Lipids and Proteins - B2 Flashcards

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1
Q

What are amino acids?

A

a single molecular repeating unit

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2
Q

How many common amino acids are there?

A

20

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3
Q

Which type of amino acid can be made by our bodies?

A

Non-essential amino acids can be made by our bodies, but we must get essential amino acids from our diet.

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4
Q

What are the 4 different groups in the structure of amino acids?

A

-Variable group (R group)
-Carboxylic acid group (carboxyl)
-hydrogen group
-Amine group (amino)

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5
Q

What reaction is used to bond two amino acids?

A

Condensation, which produces H2O.

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6
Q

What is the bond called that bonds two amino acids?

A

peptide bond

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7
Q

What are two amino acids bonded together called?

A

Dipeptide

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8
Q

What is another name for a protein?

A

Polypeptide

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9
Q

What are polypeptides?

A

A long chain of amino acids.

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10
Q

Which structure stages do all proteins go through?

A

1-3, only some go through 4.

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11
Q

What does every R group have different from each other?

A

They have a different amino acid.

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12
Q

What is the primary structure?

A

The primary structure is the no. and sequence of amino acids in a polypeptide chain.

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13
Q

Why do proteins differ from each other?

A

Because their primary structures are different from each other.

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14
Q

What are the two things that are formed in the secondary structure?

A

Alpha helix or beta pleated sheet.

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15
Q

Do alpha helix and beta pleated sheets form on the same chain?

A

Yes.

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16
Q

What is used to form the alpha helix and beta pleated sheet?

A

Using 1 polypeptide chain and hydrogen bonds.

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17
Q

What is the structure of an alpha helix?

A

Hydrogen bonds form between every 4th amino acid which causes the polypeptide chain to coil. It still has peptide bonds.

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18
Q

How are beta pleated sheets formed?

A

Hydrogen bonds form downwards.

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19
Q

What is the structure of the tertiary structure?

A

Further folded into a specific complex 3D shape. It is just a single polypeptide chain, and the way it folds depends in which bonds are present.

20
Q

What is the shape of the tertiary structure held together by?

A

This shape is held together by bonds between R groups of different amino acids.

21
Q

Which bonds are responsible for the tertiary structure?

A

Hydrogen bonds, ionic bonds, disulphide bridge(bond)

22
Q

Are hydrogen bonds weak or strong?

A

They’re weak.

23
Q

Are ionic bonds weak or strong?

A

They’re also weak, and they form between oppositely charged R groups.

24
Q

What type of bond are disulphide bridges?

A

Covalent bonds, which form between two sulphur containing R groups found in cystine amino acids. The sulphur atom in one cystine bonds the sulphur atom in another cystine.

25
Q

What are the two things that could destroy or denature the bonds?

A

Heat or pH.

26
Q

What is the quaternary structure?

A

Some proteins consist of two or more polypeptide chains joined together.

27
Q

What are some examples of a protein in the quaternary structure?

A

Hemoglobin, which has 4 polypeptide chains.
Other examples include: insulin, collagen, ribosomes and DNA polymase

28
Q

Are there any new bonds in the quaternary structure?

A

No

29
Q

What is the chemical test for proteins?

A

Biuret test:
-Add a few drops of sodium hydroxide solution
-Add a few drops of dilute copper sulphate solution(on the side of the test tube to release it slower)
-Shake it gently
-Positive result: mauve/purple/lilac

30
Q

What is the chemical test for lipids?

A

Lipid(emulsion) test:
-Dissolve the test sample by shaking with 2cm^3 ethanol
-Pour resting solution into water in a test tube
-Positive result: white emulsion is formed.

31
Q

What is a reducing sugar?

A

It donates it’s electrons and reduce other substances

32
Q

What are the two types of lipid?

A

Triglyceride and phospholipids

33
Q

What are triglycerides made from?

A

One glycerol molecule and three fatty acids.

34
Q

Is triglyceride a monomer or polymer?

A

It’s not a monomer or a polymer, just a molecule.

35
Q

Where are triglycerides stored?

A

Stored in fat cells -> calories the body doesn’t need.

36
Q

Why do hormones release triglycerides?

A

For energy between meals

37
Q

What are some of the functions of lipids/triglycerides?

A

Lipids store energy, provide insulation, form water-repellent layers on leaves, and provide building blocks for hormones.

38
Q

What are the two types of fatty acid?

A

Saturated and unsaturated.

39
Q

What is a saturated fatty acid?

A

There are no double bonds in the hydrocarbon chain, and it has the most hydrogen possible.

40
Q

Does the carboxyl group change for any fatty acid?

A

No it doesn’t.

41
Q

What is an unsaturated fatty acid?

A

It has a double bond in the hydrocarbon chain. If there is only 1 double bond, it’s monounsaturated, but if it has more than one double bond, it’s polyunsaturated. There is no hydrogen saturation.

42
Q

What is the basic structure of fatty acids?

A

-Typical fatty acid contains 12-18 carbons, though some have as few as 4 and as many as 36.
-It’s the same basic structure for saturated/unsaturated fatty acids.

43
Q

Which atom links the fatty acid to the glycerol?

A

The carbon atom.

44
Q

What is the difference between a phospholipid and a triglyceride molecule?

A

It has gained a phosphorus molecule and lost a fatty acid, so it is now a phosphate head and 2 fatty acid chains.

45
Q

Which of the phosphate head and fatty acid tail is hydrophobic and hydrophilic?

A

Phosphate head- hydrophilic
Fatty acid tail- hydrophobic

46
Q

What do the disulphide molecules form when they face each other?

A

They from a barrier - double layer barrier known as the cell’s double membrane.