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AS Biology > Topic 1.3 - Proteins > Flashcards

Topic 1.3 - Proteins Flashcards

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1
Q

What is an amino acid?

A

The monomer from which dipeptides, polypeptides and proteins are made

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2
Q

How many different amino acids are there?

A

20

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3
Q

What are amino acids made up of?

A

Amine group (NH2) and a carboxyl group (COOH) which are attached to the same C. Also an R group

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4
Q

What does amphoteric mean?

A

Molecules that can ionise as both an acid and a base

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5
Q

What is a zwitterion?

A

An ion with both positive and negative charge

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6
Q

What’s the difference between a polar molecule and a zwitterion?

A

A polar molecule doesnt have a formal charge, some atoms just pull harder on electrons than others thus creating a slight charge

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7
Q

What is a dipeptide?

A

A molecule consisting of two amino acids joined by a single peptide bond

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8
Q

What is a peptide bond?

A

A covalent bond that forms between the amine group of one amino acid and the carboxyl group of another

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9
Q

What is a condensation reaction?

A

A reaction by which two molecules are joined together to make a larger, more complex molecule with the loss of water

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10
Q

Explain the formation of a dipeptide

A

The OH of one carboxyl group and the H of another amine group join together to form water. A peptide bond forms between the C and the N, joining the two amino acids together

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11
Q

What test is used to test for proteins?

A

The biuret test

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12
Q

Explain the biuret test

A

Add an equal amount of sodium hydroxide solution to the test solution. Add a few drops of 0.5% copper sulfate solution. if it turns purple then there is protein present.

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13
Q

What are some of the important functions of protein?

A

Structural component, antibody/immunoglobins enzymes and hormones

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14
Q

What is the primary structure of proteins?

A

The order of the amino acids

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15
Q

How is the type of amino acid determined?

A

By the order of the bases on the DNA

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16
Q

How does changing one amino acid affect the protein?

A

It changes the properties of the entire protein

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17
Q

What is a polypeptide chain?

A

Amino acids linked together by peptide bonds in a chain

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18
Q

What is a protein?

A

Multiple polypeptide chains

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19
Q

What is the secondary structure?

A

When the polypeptide chain folds or twists

20
Q

What is an alpha helix?

A

When the polypeptide twists into the shape of a helix

21
Q

What is a beta pleated sheet?

A

When the polypeptide chain becomes folded

22
Q

How is the secondary structure held together?

A

By hydrogen bonds between the OH and H of the amino acids

23
Q

What is the tertiary structure?

A

When the polypeptide is further folded into a 3D structure which determines its function

24
Q

What are the types of 3D structures?

A

Globular and fibrous proteins

25
Q

In what structure do the R groups interact?

A

The tertiary structure

26
Q

What bonds are found in the tertiary structure?

A

Hydrogen, disulfide, ionic bonds

27
Q

What is the quarternary structure?

A

When two or more polypeptides are held together to form a molecule

28
Q

What is a fibrous protein?

A

Long coiled polypeptide chains

29
Q

What is an example of a fibrous protein?

A

Collagen

30
Q

What is the structure of collagen and how does this contribute to its properties?

A

3 polypeptide chains held together by covalent and hydrogen bonds makes collagen resistant to denaturing + strong

31
Q

What are the properties of fibrous proteins?

A

Insoluble, have structural roles like keratin (skin and teeth) and collagen

32
Q

What are globular proteins?

A

Spherical proteins

33
Q

What is an example of a globular protein?

A

Haemoglobin

34
Q

What is the structure of globular proteins?

A

Polypeptide chains wind so hydrophillic amino acids are at the surface and hydrophobic amino acids are at the core

35
Q

How does the structure of globular proteins help its function

A

Allows it to be soluble and therefore can be transported around the body

36
Q

What is haemoglobin?

A

A respiratory pigment found in red blood cells

37
Q

What is the structure of haemoglobin?

A

Four polypeptide chains (2 alpha chains and 2 beta chains) each bound to a haem group

38
Q

What is a prosthetic group?

A

An attachment that isn’t made from the protein

39
Q

What is in haem that allows it to carry oxygen?

A

Iron

40
Q

How does haem bind with oxygen?

A

The Fe2+ binds with an O2 molecule which changes the shape and allows more O2 molecules to bind to the haem

41
Q

When does haemoglobin have a high affinity for O2?

A

When there are high O2 conditions eg in the lungs

42
Q

When does haemoglobin have a low affinity for O2?

A

When there are low O2 conditions eg in the tissues where respiration has consumed O2

43
Q

What is transamination?

A

The conversion of one amino acid into another

44
Q

What are the essential amino acids?

A

The amino acids that can only be obtained from diet

45
Q

What is denaturation?

A

A change in shape of a protein that alters or destroys the ability of a protein to carry out its function

AS Biology (17 decks)

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