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IMS > Topic 2 - Proteins > Flashcards

Topic 2 - Proteins Flashcards

Lectures 6-8

1
Q

What is the general structure of amino acids?

A

a-Carbon atom with 4 bonds to:

  • hydrogen atom
  • amino group
  • carboxyl group
  • R group
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2
Q

How many a-amino acids are commonly found in proteins?

A

20

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3
Q

What are common ways of categorizing R groups?

A
  • Size
  • Shape (aliphatic/aromatic)
  • Hydrophobicity
  • Charge
  • Sulphur containing
  • Imino acids
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4
Q

Which amino acids contain sulphur?

A
  • Cysteine

- Methionine

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5
Q

Which alpha amino acid does not possess optical activity?

A

Glycine

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6
Q

Only which optical isomers are found in proteins?

A

L-isomers

levo-rotary

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7
Q

What are the properties of globular proteins?

A
  • Compact
  • Soluble (hydrophilic residues outside, hydrophobic hidden)
  • eg. Enzymes, Haemoglobin
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8
Q

What are the properties of fibrous proteins?

A
  • Elongated
  • Often have repeating amino acid sequences
  • Insoluble due to hydrophobic amino acid content
  • eg. membrane proteins
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9
Q

What are the cellular functions of proteins?

A
  • Structural
  • Signalling
  • Receptors
  • Enzymes
  • Binding
  • Transporters
  • Translation factors
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10
Q

What is the function of enzymes?

A

Lower the Ea of a reaction in order to catalyse metabolic reactions.

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11
Q

What factors restrict the number of combinations an amino acid chain could fold into?

A
  • Rigidity of the peptide bond

- Physical and chemical properties of the side chains

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12
Q

Which proteins assist in protein folding?

A

Chaperone proteins

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13
Q

What are the two types of chaperone proteins?

A

Molecular chaperones - bind to long segments of protein to facilitate correct binding
Chaperonins - form folding chambers which provide a stable environment to encourage correct folding

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14
Q

What may happen when a protein is incorrectly folded?

A
  • Cellular processes relying on the protein’s presence will stop (eg. cystic fibrosis, phenylketonuria)
  • Misfolded protein may accumulate and hinder normal cellular processes (eg. Alzheimer’s)
  • Misfolded protein may cause conformational changes in other proteins (eg. Creutzfelt-Jacob disease)
  • Cell may identify the protein for early destruction
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15
Q

What is an amyloid disease?

A

e.g. Alzheimer’s diseases. Fragments of normal proteins produce amyloid fibrils.

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16
Q

What is a Prion disease?

A

e.g. Creutzfeldt-Jacob disease, BSE (mad cow disease) & scrapie (sheep & goats). An infectious protein agent causes a conformational change in a normal protein.

17
Q

What are the signs of Alzheimer’s disease?

A
  • memory loss
  • loss of language ability
  • loss of the ability to mentally manipulate visual information
  • poor judgment
  • confusion
  • restlessness
  • mood swings
  • eventual death
18
Q

What is the biochemical basis of Alzheimer’s?

A
  • A fragment from a normal membrane protein, amyloid precursor protein, accumulates and aggregates forming insoluble fibrils of amyloid β protein in the brain.
  • A fragment from a normal membrane protein, amyloid precursor protein, accumulates and aggregates forming insoluble fibrils of amyloid β protein in the brain.
  • These plaques damage and destroy neurons.
19
Q

What are the signs of Creutzfeldt Jacob Disease?

A
  • Loss of neurological function
  • Memory loss
  • Loss of coordination and language ability
  • Coma
  • Eventual death
20
Q

What is the infectious agent of Creutzfeldt Jacob?

A

Prion protein PrPSc

21
Q

What is the biomedical basis of Creutzfeldt Jacob disease?

A
  • PrPSc has an identical primary sequence to a normal membrane protein PrPc but has a much higher proportion of β-pleated sheet.
  • Contact of normal soluble PrPc protein (mostly α-helical) with abnormal form PrPSc (mostly β-pleated sheet) causes the PrPc protein to acquire the abnormal PrPSc structure.
22
Q

How many mutant Haemoglobins are known?

A

> 400

23
Q

What is the function of myoglobin?

A

Oxygen STORE

IMS (13 decks)

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