Proteins Flashcards

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1
Q

Describe the structure of an amino acid. (F)

A
  • amine group (-NH2)
  • carboxyl group (-COOH)
  • alpha-carbon (C)
  • R-group (variable)
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2
Q

State how many amino acids occur in life.

A

20

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3
Q

Explain how the variety of amino acids leads to a wide range of dipeptides and very quickly to an incredible variety of polypeptide chains.

A
  • Dipeptide: 400 possible combinations (20^2)
  • Tripeptide: 8000 possible combinations (20^3)
  • etc.
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4
Q

Define the term “polypeptide chain”.

A

Chain of three or more amino acids

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5
Q

Describe how one end of a polypeptide chain differs from the other end.

A

One end is an amine group (-NH2) which has basic properties, and the other end is a carboxyl group (-COOH) and has acidic properties.

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6
Q

Define the term “primary structure” of a protein. (F)

A

The sequence of amino acids.

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7
Q

Define the term “secondary structure” of a protein and describe the two different types. (F)

A

The folding of the polypeptide chain into an alpha helix (coiled) or beta pleated sheet (flat).

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8
Q

Define the term “tertiary structure” of a protein. (F)

A

The 3D shape of a polypeptide chain.

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9
Q

Explain how the primary structure of a protein determines its tertiary structure.

A

The R-groups on the amino acids affect the bonding in the tertiary structure.

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10
Q

Define the term “quaternary structure” of a protein.

A

When two or more polypeptides associate.

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11
Q

Define the term “globular protein”. (F)

A

Spherical, water-soluble protein.

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12
Q

Define the term “prosthetic group”. (F)

A

Non-protein component of a conjugated protein

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13
Q

Give an example of a conjugated protein (the bloody one).

A

Haemoglobin

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14
Q

Give an example of an enzyme (the H2O2 one ;) ).

A

Catalase

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15
Q

Give an example of a peptide hormone (the sugary one).

A

Insulin

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16
Q

Give 3 examples of fibrous proteins.

A
  • collagen
  • elastin
  • elastin
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17
Q

Describe the structure of collagen.

A
  • 3 polypeptide chains
  • triple helix
  • every third amino acid is glycine
  • hydrogen bonds
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18
Q

Describe the structure of keratin.

A
  • lots of cysteine (with S)

- disulfide bridges (degree of disulfide bonds determines flexibility)

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19
Q

Describe the structure of elastin.

A
  • cross-linked structure

- covalent bonds between lysine amino acids

20
Q

Compare the structure of globular and fibrous proteins.

A
  • G is spherical

- F is long

21
Q

Compare the properties of globular and fibrous proteins.

A
  • G is soluble

- F is insoluble

22
Q

Compare the functions of globular and fibrous proteins.

A
  • G acts as enzymes and hormones

- F acts as structural components

23
Q

Identify the key structural components of haemoglobin.

A
  • 4 polypeptide chains
  • 2 alpha helices, 2 beta pleated sheets
  • 4 haem prosthetic groups (Fe2+)
24
Q

State the properties of haemoglobin.

A

Haem group combines reversibly with an oxygen molecule

25
Q

State the functions of haemoglobin.

A

Transports oxygen in red blood cells

26
Q

Identify the key structural components of catalase.

A
  • 4 polypeptide chains

- 4 haem prosthetic groups (Fe2+)

27
Q

State the properties of catalase.

A

Can interact with H2O2 with haem groups

28
Q

State the functions of catalase.

A

Speeds up breakdown of H2O2 formed from metabolic reactions

29
Q

Identify the key structural components of insulin.

A

3 polypeptide chains

30
Q

State the properties of insulin.

A
  • soluble

- precise shape

31
Q

State the functions of insulin.

A

Regulation of blood glucose concentration

32
Q

Describe the properties of collagen.

A
  • flexible

- tough

33
Q

Describe the location of collagen.

A
  • skin
  • tendons
  • ligaments
  • nervous system
34
Q

Describe the functions of collagen.

A

Connective tissue

35
Q

Describe the properties of keratin.

A
  • strong
  • inflexible
  • insoluble
36
Q

Describe the location of keratin.

A
  • hair
  • skin
  • nails
37
Q

Describe the functions of keratin.

A
  • protection

- adhesion

38
Q

Describe the properties of elastin.

A
  • flexible

- strong

39
Q

Describe the location of elastin.

A
  • walls of blood vessels

- alveoli in lungs

40
Q

Describe the functions of elastin.

A
  • allow flexibility to expand when needed
  • allow to return to normal size
  • strength and elasticity
41
Q

What holds the primary structure of a protein held together? (F)

A

Peptide bonds

42
Q

What holds the secondary structure of a protein held together? (F)

A

Hydrogen bonds

43
Q

What holds the tertiary structure of a protein held together? (F)

A
  • hydrogen bonds
  • ionic bonds
  • disulfide bridges
  • hydrophobic-hydrophilic interactions
44
Q

What holds the quaternary structure of a protein held together? (F)

A
  • hydrogen bonds
  • ionic bonds
  • disulfide bridges
  • hydrophobic-hydrophilic interactions
45
Q

Define the term “protein”.

A

One or more polypeptides with a specific function

46
Q

Define the term “fibrous protein”. (F)

A

Long, insoluble, structural protein.

47
Q

Define the term “conjugated protein”. (F)

A

Globular protein that contains a prosthetic group