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MCB 2610 > Exam 3 B > Flashcards

Exam 3 B Flashcards

1
Q

Catabolism

A

•The breakdown of molecules for energy, reducing potential, and building blocks
Catabolism

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2
Q

Central processes in ATP synthesis

A

•Metabolic groups of microbes
–Microbes are grouped based on how they obtain.
•Energy (chemotrophs vs. autotrophs)
•Electrons (organotrophs vs. lithotrophs)
•Carbon (heterotrophs vs. autotrophs)

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3
Q

Chemoorganotrophic Fueling Processes

A

•also called chemoheterotrophs or chemoorganoheterotrophs
•They use organic compounds as sources of energy, electrons, and carbon
•They oxidize organic molecules and transfer electrons to carriers:
–NAD+ -> NADH
–FAD -> FADH2
–donate the electrons to the electron transport chain - Respiration

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4
Q

Chemoorganotrophic Fueling Processes

A

•Respiration – involves an electron transport chain
–Aerobic – final electron acceptor is O2
–Anaerobic – final electron acceptor is an exogenous acceptor (NO3-, SO42-, CO2, Fe3+, or SeO42-)–Not Respiration - Fermentation – Uses an endogenous (inside cell) electron acceptor (e.g., pyruvate) - no ETC

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5
Q

Chemoorganic Fueling Processes - Respiration

A
  • respiration involves use of an electron transport chain
  • as electrons pass through the electron transport chain to the final electron acceptor, a proton motive force (PMF) is generated and used to synthesize ATP from ADP and Pi
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6
Q

Chemoorganic Fueling Processes - Respiration

A

•aerobic respiration
•final electron acceptor is oxygen
•anaerobic respiration
–final electron acceptor is a different exogenous acceptor such as
•NO3-, SO42-, CO2, Fe3+, or SeO42-
–organic acceptors may also be used
•In respiration ATP is made primarily by oxidative phosphorylation involving an ETC

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7
Q

Chemoorganic Fueling Processes - Fermentation

A

•uses an endogenous electron acceptor (inside cell)
–usually an intermediate of the pathway used to oxidize the organic energy source e.g., pyruvate
•does not involve the use of an electron transport chain
•ATP synthesized only by substrate-level phosphorylation - PO4 is transferred to ADP from a high energy molecule (e.g. phosphoenol pyruvate, PEP)

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8
Q

Central processes in ATP synthesis:

A

•How do cells make ATP?
–Cells produce ATP in three basic pathways:
•Substrate-level phosphorylation-taking it for the substate
•Photophosphorylation (not pictured below)
•Oxidative phosphorylation

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9
Q

Three fueling processes

A
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10
Q

Energy Sources

A
  • many different energy sources (i.e., substrates) are funneled into common degradative pathways
  • most pathways generate glucose or intermediates of the pathways used in glucose metabolism
  • Having only a few pathways greatly increases metabolic efficiency
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11
Q

Chemoorganotrophic catabolic pathways

A
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12
Q

Catabolic Pathways

A
  • enzyme catalyzed reactions whereby the product of one reaction serves as the substrate for the next
  • pathways also provide materials for biosynthesis
  • amphibolic pathways
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13
Q

Amphibolic Pathways

A

•function both as catabolic and anabolic pathways
•important ones
–Embden-Meyerhof pathway (glycolysis)
–pentose phosphate pathway
–tricarboxylic acid (TCA) cycle

Do not memorize the intermediates,

Rememebr heat is a waster product-one direction is better than both ways because it is will be inefficient.

Why would an organism have a back and forward reaction.

I

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14
Q

Aerobic Respiration

A

•process that can completely catabolize an organic energy source to CO2 using
–glycolytic pathways (glycolysis)
–TCA cycle
–electron transport chain with oxygen as the final electron acceptor
•produces ATP, and high energy electron carriers

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15
Q

The Breakdown of Glucose to Pyruvate

A

•three common routes
–Embden-Meyerhof pathway – most common
–pentose phosphate pathway
–Entner-Duodoroff pathway

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16
Q

Oxidative phosphorylation for
ATP synthesis

A

•The chemiosmotic model
•Electrons are passed through an electron transport system.
•This generates a proton gradient.
–Energy from the flow of protons can be used to drive the enzyme ATP synthase.
•This produces ATP from ADP and Pi.

17
Q

ATP synthesis

A

•Reduction and oxidation (redox) reactions
–Involve transfer of electrons from one molecule to another
•Oxidation results in loss of an electron.
•Reduction results in gain of an electron.
•Redox potential (E) is the tendency of a molecule to acquire electrons.

18
Q

Central processes in ATP synthesis

A

•Reduction and oxidation (redox) reactions
–Energy is released when electrons flow from donors with more negative redox potentials to acceptors with more positive redox potentials.
–Nicotinamide adenine dinucleotide (NAD+) is a common electron carrier molecule.
Not asked the enzymes- or pathway- just know why is happaning, the significance, etc

19
Q

The Embden-Meyerhof Pathway, GLycolysis

A

•occurs in cytoplasmic matrix of most microorganisms, plants, and animals
•the most common pathway for glucose degradation to pyruvate in stage two of aerobic respiration
•function in presence or absence of O2
two phases

20
Q

Glycolysis – Embden-Meyerhof Pathway

A

addition of phosphates

“primes the pump”

oxidation step – generates NADH

high-energy molecules –

used to synthesize ATP

by substrate-level

phosphorylation

21
Q

Summary of Glycolysis

A

glucose + 2ADP + 2Pi + 2NAD+

¯

2 pyruvate + 2ATP + 2NADH + 2H+

           (SLP)          (Ox Phos)
22
Q

The Tricarboxylic Acid Cycle

A
  • also called citric acid cycle and Kreb’s cycle
  • common in aerobic bacteria, free-living protozoa, most algae, and fungi
  • major role as a source of carbon skeletons for use in biosynthesis
  • In eukaryotes occurs in the mitochondrion
  • In prokaryotes occurs in the cytoplasm
23
Q

Carbon utilization
in microorganisms:

A

•The tricarboxylic acid (TCA) cycle

24
Q

Summary TCA Cycle

A
25
Q

How many times must the tca cucle be performed tooxidzide oe meocleucle ofgluce completetly to six molecules of co2

A

IT will have to go twice

26
Q

Electron Transport and Oxidative Phosphorylation

A
  • only 4 ATP molecules synthesized directly from oxidation of glucose to CO2
  • 2 from glycolysis and 2 from TCA (GTP)
  • most ATP made when NADH and FADH2 (formed as glucose degraded) are oxidized in electron transport chain (ETC)
  • -Snadh + 2H (gly)
  • 2NADH +2H(puv to acetylCOA)
  • 6NADH+^H(TCA)
  • 2FADH2+2H+(TCA)
27
Q

Electron Transport Chain

A
  • each carrier is reduced and then reoxidized – like a bucket brigade
  • carriers are constantly recycled
  • the difference in reduction potentials of electron carriers, NADH and O2 is large, resulting in release of great deal of energy-enough to make ATP
28
Q

Electron Transport Chain…

A
  • in eukaryotes the electron transport chain carriers are within the inner mitochondrial membrane and connected by coenzyme Q and cytochrome c
  • electron transfer is accompanied by proton movement across the inner mitochondrial membrane
29
Q

Bacterial and Archaeal ETCs

A

•located in plasma membrane
•some resemble mitochondrial ETC, but many are different
–different electron carriers
–may be branched
–may be shorter
–may have lower P/O ratio-release less energy (phosphorous to oxygen)

30
Q

Chemiosmotic Hypothesis

A

•the most widely accepted hypothesis to explain oxidative phosphorylation
–electron transport chain organized so protons move outward from the mitochondrial matrix (or from cytoplasm to periplasmic space in bacteria and archaea) as electrons are transported down the chain
–proton expulsion during electron transport results in the formation of a concentration gradient of protons and a charge gradient
–the combined chemical and electrical potential difference make up the proton motive force (PMF)

31
Q

PMF Drives ATP Synthesis

A

•diffusion of protons back across membrane (down gradient) drives formation of ATP (or movement of flagella or transport of nutrients)
•ATP synthase
–enzyme that uses PMF down gradient to catalyze ATP synthesis
–functions like rotary engine with conformational changes
–In eukaryotes found on mitochondrial inner membrane
–In bacteria and archaea found on inner plasma membrane

32
Q

Chemiosmotic hypothesis applied to mitochondria

A
33
Q

Respiration and
the electron transport system:

A

•ATP synthase
–The enzyme used to produce ATP
–As protons move through it, they cause the gamma (g) subunit to rotate, changing active site conformation.
–This facilitates addition of Pi to ADP to form ATP.

34
Q
A
35
Q

What is the the function fo the electron transport chain

A
  1. Make a gradient, to make ATP, diffusion or transport of molecules from outside to inside, and moving the flaggelum
  2. If the atp is used for other things at other time, it wont produce a lot

MCB 2610 (3 decks)

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