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Biochemistry > Zaidi Comp > Flashcards

Zaidi Comp Flashcards

1
Q

GLUT 1

GLUT 2

GLUT 3

GLUT 4

A

ubiquitous but expressed highly in brain and RBCs - high affinity

liver - low affinity

neurons - high affinity

skeletal muscle, heart, adipose tissue - insulin dependent (regulated by insulin)

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2
Q
  1. stage 1 of glycolysis
    1. glucose → ____
    2. ____ ATPs consumed
    3. ____ ATPs generated
    4. strategy of stage 1:
  2. stage 2 of glycolysis
    1. G3P → ____
    2. ____ ATPs consumed
    3. ____ ATPs generated
A
    1. G3P
    2. 2
    3. 0
    4. trap glucose in cell and form a compound that can be readily cleaved into 2 phosphorylated 3-carbon units
    1. pyruvate
    2. 4
    3. 0
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3
Q

glycolysis:

  1. glucose → ____ (via ____ )
  2. Glucose 6-Phosphate → ____ (via ____ )
  3. Fructose 6-P → ____ (via ____ )
  4. F, 1-6 BP → ____ (and DHAP) (via ____ )
  5. G3P → ____ (via ____ )
  6. 1, 3 BPG → ____ (via ____ )
  7. 3-PG → ____ (via ____ )
  8. 2-PG → ____ (via ____ )
  9. PEP → ____ (via ____ )
A
  1. Glucose 6-Phosphate (via hexokinase)
  2. Fructose 6-Phosphate (via phosphoglucose isomerase)
  3. Fructose 1,6-BP (via PFK)
  4. G3P (via aldolase)
  5. 1, 3 BPG (via G3PDH)
  6. 3-PG (via phosphoglycerate kinase)
  7. 2-PG (via phosphoglycerate mutase)
  8. PEP (via enolase)
  9. pyruvate (via pryuvate kinase)
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4
Q

major regulatory enzymes of glycolysis

A

hexokinase

PFK (rate-limiting step)

Pyruvate kinase (irreversible step)

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5
Q

entry points of other monosaccharides into glyocsis:

  • sucrose is a disaccharide of glucose and ____
  • lactose is a disacharide of glucose and ____
  • fructose quickly turned to ____ in times of high energy
A
  • fructose
  • galactose
  • fat
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6
Q

regulation of glycolysis in muscle:

____ levels regulate glycolysis

A

ATP

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7
Q

regulation of glycoysis in liver:

  • goal: to maintain blood ____ levels
  • goal: to provide building blocks for other pathways
  • trapping of glucose: ____
    • no ____ in liver
  • rate-limiting step: ____
    • activated by ____
    • inhibited by ____
  • pryuvate kinase is regulated by ____
    • phosphorylated = ____
    • dephosphorylated = ____
A
  • glucose
    • glucokinase
      • hexokinase
  • PFK
    • F-2, 6-BP
    • citrate
  • phosphorylation
    • inactive
    • active
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8
Q

excessive fructose consumption can lead to pathological conditions:

  • fructose bypasses the rate-limiting step in glycosis, the ____-catalyzed reaction
  • excess fructose is processed by glycolysis to ____ and ____ ____ in an unregulated fashion
    • excess acetyl CoA is converted to ____ ____ which results in obesity and fatty liver
A
  • PFK
  • pyruvate and acetyl CoA
    • fatty acids
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9
Q

lactose intolerace is the inabilty to metabolize ____

caused by deficiency in ____ , which breaks down lactose to glucose and galactose

A

lactose

lactase

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10
Q

defects in galactose metabolism:

  • disruption in galactose metaoblism is called ____
  • classic galactosemia (most common form) is an inherited deficiency in galactose 1-phosphate uridyl transferase activity
  • accumulated galactose can be reduced to galactitol to form ____
A
  • galactosemia
    • cataracts
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11
Q

gluconeogeneis:

occurs in ____ and ____

converts ____ into ____

major precursors:

____ of ATP/GTP consumption

A

liver and kidneys

pyruvate into glucose

lactate, amino acids, and glycerol

3

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12
Q

gluconeogenesis:

  1. pyruvate → ____ via ( ____ )
    1. Pyruvate carboxylase (PC) is a ____ enzyme
    2. OAA transported to cytoplasm (out of mitochondria via ____ shuttle
  2. OAA → ____ → ____ → ____ → ____ → ____
  3. G3P → ____
  4. fructose 1,6-BP → ____ (via ____ -rate-limiting step)
  5. fructose 6-phosphate → ____
  6. glucose 6-phosphate → ____ (via ____ )
A
  1. OAA (via pyruvate carboxylase)
    1. mitochondrial
    2. malate
  2. PEP → 2-PG → 3-PG → 1,3-BPG → G3P
  3. Fructose-1,6-BP
  4. Fructose 6-Phosphate (via fructose 1,6-bisphosphatase)
  5. glucose -phosphate
  6. glucose (via glucose 6-phosphatase)
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13
Q

glucose 6-phosphatase:

  • located in the lumen of the ____
  • ____ transports Glucose 6-phosphate to ER
  • ____ transports inorganic phosphate back into cytosol
  • ____ transports glucose back to cytoplasm
A
  • ER
  • T1
  • T2
  • T3
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14
Q

gluconeogenesis bypases the irreversible steps of glycosysis through 4 enzymes

A

pyruvate carboxylase

PEP carboxykinase

fructose 1,6-bisphosphatase

glucose 6-phosphatase

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15
Q

regulation of glycolysis and gluconeogenesis in liver:

  • fructose 2,6-bisphosphate stimulates ____ (rate limiting step in glycolysis)
  • the concentration of fructose 2,6-bisphosphate is controlled by a bi-functional enzyme with a kinase and phosphatase domain ( ____ and ____ )
  • byfunctional enzyme is regulated by ____ and ____
    • insulin: stimulates phosphoprotin phosphatase → ____ is stimulated
    • glucagon: stimulates PKA → ____ is stimulated
A
  • PFK
  • PFK2 and fructose bisphosphatase 2 (FBPase2)
  • insulin and glucagon
    • glycolysis
    • gluconeogenesis
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16
Q

cori cycle:

____ produced in skeletal muscle and RBCs can be converted back to ____ in the liver

pyruvate can enter the gluconeogenic pathway and regenerate ____

A

lactate, pyruvate

glucose

17
Q

structure of glycogen:

  • long chain ____ of glucose
  • glucose molecule within linear chain linked via ____ bonds
  • branch points formed via ____ bonds
  • non-reducing ends (multiple) contains a terminal glucose with a free ____ group at carbon-4
  • reducing end consists of glucose monomer connected to a protein called ____
  • glycogen is degraded and extended from ____ ends
A
  • homopolymer
  • a-1,4- glycosidic bonds
  • a-1,6-glycosidic bonds
  • hydroxyl
  • glycogenin
  • non-reducing
18
Q

glycogen storage:

  • stored in ____ , _____ , and other tissues
  • stored as ____
  • granules contain not only glycogen but also the ____ needed for glycogen metabolism
  • defects in these enzymes can lead to glycogen ____ disorders
A
  • liver, muscle
  • granules
  • enzymes
  • storage
19
Q

functions of glycogen:

____ glycogen: regulates blood glucose levels

____ glycogen: provides reservoir of fuel (glucose) for physical activity

A

liver

muscle

20
Q

key steps of glycogenesis:

  1. ____ and ____ of glucose
    1. glucose 6-phosphate → ____ (via ____ )
    2. glucose 1-phosphate → ____ (via ____ )
  2. ____ of a glycogen primer
    1. ____ ____ (rate-limiting step)
      1. catalyzes transfer of glucose from UDP-glucose to non-reducing end of glycogen)
  3. ____ of glycogen chains
    1. when glycogen reach _____ residues, a fragment (7 residues long) is broken off and reattached through an ____ bond via ____ )
    2. branching increases ____ of glycogen
A
  1. trapping and activation
    1. glucose 1-phosphate (via PGM)
    2. UDP-glucose (via UDP-glucose pyrophosphorylase)
  2. elongation
    1. glycogen synthase
  3. branching
    1. 11, a-1.6 bond, glucosyl (4:6) transferase
    2. solubility
21
Q

glycogenolysis:

  • in liver:
  • in muscle:
A
  • liver: glycogen → glucose 1-phosphate (via glycogen phosphorylase- rate limiting) → glucose 6-phosphate (via PGM) → glucose (via glucose 6-phosphatase)
  • in muscle: glycogen → glucose 1-phosphate (via glycogen phosphorylase -rate limiting) → glucose 6-phosphate (PGM) → pyruvate (via glycolysis)
22
Q

4 key enzymes of glycogenolysis:

  1. glycogen phosphoryalse (rate limiting)
    1. adds an ____ and releases a glucose residue as glucose-1-phosphate
    2. uses ____ ____ (vitamin B6) as a cofactor
  2. PGM
    1. converts ____ to ____
  3. transferase (debranching enzyme) transfers a block of ____ of remaining 4 glucose to the non-reducing end
  4. a-1,6 glucosidase (debranching enzyme) convert branched glycogen into a ____ structure for further action by glycogen phosphorylase
A
    1. orthophosphate
    2. pyridoxal phosphate
  2. PGM
    1. glucose 1-phosphate to glucose 6-phosphate
  3. 3
  4. linear (by taking the last of the 4 glucoses that was branched)
23
Q

glycogen synthase:

  • non-phosphorylated “a” : ____ form
  • phosphorylated “b” : ____ form
  • phosphorylated by ____
    • under control of ____
  • allosteric regulation, ____ is a powerful activator
A
  • active
  • inactive
  • glycogen synthase kinase (GSK)
    • insulin
  • glucose -6- phosphate
24
Q

glycogen phosphorylase:

  • phosphorylated “a” form : ____ form
  • nonphosphorylated “b” form : ____ form
  • both isozymes exist in equilibrium between ____ and ____
    • liver glycogen phosphorylase is inactivated by free ____
      • default “a” ____ form
    • muscle glycogen phosphorylase is activated by ____
      • default “b” ____ form
A
  • active
  • inactive
  • R and T
    • glucose
      • active
    • AMP
      • inactive
25
Q
  1. glycogensis favored in ____ state
    1. blood glucose ____
    2. insulin ____
    3. cellular ATP ____
  2. glycogenolysis favored in ____ state
    1. blood glucose ____
    2. glucagon ____
  3. glycogenolysis also favored during ____
    1. cellular ____ high
    2. ____ high
A
  1. fed
    1. high
    2. high
    3. high
  2. fasting
    1. low
    2. high
  3. exercise
    1. calcium
    2. AMP
26
Q

glycogen metabolism regulation by insulin:

  1. four key protein involved
    1. GLUT ____
    2. protein kinase ____
    3. protein phosphatse ____
    4. glycogen synthase ____ 3
  2. net result: glycogen synthesis via activation of ____ and inactivation of ____
A
    1. 4
    2. B
    3. 1
    4. kinase
  2. glycogen synthase, glycogen phosphorylase
27
Q

glycogen metabolism regulation by glucagon and epinephrine:

  1. key enzymes and second messengers
    1. ____ protein
    2. adenylate cyclase and ____
    3. protein kinase ____
    4. protein phosphatase ____
    5. phosphorylase ____
  2. net results: glycogen breakdown via inactivation of ____ and activation of ____
A
    1. G
    2. cAMP
    3. A 1
    4. kinase
28
Q

____ ____ is the glucose sensor in liver cells

A

glycogen phosphorylase

29
Q

glycogen storage diseases:

  • GSD 0 → ____ → ____
  • GSD 1 → ____ → ____
  • GSD 2 → ____ → ____
  • GSD 3 → ____ → ____
  • GSD 4 → ____ → ____
  • GSD 5 → ____ → ____
  • GSD 6 → ____ → ____
A
  • 0 → no name → glycogen synthase
  • 1 → Von Gierke → glucose 6-phosphatase
  • 2 → Pompe → Acid Maltase
  • 3 → Cori disease → debranching enzyme (a-1,6-glucosidase)
  • 4 → Andersen → glucosyl (4:6) transferase
  • 5 → McArdle → muscle glycogen phosphorylase
  • 6 → Hers → liver glycogen phosphorylase

Biochemistry (32 decks)

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