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Biochemistry > Summary of Metabolism > Flashcards

Summary of Metabolism Flashcards

1
Q

Each metabolic fuel has 3 forms. What are they?

A
  1. Storage form
  2. Transport form
  3. Interacellular metabolite form
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2
Q

When fatty acid oxidation is excessive, the excess acetyl-CoA is converted into

A

ketone bodies

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3
Q

Carbohydrates and proteins can be converted to lipids. T/F

A

True

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4
Q

Carbohydrates can be used for the synthesis of non essential amino acids.T/F

A

True

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5
Q

Acetyl-CoA can not be converted into ….. and so it can not be used for gluconeogenesis or protein synthesis

A

pyruvate

* The enzyme pyruvate dehydrogenase catalyzes an irreversible reaction with no opposite enzymes in humans to reverse it.

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6
Q

The shifting between the storage and transport form, as well as the type of the fuel being metabolized is well under the control of …….

A

ratio of insulin/glucagon

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7
Q

Insulin action is opposed by ….., ….., ….. & …..

A

glucagon, cortisol, growth hormone & epinephrine

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8
Q

The major targets for insulin action are …., …. & ….

A

liver, muscle & adipose tissue

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9
Q

After the glycogen reserves are filled, liver converts excess glucose to …… .

A

Fatty acids

* Insulin promotes fatty acids and protein synthesis

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10
Q

HMP shunt activity varies with the body’s need for …..

A

NADPH for fatty acids and cholesterol synthesis

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11
Q

Glucagon and epinephrine activity ….. during overnight fast, and HMP shunt activity is …..

A

increased, decreased

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12
Q

During overnight fast, gluconeogenesis response is …… than glycogenolysis under glucagon activity

A

slower

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13
Q

During fasting, amino acids provides the …… while fatty acids provide ….. necessary for gluconeogenesis

A

carbon skeleton, ATP

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14
Q

During prolonged fasting, levels of …… & ….. are increased

A

ketones & fatty acids

* This is in response to elevated levels of glucagon and epinephrine

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15
Q

During prolonged fasting, the brain adapts to using …. for energy, while the muscles use ……. . This shifting in form of energy used is to conserve protein

A

ketones

fatty acids

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16
Q

Protein has no transport form. T/F

A

False

it has not “storage” form, because each protein has a specific function in the cell

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17
Q

HMP shunt activity is …….. during prolonged starvation state

A

non existent

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18
Q

What are the cells that depend entirely on glucose for energy?

A

RBCs and renal medullary cells, because they lack mitochondria

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19
Q

Complete combustion of fat produce ……

A

9 kcal/g

* Fats produce much more energy than other sources of energy

20
Q

Most carbohydrates are stored as ….. in the body. A small fraction of the total carbs is found free

A

glycogen

21
Q

Why protein sparing is important during periods of starving or prolonged fasting?

A

Because degradation of more than one third of total body protein is incompatible with life

22
Q

The utilization of fuel depends on ….. & ……

A
  1. tissue studied

2. metabolic state

23
Q

Gluconeogenesis, lipolysis & proteolysis are all activated during …… . The decrease in proteolysis and carbohydrate utilization is due to ……

A

fasting state

accumulation of Acetyl-CoA, which leads to inhibition of pyruvate dehydrogenase

24
Q

The main fuel for muscles is …. & ….. in the well fed state

A

glucose & fatty acids

* Skeletal muscles are the body’s major energy consumer

25
Q

Lactate accumulates when ……. during intense muscle contraction

A

pyruvate production exceeds the TCA cycle to carry out terminal oxidation

26
Q

In the fasting state, muscles use …. & …… while sparing glucose for the brain and the RBC

A

fatty acids and ketone bodies

27
Q

Why the cardiac muscle has much higher oxidative capacity than skeletal muscles?

A

Because of their higher number of mitochondria

28
Q

Cardiac muscle uses …….. & …… during well fed state, and …… & …… during fasting state

A

glucose & fatty acids

fatty acids and ketones

29
Q

The brain relies primarily on ….. for energy, because …… can not cross the BBB.
During fasting state, the brain can use ….. for energy, although it supplies only 2/3 of the demand, the remaining one third is supplied by …..

A

glucose
fatty acids
ketone bodies
glucose

30
Q

The renal cortex mainly uses …. for energy, while the medula uses …… . However, they kidney can utilize all types or fuels for energy

A

fatty acids

glucose

31
Q

The two main energy roles for the liver is to ……. & ……

A

maintain level of blood glucose

synthesize ketones when excess fatty acids are being oxidized

32
Q

During well fed state, the liver derives most of its energy from oxidation of ….

A

excess amino acids

33
Q

Insulin stimulates the release of fatty acids from ….. & ….. by activating the enzyme …..

A

VLDL & chylomicrons

LipoprotienLipase

34
Q

During fasting, glucagon and epinephrine activate ……. to mobilize fatty acids from adipose tissue

A

hormone sensitive lipase

35
Q

……. is the only hormone in humans that promotes fuel storage.It is release from the pancreas is related to the elevated level of …….

A

Insulin

blood glucose

36
Q

What are the catabolic hormones?

A

glucagon, epinephrine, nor epinephrine, growth hormone, cortisol

37
Q

For hormones to generate signal in the cell, explain the steps that should occur

A
  1. Hormone binds to membrane g protein coupled receptor. G protein is activated
  2. The receptor communicates with adenylate cyclase through G protein (This protein uses GTP for energy to start communicating)
  3. Adenylate cyclase causes increase in intracellular cAMP
  4. cAMP activates protein kinase enzyme, which in turn phosphorylates the intracellular enzyme (activation may increase or decrease activity)
  5. Removal of the phosphate group and restoration of the original state by protein phosphatase
    see P. 361
38
Q

The hormone receptor complex can bind to DNA …… or …… sequence with the result of increase or decrease mRNA synthesis

A

enhancer & silencer

39
Q

The enhancer region in the DNA has no effect alone unless it is bound to …..

A

hormone receptor complex

* this binding increases the rate of transcription

40
Q

What are the catabolic hormones that activate adenylate cyclase?

A

glucagon, epinephrine and nor epinephrine

41
Q

Glucagon release is stimulated by ….., it acts mainly on ….. to increase ….. & …… and inhibit …..

A

low glucose, liver
glycogenolysis, gluconeogenesis
glycolysis
see p. 363 table

42
Q

What are the effects of epinephrine and nor epinephrine on alpha & beta receptors?

A
  1. Alpha: on the liver, activate second messengers (Ca, diacylglycerol) and stimulate other protein kinase, leading to glycogenolysis and gluconeogenesis
  2. Beta: located on muscles, causes activation of adenylate cyclase and increasing cAMP levels. increasing glycogenolysis and lipolysis (in adipose tissue)
    * Catecholamines are released in response to hypoglycemia
43
Q

What is the effect of insulin on cAMP?

A

It causes activation of cAMP phosphodiesterase, which degrades cAMP and causing activation of protein phosphatase (this shifts equilibrium from the phospho to dephospho form of these enzyme)

44
Q

Glucagon and insulin have effect on mRNA synthesis. T/F??

A

True

They effect the rate of synthesis for the regulatory enzymes in gluconeogenesis and glycolysis

45
Q

Cortisol causes increased ……, ……. & …..

A

proteolysis (activated proteases), lipolysis ( activate hormone sensitive lipase), gluconeogenesis (increase PEPCK & FBPase)

46
Q

Thyroid hormones metabolic effects include ….., ….., …… & ….. . They also have effect on the rate of gene expression

A

increase O2 consumption, hyperthermia, hyperglycemia, and decrease cholesterol

47
Q

The activity of cAMP is shut off by the enzyme …..

A

phosphodiesterase

Biochemistry (13 decks)

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