Biological Molecules (proteins, Carbohydrates, Lipids)

Question 1

What is a monomer?

Answer 1

Smaller units from which larger molecules are made.

Question 2

what are polymers?

Answer 2

Molecules made from a large number of monomers joined together.

Question 3

state 3 examples of monomers.

Answer 3

monosaccharides, amino acids, and nucleotides.

Question 4

what is a condensation reaction?

Answer 4

A condensation reaction, joins two molecules together with the formation of a chemical bond, and involves the elimination of a water molecule.

Question 5

What is a hydrolisis reaction?

Answer 5

A reaction that breaks a chemical bond between two molecules, and involves the use of one water molecule.

Question 6

what is a monosaccharide?

Answer 6

Monomers from which larger carbohydrates can be made

Question 7

what are the 3 common monosaccharides?

Answer 7

glucose, galactose, and fructose.

Question 8

what is a glycosidic bond?

Answer 8

A condensation reaction between two monosaccharide, forms a glycosidic bond.

Question 9

what is a disaccharide?

Answer 9

formed by the condensation of two monosaccharides.

Question 10

what disaccharide is formed by the condensation of two glucose molecules?

Answer 10

maltose.

Question 11

what disaccharide is formed by the condensation of one glucose molecule, and one fructose molecule?

Answer 11

sucrose.

Question 12

what disaccharide is formed by the condensation reaction of a glucose molecule, and a galactose molecule?

Answer 12

Lactose.

Question 13

what are the two isomers of glucose?

Answer 13

alpha - glucose, and Beta - glucose.

Question 14

how do beta and apha glucose arranged atoms differ?

Answer 14

In alpha glucose, both OH groups are on the opposite side of oxygen, and in beta glucose, one OH group is on the oxygen side, and one is oppositely to oxygen.

Question 15

how are galactoses arranged atoms?

Answer 15

both OH groups are on the same side as oxygen.

Question 16

what is a polysaccharide?

Answer 16

Polysaccharides are formed by the condensation of many glucose units.

Question 17

What monomer do glycogen and starch have?

Answer 17

The condensation of Alpha glucose.

Question 18

What monomer does cellulose have.

Answer 18

The condensation of Beta glucose.

Question 19

What are the basic structures and functions of cellulose?

Answer 19

cellulose is a long- straight, and unbranched polysaccharide.
It is mainly composed of only Beta glucose.
It is found in the cell walls of plant cells, and is essential to endure rigidity, and strength to the cell wall.
Because the chains are so straight, they can stay parallel, close to each other, and form many hydrogen bonds in between them.
These chains are grouped together to form a long straight thread, called microfibril. These microfibrils are packed together in a Macrofibril. These macrofibrils are joined together to form the cell wall.

Question 20

why is glycogen a good storage molecule?

Answer 20

1. It is large, and therefore cannot cross the cell membrane when stored.
2. It is compact, because it is coiled, so we can fit more of it in a certain space.
3. It is insoluble, therefore it does not affect the water potential of the cytoplasm on a cell.

Question 21

what is the structure of glycogen? and state the advantages of this structures.

Answer 21

It is coiled, and it has many branches. More branches, means more loose ends, the more glucose per unit of time hydrolising enzymes can hydrolise.

Question 22

describe how you would carry out a simple test for reducing sugars.

Answer 22

1. grind food sample with a bit of water.
2. Add the same volume of benedict’s reagent.
3. heat up in water bath at 90 C for 5 minutes.
4. if positive, will turn orange-brown from blue.

Question 23

describe how you would carry out a non- reducing sugar test.

Answer 23

1. first test for reducing sugar, to see if food sample is reducing or non- reducing.
2. grind food sample with water,
3. add some acid to the sample.
   4.boil the mixture for 5 minutes ( The combination of heat and acid breaks down the polysaccharide into monosaccharides, that can then be tested with benedicts raegent).
4. we neutralise the solution, using an alkali.
   6.we add benedicts raegent to the solution,
5. heat it for 5 minutes at 90 C in a water bath.
6. If positive, will turn orange-brown.

Question 24

what is the iodine test for?

Answer 24

Starch

Question 25

describe the iodine test, and explain why it works.

Answer 25

1. we add food sample to the test tube.
2. we add two drops of yellow iodine solution, then stir and shake the mixture.
3. if the food sample turns blue- black colour, that means starch is present.
   How it works:
   The blue black part of iodine, binds to the coiled chains of starch, and separates from iodine.

Question 26

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Answer 26

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