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Human Nutrition > Chapter 7 - Metabolism > Flashcards

Chapter 7 - Metabolism Flashcards

1
Q

What is metabolism?

A
  • sum total of all chemical reactions to go on in living cells
  • generation of energy from carbohydrates, proteins, & fats
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2
Q

what is aerobic metabolism?

A
  • with oxygen
  • produces energy more slowly b/c can be sustained for a long time
  • total energy yield is greater (than anaerobic)
  • ex. pyruvate breaking down slowly to acetyl CoA
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3
Q

what is anaerobic metabolism?

A
  • not requiring oxygen
  • yields energy more quickly, but can’t be sustained for long
  • ex. pyruvate to lactate
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4
Q

catabolic vs. anabolic metabolism

A

catabolic reactions break down larger molecules into smaller compounds & release energy (ATP & heat)

anabolic reactions use ATP to combine smaller molecule, like glucose, into larger compounds, like glycogen, & release small amounts of heat

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5
Q

mitochondria (structural features)

A

inner compartment - site of pyruvate-to-acetyl CoA, fatty acid oxidation, & TCA Cycle

inner membrane - site of electron transport chain

outer membrane - site of fatty acid activation

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6
Q

what is pyruvate?

A
  • amino acids, glycerol, & glucose can be converted to pyruvate
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7
Q

satiety

A

feeling of being full after eating

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8
Q

gherlin

A

appetite stimulating hormone

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9
Q

what is glycolysis?

A
  • the metabolic breakdown of glucose to pyruvate
  • is anaerobic (doesn’t require oxygen)
  • takes place in cytosol of cell where enzymes are located to breakdown glucose
  • one glucose molecule = 2 pyrite molecules
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10
Q

Is ATP used for glycolysis?

A

yes, 2 ATP needed to begin it

  • 4 ATP yielded at end of process
  • net gain of 2 ATP
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11
Q

can glucose be made from pyruvate?

A

yes, process can go either way

glucose pyruvate

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12
Q

what is the fate of pyruvate w/o oxygen?

A
  • anaerobic (glucose -> pyruvate -> lactate)

- yields energy quickly, but cannot be sustained for long

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13
Q

what is the fate of pyruvate with oxygen?

A
  • aerobic (glucose -> pyruvate -> acetyl CoA

- produces energy more slowly

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14
Q

Cori cycle

A
  • done in the liver
  • a recycling process of lactate
  • process of converting lactate from muscles to glucose that can be returned to the muscles
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15
Q

is the step from pyruvate to acetyl CoA reversible?

A

No

  • A cell cannot retrieve the carbons from CO2 to remake pyruvate & then glucose
  • it’s one way only
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16
Q

how are fats converted to energy?

A
  • break down to glycerol & fatty acids
  • glycerol converts to pyruvate
  • fatty acids convert to acetyl CoA thru fatty acid oxidation
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17
Q

fatty acid oxidation

A
  • takes place in the mitochondria

- 2 carbons at a time are cleaved off chain & combine with CoA to make acetyl CoA

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18
Q

can fatty acids make glucose?

A

cells cannot make glucose from the 2-carbon fragments of fatty acids

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19
Q

how is glucose obtained from fats (triglyceride)?

A
  • only the glycerol can yield glucose, but only a very small amount
  • fatty acids can provide abundant acetyl CoA
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20
Q

what are ketones?

A
  • the byproduct when the body uses fat for energy instead of glucose
  • back up fuel for brain & nerve function when glucose is limited
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21
Q

glucogenic

A

glycerol b/c can me transformed into glucose

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22
Q

ketogenic

A

fatty acids – b/c can be transformed into ketone bodies

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23
Q

what is ketoacidosis?

A
  • when there is a toxic level of ketones in the blood

- causes the blood to become acidic

24
Q

how are proteins converted to energy?

A
  • before entering the metabolic pathways, amino acids are deaminated (lose their nitrogen-containing amino group)
  • can enter pathway as pyruvate (are glycogenic), acetyl CoA (are ketogenic) or directly into TCA cycle (are glycogenic).
25
Q

why is deamination important?

A

amino acids must drop their N-containing amine group before they can be used for energy

26
Q

glucogenic amino acids

A

can be used to make glucose

- 14 amino acids

27
Q

ketogenic amino acids

A

can be transformed into ketone bodies

  • leucine
  • lysine
28
Q

which amino acids are both glycogenic & ketogenic?

A
  1. isoleucine
  2. tryptophan
  3. phynylalanine
  4. tyrosine
29
Q

what is deamination?

A

removal of the amine (N-containing) group

30
Q

why is deamination important?

A

an amino acid needs to be deaminated in order to be used for:

  • energy
  • production of glucose, ketones, cholesterol or fat
  • to make nonessential amino acids
31
Q

oxaloacetate

A
  • primarily made from pyruvate
  • can also be made from certain amino acids
  • CANNOT be made from fat
  • must be available for acetyl CoA to enter the TCA cycle (underscores how important carbohydrates are in the diet)
32
Q

what are the products of the TCA cycle?

A

Each cycle produces:

  • 2 Carbons that are lost to CO2 (breathed out)
  • 8 H+ atoms & their electrons
  • small amount of energy at GTP
33
Q

How does the TCA cycle contribute to protein synthesis?

A

it provides the starting material for creating non-essential amino acids through transamination

34
Q

how are non-essential amino acids made from essential amino acids?

A

by transamination - the transfer of an amino group from one amino acid to an alpha-keto acid to form a new non-essential amino acid

35
Q

why is transamination important?

A

allows cells to make amino acids they need to synthesize protein

36
Q

where is the TCA cycle carried out?

A

in the inner compartment of mitochondria

37
Q

what is coenzyme Q?

A

ubiquinone (CoQ10)

  • made in the body to help with cell function
  • is critical to converting fats, proteins, & carbs into energy
38
Q

what is the entrance point to the TCA cycle?

A

Acetyl CoA combines with oxaloacetate to form citrate in the first step of the TCA cycle

39
Q

what is the electron transport chain?

A
  • the final stage of metabolism when electrons are transferred from one complex to another
  • products are ATP & H2O
  • takes place in the inner mitochondrial membrane of cell
40
Q

in what way is the electron transport chain related to photosynthesis?

A

In both cases the electron transport chain uses the energy to pump hydrogen ions across a membrane.
cell - uses process to make ATP
photosyn - use energy to make molecules

41
Q

What is the location of the electron transport chain?

A

happens in the mitochondrial membrane

42
Q

what are the products of the electron transport chain?

A

ATP (90% of the ATP used by the body)

H20

43
Q

digestion pathway of alcohol

A

stomach - alcohol dehydrogenase (enzyme): begins to break down alcohol in stomach
small intestine - rapidly absorbs it, before metabolizing any other nutrients
liver - also makes alcohol dehydrogenase

44
Q

Alcohol metabolism - pathway 1

A
  1. alcohol dehydrogenase (ADH) w/niacin, oxidizes alcohol to acetaldehyde
  2. acetaldehyde dehydrogenase (ALDH) removes more H & forms acetate
  3. acetate forms acetyl CoA & enters TCA cycle
45
Q

alcohol metabolism - pathway 2 (when too much)

A

used when too much alcohol present & liver enzymes can’t keep up
1. MEOS - at high concentrations or repeated exposure, alcohol stimulates synthesis of enzymes in the MEOS.

46
Q

Microsomal ethanol-oxidizing system

A

MEOS

  • chronic alcohol abuse increases the # of enzymes in this pathway
  • used to metabolized drugs & other foreign bodies
  • alcohol takes precedence over drugs (may interfere w/metabolism of drugs
  • can increase alcohol tolerance
47
Q

blood alcohol concentration (bac)

A
  • if there is too much alcohol for the liver to metabolize, some stays in the blood
  • amount of alcohol in blood measured in grams/dL
48
Q

Wernike-Korsakoff syndrome

A

malnutrition - mental confusion & uncontrolled muscle movement due to thiamin deficiency’s affect on brain

  • paralysis of eye muscles
  • poor muscle coordination
  • impaired memory
  • damaged nerves
49
Q

malnutrition

A
  • heavy drinking displaces nutrients from diet
  • interferes with body’s metabolism of nutrients
  • affects B vitamin folate
  • affects liver’s ability to retain folate & kidneys excrete more
50
Q

fatty liver

A
  • presence of too much alcohol in liver stops liver from packaging & sending fatty acids to tissues
  • fat can build up
51
Q

cirrhosis of the liver

A
  • fatty liver is reversible if stop drinking
  • fibrosis - alcoholic hepatitis - 2nd stage of liver deterioration - some cells can regenerate w/good nutrition & no drinking
  • cirrhosis - advanced stage of damage; least reversible
52
Q

Consequences from excessive alcohol consumption:

A
  • liver disease
  • malnutrition
  • impaired digestion & absorption
  • weight gain
  • changes in nutrient metabolism
  • interaction w/hormones
  • cardiovascular disease
  • irreversible damage to fetus
53
Q

phenylkeonuria

A

PKU

  • born without ability to properly breakdown amino acid phenylalanine
  • example of a diet-related single-gene disorder
  • can be controlled by diet
  • symptoms include:
    • delayed mental & social skills
    • head size significantly below normal
    • hyperactivity
    • jerking movements of arms or legs
    • mental retardation
    • seizures
    • skin rashes
    • tremors
    • unusual positioning of hands
54
Q

role of liver in metabolism

A
  • most metabolically active organ in body
  • first organ to metabolize, store & distribute nutrients after absorption
  • proteins, carbs, & fats are converted to: usable forms of energy; storage forms -> glycogen, triglycerides
55
Q

how is energy defined?

A

ATP
creatine phosphate
energy storage

56
Q

creatine phosphate

A
  • a high energy compound found in muscle cells
  • acts as a reservoir of energy
  • can maintain a steady supply of ATP for short bursts of activity
  • can donate an inorganic phosphate to ADP to make ATP

Human Nutrition (8 decks)

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