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Core concepts: Biological molecules > Proteins > Flashcards

Proteins Flashcards

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Organic Chemistry 101 flashcards
1
Q

What 4 elements make up amino acids?

A

Carbon
Oxygen
Hydrogen
Nitrogen

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2
Q

What are the 3 groups found in amino acids?

A

Carboxyl group (COOH)
R group
Amino group (NH2)

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3
Q

Which is a constant and variable in amino acids?

A

Amino group - constant
R group - variable
Carboxyl group - constant

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4
Q

What are dipeptides?

A

When 2 amino acids joined together through a condensation reaction

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5
Q

What bond is formed when 2 amino acids join together?

A

Peptide bonds

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6
Q

What are polypeptides?

A

Formed by many amino acids joined together by peptide bonds
Polypeptides = polymers
Amino acids = monomers

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7
Q

What do amino acids form and what do polypeptides form?

A

Amino acids = polypeptides (chain of amino acids)
Polypeptides = proteins (functioning)

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8
Q

What are the 4 structures proteins have?

A

Primary structure
Secondary structure
Tertiary structure
Quaternary structure

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9
Q

What is a primary structure?

A

Number and the sequence of amino acids in a polypeptide chain

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10
Q

What is a secondary structure?

A

Primary structure of the polypeptide can coil to form 2 structures
Either an alpha helix or a beta-pleated sheet

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11
Q

Describe the structure of the alpha helix

A

Most common type of secondary structure
Held in a spiral shape by hydrogen bonds
Some fibrous proteins have alpha helices linked to rope-like strands
Examples - keratin and collagen

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12
Q

Describe the structure of the beta pleated sheet

A

Less common secondary structure
A flat zig-zag structure
Stabilised by hydrogen bonds
Example - protein silk

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13
Q

What is a tertiary structure?

A

More complex proteins when complete have tertiary structure
Secondary structure folds to give complex three-dimensional shapes

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14
Q

Are globular proteins tertiary structures?

A

Yes
Examples - enzymes, hormones, plasma and cell membrane proteins

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15
Q

Describe the tertiary structure of a protein

A

Secondary structure is folded
Held in a specific 3D shape by bonds and interactions
Form between R groups of some of the amino acids in the polypeptide chain

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16
Q

What bonds and interactions are present in tertiary structures?

A

Hydrogen bonds - form between O & OH
Ionic bonds - form between oppositely charged R groups
Disulphide bridges - form between S atoms (e.g. in cysteine)
Hydrophobic R groups interactions - on the inside of the protein
Hydrophilic R groups - on the outside of the protein

17
Q

What is a quaternary structure?

A

Occurs when more than 1 polypeptide chain, each with a tertiary structure, combine to form a larger protein complex

18
Q

Describe the quaternary structure of a protein

A

Tertiary structures are joined together by bonds similar to those within the tertiary structures themselves
Ionic, hydrogen, disulphide and hydrophobic interactions
Quaternary proteins are sometimes associated with non-protein groups called prosthetic groups

19
Q

What is an example of quaternary protein?

A

Haemoglobin
Protein that carries oxygen in mammalian blood
Made of 4 polypeptide chains each with a tertiary structure

20
Q

What non-protein components does haemoglobin contain?

A

Haem group
These contain iron (Fe2+)

21
Q

What bonds and interactions do quaternary structures have?

A

Ionic
Hydrogen
Disulphide
Peptide

22
Q

What are the 2 groups proteins can be classified into?

A

Fibrous proteins
Globular proteins

23
Q

What are fibrous proteins?

A

Carry out structural functions

24
Q

What are some examples of fibrous proteins?

A

Keratin - found in hair and nails
Collagen - found in connective tissue and the skin

25
Q

Describe the structure of fibrous proteins

A

Collagen is made up of 3 alpha helix polypeptide chains twisted into rope-like strands
Held together by hydrogen bonds

26
Q

What are the properties of fibrous proteins?

A

Tough
Non-specific
Insoluble (held by hydrogen bonds)

27
Q

What are globular proteins?

A

Can be tertiary proteins
Can be quaternary proteins

28
Q

What are some examples of globular proteins?

A

Enzymes
Antibodies
Plasma
Proteins
Hormones
Haemoglobin

29
Q

What are the properties of globular proteins?

A

Compact and folded into spherical molecules
Have a specific shape
Soluble in water

Core concepts: Biological molecules (9 decks)

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