Amino acids Flashcards
What do amino acids contain
They contain a COOH group and an NH2 group
What is special about an α (alpha) amino acid?
They have an NH2 and COOH group bonded to the same carbon
Draw an amino acid with an R group
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What are the equilibrium equations with H+ ions
- NH2 + H+ → NH3
2. COOH → COO- + H+
What happens to the equilibrium in acidic and alkaline solutions?
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Draw an amino acids in acidic, alkaline solutions
Draw a zwitterion
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What are all amino acids at a low pH
All NH2 groups are pronated
What are all amino acids at a high pH
All COOH groups are depronated in high pH solutions
Draw lysine at pH 7 and pH 1
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Draw the structure of glycine, alanine, lysine and glutamic acid
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What are some physical properties of amino acids?
- High melting points
- Exist as dipolar ions, attraction between them is very strong
- Soluble in water
Give an example of the reaction of Glycine with sodium carbonate and where do these reactions take place on the molecule?
Observations?
2H2NCH2COOH + Na2CO3 → 2H2NCH2COONa + CO2 +H2O
Occur at the COOH group.
Bubbles of gas produced
Give an example of the reaction of Glycine with nitrous acid.
How is the nitrous acid formed? Where does the reaction occur? Observations
Nitrous acid is formed in situ from Sodium nitrite and Hydrochloric acid (HNO2)
The NH2 group is replaced by OH group
H2NCH2COOH + HNO2 →HOCH2COOH + N2 + H2O
Bubbles of gas produced
Give an example of the reaction of glycine with copper (II) sulfate. What is formed? What does glycine act as?
Observations
A complex is formed with a coordination number of 4.
Glycine acts as a bidentate ligand
Cu2+ + 2H2NCH2COOH → [Cu(H2NCH2COOH)2]2+
Blue solution formed when solutions of copper (II) sulfate and glycine are mixed
How are peptides formed?
Amino acids react together in a condensation polymerisation to form peptides.