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Biochemistry- Unit Two
Metabolism (T Pierce)
43
Medical
Post-Graduate
03/27/2009

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Cards

Term

define anabolism

Definition
  • endergonic (pos. ΔG)
  • synthesis process in body
Term

Define catabolism

Definition
  • exergonic (neg. ΔG)
  • degradative processes of body
Term

Define metabolic pathway

Definition

series of consecutive chemical rxns in which specific substrate(s) are converted into specific product(s)

Term
Common features of metabolic pathways
Definition
  • with few exceptions, each reaction in pathway catalyzed by enzyme
  • each pathway has commited step which is usually irreversible and rate limiting
  • occurs at specific site in cell
  • regulated AT RATE LIMITING STEP
Term

Types of pathways

Definition

linear

branched

cyclic

Term

define phototrophs

Definition
obtain energy from sun through process of photosynthesis
Term
Define chemotrophs
Definition

obtain energy from oxidation of organic compounds supplied in diet (respiration)

Term
Organic fuel that is primary source of energy
Definition

oxidation of glucose (-2800 kJ) and fatty acids       (-12,000 kJ) supplied via the diet

Term
calorie value within a gram of carbohydrate
Definition
4 kcal/gram of carb
Term
Calories for every gram of fat
Definition
9 kcal/gram of fat
Term

Calories for gram of protein

Definition

4 kcal/gram of protein (much more complicated because when it is broken down, produces N product, which becomes ammonia, which is a source of energy)

Term
Calories per gram of ethanol
Definition
7 kcal/gram of alcohol
Term
Cellular fuels
Definition

glucose

fatty acids

Term
Enzyme that breaks down carbohydrates
Definition

amylase (salivary, pancreatic)

brush border enzymes

Term

Substances that break down fats into FA's

Definition

pancreatic juices

bile

Term
Fate of glucose and fatty acids in the cell
Definition
oxidized to CO2 via respiration (need molecular oxygen)
Term

Rxn of glucose being broken down to CO2

Definition
glucose + O2 → 6CO2 (releases 2800 kJ/mole)
Term
Define calorie
Definition
amount of energy needed to raise one gram of water from 14.5 to 15.5 degrees C
Term
Fate of energy released in one step.
Definition
it would only produce heat
Term
Explain why we need pathways to release energy in small discrete packets. What do we use this energy to do?
Definition

We must use specific small reactions to get small packets of energy. This energy is used to synthesize ATP (couple rxn with ATP synthesis). Any reaction that is coupled to ATP synthesis is irreversible.

Term
Gibbs free energy for ATP synthesis
Definition

33 kJ/mole

Term
Define oxidation
Definition
  • loss of electrons
  • loss of hydrogen
  • addition of oxygen
Term
Examples of oxidation
Definition
  • ferrous → ferric + e
  • cuprous → cupric +e
Term
Describe process of oxidation of organic compounds
Definition
  1. oxidation involves breaking C-H bond
  2. H bond removed with both electrons (hydride ion)
    • acts as a packet of energy (extremely reactive)
  3. carbon will become positive
  4. intermediate of C compound will rearrange by losing a proton
Term
Examples of different types of oxidations of organic compounds involved in production of ATP
Definition
  • alkane converted to alkene (ex: succinate to fumarate)
  • alcohol via dehydrogenase produces aldehyde/ ketone and hydrogen ion (positive ion)
  • aldehyde via dehydrogenase to carboxylic acid
  • decarboxylation of alpha keto acid to carboxylic acid and carbond dioxide
Term
Structures that carry hydride ion
Definition

NAD

NADP

FMN

FAD

Term
Nicotinamide nucleotides derived from what?
Definition
niacin
Term
What portion of NAD/NADP will bind within the active site of alcohol dehydrogenase?
Definition
nicotinamide
Term
clincial effects of being niacin deficient
Definition
  • develop pelagra (3 D symptoms)
    • dermititis
    • diarrhea
    • dementia
    • if not treated, DEATH
Term
Vitamin part of FMN/FAD
Definition
riboflavin
Term

type of coenzyme of flavoproteins

Definition
prosthetic groups (never leave active site)
Term
enzymes that flavoproteins interact with
Definition
  • oxygenase- transfer reducing equivalents directly to molecular oxygen with formation of hydrogen peroxide (ex: D AA oxidase)
  • dehydrogenases- oxidize substrates (ex: fatty acyl CoA DH)
  • reductases- reduce substrates (ex: glutathione reductase)

ALL INVOLVE REACTION WITH OXYGEN EITHER DIRECTLY OR INDIRECTLY!!

Term
Three oxidation states of FAD/FMN
Definition
  • FAD/FMN
  • FMN./FAD. (semiquinone form)
  • FADH2/FMNH2
Term
What are CoA and acyle carrier protein derieved from?
Definition
pantothenic acid
Term
Functions of CoA
Definition
  • carry acyl groups
  • sulfhydryl group react with carboxylic acid to form thiol ester
    • thiol ester bond is high energy
    • represents activated state of CoA that can be transferred directly to appropriate acceptor molecule
Term

Structurally, what is the difference between ACP and CoA-SH

Definition
CoA has R group attached to phosphate that is AMP. For ACP, the R group is a protein.
Term
Chemical structure of thiamin pyrophosphate (TPP)
Definition

pyrophosphate gropu added to alcohol group of a thaimine

Term
Function of thiamine pyrophosphate in enzymatic reactions
Definition
  • act as prosthetic group for
    • transketolase
    • alpha keto acid dehydrogenase (decarboxylation of alpha keto acids)
      • non-oxidative (needs only one enzyme)
      • oxidative (need a bunch of other enzymes)
Term
Products of decarboxylation via oxidative and non-oxidative mechanisms
Definition
  • non-oxidative produces aldehyde and carbon dioxide
  • oxidative produces carboxylic acid, carbon dioxide, and two electrons (via enzyme complex called dehydrogenase)
Term
Describe the alpha keto glutarate dehydrogenase complex needed to produce acyl CoA
Definition
  • decarboxylase with TPP coenzyme
  • transferase composed of lipoic acid coenzyme with a Lys attached to the carbonyl end
  • dihydrolipolyl dehgydrogenase with FAD coenzyme
Term
Steps of alpha keto acid dehydrogenase rxn
Definition
  1. add alpha keto acid to TPP in decarboxylase
  2. carbon dioxide leaves decarboxylase-TPP complex
  3. the RC=O group binds to lipoic acid in trasnferase complex
  4. CoA-SH pick up R=CO, causing two H's to come back to lipoic acid in transferase
  5. dihydrolipoyl dehydrogenase picks of hydride ions via FAD as its coenzyme
    1. this will reform the ringed structure of the lipoic acid within transferase
  6. to regenerate FAD in dihydrolipoyl dehydrogenase, NAD will pick up the hydrides from FADH2
Term
Major dehydrogenase complexes in mitochondria
Definition
  • pyruvate dehydrogenase
  • alpha keto glutarate dehydrogenase
  • alpha keto branched chain dehydrogenase
Term
Fate of the NADH produced by the dehydrogenases
Definition
  • NADH is used to fuel the ETC
  • ETC will pass electron to O2 to produce H20
  • ETC will also produce energy that will fuel the synthesis of ATP
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