Nitrogen 1 Flashcards

1
Q

What is nitrogen metabolism also known as?

A

Amino acid metabolism

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2
Q

What kinds of molecules contain nitrogen?

A

Amino acids and nucleotides

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3
Q

Where do we get our nitrogen from?

A

Our diet, not the air

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4
Q

What are the 2 stages of the nitrogen cycle in organmisms?

A

Assimilation

Degradation

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5
Q

Why is nitrogen very unreactive?

A

Nitrogen is bonded to another nitrogen with a triple bond

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6
Q

What are 3 things that supply the massive amound of energy required to breakdown nitrogen?

A

Lighting

450oC at 200atp with an iron catalyst

Bacteria

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7
Q

What does bacteria perform to breakdown nitrogen?

A

Nitrogen fixation

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8
Q

What does nitrogen fixation look like?

A
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9
Q

What is nitrogen inactivated by?

A

O2

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10
Q

How does bacteria get around O2 deactivating N2?

A

Live anaerobically

Uncouple mitochondria to burn all O2 in a cell

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11
Q

What does the process of nitrogen after it is fixed look like?

A
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12
Q

What does the flow of N2 from NH4+ to other biomolecules occur through?

A

Glutamate

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13
Q

How does glutamate pass on the nitrogen?

A

By interconverting into other molecules

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14
Q

What are the 4 amino acids in much higher concentrations in cells compared to others?

A

Alanine

Glutamine

Glutamate

Asparate

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15
Q

What do most organisms do because they cannot fix N2?

A

Conserve it by transamination

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16
Q

What is transamination?

A

Transfering amino group between diferent molecules

17
Q

What does transamination look like?

A
18
Q

What is the basic reaction formula of transamination?

A
19
Q

Why is transamination involved in both the synthesis and degradation of nitrogen compounds?

A

The reactions of transamination are reversible

20
Q

What do all amino transferases rely on?

A

The pyruidoxal phosphate cofactor

21
Q

What is the typical molecule that accepts amino groups?

A

a-ketoglutamate

22
Q

What does L-glutamate act as?

A

A temporary storage of nitrogen

23
Q

What can L-glutamate do?

A

Donate amino groups when needed for amino acid biosynthesis

24
Q

What is pyridoxal phosphate (PLP)?

A

Cofactor made from vitamin B6 (essential vitamin)

Transfers the amino group during the reaction

25
Q

What does it mean if aminotransferases are found in the plasma?

A

There is tissue damage somewhere because aminotransferases are intracellular, this damage is usually in the liver

26
Q

When do amino acids undergo oxidative catabolism?

A

Left over amino acids (from normal protein turnover)

Dietary amino acids

Proteins in the body (are broken down when carbohydrates are short)

27
Q

What happens to dietary proteins?

A

They are enzymatically hydrolysed

28
Q

What is the process of dietary proteins being enzymatically hydrolysed?

A
  1. Pepsin cuts protein into peptide in the stomach
  2. Trypsin and chymotrypsin cut proteins and large peptides into smaller peptides in the small intestine
  3. Aminopeptidase and carboxypeptidase A and B degrade peptides into amino acids in the small intestine
29
Q

Why is the stomach acidic?

A

To help breakdown proteins

30
Q

Where do the enzymes involved in the breakdown of dietary proteins come from?

A

Gastric glands in stomach lining

Exocrine cells in pancreas

Villi of small intestine

31
Q

What cellular proteins would be targeted for destruction?

A

Misfolded proteins

Foreign proteins

Unwanted proteins

32
Q

How are cellular proteins targeted for destruction?

A

Ubiquitin tags proteins that are to be degraded

33
Q

What are the fates of amino acids from broken down proteins?

A

Left intact for biosynthesis

Broken down into amino groups and carbon skeleton, where the amino group is disposed of in the urea cycle

34
Q

What are the 3 fates of carbon skeletons from broken down amino acids?

A

Glucose or glycogen synthesis

Cellular respiration

Fatty acid synthesis