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Microbiology > Exam 3 > Flashcards

Exam 3 Flashcards

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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
Q

Catalase

A

breaks down H2O2 into H2O and O2

H2O2 is a byproduct of aerobic respiration

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26
Q

chemiosmosis

A

movement of H+ back into the cell

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27
Q

Anaerobic respiration

A

non-O2 terminal electron acceptor

28
Q

When to ferment

A

Some bacteria lack an ETC

When terminal e- acceptor is unavailable

29
Q

Investment Stage of Glycolysis

A

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
Q

Harvest Phase of Glycolysis

A

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
Q

After glycolysis

A
  • 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
Q

Dihydroxyacetone

A
  • 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
Q

Entner-Doudorff (ED) glycolysis

A
  • 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
Q

Pentose Phosphate Pathway

A
  • 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
Q

Transition step

A
  • 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
Q

TCA steps

A
  • 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
Q

TCA cycle total

A
  • 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
Q

ATP total for aerobic respiration

A
39
Q

Glyoxylate Bypass

A
  • 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
Q

NAD+ and FADH reused

A
  • back into glycolysis, transition step, and TCA
41
Q

ATP synthase parts

A
  • 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
Q

ATP Synthase Steps

A
  • 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
Q

Beta subunit

A
  • 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
Q

Non glucose carbohydrates

A
  • 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
Q

Triglyceride

A
  • 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
Q

Beta Oxidation

A
  • fatty acid chains broken into 2 carbon chunks
  • each converted into Acetyl-CoA
    • end of transition, beginning of TCA
47
Q

Deamination

A
  • breakdown proteins into AA
  • AA inot molecules for respiration
  • alanine + a-ketoglutarate = pyruvate + glutamate
  • aspartic acid - oxaloacetic acid
48
Q

16C fatty acid chain

A

8 acetyl-CoA

12 ATP per turn of TCA

8 ATP, 24 NADH, 8 FADH2 = 96 ATP

49
Q

Anaerobic respirtation

A
  • 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
Q

Fermentation

A
  • 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
Q

EtOH

A

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
Q

Lactose intolerance

A
  • 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
Q

Lyme Disease Bacteria and Tick

A

Borrelia burgdorferi - bacteria

Ixodes scapularis - tick

54
Q

Borrelia burgdorferi

A
  • 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
Q

3 interrelated components for Lyme disease

A
  • Bb
  • Ixodes scapularis or similar
  • Mammals (deer or mice)
56
Q

Glycerol

A
  • prevents formation of ice crystals
  • cryoprotectant
  • in ticks
  • can be used for energy when glucose not available
57
Q

About Lyme Disease

A
  • 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
Q

Bb metabolism of Glucose

A
  • Only occurs in mammals
  • Produce pyruvate from glycolysis
  • Pyruvate goes to fermentation - No ETC
    • lactic acid fermentation
59
Q

GlpF

A

glycerol transporter into the cell

60
Q

GlyK

A

kinase that adds phosphate

61
Q

GlpD

A

dehydrogenase

oxidize glycerol-3-P to dihydroxyacetone-P (DHAP)

reduce NAD+ to NADH

62
Q

Glycerol metabolism steps

A
  • 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
Q

Can Bb use glycerol as a carbon source to generate ATP

A
  • 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
Q

Mice Lyme disease

A
  • 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
Q

non zero for GlyD mutant

A
  • theory that Bb metabolized chitobiose
  • another mutant of GlyD that performs the same task

Microbiology (6 decks)

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