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Biology A Level 1 > Topic 1.6 - Proteins > Flashcards

Topic 1.6 - Proteins Flashcards

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1
Q

What are the basic monomers that make up proteins?

A

Amino acids

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2
Q

What is an amino acid made up of?

A
  • Central carbon (to which it is all attached to)
  • Amino group (NH2)
  • Carboxyl group (COOH)
  • Hydrogen atom (H)
  • R (side group) = a variety of different chemical groups
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3
Q

What is the primary structure of proteins?

A
  • The sequence in which the amino acids are ordered in to form a polypeptide
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4
Q

What are amino acids joined by?

A

Peptide bonds

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5
Q

How are peptide bonds formed?

A

Through condensation reactions, where water is produced as a product.
- The -OH comes from the carboxyl group of one amino acid and the other -H comes from the amino group of another amino acid when they bond together.

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6
Q

How many amino acids naturally occur?

A

20

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7
Q

What is the secondary structure of proteins?

A

Where the sequence bends/folds to form a 3D shape

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8
Q

What does the primary protein structure look like? And what bond joined them?

A

A long chain of amino acids (a polypeptide) joined by peptide bonds

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9
Q

What two types are there of secondary structure?

A
  • Alpha helix

- Beta sheet

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10
Q

What bonds form/hold together the secondary structure of proteins?

A

Hydrogen bonds

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11
Q

What is the tertiary structure?

A

Where most proteins form their final, specific shape.
The 3rd protein structure is further folded and twisted to give it a more complex 3D structure

If it is not folded correctly, it cannot perform its intended biological activity.

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12
Q

What bonds or interactions form/hold the tertiary structure?

A
  • Ionic bonds
  • Hydrogen bonds
  • Disulfide bridges (covalent so are stronger than other bonds)
  • Hydrophilic/hydrophobic interactions
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13
Q

Give an example of a protein that has a quaternary structure.

A
  • Haemoglobin
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14
Q

What is the quaternary structure of proteins?

A

Where multiple polypeptide chains can be joined together, and sometimes prosthetic groups can be added too (non-protein, e.g. HAEM group, iron ion in haemoglobin is a prosthetic group)

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15
Q

What enzymes are needed in protein digestion and why?

A

Endopeptidases - break polypeptide into smaller chains

Exopeptidases - remove end terminal amino acids

Dipeptidases - hydrolyse dipeptides into amino acids

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16
Q

What makes a dipeptide?

A

2 amino acids bonded together with a peptide bond

17
Q

What makes a polypeptide?

A

Multiple amino acids joined together through polymerisation (a series of condensation reactions)

18
Q

What is the test for proteins?

A

Biuret test

19
Q

How would you conduct a test for proteins?

A
  • Add 2cm cubed of sample and 2cm cubed (equal amounts) of sodium hydroxide into a test tube
  • Add a few drops of very dilute (0.05%) copper (||) sulphate and mix gently
  • The presence of a peptide bond will be indicated when the solution turns from blue to purple
20
Q

What does the biuret test detect?

A

Peptide bonds

21
Q

How are the weak hydrogen bonds form?

A

The slightly positive charge on the hydrogen and the slightly negative charge of the oxygen are attracted to each other

22
Q

What does the primary structure of a protein determine?

A

It’s shape and function

23
Q

What changes in the structure of different amino acids?

A

The R group changes, but all amino acids have the same general structure

24
Q

What is a glycoprotein?

A

When a carbohydrate combines with a protein

25
Q

What is formed when a lipid and protein combine?

A

A lypoprotein

26
Q

What is a fibrous protein?

A

A protein with a elongated shape forming a rod or wire like shape, that are usually inert structural or storage proteins

27
Q

What are globular proteins?

A

Proteins formed by compact amino acid chains, then folded into intricate chains that resemble spheres
They usually have metabolic functions.

28
Q

Give an example of a fibrous protein

A

Collagen, Keratin, Elastin

29
Q

Are fibrous proteins soluble or insoluble in water?

A

Insoluble

30
Q

Are globular proteins soluble in water?

A

Soluble

31
Q

What do fibrous proteins provide?

A

Structural support for cells and tissues

32
Q

Give an examples of a globular protein and what it does:

A

Haemoglobin - transports oxygen around the body

Immunoglobulins - antibodies which white blood cells produce to attack pathogens

Many enzymes - hydrolyse/catalyse in metabolism to make up/break down nutrients we need

Biology A Level 1 (11 decks)

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