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Flashcards in Chapter 6 Deck (77):
1

Importance of microbial metabolism

1. Model to study eukaryote metabolism (E.coli)
2. Food from fermentation
3. Method to ID bacteria
4. Designing and understanding antimicrobial drugs
5. Biofuels

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Metabolism

All chemical reactions in a cell

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Two types of metabolism

Catabolism
Anabolism

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Catabolism

processes that degrade compounds, often release energy
ex. Cellular respiration breaking down glucose to form ATP

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Anabolism

process that synthesize macromolecule subunits, use ATP energy
Ex. Photosynthesis, protein synthesis, DNA synthesis

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Enzymes

protein catalysts

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Catalyst

molecules that speed up chemical reactions but are not altered by the reaction

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Enzymes and catalysts

Some enzymes are catalysts but not all.

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Substrate

combines with enzyme at the active site and product is released.
Enzymes are very specific to substrate and the reaction

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Enzymes have optimal ranges of.....

temperature, pH, salt concentration.
Outside optimal range can denature the enzyme or slow it down

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3 types of enzyme inhibitors

Competitive inhibition
Non-competitive inhibition
Feedback inhibition

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Competitive inhibition

- not permanent
- binding site is blocked by the other inhibitor to inhibit enzyme
- sulfa drugs inhibit an enzyme that makes folic acid

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Non-competitive inhibition

- permanent change to enzyme
ex. mercury breaks sulfer bonds in amino acid cysteine and changes the proteins shape.

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Feedback inhibition

- can be permanent, but most of the time not
- When final product is available from an outside source the enzyme will stop making it to conserve energy.
-Final product binds to allosteric site which changes the active site to make it unable to make more final products

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Cofactor

non-protein helpers
- must be present for substrate to bind to active site and work

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Coenzymes

organic cofactors, often made from vitamins

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Electron carriers

NAD+/NADH, NADP+/NADPH, FAD/FADH2

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NAD is derived from which vitamin

Niacin

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FAD is derived from which vitamin

Riboflavin

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Overall equation for cellular respiration

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

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3 steps of cellular respiration

Glycolosis
Transition Step (Krebs or Citric Acid Cycle)
Electron Transport

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Electron Transport
(prokaryote vs eukaryote)

Differences in transport proteins and location

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Prokaryote Electron Transport Proteins

-Differences between types of prokaryotes
- Cytochrome C found in Neisseria, Psudomonas, Caphylobacter can be tested for with OXIDASE TEST
- Menaquinone found in some prokaryotes is also a source of vitamin K

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Source of vitamin K

Menaquinone

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Oxidase test tests for...

Cytochrome C: found in Neisseria, Pseudomonas, and Camphylobacter

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ATP Yield

3 ATP from each NADH
2 ATP from each FADH2
38 total ATP in prokaryotes
36 total ATP in eukaryotes

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Why is there a difference in ATP yield between prokaryotes and eukaryotes

Difference is due to transport of NADH from glycolysis

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Fermentation

-occurs if oxygen is not available or electron transport mechanisms are not present.
- Does not make ATP, but makes NAD+ which can go back to glycolysis

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Glycolysis

Glucose -> pyruvate + 2 ATP + 2 NADH

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Lactic Acid fermentation

Glucose -> pyruvate -> Lactic acid
Tooth decay
Food products

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Types of lactic acid bacteria

lactobacillus, lactococcus, streptococcus

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Ethanol Fermentation

Glucose -> Pyruvate -> Ethanol + CO2

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what is responsible for production of beer, wine, champagne, rum, whiskey and bread

Saccharomyces (yeast)

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what is responsible for production of tequila

Zymomonas (bacteria)

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what is responsible for production of vinegar

Acetic acid bacteria (Aceobacteria)

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Ethanol fermentation create ethanol for use as a...

biofuel

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Other types of fermentation

Butyric acid
Propionic acid

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Butyric Acid

-Clostridium (obligate anaerobes)
- Used to produce solvents butanol and acetone

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Propionic Acid

- Propionibacterium
- used to make swiss cheese
- CO2 makes holes in cheese
- Propionic acid gives flavor

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Mixed acids
(ID of bacteria by fermentation method)

Some bacteria produce several acids

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Methyl Red Test
(ID of bacteria by fermentation method)

red color develops at pH less than 4.5
Ecoli +, Klebsiella and Enterobacter -

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2,3 Butanediol
Voges-proskauer test
(ID of bacteria by fermentation method)

red color when intermediate acetoin present
- E.coli - , Klebsiella and enterobacter +

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Anaerobic respiration

- Chemoautotrophs
- Inorganic molecules used as terminal electron acceptor instead of oxygen
- Hydrogen, Sulfer, Iron, Nitrogen

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Photosynthesis overall equation

6CO2 + 6H2O + light energy -> C6H12O6 + 6O2

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Cyanobacteria

-Blue green "algae"
- photosynthesis very similar to plants and algae

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Anoxygenic photosynthetic bacteria

- Green and purple bacteria
- Do not produce oxygen
- CO2 + H2A + light energy -> C6H12O6 + A2

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Photosystems

Complexes of pigments and proteins capture light energy by exciting electrons

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Cyanobacteria, plants and algae
(photosystems)

- have two different photosystems
- get new electrons from H2O

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Green and purple bacteria
(photosystems)

have only 1 type of photosystem

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Pigments

- Chlorophyll in cyanobacteria, plants and algae
- Baceriochlorophyll in green and purple bacteria

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Location of photosynthesis for Eukaryotes

chloroplasts containing thylakoid membranes

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Location of photosynthesis for Cyanobacteria

thylakoid membranes only

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Location of photosynthesis for green bacteria

chlorosomes

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Location of photosynthesis for purple bacteria

invaginations in cell membrane
recall endosymbiotic theory

55

Central Metabolic pathways

- cellular respiration also provides precursors to many biosynthesis reactions
- intermediate molecules can go on to cellular respiration processes or be used to synthesize lipids, amino acids and nucleotides

56

Lipid synthesis

triglycerides and phospholipids contain glycerol and fatty acids

57

Fatty acids

- acetyl group from Acetyl-CoA attaches to a transport protein
- 2-carbon units are added to this to make long chains of fatty acids

58

Glycerol

made from a molecule made during glycolysis

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Amino acid synthesis

Proteins- amino acids joined by peptide bonds, often with complex foldings

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Glutamate (amino acid synthesis)

- Glutamate is a precursor to other amino acids
- made by adding ammonia to molecule from Krebs cycle
- other amino acids (example aspartate) are made by taking NH2 (amino group) from glutamate

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Aromatic Amino Acids (amino acid sythesis)

-tyrosine, phenylalanine, tryptophan
- multistep, branching pathway
- precursors come from pathhways of cellular respiration
- Example: negative feedback

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Where does glycolysis take place in eukaryotes

cytoplasm

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What molecule is the coenzyme that carries electrons in glycolosis

NADH

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How many ATP are made from glycolysis

2

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What molecule is produced from glycolysis and how many carbons does it have

pyruvic acid (3 carbons)

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Where does glycolysis take place in prokaryotes

cytoplasm

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Where does the 2nd step (trasition step TCA cycle) take place in eukaryotes

in Cristae membrane of mitochondria

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What two molecules are made from pyruvic acid in the transition step before the Krebs cycle can occurr

Acetyl CoA (2 carbons) and CO2

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What byproduct is released in Krebs cycle

CO2

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How many ATP per glucose are produced from the Krebs cycle

2

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Where does this second step (krebs cycle) take place in prokaryotes

Outter cell membrane

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What are the names of the two electron carriers used in the Krebs cycle

NAD & FAD

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Where does electron transport occur in eukaryotes

Mitochondria

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What makes up most of the molecules in the chain of electron transport chain

proteins

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What is the final electron acceptor in aerobic respiration and what byproduct is made

Oxygen with H20 being the byproduct

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Where does electron transport occur in prokaryotes

Cytoplasmic membrane

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How many ATP per glucose are made in eukaryotes and prokaryotes

eukaryotes: 36
prokaryotes: 38