Unit 1: Protein structure Flashcards

1
Q

What is the primary structure of a protein ?

A

The individual amino acid sequence

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2
Q

What is the secondary structure of a protein ?

A

The spatial arrangement of a polypeptides backbone. e.g a-helix and b-pleated sheets

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3
Q

What is the tertiary structure of a protein ?

A

The three dimensional structure of the entire polypeptide chain

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4
Q

What is the quaternary structure of a protein ?

A

How polypeptide chains fit together to form a protein

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5
Q

Within a polypeptide chain, what are individual amino acids referred to as ?

A

Residues

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6
Q

How many amino acids need to be present for a polypeptide to be referred to as a protein ?

A

Over 50

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7
Q

What enzyme is used to catalyse the formation of a peptide bond ?

A

Peptidyl transferase

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8
Q

The peptide bond is polar, what does this mean ?

A

That the spatial arrangement of atoms is fixed and the bonds cannot rotate/ spin

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9
Q

What are the only 2 bonds that can rotate in a polypeptide ?

A
  • C-NH
  • C-C
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10
Q

What bonds are needed for primary structure of proteins ?

A

Covalent bonds maintain the primary structure

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11
Q

What bonds are needed for the secondary structure of proteins ?

A

Hydrogen bonds maintain the secondary structure

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12
Q

What 3 bonds are needed for the tertiary structure of proteins ?

A
  • Hydrophobic
  • Van der Waals
  • Electrostatic bonds
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13
Q

What 2 bonds are needed for the quaternary structure of proteins ?

A
  • Van der Waals
  • Electrostatic bonds
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14
Q

What is the a-helix referred to as and what direction do the hydrogen bonds run in ?

A
  • Twisted sheet
  • H bonds run parallel to the helix axis
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15
Q

What is the b-sheet referred to as and what direction do the hydrogen bonds run in ?

A
  • Flat sheet
  • H bonds run perpendicular to chain direction
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16
Q

What are r groups and where are they found ?

A
  • R groups influence the way proteins interact with other proteins and the environment
  • R groups are pointed outward but are not used in the helix structure
17
Q

What are the 2 types of b-sheet ?

A
  • Anti parallel
  • Parallel
18
Q

What direction do bonds run in a parallel b-sheet ?

A
  • All same direction
  • All downwards
19
Q

What direction do bonds run in an antiparallel b-sheet ?

A
  • Alternate directions
  • Down, Up, Down, Up
20
Q

What are some characteristics of non polar amino acids ?

A
  • They have very oily side chains
  • Important interactions with environment
21
Q

What is one characteristic of a polar amino acid ?

A

They have a partial positive and negative end

22
Q

What are some characteristics of electrically charged amino acids ?

A
  • Acidic AAs are negatively charged
  • Basic AAs are positively charged
  • Important electrostatic interactions
23
Q

What are the 3 classes of amino acid R groups ?

A
  • Non-polar
  • Polar
  • Electrically charged
24
Q

Why is cysteine an important AA ?

A

It contains disulphide bonds that are important for protein structure

25
Q

What is a domain ?

A

The smallest stable unit of tertiary structure

26
Q

Why are domains stable ?

A

As they are independent structural units that represent independent functional units

27
Q

What is domain shuffling ?

A

The idea that throughout evolution domains have been swapped between proteins

28
Q

Give 2 examples of proteins with a quarternary structure

A
  • Haemoglobin
  • Collagen
29
Q

What is the T state and R state with relation to haemoglobin ?

A

T-state = Tense and is when oxygen is unbound
R- state = Relaxed and is when oxygen is bound

30
Q

What amino acid is crucial for collagen structure ?

A

Glycine

31
Q

What chains are found in collagen structure ?

A
  • A triple- y- helix
  • 3 Helical chains
32
Q

What are 5 of the biggest stressors on a cell ?

A
  • Hypoxia
  • Heat/cold shock
  • Cell cycle arrest
  • Apoptosis
  • Senescence
33
Q

What is p53 ?

A

A transcription factor

34
Q

How is the structure of p53 related to its function ?

A
  • Tetramerization: Forms a stable tetramer for effective DNA binding and transcriptional activity.
  • DNA-Binding Domain (DBD): Binds specific DNA sequences to regulate target genes.
  • Transactivation Domains: Recruit transcriptional machinery to activate/repress gene expression.
  • Post-Translational Modifications: Alter structure and stability in response to cellular stress.
  • Conformational Flexibility: Allows interaction with various proteins for signaling.
  • Mutations: Structural changes can lead to loss of function and cancer development.