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Chemistry 4 > Vitamins and proteins > Flashcards

Vitamins and proteins Flashcards

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1
Q

Define biomacromolecule.

Provide a description.

A

An organic compound that occurs naturally in living organisms.
Consis primarily of C and H but also N, O, P, S
They are large molecules with specific biological functions.
Eg. nutrients in food

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2
Q

Define macronutrients.

A

Proteins, carbohydrates, and fats that provide most of the energy in the human diet.

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3
Q

What are 2- amino acids?

α-amino acids

A

Small molecules containing a carboxyl and an amino functional group bonded to the same carbon atom.

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4
Q

Are all amino acids chiral?

A

No, glycine is not chiral. It is the simplest amino acid.

All other amino acids are chiral as they have 4 different groups bonded to carbon 2.

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5
Q

How is a protein formed?

A

When 2-amino acids undergo condensation polymerisation.
Reaction occurs between the carboxy group of one amino acid and the amino group of another amino acid. This forms a peptide (amide) functional group.

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6
Q

What is the function of proteins?

A
  • required for growth and repair of cells
  • transport molecules
  • makeup enzymes, hormones, and structural components
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7
Q

What are minerals?

A

Inorganic substances that required in various amounts for bodily functions.

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8
Q

What is the function of vitamins?

Provide an example.

A

Regulate most metabolic processes.

Eg. produce energy and growth development

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9
Q

What are the functions of carbohydrates?

A
  • Providing energy and regulation of blood glucose
  • Sparing the use of proteins for energy
  • Breakdown of fatty acids and preventing ketosis
  • Biological recognition processes
  • Dietary fiber
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10
Q

What are the functions of fats?

A
  • required to store vitamins
  • provide energy
  • insulate
  • maintain cell membranes
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11
Q

What are vitamins?

A

Organic compounds needed in small quantities on a regular basis to maintain a healthy diet.

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12
Q

What are the two types of vitamins?

A

Fat soluble and water soluble.

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13
Q

What are the fat-soluble vitamins?

A

D, E, A, K
Absorbed in the intestines and moved by lymphatic system.
Stored in fat deposits.
Nonpolar nature.

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14
Q

What are the water-soluble vitamins?

A

8 different B group vitamins and vitamin C
Absorbed directly into bloodstream.
Excreted through kidneys.
Contain polar functional groups -O and -N

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15
Q

What is the function of water-soluble vitamins?

A

Operate in cells to help catalyse cellular reactions.

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16
Q

Define an essential vitamin.

A

Vitamins that must be supplemented into the diet as they cannot be synthesised by the human body.

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17
Q

Define a non-essential vitamin.

A

Vitamins that can be synthesised by the human body.

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18
Q

What are amino acids?

A

Monomers in peptide chains calles amino acids.

Contain -NH2 and -COOH

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19
Q

What are essential amino acids?

A

Cannot be synthesised by animals and therefore must be supplied by the diet.

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20
Q

Describe the reactions amino acids undergo to form polypeptide chains. (2)

A
  • the reaction catalysed by enzymes

- H2O molecule is a product

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21
Q

What are the four hierarchical levels of protein structures?

A

Primary: the sequence of amino acids in polypeptide chain
Secondary:
Tertiary: 3D shape caused by side-chain interactions
Quaternary: When a protein contains 2 or more polypeptide chains

22
Q

What is a zwitterion?

A

A dipolar ion containing equal positive/ negative charge.

23
Q

What is an enzyme?

A

A biological catalyst which offers an alternate path with a lower activation energy, increasing the rate of reaction.

24
Q

Provide an explanation of the lock and key model.

A

Proposes the active site is rigid and complementary to the shape of the substrate accounting for the specificity of enzymes.

25
Q

Provide an explanation of the induced fit model.

A

Proposes the active site is considered to be flexible and can adjust to the shape of the substrate.
This explains why enzymes can react with a range up substrates.

26
Q

What factors affect the activity of an enzyme?

A
  • temp
  • pH level
  • concentration
27
Q

How is protein digested?

A

Proteins are hydrolysed by pepsin in the intestine. It is further hydrolysed in small intestine.

28
Q

Are all enzymes chiral?

A

yes

29
Q

What is denaturation?

A

Is the process that destroys the biological activity of proteins such as enzymes because the 3D shape is changed, resulting in a change in the shape of the active site.

30
Q

In what ways can denaturation occur? (3)

A
  • change of pH
  • increase the temperature
  • addition of certain chemicals: metal ions
31
Q

How does denaturation occur?

A

The change in conditions causes unfolding of the protein chains due to the breaking of bonds between side chains.

32
Q

What conditions determine enzyme activity?

A
  • pH
  • temperature
  • amount of active enzyme present
33
Q

What are the acid-base properties of enzymes?

A

The polar functional groups on 2-amino acids behave differently in acidic and basic

  • low pH: the amine group acts as a base and acceots a proton
  • high pH: the carboxyl group acts as an acid and donates a proton
34
Q

What type of bonding is involved in the primary structure?

A
  • amino acids are linked together by covalent binds known as peptide links
35
Q

What type of bonding is involved in the secondary structure?

A
  • folding and twisting of chain is held in place by hydrogen bonds
36
Q

What type of bonding is involved in the tertiary structure? (5)

A

The overall 3-D shape of protein is determined by the interactions that result from:

  • hydrogen bonding
  • dipole-dipole bonding
  • covalent s-s links
  • ionic attractions
  • dispersion
37
Q

What is the difference between denaturing a protein and hydrolysing a protein?

A

Denaturing results in the active site changing shape as high temp destroys 3D shape by breaking bonds that hold the tertiary structure in place, however, the overall protein remains intact whereas hydrolysing protein breaks peptide links, therefore protein is separated into individual amino acids.

38
Q

What type of bonding is involved in the quaternary structure? (5)

A

Some proteins consist of several associated polypeptide chains. These polypeptides are mainly held together by dispersion forces.
Dipole–dipole attractions, hydrogen bonds, ionic interactions and disulfide bonds involving R groups may also occur.

39
Q

What is a cofactor?

A

A cofactor may be a metal ion or another non-protein organic compound, called a coenzyme.

40
Q

What is the function of a coenzyme?

A

They bind to an enzyme to change the shape of the active site and thereby produce an active enzyme.
The change in shape of the enzyme’s surface enables interaction wtith the substrate.

41
Q

What occurs as a result of denaturation?

A

Coagulation and clumping.
This prevents the protein returning to its original structure, with the result that it can no longer function since the shape of the active site is different and the substrate can no longer bind to the enzyme.

42
Q

Describe two properties of enzymes which are used in the chemical industry?

A
  • operate under mild conditions

- are often selective in the reactions that they catalyse

43
Q

Why are enzymes described as specific?

A

Each enzyme has a unique 3D shape. It interacts with the substrate which has a complementary shape to the active site, allowing it to fit in. This accounts for the specificity of enzymes.

44
Q

Compare vitamin C with vitamin D.

A 
Vit C:
- water soluble
- found in (aq) environments 
- polar 
- essential vitamin and an antioxidant 
Vit D:
- fat soluble
- found in fatty tissues
- overall non-polar structure
- non essential vitamin
45
Q

Why is vitamin C water soluble?

A

Presence of four polar -OH groups makes it very soluble in water due to the formation of hydrogen bonds which can interact with water.

46
Q

What is the difference between a dipeptide, tripeptide and a polypeptide?

A
  • Dipeptide formed when 2 amino acids react to form one peptide link
  • Tripeptide formed when 3 amino acids react to form two peptide link
  • Polypeptide formed when many amino acids react
47
Q

What is a polypeptide chain called when there are 50 or more amino acids?

A

Protein

48
Q

What is the difference between an essential amino acid and a non-essential amino acid? (4)

A
  • essential: must be supplemented in diet as they cannot be synthesised by human body. There are 9 of them.
  • non-essential: they can be synthesised by human body from appropriate precursors. There are 11 of them.
49
Q

What are excess amino acids broken down into?

A

Broken down into to form toxic ammonia NH3.

This is converted into urea CO(NH2)2 which is excreted through urine.

50
Q

Why are vitamins D E A K far more likely to result in an overdose compared to other vitamins?

A

It is difficult to overdose on water soluble vitamins as excess vitamins can be excreted in urine. Vitamins D E A K are lipid soluble and retained for long periods in the body so are susceptible to overdosage.

51
Q

Explain the role of a coenzyme.

A

Coenzymes are small organic molecules such as biotin that bind to the active site of the relevant enzyme to assist in its catalytic function.

Chemistry 4 (7 decks)

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