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Microbiology > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q

Overall Glucose Catabolism

A
  • glycolysis - glucose to pyruvate. make NADH and ATP
    • NO oxygen required
  • fermentation - pyruvate to acids, gases, and alcohols
    • no oxygen or e- acceptor
  • transition step - pyruvate to Acetyl-CoA. Produce NADH
  • TCA/CAC/Krebs - Acetyl-CoA to release CO2 and reduced electron carriers, ATP
  • Electron Transport system - e- from carriers to the power ATP synthase
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2
Q

Glucose is favorable

A

preferred CHO source because it does not require manipulation before it can be used (enter glycolysis)

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3
Q

Ways to generate ATP

A
  • Cellular respiration via glycolysis
  • fermentation
  • beta oxidation
  • deamination
  • the final products can be fed into cellular respiration
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4
Q

Anabolism

A
  • building polymers from monomers
  • ex. photosynthesis
  • requires energy - endergonic reaction
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5
Q

Catabolism

A
  • breaking down polymers into monomers (hydrolysis)
  • ex. cellular respiration
  • releases energy - exergonic
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6
Q

Compare/contrast anabolism and catabolism

A
  • often coupled reactions
  • both mediated by enzymes
  • synthesis vs hydrolysis
  • energy required or released
  • energy released from catabolism often powers anabolic reactions
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7
Q

Metabolism

A
  • sum of catabolic and anabolic reactions
  • manage cells energy sources
  • may involve intermediate steps that are neither cat. or ana.
    • isomerases - rearrange molecular structures
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8
Q

kinase

A

phosphorylates

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9
Q

phosphatase

A

remove phosphate

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10
Q

catalyst

A
  • substance that increases rate of chem reaction without under going a change itself
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11
Q

How do catalysts work

A
  • decrease activation energy
  • increase probability that a chem reaction will occur
    • bring 2 substrates together
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12
Q

Characteristics of enzymes

A
  • reusable
  • specific
  • active site shape determines the activity and function
  • only a small amount if required
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13
Q

Steps of enzyme and substrate interaction

A
  • enzyme has a uniquely shaped active site
  • active site binds to the complementary substrate and forms the enzyme-substrate complex
  • enzyme decreases activation energy and the reaction occurs
    • enzyme breaks apart the substrate
  • products released
  • enzyme can be reused
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14
Q

Activation Energy

A
  • Energy required for a reaction to occur
  • enzymes decrease the activation energy
  • destabalize bonds during catabolism
  • bring molecules together (proximity) for anabolic reactions
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15
Q

Co-factors

A
  • required for optimal function
  • some are inorganic (metals)
  • some organic cofactors are also e- carriers
    • flavin adenine nucleotide
    • nicotinamide adenine dinucleotide
  • If organic than it is called a “co-enzyme”
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16
Q

Enzymatic pathways

A
  • linear - intermediates used in next step and modifications accumulate
  • branched - intermediates have several pathway options
  • cyclical - start and end products are the same
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17
Q

Competitive inhibition

A

competitive inhibitor binds and fills the active site and prevents substrate from binding

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18
Q

Noncompetitive inhibition

A
  • inhibitor binds to the allosteric site (noncompetitive site), active site changes confirmation and substrate cannot bind
  • feedback inhibition - the end product binds to the allosteric site and inhibits the first enzyme in the pathway
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19
Q

Processes that require ATP

A
  • sec med transfer
  • Type I and III transfer
  • transformation
  • ABC transport
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20
Q

About ATP

A
  • Cant be stored directly
  • stored as glycogen or lipids
  • need 1,000,000 ATP molecules per second
  • Adenosine di/tri phosphate
  • unstable bonds between phosphates because neg. charges on O
  • couple energy requiring and releasing reactions
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21
Q

Substrate level phosphorylation

A

remove phosphate from a substrate to make ATP and product

enzyme mediated

  • occurs in glycolysis (twice)
  • occurs in TCA when succinyl-CoA to succate
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22
Q

oxidative phosphorylation

A
  • makes most ATP
  • uses e- transport chain (series of proteins in the membrane)
  • use energy from electrons to pump H+ out of the cell and into periplasmic space or extracellular space
  • H+ will want to come back into the cell and ATP synthase will be powered by electrochemical gradient
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23
Q

Oxidative Phosphorylation

A
  • occurs at the cell membrane
  • cytochromes are the proteins
  • iron is the cofactor
  • positive outside of the cell and negative inside the cell
  • energy from the electrons is used to pump H+ out of the cell
  • NADH - NAD+ and FADH2 - FAD
  • e- carriers drop the electrons at cytochrome I or II
    • NADH (I) and FADH2 (II)
    • reason for less ATP from FADH2 than NADH
    • FADH2 electrons are lower energy
  • Each cytochrome becomes more EN, O2 the highest EN on the chain
  • cytochrome IV (cytochrome c oxidase) takes e- to terminal electron acceptor
  • uses 2 H+ from inside of the cell to make H2O
    • increases the gradient. removes H+ from inside
  • ATP synthase uses H+ gradient to make ATP
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24
Q

Quinones

A
  • reside in the membrane and help to shuttle electrons between cytochromes
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25
Catalase
breaks down H2O2 into H2O and O2 H2O2 is a byproduct of aerobic respiration
26
chemiosmosis
movement of H+ back into the cell
27
Anaerobic respiration
non-O2 terminal electron acceptor
28
When to ferment
Some bacteria lack an ETC When terminal e- acceptor is unavailable
29
Investment Stage of Glycolysis
In: Glucose, 2 ATP Out: 2 G3p, 2 ADP * glucose phosphorylated by ATP - glucose 6-P * Isomerase to fructose 6-P * phosphorylated by ATP - _Fructose 1,6 bisphosphate_ * split into DHAP (dihydroxyacetone phosphate) and G3P (glyceraldehyde 3-P) * DHAP isomerization Isomerase at 2 and 5 kinase at 1 and 3
30
Harvest Phase of Glycolysis
In: 2 G3P, 4 ADP, 2 NAD+, 2 phosphate Out: 2 pyruvate, 4 ATP, 2 NADH, 2 H2O * Phosphate added to G3P, NAD+ reduced to NADH * Substrate level phosphorylation of ATP, 1,3 bisphosphoglycerate to 3-phosphoglycerate * Isomerization - 3-phosphoglycerate to 2-phosphoglycerate * Dehydration reaction to generate higher energy molecule (phosphoenol pyruvate (PEP)) * Substrate level phosphorylation of ATP, PEP to pyruvate
31
After glycolysis
* pyruvate byproduct * if O2 present - transition step and TCA * if no O2 but ETC with other terminal electron acceptor - transition and TCA * no O2 or ETC - fermentation
32
Dihydroxyacetone
* can be imported from the environment * dihydroxyacetone kinase phosphorylates it and forms DHAP * skips the need for glucose. DHAP can isomerize into G3P * input for harvest phase of glycolysis
33
Entner-Doudorff (ED) glycolysis
* Used by enteric bacteria, because sugar acids are in the gut * Uses _sugar acids_ or glucose-6-P from EMP * Uses NADPH that is NADH + P (NADH adn NADPH are coenzymes) * fructose 1,6 bisphosphate is missing and only one phosphate group is on the intermediate * Only 1 3C phosphorylated sugar when it splits * pyruvic acid and G3P * only one molecule can move on to the harvest phase * 1 net ATP instead of 2 (EMP) * Total out: 2 pyruvate, 1 NADH, 1 NADPH, 1 ATP (net)
34
Pentose Phosphate Pathway
* Start from 6-P-gluconate (ED pathway) * key intermediate is ribose-5-P (origin of the name) * create varying carbon length intermediates * anabolic and catabolic uses * produces ATP and 2 NADPH (mostly for anabolic) * critical for biosynthesis (AAs, vitamins)
35
Transition step
* NAD+ reduced to NADH and CO2 liberated - oxidative phosphorylation * 2C intermediate combines with cofactor CoA to form AcetylCoA * Catalyzed by pyruvate dehydrogenase complex (PDC) * PDC is regulated in order to control how much pyruvate goes into TCA * Shut off or reduce PDC when O2 is not present and fermentation needs to occur * 1st committed step to enter TCA cycle
36
TCA steps
* oxaloacetate combines with Acetyl-CoA to form citrate * isomerize to isocitrate * 2 oxidative dephosphorylation (liberate 2 CO2 and 2 NADH) * a-ketoglutarate (5C) then succinate (4C) * Succinyl CoA forms and 1 ATP produced (substrate level phos) * energy from CoA bond to succinyl * Succinate to fumarate isomerization. Produce FADH2 * not enough energy to make NADH * Fumarate + H2O = Malate (4C) * Malate to oxaloacetate. NADH produced
37
TCA cycle total
* per molecule of glucose * In: 2 pyruvate which goes to 2 Acetyl-CoA * Out: 6 CO2, 8 NADH, 2 FADH2, 2 ATP * NADH produces 3 ATP * FADH2 produces 2 ATP
38
ATP total for aerobic respiration
39
Glyoxylate Bypass
* redirects isocitrate * generates less ATP and NADH * Conserves carbon * when glucose is scarce and need C for biosynthesis * Avoid 2 oxidative decarboxylation steps * saves 2 CO2 (not a usable form of C) * miss out on 2 NADH and 1 ATP * Isocitrate to glyoxylate and succinate * mediated by isocitrate lyase * glyoxylate to malate via malate synthase * requires a 2nd Acetyl-CoA from a fatty acid in order to convert glyoxylate to malate * mycobacterium tuberculosis
40
NAD+ and FADH reused
* back into glycolysis, transition step, and TCA
41
ATP synthase parts
* Headpiece (F1) * 9 subunits * in the cytoplasm * Catalytic complex * Beta subunit is where ATP is formed * Basal unit (Fo) * 15 subunits * within the membrane * proton transporting channel
42
ATP Synthase Steps
* H+ enters through A component of basal subuit. then into C complexes and the basal unit starts to rotate * gamma is attached to the c complex and penetrates the headpiece * b holds headpiece in place * gamma subunit rotates in the headpiece and causes a conformational change in beta subunit * conformational changes catalyzes ATP formation
43
Beta subunit
* gamma is the core of the headpiece in the middle of beta subunit * rotating gamma causes change in beta then ADP + P = ATP * 3 ATP per turn of the headpiece
44
Non glucose carbohydrates
* Lactose - disaccharide made of galactose and glucose * metabolized by lactase * galactose converted to Glucose-6-phosphate * Sucrose - disaccharide made of fructose and glucose * metabolized by sucrase * fructose converted to fructose-1-phosphate then DHAP then G3P * stored polysaccharides - starch (linear) and glycogen (branched) * bacteria cant store glucose alone * break off glucose monomers and enter as Glucose-6-P
45
Triglyceride
* 3 fatty acids * glycerol * broken down by lipase * fatty acid chains contain an even number of carbons between 4 and 28 C * glycerol - DHAP - G3P
46
Beta Oxidation
* fatty acid chains broken into 2 carbon chunks * each converted into Acetyl-CoA * end of transition, beginning of TCA
47
Deamination
* breakdown proteins into AA * AA inot molecules for respiration * alanine + a-ketoglutarate = pyruvate + glutamate * aspartic acid - oxaloacetic acid
48
16C fatty acid chain
8 acetyl-CoA 12 ATP per turn of TCA 8 ATP, 24 NADH, 8 FADH2 = 96 ATP
49
Anaerobic respirtation
* human gut, deep sea vents, swamps/sediment * Alternative terminal e- acceptor - NO3-, SO4 2-, CO3 2- to CH4 * Produces less ATP than aerobic respiration * incomplete TCA cycle * not all cytochromes in ETC are functional
50
Fermentation
* No ETC * No term e- acceptor unavailable * form ATP via substrate level phosphorylation * NADH reduces pyruvate * NAD+ recycle back to glycolysis * Yield 2 ATP and fermentation products * possibly lactate * Swiss cheese - holes from gas by product of fermentation * NADH and NAD+ are cyclic
51
EtOH
pyruvate to acetaldehyde to ethanol decarboxylation NADH and NAD+ are cyclic produce 2 ATP 2e- onto aldehyde to make alcohol and NAD+ is recycled into the harvest phase
52
Lactose intolerance
* lactase is inactive * unable to break into galactose and glucose * whole lactose in the gut, increase solute, increase H2O into gut * move to large intestine where bacteria can break it down * byproducts - H2 gas, CO2, lactic acid, acetic acid
53
Lyme Disease Bacteria and Tick
Borrelia burgdorferi - bacteria Ixodes scapularis - tick
54
Borrelia burgdorferi
* spirellum morphology * syphilis also has the same morphology * vector born pathogen - carried by a vector * vector - carries the bacteria * other vector pathogens - malaria and zika * Lives in the mid gut
55
3 interrelated components for Lyme disease
* Bb * Ixodes scapularis or similar * Mammals (deer or mice)
56
Glycerol
- prevents formation of ice crystals - cryoprotectant - in ticks - can be used for energy when glucose not available
57
About Lyme Disease
* mostly transmitted by nymphs (small in size) * fixed to the host for 36hrs to 5 days * bacteria in the saliva * 3 stages of Lyme Disease * Early Localized - bullseye rash (erythema migrans) * Second Stage (early disseminated) - bells palsy * Late disseminated - chronic fatigue, swelling, penicillan kind of effect - attacks cell wall * Ticks are vectors of many pathogens - not only lyme disease
58
Bb metabolism of Glucose
* Only occurs in mammals * Produce pyruvate from glycolysis * Pyruvate goes to fermentation - No ETC * lactic acid fermentation
59
GlpF
glycerol transporter into the cell
60
GlyK
kinase that adds phosphate
61
GlpD
dehydrogenase oxidize glycerol-3-P to dihydroxyacetone-P (DHAP) reduce NAD+ to NADH
62
Glycerol metabolism steps
* GlpF * GlpK * GlpD produces DHAP * G3P * Harvest phase of glycolysis * 1 glycerol = 1 ATP, 2 NADH * Pyruvate reduced to lactate * NAD+ and NADH are cyclic
63
Can Bb use glycerol as a carbon source to generate ATP
* mutate GlpD and not GlpF or GlpK * GlpF and GlpK required in the chain before the branch point * cell could die because it cant make phospholipids/biosynthesis * GlpD is first committed step into glycolysis * only effects glycolytic steps and NOT anabolic processes * Cant grow with glycerol as major C source * wild type survive * GlpD mutant - poor growth * GlpD mutant survived well in mouse b/c glucose * doesnt need GlpD * In vivo
64
Mice Lyme disease
* mice infected with wild type Bb. Allow ticks to feed then look at number of Bb in the ticks * mice infected with GlpD mutant Bb. Allow ticks to feed then look at number of Bb in the ticks * Same number of Bb bc feeds on blood of mammal (glucose) * then count Bb after 7-8 weeks * must use glycerol. Increase in Bb in wild type * Limited Bb in mutated
65
non zero for GlyD mutant
- theory that Bb metabolized chitobiose - another mutant of GlyD that performs the same task

Microbiology (6 decks)

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