Nitrogen 1

Question 1

<p>What is nitrogen metabolism also known as?</p>

Answer 1

<p>Amino acid metabolism</p>

Question 2

<p>What kinds of molecules contain nitrogen?</p>

Answer 2

<p>Amino acids and nucleotides</p>

Question 3

<p>Where do we get our nitrogen from?</p>

Answer 3

<p>Our diet, not the air</p>

Question 4

<p>What are the 2 stages of the nitrogen cycle in organmisms?</p>

Answer 4

<p>Assimilation</p>

<p>Degradation</p>

Question 5

<p>Why is nitrogen very unreactive?</p>

Answer 5

<p>Nitrogen is bonded to another nitrogen with a triple bond</p>

Question 6

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

Answer 6

<p>Lighting</p>

<p>450^oC at 200atp with an iron catalyst</p>

<p>Bacteria</p>

Question 7

<p>What does bacteria perform to breakdown nitrogen?</p>

Answer 7

<p>Nitrogen fixation</p>

Question 8

What does nitrogen fixation look like?

Answer 8

any natural or industrial process that causes free nitrogen

Question 9

<p>What is nitrogen inactivated by?</p>

Answer 9

<p>O₂</p>

Question 10

<p>How does bacteria get around O₂deactivating N₂?</p>

Answer 10

<p>Live anaerobically</p>

<p>Uncouple mitochondria to burn all O₂in a cell</p>

Question 11

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

Answer 11

Fixation converts nitrogen in the atmosphere into forms that plants can absorb through their root systems. A small amount of nitrogen can be fixed when lightning provides the energy needed for N2 to react with oxygen, producing nitrogen oxide, NO, and nitrogen dioxide, NO2.

Question 12

<p>What does the flow of N₂from NH₄⁺to other biomolecules occur through?</p>

Answer 12

<p>Glutamate</p>

Question 13

<p>How does glutamate pass on the nitrogen?</p>

Answer 13

<p>By interconverting into other molecules</p>

Question 14

<p>What are the 4 amino acids in much higher concentrations in cells compared to others?</p>

Answer 14

<p>Alanine</p>

<p>Glutamine</p>

<p>Glutamate</p>

<p>Asparate</p>

Question 15

<p>What do most organisms do because they cannot fix N₂?</p>

Answer 15

<p>Conserve it by transamination</p>

Question 16

<p>What is transamination?</p>

Answer 16

<p>Transfering amino group between diferent molecules</p>

Question 17

What does transamination look like?

Answer 17

process by which amino groups are removed from amino acids and transferred to acceptor keto-acids to generate the amino acid version of the keto-acid and the keto-acid version of the original amino acid.

Question 18

<p>Why is transamination involved in both the synthesis and degradation of nitrogen compounds?</p>

Answer 18

<p>The reactions of transamination are reversible</p>

Question 19

<p>What do all amino transferases rely on?</p>

Answer 19

<p>The pyruidoxal phosphate cofactor</p>

Question 20

<p>What is the typical molecule that accepts amino groups?</p>

Answer 20

<p>a-ketoglutamate</p>

Question 21

<p>What does L-glutamate act as?</p>

Answer 21

<p>A temporary storage of nitrogen</p>

Question 22

<p>What can L-glutamate do?</p>

Answer 22

<p>Donate amino groups when needed for amino acid biosynthesis</p>

Question 23

<p>What is pyridoxal phosphate (PLP)?</p>

Answer 23

<p>Cofactor made from vitamin B6 (essential vitamin)</p>

<p>Transfers the amino group during the reaction</p>

Question 24

<p>What does it mean if aminotransferases are found in the plasma?</p>

Answer 24

<p>There is tissue damage somewhere because aminotransferases are intracellular, this damage is usually in the liver</p>

Question 25

<p>When do amino acids undergo oxidative catabolism?</p>

Answer 25

<p>Left over amino acids (from normal protein turnover)</p>

<p>Dietary amino acids</p>

<p>Proteins in the body (are broken down when carbohydrates are short)</p>

Question 26

<p>What happens to dietary proteins?</p>

Answer 26

<p>They are enzymatically hydrolysed</p>

Question 27

<p>What is the process of dietary proteins being enzymatically hydrolysed?</p>

Answer 27

<ol> <li>Pepsin cuts protein into peptide in the stomach</li> <li>Trypsin and chymotrypsin cut proteins and large peptides into smaller peptides in the small intestine</li> <li>Aminopeptidase and carboxypeptidase A and B degrade peptides into amino acids in the small intestine</li></ol>

Question 28

<p>Why is the stomach acidic?</p>

Answer 28

<p>To help breakdown proteins</p>

Question 29

<p>Where do the enzymes involved in the breakdown of dietary proteins come from?</p>

Answer 29

<p>Gastric glands in stomach lining</p>

<p>Exocrine cells in pancreas</p>

<p>Villi of small intestine</p>

Question 30

<p>What cellular proteins would be targeted for destruction?</p>

Answer 30

<p>Misfolded proteins</p>

<p>Foreign proteins</p>

<p>Unwanted proteins</p>

Question 31

<p>How are cellular proteins targeted for destruction?</p>

Answer 31

<p>Ubiquitin tags proteins that are to be degraded</p>

Question 32

<p>What are the fates of amino acids from broken down proteins?</p>

Answer 32

<p>Left intact for biosynthesis</p>

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

Question 33

<p>What are the 3 fates of carbon skeletons from broken down amino acids?</p>

Answer 33

<p>Glucose or glycogen synthesis</p>

<p>Cellular respiration</p>

<p>Fatty acid synthesis</p>