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MCM Exam 1 > Lect 1 Fundamentals Biochemical Reactions > Flashcards

Lect 1 Fundamentals Biochemical Reactions Flashcards

1
Q

Metabolism is a _

A
  • Series of Biochemical reactions
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2
Q

Metabolism’s purpose is to _

A
  • capture/harness energy from nutrients to sustain life
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3
Q

Metabolism’s goals are _

A

Produce energy (catabolism)

Synthesize biomolecules (anabolism)

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4
Q

Exergonic/Endergonic Definitions

A

Exergonic releases energy (deltaG < 0)

Endergonic consumes energy (deltaG > 0)

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5
Q

Free Energy Change (delta G) = _

What is the Free Energy Equation?

A

delta G = Dynamics of biochemical reaction

deltaG = deltaGo’ + RT ln [C][D]/[A][B]

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6
Q

Keq is equal to the ratio of the _

A

Products over Reactants

[C][D] / [A][B]

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7
Q

Equilibrium Constant (Keq) & Standard Free Energy (deltaGo’) relationships

A

delta G is directly related to Keq

Keq = 1 –> deltaGo’ = 0

Keq > 1 –> deltaGo’ < 0

Keq < 1 –> deltaGo’ > 0

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8
Q

What are the kcal/mol values of:

ATP –> ADP + Pi

ATP –> AMP + PPi

PPi –> Pi + Pi

A

ATP –> ADP + Pi = -7.3 kcal/mol

ATP –> AMP + PPi = -10.9 kcal/mol

PPi –> Pi + Pi = -4.0 kcal/mol

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9
Q

Mass Action (Le Chatelier)

A
  • Keq dependent on [R] and [P]
  • Altering [R] or [P] alters reaction kinetics
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10
Q

Input of Energy (Couple Reactions)

A

Endergonic + Exergonic

Must share a common intermediate

Final deltaGo’ determines reaction fate

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11
Q

Addition/Elimination Rxn

A

Transfer atom to multiple bond or elimination of atom to form double bond

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12
Q

Substitution Rxn

A

Replace functional group with another

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13
Q

Rearrangements (Isomerizations)

A

Shifting functional group within a molecule

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14
Q

Oxidation-Reduction Rxn

A

Transfer of e- from one molecule to another

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15
Q

Acid Base Rxn

A

Donating protons (acids) and accepting protons (bases)

Most important to preserve life

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16
Q

Physiological pH Range

A

7.37-7.43

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17
Q

What is the dissociation constant (K)

What is pKa an indicator of

A

Equilibrium constant indicating tendency of acid to dissociate

Acid strength (low pKa = strong acid)

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18
Q

How does the Kidney regulate blood pH

A

Remove H+ in form of NH4+ and reabsorb HCO3-

Low pH: increased H+ removal and HCO3- reabsorption

High pH –> less H+ removal and HCO3- reabsorption

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19
Q

Name the Disorders Associated with Acid-Base Imbalances

A

Respiratory Acidosis (Hypoventilation)

Respiratory Alkalosis (Hyperventilation

Metabolic Acidosis

Metabolic Alkalosis

20
Q

Enzymes are biological _ that _ reaction rates

They bind to _ and convert them to _

A

Catalysts

Increase

Substrates to Products

21
Q

Enzymes increase reaction rate by _

A
  • Lowering activation energy (EA)
    • Minimum amount of energy to convert S to intermediate
  • Stabilizing transition state intermediate
  • Provide more energetically favorable reaction pathway
22
Q

Name the Enzyme Classes

A

Oxidoreductases

Transferases

Isomerases

Lyases (Synthases) - add/remove atoms to form double bond

Ligases (Synthetases) - form bonds with ATP hydrolysis

Hydrolases - cleave bonds via addition of water

23
Q

Enzymes made up of _ and folded into _ and _ structure

A
  • Polypeptides
  • Folded into tertiary and quaternary structure
24
Q

What is the purpose of the Active Site

A
  • Substrate binding location
25
Q

Lock and Key Hypothesis

A

Substrate is perfect fit for active site

26
Q

Induced Fit Hypothesis

A

Binding induces conformation changes in active site

27
Q

What are Cofactors?

How do they interact with enzyme?

A

Metal ions, Essential trace elements

Interact with enzyme via noncovalent interaction and stabilize active site

28
Q

Common Cofactor Examples and their Enzymes

A

Cu: Cytochrome C Oxidase

Fe: Heme proteins

Mg: ATPases

Se: Glutathione peroxidase (antioxidant) - detoxify H2O2

Zn: Carbonic Anhydrase

29
Q

What are Coenzymes?

A

Small organic molecules dervied from vitamins

30
Q

Difference between Co-Substrate and Prosthetic Groups

A
  • Co-Substrate: Temporary Association (bind then detach in altered state)
  • Prosthetic: Permanent Association (FAD, FMN, Heme)
31
Q

What Factors Affect Enzyme Activity?

A
  • Temperature: 37oC
    • ​Rate doubles every 10oC until optimal temperature
    • Heat induced denaturation
  • pH: between 4-8
    • Exception: gastric enzymes (Pepsin)
  • Covalent Modification
    • Phosphorylation/Dephosphorylation
32
Q

What is the proton pump and where is it located?

Why would PPIs be prescribed?

A
  • Proton Pump = H+/K+ ATPase
    • Parietal cells lining gastric lumen
  • Pumps H+ into lumen –> Combines with Cl- to form HC
  • Indigestion, heartburn, ulcers require decrease gastric acid
    • PPIs prescribed (Omeprazole, lansoprazole)
      • Reduce HCl production
33
Q

What is Hypochlorhydria?

A
  • Lower HCl production –> Reduce nutrient absorption, increase food poison sensitivity, reduce gastric enzyme efficiency (pepsin, gastric amylase, gastric lipase)
34
Q

Enzyme Kinetics describes what?

What 3 things is it dependent on?

A
  • Rate of enzyme-catalyzed reaction
  • Dependent on:
    • Initial Substrate [S]
    • Enzyme-Substrate affinity (Km)
    • Reaction velocity (v, Vmax)
35
Q

What are the Michaelis Menten and Lineweaver Burk Equations?

A

Know the MM equation

36
Q

Describe the Michaelis-Menten and Lineweaver Burk Plots

What do the x and y intercepts and slope mean on LB Plots?

A

x-int = -1 / Km

y-int = 1 / Vmax

slope = Km / Vmax

37
Q

How does Competitive Inhibition work?

Effects on Vmax and Km?

Can it be overcome?

Describe the inhibition on the graphs

A
  • Compete with substrate binding
  • No effect on Vmax
  • Km increased
  • If [I] is fixed, then increasing [S] allows substrate to outcompete inhibitor
38
Q

How does Noncompetitive Inhibition work?

Effects on Vmax and Km?

Can it be overcome?

Describe inhibition on graphs

A
  • Binds to E and to ES complex
  • Decrease in Vmax
  • Km unaffected
  • Inhibitor effects cannot be overcome by increasing substrate concentration
39
Q

How does Uncompetitive Inhibition work?

Effects on Vmax and Km?

Describe inhibition on graphs

A
  • Only binds to ES complex
  • Decrease in Vmax and Km by same factor
40
Q

What are Metalloenzymes?

How does chelation affect the enzymes?

A
  • Enzymes requiring metal ions as cofactors (Mg, Zn)
  • Chelating of cofactors will inhibit enzyme activity
    • Chelating agent: Ethylene Diamine Tetraacetic Acid (EDTA)
41
Q

Why is Lead (Pb) toxic?

Heme is a coenzyme of _

Pb poisoning Sx include _

Tx with _ and why does it work?

A
  • Inhibits 2 enzymes in heme biosynthesis
  • Heme is coenzyme of hemoglobin
  • Sx: abdominal pain, sideroblastic anemia, irritability, HA, signs of impaired nervous system development and encephalopathy
  • Tx: Ca-EDTA with dimercoprol
    • Pb (higher affinity for EDTA) displaces Ca to form Pb-EDTA (excreted)
42
Q

Irreversible Inhibition caused by _ and what are examples of inhibitors?

Effects on Vmax and Km?

Can it be overcome?

A
  • Destruction/Covalent Modification of functional groups of AAs in enzyme
    • Ex: Pb, Hg, organophosphates, cyanide, sulfide, aspirin
  • Decrease Vmax and Km unchanged
  • Only overcome by new E synthesis
43
Q

How do Allosteric Enzymes work?

A
  • Activity modulated by noncovalent binding of metabolite to site other than the catalytic site
  • Affects S binding by inducing conformational changes
  • Effectors: positive (activators, lower Km) or negative (inhibitors, raise Km)
    • Feedback Inhibition
44
Q

What are Isozymes?

A
  • Enzymes with the same catalytic function, different primary sequence
    • Different biophysical properties
45
Q

Isozymes that are Markers of MI and how are they detected?

A

Creatine Kinase (CK-MB)

Aspartate Aminotransferase (AST)

LDH-1

Blood serum levels increase after MI

46
Q

Troponin in MI

A
  • Troponin is Trimeric
  • Troponin cTn-I (cardiac muscle) used as biomarker for detection of MI
47
Q

What are Proenzymes (Zymogen)?

How do they become active?

A

Inactive precursor of enzyme

Need proteolytic breakdown to be active via cleavage of specific peptide bond

MCM Exam 1 (11 decks)

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