Amino Acids, Proteins & DNA Flashcards

1
Q

What is a zwitterion

A

An amino acid in neutral conditions
- has a COO- group and a NH3+ group

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2
Q

Why do zwitterions have a higher melting point than amino acids that are not charged

A

Because of the ionic interaction between zwitterions compared to the weaker H bonding that occurs in the no charge form

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3
Q

Describe a basic vs an acidic amino acid

A

Basic - have an extra amine group
Acidic - have an extra carboxylic acid group

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4
Q

What happens to amino acids structure in acidic conditions/low pH

A

All amine groups change to NH3+

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5
Q

What happens to amino acids structure in alkaline conditions/high pH

A

All carboxyl groups change to COO-

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6
Q

How could you determine protein structure from a diagram?

A

Does the chain show bending and folding?. If no - 1°
Does it show bonding between R groups? No- 2°, yes - 3°

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7
Q

Describe how secondary protein structure forms

A
  • nitrogen and oxygen are very electronegative
  • Therefore C=O and N-H are polar
  • Which results in the formation of a hydrogen bond between O and H
  • The loan pair on the oxygen atom is strongly attracted to the Delta positive H
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8
Q

Why can a stereospecific active site only bond to one enantiomeric form of a substrate or a drug

A

If the substrate is chiral then it is likely that only one enantiomer will have the correct stereochemistry to fit in the active site of the enzyme. So only one isomer will be catalysed

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9
Q

How do scientists design enzyme inhibitors

A

With computers

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10
Q

How would you identify the DNA base in the question

A
  • if it has 2 rings and O2 then it’s guanine, if it has no O2 then it’s adenine
  • if it has 1 ring and CH3 then it’s thymine. If it has no CH3 then it’s cytosine
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11
Q

How do DNA bases react with sugar phosphate

A

The N-H group on the base reacts with the OH on the sugar

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12
Q

Why does cisplatin prevent DNA replication and treat cancer

A

It bonds to the DNA in cancer cells and creates a distortion in the strand so it can’t unwind and be copied

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13
Q

What kind of bonds are disulfide bridges

A

Covalent bonds

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