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microbio > lecture 7 and 8 > Flashcards

lecture 7 and 8 Flashcards

1
Q

what are the three types of work?

A
  • Chemical work - synthesis of complex molecules
  • Transport work - takes up nutrients, eliminates wastes, and maintains ion balances
  • Mechanical work - cell motility and movement of structures within cells
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2
Q

frst law of thermodynamics

A

energy can not be created or destroyed only converted

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3
Q

The second law of thermodynamics

A

in any natural process, the total “entropy” (disorder) of a system always increases or stays the same
(physical and chemical processes proceed in ways that the disorder of the universe increases )

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4
Q

Entropy

A

the amount of disorder in the system

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5
Q

Gibs free energy
what sign is G for exergonic and endergonic ?

A

The available energy that can be used
- extergonic: negative
- endogonic - postive

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6
Q

what kind of reaction is ATP when P is given up?

A
  • spontaneous and It powers cellular work by coupling exergonic reactions to endergonic reactions
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7
Q

what does energy coupling power?
how does it work?

A
  • cellular work
  • Cells can drive no-spontaneous (endergonic) reactions by supplying them with free energy released by spontaneous (exergonic ) reactions - coupling
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8
Q

when would atp not be needed?

A

A -> B + C
D + E -> F
The energy from this reaction can be used to support a neighboring one - it will be quicker than just using ATP

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9
Q

Redox reactions

A
  • Transfer of electrons from an electron donor to an electron acceptor
  • The donor stores less energy and the acceptor stores more energy
  • The more electrons a molecule has the more energy-rich it is
  • OIL RIG (oxidation is loss and reduction is gain)
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10
Q

what is Standard redox potential (Eo)?
what does it eman when it is postive or negative?

A
  • This is the equilibrium constant for an oxidation-reduction reaction
  • A measure of the tendency of the donor agent to lose an electron
  • The more negative Eo is the better electron donor it is
    Spontaneously donates electrons
    The more positive Eo is the better electron acceptor it is
    Greater affinity for electrons
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11
Q

what is ETC?
why is the first electron important?

A
  • Organized and membrane-bound electron carriers
  • The first electron carrier to have the most - E
  • The potential energy stored in the first redox couple is released and used to by ATP
    The first carrier is reduced and electrons move to the next carrier and so on
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12
Q

what are teh three types of biochemical pathways?

A

Linear -s starting molecule and end product defined
Cyclic all molecules are considered intermediates
allows for extra input and regenerates starting components etc
Branching - can yield more than one produc

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13
Q

What are important parts of biochemical pathways when forming complex networks?

A
  • Regulation of metabolism is important
  • It conserves energy and materials and maintains the metabolic balance despite changes in the environment
  • Pathways overlap and feed into each other
  • In each step in a reaction an enzyme controls it and multiple pathways may be available
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14
Q

What can enzymes do?

A
  • Speed up a reaction without being consumed by it
  • Promotes formation and breaking of covalent bonds
  • Extremely specific to the substrate and chemical reaction
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15
Q

how can enzymes change reaction rates?
- what effect does not having enzymes have on the activation energy?

A
  • Enzymes increase the rate of reactions but don’t alter their equilibrium constants
  • A typical exergonic reaction
  • The enzyme speeds up the reaction by lowering Ea
  • Without the enzyme, the activation energy is much higher compared with an enzyme
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16
Q

Activation energy

A

the energy required to form a transition state complex

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17
Q

How does net energy of Gibbs energy change with relation to enzymes?

A

The net energy for G is unchanged - enzymes do not change your overall energetic gain but favor the reaction to happen

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18
Q

how do enzymes lower Ea?

A
  • Enzymes bring substrates together in the active site
  • Induced fit model for enzyme-substrate interaction
  • Substrates orientated properly to form transition state complex
19
Q

how can substrate concentrations affect enzyme activity?
what can impact enzyme activity?

A
  • The reaction rate increases as substrate concentration increases
  • No further increase occurs after all enzyme molecules are saturated with substrates
  • substrate concentration
    -pH
  • Temperature
  • `Denaturation
20
Q

what are the types of enzyme inhibition? what can they do?

A
  • Competitive inhibitor - directly competes with the binding of a substrate to a catalytic site
  • Non-competitive inhibitor - binds at enzyme site other than active site and changes enzyme shape so that it becomes inactive or less active
  • Allosteric effector - binds reversibly and noncovalently at a regulatory site
    =Changes the shape of the enzyme and alters the activity of the catalytic site
21
Q

what is covalent modification of enzymes? Advantages?

A
  • Reversible on and off
  • Addition or removal of a chemical group (phosphate methyl or adenyl)
  • Advantages
    =Respond to more stimuli in varied ways
    =Regulation of enzymes that catalyze covalent modifications adds a second level of regulation
22
Q

what discovery did Cech and Altman make?

A

some RNA molecules can catalyze reactions

23
Q

Phototrophs
chemotroph

A
  • uses light as an energy source
  • obtained energy from the oxidation of chemical compounds
24
Q

lithotrophs
organotrophs

A

uses reduced inorganic substances for electrons
extracts electrons from reduced organic compounds

25
Q

heterotrophs
autotrophs

A

uses organic molecules such as carbon sources
- use CO2 as their sole or principal carbon source (obtained energy from other sources)

26
Q
  • what are the two types of respiration?
  • what does it use?
  • how do electrons and protons move?
A
  • aerobic respiration - final electron acceptor is oxygen
  • anaerobic respiration - final electron acceptor is different oxidized molecules like NO3-, SO4^2- or Fe^3+
  • uses an electron transport chain
  • electrons pass through ETC to the terminal electron acceptor creating a portion motive force (PMF or proton gradient) and makes ATP
27
Q

what is respiration’s energy source?
glucose catabolism
- forms what?
- produces?
- what is oxidized?

A
  • generate glucose or intermediates using glucose metabolism
  • forms pyruvate which is oxidized t CO2 and makes GTP, NADH and FADH2 which is then oxidized by ETCusing O2 as terminal e- acceptor
28
Q

What are the three main pathways that catabolize glucose into pyruvate?

A
  • Embeden-Meyerhof pathway (most common)
  • Entner-Douddoroff pathway
  • pentose phosphate pathway (hexose monophosphate pathway)
29
Q

when is the Entner-Douddoroff pathway used?
- net yield

A
  • used by gram-negative bacteria, certain gram-positive bacteria and archaea
  • 1 ATP, 1 NADPH, 1 NADH
30
Q

for the pentose phosphate pathway, it happens in the cytosol what effect does that have?
what is it an alternative pathway to?
-

A
  • +/- O2
  • ## glycolysis
31
Q

what does the link reaction make?
what does oxidizing pyruvate form?

A
  • 1 glucose -> 2 pyruvate -> 3co2
  • NADH , 1 CO2 and acetyal co-A
32
Q

what does the Krebs cycle produce?

A

2 CO2 3 NADH 1 FADH2 1 GTP

33
Q

how much ATP is made from oxidation of glucose?
where is majority of the ATP being made?

A

4 ATP
in ETC

34
Q
  • what is the maximum total yield of ATP during aerobic respiration?
  • what are the factors that affect ATP yield?
A
  • 32
  • factors
    = bacterial ETC is shorter
    = ATP production may vary with environmental conditions
    = PMF in bacteria and archea is used for other purposes than ATP production
    = precursors metabolites may be used for biosytnesis
35
Q
  • what are the terminal electron in anaerobic respiration?
  • How much ATP is produced?
A
  • something other than O2 - nitrate, sulfur, co2, metals
  • less ATP because Eo of electron acceptors is less positive than EO of O2
36
Q

what are the three different ETC?

A
  • aerobic respiration - O2 as terminal electron acceptor and max energy is made
  • dissimilatory nitrate reduction - nitrate is the terminal electron acceptor, makes it unavailable for the cell to assimilate or uptake
  • denitrification - reduction of nitrates to nitrogen gas
37
Q
  • what is the electron acceptor in termination?
  • what is missing?
  • what is produced by glycolysis?
A
  • endogenous electron acceptor which is an intermediate of the pathway to oxidize organic energy sources
  • no ETC, ATP synthesised only by substrate level phosphorylation
38
Q

in chemoliptrophy who uses it? where do its electrons come from? terminal electron acceptor?

A
  • certain bacteria and archea
  • inorganic molecules
  • O2
39
Q

photohetrotrophy?

A

energy from sunlight is amde into ATP but organisms with supplement growth with pre-made organic compounds that are available in the envrioenmnet

40
Q

what is made?
noncyclic electron flow
cyclic electron flow

A
  • ATP and NADPH
  • ATP
41
Q

what are the unique properties of anoxygenic photosyntheiss?

A

-

42
Q

anoxygenic pathway does not have?
unique properties?

A
  • water i snot usded as an electron source and so o2 is not produced
  • pigments used
    -only 1 photosyetsm is used
  • mechanisms ised o generate reducing power
43
Q

rhodopsin based photottraphy

A
  • microbes use this in nutrient depelited envrionmnet where organic carbon is limited
44
Q

archaerhodopsin

A
  • purple pigment
    membrane ortein
    functions as a light driven proton pump
    PMF is generated
    no ETC involeed

microbio (5 decks)

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