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Microbiology > Chapter 5: Microbial Metabolism > Flashcards

Chapter 5: Microbial Metabolism Flashcards

1
Q

Metabolism:

A

o The sum of all chemical reactions.
• Catabolism – BREAK down.
• Anabolism – BUILD up.

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2
Q

Catabolism:

A

o Breakdown of complex molecules into simpler molecules.
o Provides energy and building blocks for anabolism.
o ATP turns into ADP and P and Energy.

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3
Q

Anabolism:

A

o Build complex molecules out of simpler molecules.
o Uses energy and building blocks from catabolic reactions.
o ADP and P and Energy turn into ATP.

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4
Q

Microbial Metabolism:

A

o Although microbial metabolism can cause disease and food spoilage, many pathways are beneficial rather than pathogenic.
• Enzymes facilitate metabolic reactions.
• ATP is used by microbes and other cells to manage energy needs.
• Catabbolic reactions couple with ATP synthesis.
• Anabolic reactions couple with ATP breakdown.

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5
Q

Metabolic Pathways:

A

o A METABOLIC PATHWAY is a sequence of enzymatically catalyzed chemical reactions in a cell.
• They are determined by enzymes.
• Enzymes are encoded by genes.

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6
Q

Enzymes:

A

o Proteins.
o Catalyze chemical reactions.
o 3D globular shape.

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7
Q

Catalysts:

A

o Speed up a chemical reaction.

• Not permanently altered themselves.

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8
Q

Substrate:

A

o The substance that the enzyme acts on.

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9
Q

Active Site:

A

o The location upon the cell in which the substrate would act upon.

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10
Q

Coenzymes and Cofactors:

A

o Important Coenzymes:
• NAD, NADP, FAD, Coenzyme A.
o Cofacters can be metal ions:
• Zinc, copper, magnesium, manganese, calcium, cobalt.

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11
Q

Six Enzyme Classes Based on Type of Reaction they Catalyze:

A 
o	Oxidoreductase.
o	Transferase.
o	Hydrolase.
o	Lyase.
o	Isomerase.
o	Ligase.
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12
Q

Factors Influencing Enzyme Activity:

A

o Temperature (denature proteins when high).
• If temperature increases, rate of reaction increases until the enzyme (protein) id denatured by heat and inactivated.
• This causes the reaction rate to fall steeply.
o pH (denature proteins when high).
o Substrate Concentration.
• Increasing concentration of substrate molecule causes rate of reaction to increase until the active sites on all the enzyme molecules are filled.
• At this point the max rate of reaction is reached.
o Inhibitors.
• Competitive Inhibition: substrate and and competitive inhibitors compete for the active site of an enzyme.
• Noncompetitive inhibition: act on other parts of the apoenzymes or on the cofactor and decrease the enzymes ability to combine with the normal substrate.

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13
Q

Steps of Feedback Inhibition:

A

o 1. Substrate Binds.
o 2. Product Produced.
o 3. End-product binds to enzyme.
o 4. Pathway shuts down.

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14
Q

Testing for an Enzyme:

A

o Control:
• Urease Negative.
o Test:
• Bacterial urease hydrolyzes urea, producing ammonia.
• Raises the pH and indicator in medium turns fuchsia.

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15
Q

Ribozymes:

A

o RNA that function as catalysts by cutting and splicing RNA.

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16
Q

What is a coenzyme?

A

o Many Coenzymes are derived from B vitamins – nonprotein – associated with and activates an enzyme.

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17
Q

Why is enzyme specificity important?

A

o Allows the enzyme to find the correct substrate in a vast sea of molecules.

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18
Q

What happens to an enzyme below its optimal temperature?

A

Slow Reaction

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19
Q

What happens to an enzyme above its optimal temperature?

A

Denatures

20
Q

Why is feedback inhibition noncompetitive inhibition?

A

Product binds to an allosteric site

21
Q

What is a ribozyme?

A

o RNA that acts as a catalyst specifically on strands of RNA.

22
Q

Oxidation-Reduction Reactions:

A

o OXIDATION: Removal of electrons.
o REDUCTION: Gain of electrons.
o REDOX REACTION: Paired reaction.

23
Q

The Generation of ATP:

A

o ATP is generated by the phosphorylation of ADP.
o Organisms use 3 different mechanisms of phosphorylation to generate ATP from ADP:
• SUBSTRATE-LEVEL PHOSPHORYLATION: ATP generated when high-energy PO4– added to ADP generates ATP - Occurs in glycolysis.
• OXIDATIVE PHOSPHORYLATION: Generate ATP in the ELECTRON TRANSPORT CHAIN.
• PHOTO-PHOSPHORYLATION: Occurs only in light-trapping photosynthetic cells. Light energy is converted to ATP when the transfer of electrons (oxidation) from chlorophyll pass through a system of carrier molecules.

24
Q

Metabolic Pathways of Energy Production:

A 
o	Store energy in and release energy from organic molecules.
o	Breakdown of Carbs to release energy. 
•	Glycolysis.
•	Krebs cycle.
•	Electron transport chain.
25
Q

Glycolysis:

A

o First step is catabolism of glucose for both respiration and fermentation.
o Glucose in and 2 pyruvate (pyruvic acid) out.
o 4 total ATP, but 2 are consumed for a net gain of 2 ATP.

26
Q

Additional Pathways of Glycolysis:

A

o PENTOSE PHOSPHATE PATHWAY:
• Uses pentoses and produces NADPH.
• Operates simultaneously with glycolysis.
o ENTNER-DOUDOROFF PATHWAY:
• Produces NADPH and ATP.
• Does not involve glycolysis.
• Occurs in Pseudomonas, Rhizobium, and Agrobacterium.

27
Q

Krebs Cycle:

A

o The KREBS CYCLE, or citric acid cycle, is a part of cellular respiration.
o It is a series of chemical reactions used by all aerobic organisms to generate energy.
o PYRUVATE from GLYCOLYSIS is reconfigured to ACETYL CO-A.
o Produces CO2 and many ELECTRONS in the form on FADH2 and NADH that move on to the ELECTRON TRANSPORT CHAIN.

28
Q

Electron Transport System:

A

o MOST ATP PRODUCTION OCCURS BY OXIDATIVE PHOSPHORYLATION (ELECTRON TRANSPORT CHAIN).
o In bacteria, the electron transport chain is located on the cytoplasmic membrane. In Eukaryotes in the mitochondrial membrane.
o The chain consists of a series of electron carriers.
o Electrons are transferred from one electron carrier to the next in the electron transport chain.
o As electrons move along each step of the chain, they give up a bit of energy.
o At the end of the chain, the electrons are transferred to oxygen, and water is formed as a by-product.

29
Q

Cellular Respiration:

A 
o	Series of Redox Reactions that Generate ATP:
•	Way for Cells to Gain Energy.
o	AEROBIC RESPIRATION:
•	With Oxygen.
•	Final Electron Acceptor IS OXYGEN.
•	GLYCOLYSIS, KREBS CYCLE and ETS.
o	ANAEROBIC RESPIRATION:
•	Without Oxygen.
•	Final Electron Acceptor IS NOT OXYGEN.
•	GLYCOLYSIS, Part of the KREBS CYCLE.
30
Q

Aerobic Resiration Yield:

A

o AEROBIC RESPIRATION:
• Final electron acceptor in ETS is O2.
• Total 36-38 ATP per glucose.
o ANAEROBIC RESPIRATION:
• Final electron acceptor in ETS is not O2.
• Yields much less energy than aerobic respiration.

31
Q

Fermentation:

A

o AFTER GLYCOLYSIS, Pyruvic Acid is converted to an organic product.
o DOES NOT REQUIRE OXYGEN, BUT MAY OCCUR IN ITS PRESENCE.
o Pyruvic acid and the electrons carried by NADH from glycolysis are incorporated into fermentation end-products.
o FERMENTATION IS IMPORTANT IN:
• Spoilage of food by microorganisms.
• Production of alcoholic beverages.
• Production of acidic dairy products.
• Identification of bacterial organisms.
o ALCOHOL FERMENTATION:
• Glycolysis.
• 2 Pyruvic acid become:
• Produces ethanol + CO2.
o LACTIC ACID FERMENTATION:
• Glycolysis.
• 2 Pyruvic acid become:
• Homolactic fermentation:
• Produces lactic acid only.
• Heterolactic fermentation:
• Produces lactic acid and other compounds.
o RELEASES ENERGY FROM OXIDATION OF ORGANIC MOLECULES
• DOES use GLYCOLYSIS.
• DOES NOT require oxygen, but may occur in its presence.
• DOES NOT use the KREBS cycle or ETC.
• Uses an organic molecule as the final electron acceptor.

32
Q

Catabolism of Organic Food Molecules:

A

o Proteins, Carbohydrates, and Lipids can all be sources of electrons and protons for respiration.
o Each type enter Glycolysis or the Krebs Cycle at various points.

33
Q

Protein Catabolism:

A

o Peptone Iron Agar.
o Detects H2S production.
o H2S precipitates with iron in the medium.
o CONTROL:
• Urease Negative
o TEST:
• Bacterial urease hydrolyzes urea, producing ammonia.
• Raises the pH and indicator in medium turns fuchsia.

34
Q

Overview of Metabolism:

A

o Metabolism is the basis of all life.
o Metabolism often forms the basis of antibiotic therapy because some antibiotics interfere with metabolic reactions.
o Glycolysis is a preparatory stage for other processes, like the anaerobic process.
o The Krebs cycle generates energy-carriers.
o The electron transport system produces a lot of ATP either by aerobic or anaerobic conditions.
o Fermentation pathways follow glycolysis.

35
Q

Nutritional Classification of Organisms:

A

o Organisms can be classified based on their energy source.
• Phototrophs use Light.
• Chemotrophs use Chemicals.

36
Q

Photoautotroph:

A

o Energy source: Light
o Carbon Source: CO2
o Example: Oxygenic: cyanobacteria plants Anoxygenic: green, purple bacteria.

37
Q

Photoheterotroph:

A

o Energy Source: light
o Carbon source: organic compounds.
o Example: green, purple nonsulfur bacteria.

38
Q

Chemoautotroph:

A

o Energy source: chemical
o Carbon source: CO2.
o Example: Iron-oxidizing bacteria.

39
Q

Chemoheterotroph:

A

o Energy source: chemical
o Carbon source: Organic Compounds.
o Example: Fermentative bacteria. Animals, protozoa, fungi, bacteria.

40
Q

Polysaccharide Biosynthesis:

A

o Glucose-6-phosphate, an intermediate of Glycolysis produces Glycogen.
o Fructose-6-phosphate, an intermediate of Glycolysis produces Peptidoglycan in bacteria.

41
Q

Lipid Biosynthesis:

A

o Intermediates of Glycolysis produces Glycerol.
o Acetyl CoA produces Fatty Acids.
o And the two of them together form Simple Lipids.

42
Q

Pathways of Amino Acid Biosynthesis:

A

o Adding or transferring amino groups of intermediate products from each of these pathways form Amino Acid.
o Pentose Phosphate Pathway.
o Krebs Cycle.
o Entner-Doudoroff Pathway.

43
Q

Amino Acid Biosynthesis:

A

o TRANSAMINATION is making new amino acids with the amino group of old amino acids.
o Glutamic Acid and Aspartic acid are both amino acids.
o Oxaloacetic acid and alpha-ketoglutaric acid are intermediated in the Krebs cycle.

44
Q

Amphibolic Pathways:

A

o Metabolic pathways that have both catabolic and anabolic functions.

45
Q

Glycolysis Summary:

A 
o	One glucose is used.
o	Partial oxidation of the sugar.
•	Two NADH are reduced.
o	2 ATP are consumed.
o	4 ATP total are made.
o	Net of 2 ATP produced.
o	2 pyruvates are end products.
46
Q

Kreb’s Cycle Summary:

A

o Each pyruvate molecules (2) breaks down into 3 CO2, 4 NADH, 1 FADH2, and 1 ATP.
o Each glucose now completely oxidized to CO2.
o Electrons are temporarily on carrier molecules.
o 4 ATP total made by substrate level phosphorylation.

Microbiology (5 decks)

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