboring cells

251
Q

signal transduction pathways

A

include the intracellular events stimulated by an extracellular signal

252
Q

the function of a __ is to add phosphates to proteins, whereas a __ functions to remove the phosphates

A

protein kinase, protein phosphatase

253
Q

which of the following receptor types is NOT a membrane receptor

a. channel-like receptor
b. enzymatic receptor
c. G protein-coupled receptor
d. steroid hormone receptors

A

steroid hormone receptors

254
Q

how does the function of an intracellular receptor differ from that of a membrane receptor?

A

the intracellular receptor binds DNA

255
Q

signaling through receptor tyrosine kinases often

A

leads to the activation of a cascade of kinase enzymes

256
Q

what is the function of Ras during tyrosine kinase cell signaling?

A

it links the receptor protein to the MAP kinase pathway

257
Q

which of the following best describes the immediate effect of ligand binding to a G protein-coupled receptor?

A

the G protein trimer releases a GDP and binds a GTP

258
Q

the action of steroid hormones is often longer-lived than that of peptide hormones. this is because they

A

they turn on gene expression to produce proteins that persist in the cell

259
Q

the ion Ca2+ can act as a second messenger because it is

A

normally at a low level in the cytoplasm

260
Q

different receptors can have the same effect on a cell. one reason for this is that

A

signal transduction pathways intersect- the same pathway can be stimulated by different receptors

261
Q

in comparing small G proteins like Ras and GPCR proteins, we can say that

A

both proteins have intrinsic GTPase activity that stops signaling & both proteins are active bound to GTP

262
Q

the same signal can have different effects in different cells because there

A

a. are different receptor subtypes that initiate different signal transduction pathways.
b. may be different coactivators in different cells.
c. may be different target proteins in different cells’ signal
transduction pathways.

263
Q

The receptors for steroid hormones and peptide hormones are fundamentally different because

A

peptides are hydrophilic and steroids are hydrophobic

264
Q

what are the intermediates of the Krebs cycle?

A

“Can I Keep Selling Substances For Money, Officer?”

oxaloacetate (4C) and acetyl-CoA work to make citrate (6C) -> isocitrate (6C) -> a-Ketoglutarate (5C) -> succinyl-CoA (4C) -> succinate (4C) -> fumarate (4C) *FADH to FAD -> malate (4C) *H2O -> oxaloacetate (4C)

“Can I Keep Selling Substances For Money, Officer?”
Citrate
Isocitrate
Ketoglutarate
Succinyl CoA
Succinate
Fumarate
Malate
Oxaloacetate
265
Q

doorbell and finger example

A

ligand is finger
receptor is the doorbell
push button, signal transduction takes place
door bell ringing, stimulating the signal to go off

266
Q

phosphorylation

A

how response is regulated

-kinase

267
Q

dephosphorylation

A

phosphatase removes phosphate from protein

268
Q

steroids are __

A

lipids

269
Q

receptor kinases

A
  • protein kinases phosphorylate proteins to alter protein function
  • receptor tyrosine kinases (RTK)
270
Q

RTKs

A
  • Influence cell cycle, cell migration, cell metabolism, and cell proliferation
    a) Alteration to function can lead to cancer
  • Membrane receptor
  • Plants possess receptors with a similar overall structure and function
  • have 3 domains
  • When a ligand binds, dimerization and autophosphorylation occur
  • Cellular response follows – depends on cellular response proteins
271
Q

RTKs deal with what 3 amino acids?

A

Ser
Thr
Tyr

272
Q

kinases __

A

phosphorylate

273
Q

what are the 3 domains of RTKs

A
  • a single transmembrane domain
    a) Anchors them in membrane
  • Extracellular ligand-binding domain
  • Intracellular kinase domain
    a) Catalytic site of receptor acts as protein kinase
274
Q

insulin receptor

A
  • Activated receptor has phosphorylated sites that allow docking
  • Insulin binds to an RTK; insulin response protein binds to the phosphorylated receptor and is itself phosphorylated; signal is transmitted downstream to lower blood sugar
275
Q

insulin

A

a hormone that helps to maintain a constant blood glucose level

276
Q

kinase cascade

A

series of proteins that phosphorylate other proteins

- Mitogen-activated protein (MAP) kinases

277
Q

Mitogen-activated protein (MAP) kinases

A
  • class of cytoplasmic kinases
  • mitogen stimulates cell division
  • Activated by signaling module called a phosphorylation cascade/kinase cascade
  • Series of protein kinases that phosphorylate each other in succession
  • Amplifies the signal because a few signal molecules can elicit a large cell response
278
Q

signal amplification

A

signal -> receptor -> activator -> kinase cascade -> response proteins -> cell responses

279
Q

scaffold proteins

A
  • bind series of kinases on 1 protein
  • goes very quickly; leads to rapid response/transfer
  • Thought to organize the components of a kinase cascade into a single protein complex
  • Binds to each individual kinase such that they are spatially organized for optimal function
  • Benefit in efficiency
  • Disadvantage in reducing amplification effect
280
Q

Ras proteins

A
  • Small GTP-binding protein (G protein)
  • Link between the RTK and the MAP kinase cascade
  • is mutated in many human tumors, indicative of its central role in linking growth factor receptors to their cell response
  • is active when bound to GTP
  • inactive when bound to GDP
  • Ras switch is flipped by exchanging GDP for GTP (stimulated by GEFs) and by Ras hydrolyzing GTP to GDP.
  • Activated Ras activates the first kinase in the MAP kinase cascade
  • Ras can regulate itself – stimulation by growth factors is short-lived
281
Q

G protein-coupled receptors (GPCRs)

A
  • Single largest category of receptor type in animal cells
  • Receptors act by coupling with a G protein
  • G protein provides link between receptor that receives signal and effector protein that produces cellular response
  • All G proteins are active when bound to GTP and inactive when bound to GDP
  • Effector proteins are usually enzymes
282
Q

effector proteins are usually __

A

enzymes

283
Q

second messengers

A

stimulate the activation of processes in the cell

  • Often, the effector proteins activated by G proteins produce a second messenger
  • 2 common effectors
    1) Adenylyl cyclase
    2) Phospholipase C
284
Q

adenylyl cyclase

A
  • Produces cAMP
  • cAMP binds to and activates the enzyme protein kinase A (PKA)
  • PKA adds phosphates to specific proteins
285
Q

phospholipase C

A
  • PIP2 is acted on by effector protein phospholipase C
  • Produces IP3 plus DAG
    a) IP3 leads to produce calcium
  • Both act as second messengers
286
Q

Inositol Phosphates and calcium

A
  • Ca^(2+) serves widely as second messenger
  • Intracellular levels normally low
  • Extracellular levels quite high
  • IP3 binds to receptors on the ER, signals the release of Ca^(2+)
  • Ca^(2+) initiates some cellular responses by binding to calmodulin
287
Q

response to second messengers

A
  • Different receptors can produce the same second messengers
  • Hormones glucagon and epinephrine can both stimulate liver cells to mobilize glucose
    a) Different signals, same effect
    b) Both act by same signal transduction pathway
288
Q

epinephrine

A

boosts u up

289
Q

receptor subtypes

A
  • Single signaling molecule can have different effects in different cells
  • Existence of multiple forms of the same receptor (subtypes or isoforms)
  • Receptor for epinephrine has 9 isoforms
    a) Encoded by different genes
    b) Sequences are similar but differ in their cytoplasmic domains
  • Different isoforms activate different G proteins leading to different signal transduction pathways
290
Q

GPCRs and RTKs can activate same pathways

A
  • RTKs and GPCRs can both activate the MAP kinase cascade
  • RTKs and GPCRs can both activate phospholipase C
  • Cross-reactivity provides cells with flexibility
291
Q

non polar __ pass thru the phospholipid bilayer

A

can

292
Q

3 things that happen when an RTK is stimulated

A
  1. ligand binds to RTK
  2. RTK will dimerize
  3. dimerized form will autophosphorylate each other
  4. phosphorylated form will phosphorylate other proteins and those proteins will do the same throughout cell
293
Q

coupled receptor

A
  • not gonna be directly responding

- activated which will then result in activating effector proteins to respond

294
Q

example of an RTK

A

insulin receptor

295
Q

end process of insulin receptor

A

taking glucose out of circulatory system and forming glycogen, a stored form

296
Q

unlike insulin, glucagon and epinephrine..

A

stimulate breakdown of glycogen to release glucose into the system

297
Q

every time u lose an carbon,

A

energy is released and captured by e- carrier

298
Q

purpose of cell resp is to produce

A

ATP

299
Q

NAD+

A

accepts e- and becomes reduced to NADH

300
Q

glycolysis

A

Occurs in the cytosol of the cell
Begins cell resp by breaking glucose into 2 molecules of a 3-C compound called pyruvate
begins w a single molecule of glucose and concludes w/ 2 molecules of pyruvate
Glucose has 6-C, same 6-C end up in 2 molecules of pyruvate

301
Q

pyruvate oxidation in krebs cycle

A

Takes place within the mitochondria
Pyruvate is oxidized to a 2-C compound
The citric acid cycle then completes the breakdown of glucose to CO2
The cell makes a small amnt of ATP during glycolysis and the citric acid cycle
Main function of first 2 stages is to supply the 3rd stage of resp w/ e-

302
Q

oxidative phosphorylation

A

happens in inner mito membrane
Involves e- transport and chemiosmosis
Most of ATP produced by cell resp is generated here
The e- are finally passed to O2, which becomes reduced to H2O
As e- are passed down the e staircase, the ETC also pumps H+ ions across the inner mitochondrial membrane into narrow intermembrane space
Result is a conc gradient of H+ across the membrane
In chemiosmosis, the PE of this conc gradient is used to make ATP

303
Q

substrate level phosphorylation

A

an enzyme transfers a phosphate group from a substrate molecule to ADP, forming ATP
ATP is also generated by this in the citric acid cycle

304
Q

does pyruvate enter the Krebs cycle?

A

no

305
Q

parts of the mitochondria

A
  • outer membranes
  • intermembrane space
  • inner membranes (oxidative phos)
  • matrix (citric acid cycle)
306
Q

NADH and FADH2 go thru the __

A

ETC

307
Q

carbon cycle

A

C cycles from CO2 to glucose and back to CO2; uses the high e molecules to make glucose from CO2

308
Q

pyruvate is a _C molecule

A

3

309
Q

products of glycolysis

A

2 net ATP, 2 NADH, 2 pyruvates

310
Q

products of the citric acid cycle

A

ATP, NADH, and FADH2, CO2

311
Q

products of oxidative phosphorylation

A

2 pyruvates, 2 H2O, 2 ATP, 2 NADH, and 2 (H+)

312
Q

cell resp equation

A

C6H12O6 + 6O2 → 6CO2 + 6H2O (glucose + oxygen -> carbon dioxide + water)

313
Q

psyn equation

A

6CO2 + 6H2O + light energy = C6H12O6 + 6O2

314
Q

products of grooming pyruvate

A

NADH, CO2, acetyl Co-A

315
Q

energy in glucose must be converted into __, which is very reactive and can be used by cells

A

ATP

316
Q

main point of chemiosmosis

A

H+ moves down conc gradient, use ATP synthase, and make ATP

317
Q

main point of ETC

A

put e- in protein to pump H+ protons from mito matrix to inner membrane

318
Q

main purpose of light rxn

A

ATP and NADPH; use light e to convert low to high e molecules

319
Q

main purpose of dark rxn

A

make CO2 into glucose

320
Q

psyn

A

Plants make glucose & O2 from e in sunlight, CO2, and H2O
In chloroplasts

321
Q

chlorophyll

A

a light-absorbing pigment in the chloroplasts that plays a central role in converting solar e to chem e

322
Q

2 membranes in chloroplast

A

thylakoids and stroma

323
Q

which way do e- move in psyn?

A

Water is split, and its e- are transferred along w/ H+ ions to CO2, reducing it to sugar. The PE of e- increases as they move from H2O to CO2. the light e captured by chlorophyll molecules in the chloroplast provides this e boost

324
Q

e- acceptor of psyn

A

NADP+

325
Q

NADPH

A

temporarily stores e- and provides “reducing power” to the calvin cycle

326
Q

sugar isn’t made in psyn until ____

A

Calvin cycle

327
Q

Calvin cycle

A

occurs in the stroma of chloroplast; a cyclic series of rxns that assembles sugar molecules using CO2 and the e rich products of the light rxns; sometimes referred to as “dark rxns” or “light-independent rxns” bc none of the steps requires light directly

328
Q

carbon fixation

A

the incorporation of C from CO2 into organic compounds

After carbon fixation, the carbon compounds are reduced to sugars

329
Q

In the stroma, the enzyme __ combines CO2 with RuBP

A

rubisco

330
Q

ATP and NADPH are used to reduce a 3C intermediate to__

A

G3P

331
Q

the more ordered something is the __ energy it has

A

less

332
Q

example for ordered

A

less ordered room to a more ordered room, u put in energy to get ur room clean. therefore, the energy is released

333
Q

disorder happens __

A

spontaneously

334
Q
  • ΔG
A

products have less free e

  • exergonic
  • spontaneous
335
Q

+ ΔG

A

products have more free e

  • endergonic
  • ordered
336
Q

shape of enzymes affects the _ of the rxn

A

rate

337
Q

in catabolism of protein, glutamate is converted to __

A

Ketoglutarate

338
Q

competitive vs non-competitive inhibition

A

competitive:

  • binds to the site of the substrate
  • it inhibits the substrate from binding
  • decreases activity of enzyme
  • competes for active site

non-competitive:

  • binds to an allosteric site or site on another part of the enzyme
  • changes the SHAPE of enzyme
  • substrate doesn’t match the shape
  • aka allosteric inhibition
339
Q

allosteric inhibition is an __

A

on/off switch

340
Q

active vs inactive inhibition

A 
active:
- allosteric activator
- increases enzyme activity
- products formed 
inactive:
- allosteric inhibitor 
- decreases enzyme activity 
- no products formed
341
Q

the glycolytic pathway

A

glucose -> glucose 6-phosphate -> fructose 6-phosphate -> fructose 1, 6-biphosphate ** separates into 2

1) dihydroxyacetone phosphate
2) glyceraldehyde 3-phosphate (G3P)
- 1, 3- diphosphoglycerate (BPG)
- 3- phosphoglycerate (3 PG)
- 2- phosphoglycerate (2 PG)
- phosphoenolpyruvate (PEP)
- pyruvate

342
Q

enzymes of the Krebs cycle

A

Acetyl-CoA + oxolacetate -> citrate synthase, -> citrate -> aconitase, ->isocitrate -> isocitrate dehydrogenase, –> Ketoglutarate -> Ketoglutarate dehydrogenase, -> succinyl-CoA -> succinyl CoA synthase, -> succinate -> succinate dehydrogenase, -> fumarate -> fumarase, -> malate -> malate dehydrogenase -> oxolacetate

343
Q

products of the Krebs cycle

A
  • 3 NADH net: 6
  • 2 CO2 net: 4
  • 1 ATP net: 2
  • 1 FADH2 net: 2
344
Q

net means

A

x 2 to get overall #

345
Q

c4 plants diagram

A

mesophyll vs bundle sheath

-mesophyll:
O2 + PEP = 5C -> oxolacetate -> malate (4C) -> enters bundle sheath shell
->
1) pyruvate
2) CO2 -> enters Calvin cycle -> G3P -> glucose

346
Q

CAM plants diagram

A

night vs day

night:
CO2 -> C4 -> CO2 -> Calvin cycle -> G3P

347
Q

What oxidizing agent is used to temporarily store high energy electrons harvested from glucose molecules in a series of gradual steps in the cytoplasm?

A

NAD+

348
Q

an exergonic rxn occurs __

A

spontaneously

349
Q

what is activation e?

A

The energy required to initiate a chemical reaction.

350
Q

NADPH is made by

A

the passing of electrons from photosystem I to an electron transport chain.

351
Q

in aerobic respiration, chemiosmotic generation of ATP is driven by:

A

a difference in H+ concentration on the two sides of the inner mitochondrialmembrane.

352
Q

For photosynthesis in green plants, the electron donor for the light dependent reaction is

A

water

353
Q

What color of light is least strongly absorbed by chlorophyll?

A

green

354
Q

ATP hydrolysis drives __ reactions

A

endergonic

355
Q

Visible light has a wavelength range of

A

400-740 nanometers.

356
Q

What happens to the oxygen that is used in cellular respiration?

A

its reduced to make water

357
Q

Most enzymes are composed of ___

A

proteins

358
Q

what are the common monosaccharides?

A

glucose and fructose

359
Q

what are the common disaccharides?

A

sucrose, lactose, and maltose

360
Q

what are the common polysaccharides?

A

starch and glycogen

361
Q

The Krebs Cycle is an __ pathway, while the Calvin cycle is an ___ pathway

A

Amphibolic ; anabolic

BIO 1510 (10 decks)

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