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Biog1440 > Prelim 1 Biog1440 > Flashcards

Prelim 1 Biog1440 Flashcards

1
Q

Cell membrane

A

membrane that separates the cell from its environment

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2
Q

Phospholipids

A

Synthesized from glycerol & two fatty acid side chains in ester linkage. The third alcohol (-OH) functional group is linked to a phosphate containing head group.

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3
Q

Amphipathic

A

Contain both hydrophobic and hydrophilic molecules

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4
Q

Hydrophobic

A

Not soluble with water

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5
Q

Hydrophilic

A

Polar, soluble with water

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6
Q

4 major phospholipids

A

Phosphatetidylcholine, phosphateidylethanolamine, phosphatidylserine, sphingomyelin *additional: Phosphatidylinositol

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7
Q

Entropy

A

The measure of randomness of a system
High entropy: high disorder & low energy
Low entropy: Lower disorder & greater energy

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8
Q

Hydrophobic effect

A

Hydrophobic molecules mix well in hydrophobic solvents & hydrophilic molecules with hydrophilic solvents (water) LIKE MIXES WITH LIKE

Phospholipids will spontaneously assemble into bilayers due to hydrophobic effect. Hydrophobic molecules with water tend to form cage like shells (altercate) separating water which forms an ice like layer.
Which is chaotic=entropy which is favorable though it goes against thermodynamics

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9
Q

Fluid mosaics

A

Phospholipids are not covalently linked to one another, they’re held together by weak hydrophobic forces. So these phospholipids can diffuse around in the plane of the membrane from side to side.

Chemical composition can change to maintain membrane fluidity. A model of membrane structure in which proteins are inserted in a fluid phospholipid biolayer

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10
Q

Fluidity

A

Controlled by the introduction of a double bond into a fatty acid side chain which leads to bends or kinks in the fatty acid chain which weakens the intra & intermolecular packing interactions (ex. cholesterol)

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11
Q

Cholesterol

A

At warm temperatures (37 degrees) it limits excess fluidity. At cool temperatures cholesterol maintains fluidity, prevents tight packing of FA chains.

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12
Q

Laterally

A

Lipids and proteins can drift laterally but the size of the proteins & their interactions often limit their movement.

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13
Q

Peripheral membrane

A

Surface of the membrane but don’t actually extend into the membrane. Operationally defined as proteins that dissociate from the membrane following treatments with polar reagents, such as solutions of extreme pH or high salt concentration that DO NOT disrupt the phospholipid bilayer

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14
Q

Integral membrane

A

Extends through the bilayer and usually peaks out of both sides. Proteins can be released only by treatments that disrupt the phospholipid bilayer (ex. detergents)

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15
Q

Outer leaflet

A

Mainly phosphatidylcholine & sphingomyelin

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16
Q

Inner leaflet

A

Phosphatidylethanolamine & phosphatidylserine

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17
Q

Why is the phospholipid important?

A
  1. The interior phospholipid bilayer uses hydrophobic fatty acid chains which makes it impermeable to water
  2. Bilayers of phospholipids are fluid so the fatty acids of phospholipids have one or more double bonds which introduce kinks into the hydrocarbon chains & makes them difficult to pack together; therefore the long hydrocarbon chains move freely in the interior of the membrane so its flexible.
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18
Q

Cells can vary the properties of their membranes in two ways:

A
  1. They can change the type of polar head group (chlorine-serine-glycerol-ethanolamine) which changes the charge & properties of the membrane
  2. Change the length & shape of fatty acids
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19
Q

Homeoviscous Adaptation

A

Cells actively regulate membrane fluidity by changing the shape of their fatty acids depending on the temp they are grown

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20
Q

Transmembrane Proteins

A

Typically require assistance to integrate into membranes

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21
Q

SecYEG Translocon

A

Proteins that help other proteins cross or move into the membrane where they become integrated into the membrane. Once the protein is integrated, it can be modified.

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22
Q

Osmosis

A

The net movement of water (solvent) across a selectively permeable membrane into a region of higher solute concentration.

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23
Q

Facilitated diffusion

A

Speeds the passive movement of solutes across the membrane.
When transport proteins speed the passive movement of molecules across the plasma membrane (down a concentration gradient).

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24
Q

Active transport

A

Requires the energy of ATP or the energy available in other gradients (e.g. PMF) & leads to the accumulation of solutes against their gradients.
Uses energy to move solutes against (up) their gradients.
Can also use energy stored in chemical gradients

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25
Q

Six Major Functions of Membrane Proteins

A
  1. Transport - water & solutes
  2. Cell-cell recognition
  3. Intercellular joining
  4. Attachment to the cytoskeleton & extracellular matrix (ECM)
  5. Enzymatic activity
  6. Signal transduction
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26
Q

Cell-cell recognition

A

This type of intermolecular recognition helps cells adhere to each other & recognize each other. Protein complex spanning red blood cell membrane, the carbohydrate types give rise to the ABO blood groups.

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27
Q

Intercellular joining

A

Many cells are joined together by gap junctions (plasmodesmata in plant cells), made up of the protein connexin. So proteins can play important functions in helping cells join & communicate with each other.

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28
Q

Attachment to the cytoskeleton & extracellular matrix

A

Many eukaryotic cells are surrounded by a complex environment which may include an extracellular matrix. This matrix may include a variety of polymers, proteins & carbs. This matrix provides a substrate for the interaction of many different cell types.

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29
Q

Enzymatic activity & signal transduction

A

Proteins are important in cell signaling bc many proteins have an enzymatic function & some of these enzymes are important in signal transduction (GPCRs)

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30
Q

GCPRs

A

Largest family of cell surface receptors in humans
Activate the “G proteins”
G proteins affect the production of “second messenger” molecules

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31
Q

Passive transport

A

Is diffusion of a substance across a membrane with no energy expenditure

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32
Q

Osmosis

A

Diffusion of free water across a selectively permeable membrane, like a plasma membrane (more technically, it is the movement of solvent across a selectively permeable membrane into a region of higher solute concentration).

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33
Q

Isotonic solution

A

Solute concentration is the same as that inside the cell; no net water movement across the plasma membrane

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34
Q

Hypotonic solution

A

Solute concentration outside is less than that inside the cell; therefore. H20 concentration is higher… cell gains water

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35
Q

Hypertonic solution

A

Solute concentration is greater outside than inside; cell loses water.

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36
Q

Plant cells turgid

A

Plant cells are normally “swollen”; this is turgor pressure and is constrained by the cell wall.
Hypotonic: turgid
Flaccid: Isotonic
Hypertonic: Plasmolyzed

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37
Q

Aquaporins

A

Facilitate the diffusion of water (Aquaporins are integral membrane proteins)
Have a water channel that allows water to pass

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38
Q

Cotransport

A

Also called secondary active transport uses the energy of ATP directly as in the proton pump.

Couples H+ with sucrose [needed molecules]

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39
Q

Membrane potential

A

The voltage difference across a membrane

Voltage is created by differences in the distribution of positive & negative ions across a membrane.

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40
Q

Electrochemical gradient

A

Two combined forces, collectively called the electrochemical gradient, drive movement of ions across a membrane.

  • -> A chemical force (the ion’s concentration gradient)
  • -> An electrical force (the effect of the membrane potential on the ion’s movement)
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41
Q

Plants and microbes use

A

Proton pumps that are powered by ATP. The gradient of protons is an energy source for cells.

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42
Q

Bulk transport

A

Uses exocytosis; cell transports molecules out of the cell (uses energy)

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43
Q

Endocytosis

A

Phagocytosis, Pinocytosis, Receptor-Mediated Endocytosis

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44
Q

Phagocytosis

A

A process in which particles present in the environment can be engulfed into a vacuole. Some cells may use this to feed.

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45
Q

Pinocytosis

A

A process in which vacuoles may be used by the cell to drink (water)

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46
Q

Receptor-Mediated Endocytosis

A

Whereby compounds binding to the surface of the cell can trigger an engulfment reaction

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47
Q

Model for a cell membrane

A 
Ideally we want a cell that is 
-Abundant & easy to isolate 
-Has a typical eukaryotic membrane 
-Lacks internal membranes 
Therefore, Red Blood Cells
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48
Q

O2, CO2, H20

A

Can diffuse into the membrane without a carrier

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49
Q

Uniporters

A

A uniporter carries one molecule or ion

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50
Q

Symporter

A

A symporter carries two different molecules or ions, both in the same direction

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51
Q

Antiporter

A

An antiporter also carries two different molecules or ions, but in different directions.

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52
Q

Metabolism

A

The totality of an organism’s chemical reactions. Much of metabolism is organized into pathways that utilize enzymes to convert a substrate to a desired product or products.

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53
Q

Enzymes

A

Proteins that speed up metabolic processes by acting as catalysts mainly by lowering the energy of activation of a reaction.
Speed up reactions by reducing Ea. However, delta G is unaffected, enzymes speed up kinetics, does not affect thermodynamics

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54
Q

Delta G

A

The favorability of reactions or pathways is given by delta G, Gibbs free energy.
Negative G are energetically favorable and can do work
G=0 cannot be used to do work
The free-energy change of a reaction is the free energy difference between the reactants and products (free energy of the products minus free energy of the reactants). The energy change is the sum of the changes in enthalpy.
Delta G= Delta H - T(Delta S)

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55
Q

ATP’s importance in enzymatic activity

A

ATP is a critical energy coupling molecule since its hydrolysis has a large negative delta G.

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56
Q

Eukarya

A
  • More complex cells
  • Made for multicellular organisms
  • Rely on chemistry invented early in evolution
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57
Q

Unity if biochemistry

A

The biochemistry that underlies life evolved early and it has been retained throughout the many branches of life

*aerobic prokaryote and photosynthetic prokaryote as the early mitochondria and chloroplast

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58
Q

Endosymbiosis

A

Describes the process of “taming” of a bacterial cell after engulfment by an ancestral Eukaryote (over many, many generations)

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59
Q

Mitochondria

A

(respiration) evolved from an aerobic, O2 respiring bacterium. Generates ATP and is known as the powerhouse of a cell.

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60
Q

Chloroplast

A

(photosynthesis) evolved from a photosynthetic (O2 generating) bacterium. Responsible photosynthesis.

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61
Q

A+B kf kf AB

Keq= [AB]/[A][B]

A

A and B are reactants (enzyme substrates).

AB is the product

62
Q

Keq

A

The equilibrium constant. Determines the equilibrium

63
Q

kf and kr

A

Rate constants kf and kr are used when calculating reaction rates

64
Q

Keq>1

A

Reaction favors the product

65
Q

Keq<1

A

Reactions that are unfavorable

66
Q

Negative Delta G

A

Reactions with a negative delta G are spontaneous, require no energy input. Spontaneuous energy can perform work. E.g. active transport?*

67
Q

Positive Delta G

A

Reactions with a positive delta G are not spontaneous, require energy input to proceed.
e.g. ATP Production

68
Q

Delta G=-RTInKeq

A

When Keq is <1, ex. -1, and you plug it into the formula, the delta G will be positive which means that the reaction is not spontaneous and requires energy input. This is true because when Keq<1, the reaction is unfavorable energetically

69
Q

Exergonic Reactions

A

-Releases energy
-Spontaneous
-Delta G<0
- Large negative delta G = irreversible reaction
Memorize exergonic and endergonic graphs

70
Q

Endergonic reaction

A

-Requires input of energy
-Not spontaneous
-Delta G>0
Memorize exergonic and endergonic graphs

71
Q

What if delta G is zero?

A

It will lean more towards the negative side.

72
Q

Kinetics

A

Measures how fast a reaction proceeds. Defined by rate constants [k]

73
Q

Forward Reaction

A

Rate=kf[A][B]

74
Q

Reverse Reaction

A

Rate=kr[AB]

75
Q

At equilibrium…

A

The forward and reverse reactions are equal, and the relative concentrations of products and reactants stop changing

  • the reaction is still going on, but there is no net effect on the concentrations of reactants and products
  • equilibrium does not mean that the concentration of reactants and products are equal, but only that their concentrations have stabilized at a particular ratio
76
Q

The more reactants there are…

A

The more rapidly the reaction will proceed, as reactants are used up, it will slow down

77
Q

The reverse rate reaction…

A

occurs at a very slow rate. As the reaction proceeds and AB accumulates in the system, the reverse reaction will begin to occur more rapidly.

78
Q

Reactions will proceed until they reach…

A

Equilibrium

79
Q

Keq=kf/kr

A

Therefore, Keq=ratio of the forward and reverse rate constants

80
Q

Transition State

A

Determines kinetics or how rapidly the reaction occurs

  • unstable
  • high energy
  • thermodynamically unfavorable
81
Q

(Ea)

A

The activation energy for the forward reaction. Determines kf under a given set of conditions.

82
Q

Spontaneous reactions (in terms of energy requirements)

A

Can also be initiated by an input of energy or by lowering the activation energy

83
Q

Cofactors

A

Enzymes may also require cofactors for their function

  • -> metalloenzymes
  • Use metal ions as cofactors
  • All cells require metals for life
  • Cofactors aid enzymes so they can lower activation energy
84
Q

Organic cofactors

A

NADH, NADPH, FAD

85
Q

Concentration

A

Creates high local concentration of substrates (next to each other)

86
Q

Orientation

A

Holds them in a precise orientation

87
Q

Facilitation (please watch this explanation again when you come across this card)

A

Speeds reactions using active site “acids” and “bases” or other functional groups and cofactors

Uses side chains of amino acids to regulate pH.

88
Q

Stabilization of transition state

A

Uses binding energy energy to stabilize the transition state, thereby increasing the probability of reaction

89
Q

Active site

A

The binding of substrates to enzymes occurs at a specific pocket on the surface of an enzyme

90
Q

Induced fit

A

substrate binding changed shape of enzyme

91
Q

Competitive

A

Molecules structurally similar to the substrate can bind to the active site; block substrate binding

Substrate increases its abundance to increase its probability of binding at the active site.

92
Q

Non-competitive

A

Molecules bind to a separate site (allosteric site); do not block substrate binding, but block enzyme function (e.g. prevent “induced fit”)

93
Q

Allosteric regulation

A

A regulatory molecule binds a proteins at one site, affects the protein’s function at another site, can either inhibit or stimulate enzyme activity

94
Q

Feedback Inhibition (look at diagram from slides/videos)

A

A special case of negative, allosteric regulations, The product of a pathway acts as a negative allosteric regulator of the first step in the pathway. An example of non-competitive enzyme inhibition
Allows chemical flow (flux) through the pathway to respond to cellular needs (when product is high, pathway turns off) - mechanism of homeostasis.

95
Q

How can endergonic reactions become more energetically favorable?

A
  • Energy from exergonic ATP hydrolysis can drive an otherwise endergonic reaction (coupling the reaction)
  • Drain the product to be less than one
96
Q

What can affect enzymatic activity?

A

Temperature, pH, and chemicals that specifically influence the enzyme

97
Q

Catabolism

A

Breakdown of organic compounds to simpler components.

  • Often oxidation reaction
  • Importance: can yield energy and detoxify reactions
98
Q

Anabolism

A

Buildup of complex molecules from simpler ones

  • usually requires energy
  • Common precursors (from central metabolism)
  • Phospholipids
  • Macromolecules (proteins, nucleic acid)
99
Q

Key Steps in Cellular Respiration

A
  • Glycolysis
  • Pyruvate Oxidation
  • TCA Cycle
  • Oxidative Phosphorylation
100
Q

Results of Cellular Respiration

A

Oxidation of glucose all the way to carbon dioxide and water, generation of ATP, & generation of many precursor molecules that can be used to build up other molecules important for the cell

101
Q

Redox reactions

A 
Oxidation-reduction reactions (redox):
Transfer electrons between reactants 
- Loss of Electrons, Oxidation (LEO)
- Gain of Electrons, Reduction (GER)
Xe- + Y --> X + Ye-
Oxidation: Xe- loses an electron, becomes X 
X is the reducing agent for Y. 
Reduction: Y gains an electron, becomes Ye- 
Y is the oxidizing agent for x
102
Q

Why is oxygen so important in respiration?

A

Oxygen happens to be one of the most powerful oxidizing agents in biology. It has the highest redox potential of any electron acceptor.

103
Q

Cellular Respiration

A

Formula:
C6H12O6 + 6O2 –> 6CO2 + 6H2O
Source of most cellular energy

104
Q

Glycolysis (catabolic)

A

The lysis or breaking apart of the sugar. This yields 2 molecules of pyruvate.
C6H1206 + 2NAD+ + 2ADP = 2Pi –> 2 pyruvate (C3H4O3) + 2ATP + 2NADH + 2H+
Key inputs: Glucose, 2 ATP (in), 2NAD+
Outputs: 2 pyruvate, 2 NADH, 4 ATP

105
Q

Pyruvate oxidation

A

Pyruvate is then oxidized into acetyl-CoA and CO2
2 pyruvate +2NAD+ + 2CoA –> 2acetyl-CoA + 2NADH +2H+ + 2CO2
Key inputs: 6 Carbons (per glucose). 2NAD+, 2CoASH (free CoA)
Key outputs: 2CO2, 2NADH, 2Acetyl-CoA,

106
Q

Tricarboxylic acid cycle (TCA)

A

Pyruvate is transferred into the TCA cycle where it is further oxidized with the generation of reducing equivalent electrons carried by carrier cofactors in the cell. Oxidizes acetly-CoA making NADH, FADH2, and ATP.
2Acetyl-CoA +4H20 +6NAD+ +2FAD + 2ADP + 2pi –> 4CO2 + 6NADH + 2FADH2 + 2CoASH + 2ATP + 6H+
Each turn of the cycle:
Key steps:
-2 carbons in as acetyl-CoA per glucose, turns the cycle twice
-2 carbons out as CO2 through oxidation
-3 NAD+ reduced to NADH, and 1 FAD reduced to FADH2
Output: 1 ATP per cycle

107
Q

Oxidative Phosphorylation

A

Electrons are transferred through what’s called the electron transport chain to generate a proton gradient that can then be used to generate ATP. Accounts for most of the ATP synthesis makes a proton gradient from NADH, FADH2, oxidation by O2.
10NADH + 25ADP + 25Pi –> 10NAD+ + 10H+ + 25ATP
* reoxidizes NADH and FADH2
Key inputs: NADH & FADH2
Outputs: NAD+, FAD+, H2O and ATP (mainly)
-As NADH oxidized, the electrons are transported down a chain of protons (ETC) to O2
-As they pass electrons, they produce a H+ gradient (PMF) across the membrane (10 H+ per NADH)
- H+ ions flow by chemisomosis through to generate ATP from the H+ gradient
-The ATPase is an “active transporter” that can use ATP hydrolysis to transport, BUT during chemiosmosis it runs in reverse

108
Q

Glycolysis is in the ____ of the cell and the rest of the breakdown occurs in the

A

Mitochondria

109
Q

Coenzyme A

A

Example of an enzyme cofactor
Synthesized in 5 steps from 4 ATPS, Pantothenate, and Cysteine
Important because it carries the acetyl groups into the next stage

110
Q

Chemiosmosis

A

H+ flowing back through F1F0 synthase
Provides energy to make ATP
Movement of ions across semipermeable membrane, down their concentration gradient

111
Q

Electron Transport Chain

A
  • Electrons from NADH flow to acceptors with increasingly larger redox potential (change E)
  • Means accceptors have increasing tendency to accept electrons; like molecules flowing down a concentration gradient, from high to low
112
Q

Redox potential increases…

A

As electrons flow which means electron donor < electron carrier < electron acceptor (O2)

113
Q

Q= coenzyme Q (ubiquinone)

A

A lipid soluble, diffusible electron carrier

114
Q

Proton Motive Force

A

Proton gradient used to drive ATP synthesis

115
Q

Basal Metabolic Rate

A

The rate of O2 consumption when a person is totally at rest in a constant temperature environment can be used to establish the BMR, this is the minimum amount of energy needed, in calories, to support life.

116
Q

Q10

Equation: Q10 = (R2/R1)^(10/T2-T1)

A

Is a quotient describing the sensitivity of a process to temperature. Tells us how sensitive an enzyme is to change in temperature.

117
Q

Anaerobic respiration

A

Respiration without oxygen. Instead of O2 being the oxidizing agent, other electron acceptors have this role.
ex. Sulfate, nitrate

118
Q

Production of methane

A

In certain archaea, a specialized form of anaerobic respiration occurs in which H2 gas is the electron donor and CO2 is the electron acceptor, resulting in methane.

119
Q

Fermentation

A

respiration without oxygen or a proton gradient. The first sets of reactions are the same as glycolysis, where the oxidizing agent is NAD+ which becomes reduced to NADH, enabling the oxidation of glucose to pyruvate

  • pyruvate can be reduced to lactate or ethanol
  • no regeneration of NAD+
  • glycolysis would stop when NAD+ is depleted
120
Q

Photosynthesis

A

Uses light energy to generate ATP, and the reduced compound, NADPH
-organic molecules produced by photosynthesis support both catabolic and anabolic metabolism
~50% is used for growth and assembly of macromolecules (anabolism)
~50% is used for respiration to provide energy (catabolism)

121
Q

Photons are absorbed by…

A

pigments and electrons are shifted to an excited state

122
Q

PS II

A

Excited electrons are transferred from the reaction center (P680 special pair of chlorophyll molecules) to the primary electron acceptor (phophytin)
The electron then enters an ETC which allows a pumping of protons (to establish a proton gradient)
The proton gradient is used to make ATP by chemiosmosis (this is called photophosphorylation) rather than ox phos

123
Q

Photophosphorylation and Ox Phos are examples of..

A

Chemiosmosis

124
Q

PS I

A

The electrons lost from the P680 reaction center are replaced with electrons generated by the spitting of H2O in the oxygen-evolving complex (OEC), which results in protons (H+), oxygen atoms that combine into O2 & electrons.
Contains the P700 reaction center, and excited electrons enter a second ETC where they are ultimately captured as the reduced NADPH

125
Q

What is produced from the z scheme?

A

ATP, NADPH

126
Q

Heterotrophs

A

Rely on complex carbon sources

127
Q

Autotrophs

A

Can obtain carbon from inorganic sources CO2; plants and photosynthetic microbes

128
Q

Photo

A

Light

129
Q

Chemo

A

Chemical energy

130
Q

Phototrophy

A

Energy from light

131
Q

Chemotrophy

A

Energy from chemicals

132
Q

Methanogenesis

A

Methane gas can be generated and released into the atmosphere, and also in livestock (particularly cattle) where, as they graze on food stuffs (these are chemoheterotrophs, of course) the biomass that they’ve consumed ends up undergoing a complex fermentation in the cow rumen. And in this environment, these fermentation end-products support methanogenesis. leading to the production of methane.

133
Q

Branched respiratory

A

Bacteria will happily use O2 if its available but can adapt to anaerobic conditions by using alternative electron acceptors
ex. nitrate, sulfate, fe, mn (metals)

134
Q

Nitrogen fixing bacteria

A

Bring nitrogen from the atmosphere into a fixed form that can be used by other organisms

Respiratory dehydrogenases

135
Q

Methanogens

A

The roles of plants and cyanobacteria in this cycle by fixing carbon dioxide into organic matter, the roles of plants/animals/microbes in recycling that fixed organic matter by aerobic oxidation, respiration, to regenerate CO2

136
Q

Great Oxidation Event

A

Cyanobacteria invented oxygenic photosynthesis and is responsible for the O2 in the atmosphere.

137
Q

Thylakoid membrane

A

Inside the chloroplast and harvests light. The output of the light reactions in the thylakoid is reducing equivalence.

138
Q

Calvin Cycle

A

Carbon dioxide is going to be fixed into organic carbon and ultimately into sugars. This requires the ATP and NADPH generated by the light reaction.

139
Q

Light Reactions

A

Convert light energy to ATP and NADPH
Inputs: light, H20
Outputs= ATP, NADPH, O2

140
Q

Z scheme

A

Two photosystems in sequence

141
Q

Photosystem II

A

Photosystem 2 is going to use light energy to generate an electron that is not and has high reduction potential
The connection between the two systems is an electron transport chain where generating a proton motive force can then be harvested as ATP.

142
Q

Photosystem I

A

The electron delivered from photosystem two can again be accelerated to a very high-energy state using energy input from a photon.
That very high energy electron can then be used to create a reducing molecule, NADPH

143
Q

Action spectrum

A

The amount of oxygen being released by photosynthetic cells when you shine them on different wavelengths (there isn’t much activity on green which is why plants reflect a green color)

144
Q

Carotenoids

A

They can absorb light energy very well and transfer the energy through a non radiative energy transfer process. They can transfer energy to other chlorophyll molecules. They provide photo-protection by absorbing excessive light.

145
Q

Donor energy transfer

A

Energy transfer between molecules does not depend upon transfer of light or electrons but is due to donor energy transfer that requires direct interaction between the molecules.

146
Q

Oxygen Evolving Complex

A

Oxidizes H20 to replenish electrons.

2H20 –> O2 +4H+ 4 electrons

147
Q

Reducing equivalent

A

Any of a number of chemical species which transfer the equivalent of one electron in redox reactions

148
Q

Cyclic photosynthesis

A
  • Involves one photosystem
  • There is no terminal electron acceptor
  • Makes ATP through chemiosmosis
  • Cyclic electron flow; does not make NADPH
149
Q

Sensor Proteins

A

Detect if the membrane fluidity is too low in cold temperatures.

150
Q

NarGHI

A

The NarGHI in the inner membrane will accept electrons from reduced quinone carriers. The electrons are transferred through a series of carriers, hemes that have a central iron atom and iron sulfur clusters all the way to nitrate, where nitrate is reduced to nitrite. In the process, two protons are released into the periplasm to help generate PMF and sustain ATP generation.

Active when O2 isn’t available

Biog1440 (4 decks)

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