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Biochem > Intro To Metabolism > Flashcards

Intro To Metabolism Flashcards

1
Q

Fasted refers to

A

Overnight fast

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2
Q

Big picture of metabolism

A

Chemical energy contained in macronutrients needs to be converted into energy cell can use to do work

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3
Q

Primary organ of metabolic regulation

How?

A

Liver

Maintains blood glucose and amino acid homeostasis

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4
Q

Liver insulin transporter’s Km

A

High Km –> can always bring in glucose especially after a meal

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5
Q

Transporters function like

A

Enzymes

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6
Q

Metabolism involves (3)

A
  1. Homeostasis
  2. Redistribution of chemical energy between compounds
  3. Integration of metabolic pathways
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7
Q

Homeostasis

2 types?

A

Maintaining a constant internal environment
- changes do occur but mechanisms are in place that compensate for those changes to bring back to “normal”

Metabolic homeostasis and pH homeostasis

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8
Q

How are metabolic and pH homeostasis connected?

A

Metabolism releases weak organic acids and CO2

Need to maintain constant level of blood glucose

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9
Q

Fuel availability

A

stored energy in form of glycogen or fat

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10
Q

Metabolic homeostasis is the balance between

A

Fuel availability and what tissues need

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11
Q

Metabolic homeostasis is determined by (3)

A
  • nutrient levels
  • hormone signals
  • nerve signals
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12
Q

What region of hypothalamus controls feeding?

A

ARC region

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13
Q

Orexigenic neurons

A

Promote feeding behavior

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14
Q

Anorexigenic neurons

A

Inhibit feeding behavior

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15
Q

When you take in nutrients, ______ levels rise and 2 things occur:

A

Insulin levels rise

  1. Metabolize some energy to maintain body function
  2. The excess calories are stored for breakdown during times of fasting
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16
Q

Importance of maintain blood glucose

A

Brain needs ~75% of daily need for glucose

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17
Q

Fiber

A

Restricts how rapidly glucose levels (thus insulin levels) rise in the blood

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18
Q

What happens to blood glucose, insulin, and glucagon levels after a meal?

A
  • Blood glucose levels rise
  • Insulin levels follow blood glucose and rise too
  • Glucagon levels stay relatively constant
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19
Q

Insulin

Made by?
Responds to?
Corresponds to?

A

Insulin = FED STATE

  • Made by beta cells of pancreas
  • Responds to elevated blood glucose
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20
Q

Type 1 vs. Type 2 diabetic

A

Type 1: beta cells have been destroyed therefore do not produce insulin

Type 2: produce insulin, but no response because signal transduction cascade is affected

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21
Q

Insulin = “______ hormone”

Why?

A

Anabolic hormone

Promotes synthesis of macromolecules

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22
Q

Insulin stimulates

A

Glucose transport into skeletal muscle and adipose tissue

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23
Q

Once glucose is in skeletal muscle –>

A
  • Metabolized for energy

- Stored as glycogen

24
Q

Once glucose is in adipose tissue –>

A

Converted to fatty acids which are then esterified to glycerol backbone to yield triglycerides

25
Q

In liver, glucose is

A

Made into glycogen and energy

Any excess can go into fatty acids

26
Q

Glucagon

Made by?
Responds to?
Corresponds to?

A

Glucagon = FASTED STATE

  • Made by alpha cells of pancreas
  • Signals that current supply of glucose is low for the cell’s needs
27
Q

Glucagon = “______ hormone”

Why?

A

Catabolic

It promotes the breakdown of stored fuels (glycogen and fat) to provide energy when it is not coming from the diet

28
Q

Glucagon signal transduction is the same as

A

Epinephrine

29
Q

Glucagon has no effect on ________ because ________

A

Skeletal muscle because no receptors

30
Q

_______ and _________ respond to glucagon

A

Liver and fatty acids

31
Q

In response to glucagon, in liver ____

A

Glycogen is broken down to glucose –> exits liver and enter blood

32
Q

In response to glucagon, in adipocytes ______

A

Triglycerides broken down to fatty acids –> exit liver and enter blood to provide alternative source of energy

33
Q

2 major fuel stores

A
  1. Glycogen - limited

2. Triglycerides/fatty acids- longer period of time; more nrg when oxidized

34
Q

High insulin : glucagon ratio =

A

FED

35
Q

What happens when high insulin: glucagon ratio?

A

Brain senses blood glucose is high –> CNS sends signal to pancreas to release insulin –> stimulates transport of glucose into skeleton muscle and adipose tissue –> synthesis of glycogen or fatty acids which are eventually converted into triglycerides

36
Q

Low insulin: glucagon ratio =

A

FAST

37
Q

What happens when low insulin:glucagon ratio?

A

Brain senses blood glucose is low –> CNS sends signal to pancreas to release glucagon –> promotes breakdown of liver glycogen and release of glucose into blood

(Gluconeogenesis in liver)

38
Q

Glycogen breakdown can be stimulated by

A

Glucagon or epinephrine

39
Q

In fasted state, most of the glucose generated is _________. Why?

A

Is selectively saved for the brain and RBC because brain and RBC cannot oxidize fatty acids for energy

NOT metabolized for energy

40
Q

Catabolism =

A

Breakdown

Oxidative, exergonic

Paired to making ATP which is consumed in anabolic reactions

41
Q

Anabolism =

A

Reductive, endergonic

Synthesis requiring reducing equivalents

Coupled to splitting ATP

42
Q

What makes ATP an efficient energy currency?

A

“High phosphoryl transfer potential”

43
Q

Why is ATP hydrolysis favorable? (3)

A
  1. It reduces the electrostatic repulsion of the 3 negative charged phosphate groups
  2. The inorganic phosphate has resonance stabilization, therefore entropy is increased
  3. Stabilization due to hydration with H2O molecules
44
Q

Energy is ATP is contained in

A

The 3 phosphate bonds

45
Q

Other molecules with high phosphoryl transfer potential (3)

A
  1. Phosphoenolpyruvate
    - glycolytic intermediate
  2. Creatine phosphate
  3. 1,3- Biphosphoglycerate (1,3-BPG)
    - glycolytic intermediate
46
Q

high phosphoryl transfer potential requirements (3)

A
  1. Have a phosphate
  2. Can transfer the phosphate to another molecule with lower energy
  3. Usually a lot of energy released when phosphate is transferred
47
Q

ATP levels are maintained in equilibrium by

A

Adenylate cyclase

2 ADP ATP + AMP

48
Q

If ATP levels decrease:

A

ADP levels increase by ~50%

AMP levels increase by several hundred fold

49
Q

_____ is signal for low energy state

A

AMP

50
Q

Small drop in ATP concentration is magnified by

A

Changes in AMP and ADP

51
Q

How are ATP-generating and ATP-utilizing (biosynthesis) pathways related?

A

They function inversely based on ATP availability

52
Q

Energy charge:

0 =
1 =
Cellular range =

A 
0 = no ATP, all AMP
1 = all ATP, no AMP

Cellular range = 0.8-0.95
- Always trying to get back here (point of intersection)

53
Q

If have all ATP, rate of ATP generation is ______.

If have no ATP, rate of ATP utilizing is ______.

A

Low

Low (b/c no availability)

54
Q

If decrease ATP –> energy charge ______ and _________

A

Energy charge drops and rate of ATP generation increase

55
Q

If have ATP, _______

A

Rate of biosynthesis increases

Biochem (15 decks)

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