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Cells and Biomolecules NES1303 > Proteins: Structure and Function > Flashcards

Proteins: Structure and Function Flashcards

1
Q

How many types of amino acids are there?

A

20

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2
Q

What atoms are amino acids made up of?

A

all contain C, H, O, N, some S

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3
Q

What is the basic structure of an amino acid?

A
  • central carbon atom C
  • carboxylic acid group COOH
  • amino group NH2
  • Hydrogen H
  • R-groups
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4
Q

What is physiological pH?

A

7.4

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5
Q

What groups ionise at physiological pH? In what way?

A

-NH2 and -COOH groups ionise to -NH3+ and -COOH-

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6
Q

What are the properties of nonpolar side chains?

A
  • hydrocarbon rings or chains
  • side chains are hydrophobic
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7
Q

What are two examples of amino acids with nonpolar side chains?

A
  • Alanine (Ala/A): AA general + -CH3
  • Phenylalanine (Phe/F): AA general + -CH2-[phenylring]
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8
Q

What are the properties of polar but uncharged side chains?

A

They contain hydroxyl and amide groups and are hydrophilic

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9
Q

What are two examples of amino acids with polar but uncharged side chains?

A
  • Serine (Ser/S): AA general + -CH2OH
  • Tyrosine (Tyr/Y): AA general + CH2 + ring + OH
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10
Q

What are the properties of polar (acidic) side chains?

A

They contain carboxylic acid groups and are negatively charged at physiological pH

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11
Q

What is an example of an amino acid with polar but acidic side chains?

A

Aspartic acid (Asp/D): AA general + CH2 + COO-

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12
Q

What are the properties of polar (basic) side chains?

A

Contain basic groups which are positively charged at physiological pH

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13
Q

What is an example of an amino acid with a polar but basic side chain?

A

Lysine (Lys/K): AA general + CH2 + CH2 + CH2 + CH2 + NH3

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14
Q

What are special amino acids?

A

Amino acids with side chains that fit none of the other categories

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15
Q

What are two examples of special amino acid chains?

A
  • Cysteine (Cys/C): AA general + CH2 + SH
  • Glycine (Gly/G): AA general + H
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16
Q

What is a condensation reaction?

A

A new covalent bond is formed between two atoms with the release of water?

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17
Q

What is a hydrolysis reaction?

A

A covalent bond is split by addition of water to a reaction (reverse of condensation)

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18
Q

How are amino acids linked together?

A

Through condensation: a peptide bond is formed. Product is called an amide.

19
Q

What is the primary structure of a protein?

A

The amino acid chain, aka polypeptide chain, sequence.

20
Q

What is the secondary structure of a protein?

A

Conformations that can be adopted by different parts of a polypeptide chain due to formation of hydrogen bonds

21
Q

What are the two types of secondary structure for proteins?

A

alpha helix and beta sheet

22
Q

What are the properties of an alpha helix?

A
  • 3.6 amino acids per turn
  • side chains/R-groups face outward of the helix
  • the C=O of one amino acid is bonded to the 4th amino acid away from it
23
Q

How can beta sheets be aligned?

A

parallel and antiparallel

24
Q

What is the tertiary structure of a protein?

A

The overall 3D configuration of a protein: The bending and folding of secondary structures. The shape is held by interactions between amino acids and side chains.

25
What are the 4 types of interactions in tertiary structures?
- hydrogen bonds - electrostatic bonding - disulphide bridges - hydrophobic interactions
26
What are hydrogen bonds? | Wasserstoffbrueckenbindungen
Bonds between hydroxyls and carbonyl groups
27
What are electrostatic bonds?
bonds between charged atoms of side chains
28
What are disulphide bridges?
Bridges between cysteine residues: -SH HS- -> -S-S-
29
What are hydrophobic interactions?
Associate together and repel water. Will be in the middle of 3D structures to stay as far away from water as possible.
30
What is the correlation between energy level and protein conformation?
Proteins will fold into the shape with the lowest potential energy level.
31
What are quaternary structures?
A multisubunit protein from many tertiary structure proteins. They have the same bonds as in tertiary structures.
32
actin function
movement
33
insulin function
hormone
34
casein function
nutrient
35
haemoglobin function
transport
36
antibodies function
defence
37
what proteins have a structural function
fibrous
37
what proteins carry out many different functions (involve the protein specifically recognising another molecule)
globular
38
what is a buffer made out of?
weak acid and conjugate base
39
What is the effect of a buffer?
to minimise change in in pH if either acid or alkali are added
40
what is denaturation?
Proteins are described as denatured when their three-dimensional structure is altered so that they can no longer carry out their function
41
what are three factors which can denature proteins?
heat, pH and detergent
42
what is the

Cells and Biomolecules NES1303 (2 decks)

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