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Biochemistry > Protein and amino acid metabolism > Flashcards

Protein and amino acid metabolism Flashcards

(51 cards)

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1
Q

Which substances lead to Acetyl CoA?

A
  • Pyruvate (from amino acids and glucose)
  • Ethanol
  • Acetoacetate (ketone body)
  • Palmitate (fatty acid)
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2
Q

Can amino acids be stored?

A

No

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3
Q

How are surplusses of amino acids used?

A
  • Energy production (Nitrogen excreted)
  • Fat production
  • Protein synthesis if needed
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4
Q

How is pepsin activated?

A

From pepsinogen by H+

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5
Q

How is trypsin activated?

A

From trypsinogen by enteropepsidase

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6
Q

Which enzymes does trypsin activate?

A
  • Chymotrypsin
  • Elastase
  • Carboxypeptidases
  • Lipase
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7
Q

How is the proteolysis of zymogens regulated to prevent damage in the digestive system?

Zymogens are dangerous pro-enzymes

A

Trypsin inhibits the production of itself

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8
Q

How is a peptide bond formed?

A

Amino group + carboxylate group

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9
Q

How are amino acids taken up by the liver?

A
  1. Amino acids enter the serosal cell along Na+
  2. Na+ is actively transported out and potassium is taken up
  3. Amino acids enters the portal vein by transporters
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10
Q

How do gut cells use amino acids?

A

To produce energy

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11
Q

How do levels of amino acids in the blood change?

A
  • Dietary protein
  • Endogenous protein
  • Protein synthesis
  • Nitrogen products excreted into urine
  • Amino acids produced from glucose
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12
Q

How are amino acids used during gluconeogenesis?

A
  • Carbon skeletons for glucose synthesis
  • Nitrogen excreted in form of NH4+
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13
Q

What is the simplest route from amino acid to energy, glucose or fat?

A

From Alanine to pyruvate by alanine aminotransferase

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14
Q

What is a transamination reaction?

A

Amino acid is added to ketoacids to form new amino acids

Transamination reactions are used for synth. and degr. for new AA

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15
Q

Which amino acids lead to pyruvate?

A
  • Alanine
  • Serine
  • Cysteine
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16
Q

Which amino acids lead to oxaloacetate?

A
  • Aspartate
  • Asparagine
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17
Q

How does aspartate lead to oxaloacetate?

A

Transamination reaction

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18
Q

How does aspartate convert to asparagine?

A

By glutamine to glutamate by asparagine synthetase

With 1 ATP

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19
Q

How can asparagine convert to aspartate?

A

With H20 to NH4+ by asparaginase

Asparagine loses an amine group

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20
Q

Which amino acids lead to alpha-ketoglutarate?

A
  • Arganine
  • Histidine
  • Glutamine
  • Proline
  • Glutamate

The 4 AA’s lead to glutamate which leads to a-ketoglutarate

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21
Q

Which AA’s lead to succinyl CoA

Succinyl CoA is metabolite after a-ketoglutarate in TCA

Study These Flashcards
A
  • Valine
  • Threonine
  • Isoleucine
  • Methionine
22
Q

Which AA’s lead to Fumarate

Fumarate is metabolite in TCA

Study These Flashcards
A
  • Aspartate
  • Tyrosine
  • Phenylalanine
23
Q

Which AA’s can be comverted to acetyl CoA?

Study These Flashcards
A
  • Threonine
  • Lysine
  • Isoleucine
  • Tryptophan
24
Q

How are ketone bodies formed from acetyl CoA?

Study These Flashcards
A

Acetyl CoA+Acetoacetyl CoA to HMG CoA to acetoacetate (ketone body)

25
Which amino acid converts into HMG CoA?
Leucine
26
Which AA's convert to acetoacetate (ketone body)
* Phenylalanine * Tyrosine
27
Which two AA's are only ketogenic?
* Leucine * Lysine | Look at slide 32 for all amino acids
28
How are newborns screened for deficiencies in AA degradation?
Heelprick
29
How are non-essential amino acids synthesised?
Transamination reactions | These are reversible
30
Which vitamin is needed for transamination reactions? | Look at slide 35!!!
B6 | PLP is an active complex of B6
31
Which AA is increased when there is a surplus of other AA's?
Glutamate | Glutamate can be produced from a-ketoglutarate (TCA)
32
How can glutamate be converted to a-ketoglutarate?
* Transamination * Deamination by glutamate deaminase | Byproduct NH4+
33
How can surplus nitrogen be secreted through glutamate?
1. Transamination from a-ketoglutarate to glutamate 2. Deamination by glutamate dehydrogenase
34
Where does the urea cycle take place?
Liver
35
Which enzyme converts pyruvate to acetyl CoA?
Pyruvate dehydrogenase | Lipogenesis
36
Which enzyme converts pyruvate to oxaloacetate? | Gluconeogenesis
Pyruvate carboxylase
37
What is negative nitrogen balance?
If more nitrogen is lost than put in
38
Which tissue is lost during fasting?
Muscle tissue | Because amino acids are the source of glucose and not fat
39
What is the glucose-alanine cycle?
1. Alanine from muscle 2. Alanine to pyruvate in liver 3. Pyruvate to glucose in liver
40
Which proteins are preferably used for gluconeogenesis?
Proteins with high alanine and glutamine content
41
Where can alanine and glutamine rich proteins be found?
In the forearms
42
How are fatty acids metabolized?
Through the TCA cycle and released as CO2 | Fatty acids cannot produce glucose, that is why muscle is used
43
Which compound from triglycerides can be used for gluconeogenesis?
Glycerol
44
What are the primary enzymes in glycolysis?
1. Glucokinase 2. Phosphofructokinase 3. Pyruvate kinase 4. Pyruvate dehydrogenase | Kinases add phosphate groups
45
Which are the primary enzymes during gluconeogenesis?
1. Pyruvate decarboxylase 2. PEP carboxykinase 3. Fructose-1,6-biphosphatase 4. Glucose-6-phosphatase | Fructose-2,6-biphosphate most important regulator
46
Via which TCA metabolite does pyruvate convert into glucose?
Oxaloacetate
47
Where does the conversion of pyruvate to oxaloacetate take place? | By enzyme pyruvate carboxylase (adds carboxyl group)
Mitochondria | Oxaloacetate cannot easily cross this membrane
48
Which molecule inhibits the TCA cycle?
NADH
49
Which metabolites can indirectly be converted into glucose?
* Malate * Oxaloacetate
50
Gluconeogenesis needs energy, how is this produced?
By beta-oxidation | fatty acid processing to acetyl CoA
51
Pyruvate carboxylase is activated by which matabolite?
Acetyl CoA

Biochemistry (13 decks)

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