6.2.2: Amino acids, amides and chirality Flashcards

1
Q

What are the two functional groups of amino acids?

A

NH2 and COOH (amine and carboxylic acid)

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2
Q

Draw a general formula for α-amino acids.

A

NH2
R-C-COOH
H

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3
Q

Are α-amino acids chiral? Why?

A

Yes, one carbon has 4 different substituents.

Except glycine, where R = H.

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4
Q

Define a zwitterion.

A

Ions which have both a permanent positive and negative charge, but are neutral overall.

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5
Q

How do zwitterions occur in amino acids?

A

COOH is deprotonated → COO_

NH2 is protonated → NH3+

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6
Q

What happens to amino acids in acidic conditions?

A

Gains a proton on NH2 group

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7
Q

What happens to amino acids in alkaline conditions?

A

Loses a proton from COOH group

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8
Q

What is the peptide linkage?

A

-CONH (C=O, H-N)

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9
Q

What property must a carbon atom have for the
molecule to display optical isomerism about that
carbon atom?

A

4 different substituents attached to one carbon atom

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10
Q

What are the similarities and differences between

two optical isomers?

A

Same atoms and bonds, but they are non superimposable mirror images of one another. NOT IDENTICAL in chemical properties necessarily.
Differ in the way they rotate plane polarised light - rotate
plane of polarisation by the same angle but in different
directions

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11
Q

What word is used to describe optically active

molecules?

A

chiral

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12
Q

Give two examples of chiral molecules

A

All alpha amino acids, except glycine.

Lactic acid / 2-hydroxypropanoic acid

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