Biological Molecules COPY

Question 1

What does macromolecule mean?

Answer 1

• A large biological molecule
• Three types or macromolecules in living organisms: polysaccharides, proteins (polypeptides) and nucleic acids (polynucleotides)

Question 2

What are polymers?

Answer 2

• They are giant molecules made up of repeating monomers which are similar or identical to each other, joined together in a chain
• Examples of biological polymers are polysaccharides, proteins and nucleic acids

Question 3

What is the general formula for carbohydrates?

Answer 3

Cx(H20)y

Question 4

What are the three main groups of carbohydrates?

Answer 4

monosaccharides, disaccharides and polysaccharides

Question 5

What is a monomer?

Answer 5

• It is a relatively simples molecule which is used as a basic building block for the synthesis of a polymer
• Many monomers are joined together to make the polymer, usually by condensation reactions
• Common examples of molecules used as monomers are monosaccharides, amino acids and nucleotides

Question 6

What is a monosaccharide?

Answer 6

1. Is a molecule consisting of a single sugar unit with the general formula (CH2O)n
   - Monosaccharides are sugars
   - General formula: (CH2O)n and consist of a single sugar molecule
   - The main types of monosaccharides, if they are classified according to the number of carbon toms in each molecule are:
2. Trioses (3C)
3. Pentoses (5C) e.g. ribose and deoxyribose
4. Hexoses (6C) e.g. glucose, fructose and galactose
   - Monosaccharides are used as a source of energy in respiration and are important building blocks for large molecules e.g. glucose used to make starch

Question 7

What is a disaccharide?

Answer 7

1. Is a sugar molecule consisting of two monosaccharides joined together by a glycosidic bond
   - They are sugars
   - The three most common:
2. Maltose (glucose + glucose)
3. Sucrose (glucose + fructose)
4. Lactose (glucose +galactose)
   - The joining of two monosaccharides takes place by a condensation reaction

Question 8

What is a polysaccharide?

Answer 8

1. Is a polymer whose subunits are monosaccharides joined together by glycosidic bonds
   - The final molecule may be several thousand monosaccharide units long
   - The most important polysaccharides are starch, glycogen and cellulose, all of which are polymers of glucose
   - Polysaccharides are NOT sugars

Question 9

Describe the ring structure of alpha glucose

Answer 9

The hydroxyl group, -OH, on carbon atom 1 is below the plane of the ring

Question 10

Describe the ring structure of beta glucose

Answer 10

The hydroxyl group, -OH, on carbon atom 1 is above the plane of the ring

Question 11

Why is there a ring structure?

Answer 11

The chain of carbon atoms e.g. in pentoses and hexoses, is long enough to close euro on itself to form a more stable ring structure
E.G. When glucose forms a ring, carbon atom number 1 joins to the oxygen on carbon atom number 5. The ring therefore contains oxygen, and carbon atom number 6 is not part of the ring

Question 12

What is the difference between the molecular formula and the structural formula?

Answer 12

-The molecular formula show the number of each element in a compound and the structural formula shows the arrangements of atoms, using a diagram (CHECK)

Question 13

What happens during a condensation reaction?

Answer 13

1. For each condensation reaction, two hydroxyl groups line up alongside each other
2. One combines with a hydrogen atom from the other to from a water molecule
3. This results in an oxygen “bridge” to forming between the two molecules, holding them together and forming a disaccharide.
   - The bridge is called a glycosidic bond (a linkage/bond between two monomers) -CHECK or just molecules?

Question 14

What is the reverse of the condensation reaction?

Answer 14

1. The addition of water, called hydrolysis
   - This takes place during the digestion of disaccharides and polysaccharides when they are broken down to monosaccharides

Question 15

What is starch made up of?

Answer 15

Starch is a mixture of amylose and amylopectin

Question 16

How is amylose made?

Answer 16

1. Amylose is made by condensations between alpha glucose molecules
2. In this way a long, unbranching chain of several thousand 1,4 linked glucose molecules is built up
   (they are linked between carbon atoms 1 and 4 of successive glucose units)
3. The chains are curved and coil up into helical structures, making the final molecule more compact

Question 17

How is amylopectin made?

Answer 17

1. Made of many 1,4 linked alpha glucose molecules
2. But the chains are shorter than in amylose and branch out to the sides
3. The branches are formed by 1,6 linkages

Question 18

Where is starch found?

Answer 18

• Mixtures of amylose and amylopectin molecules build up into relatively large starch grains, which are commonly found in:
  1. Chloroplasts
  2. In storage organs such as potato tubers and the seeds of cereals and legumes

Question 19

What is glycogen made up of?

Answer 19

1. Glycogen is made of chains of 1,4 linked alpha glucose with 1,6 linkages forming branches
   - Glycogen molecules tend to be even more branched than amylopectin molecules
   - Glycogen molecules clump together to form granules, which are visible in liver cells and muscle cells, where they form an energy reserve