Chapter 1 - Biological molecules

Question 1

what is the general formula for monosaccharides?

Answer 1

(CH2O)n

Question 2

what is the test for a reducing sugar?

Answer 2

when a reducing sugar is heated with benadicts reagent it forms an insoluble red precipitate of copper oxide

Question 3

what is a reducing sugar?

Answer 3

a reducing sugar is a sugar that can donate electrons to another chemical

Question 4

how is maltose made?

Answer 4

glucose + glucose = maltose

Question 5

how is sucrose made?

Answer 5

glucose + fructose = sucrose

Question 6

how is lactose made?

Answer 6

glucose + galactose = lactose

Question 7

what is a glycosidic bond?

Answer 7

it is formed when monosaccharides join and a molecule of water is removed.

Question 8

what is hydrolyis?

Answer 8

the addition of water that causes a breakdown

Question 9

what is a monosaccharide?

Answer 9

a single monomer of a carbohydrate.

Question 10

what is the test for starch?

Answer 10

• place the sample being tested in test tube
• add two drops of iodine and stir
• blue/black colour if starch is present

Question 11

why is starch suited for its purpose?

Answer 11

• insoluble; so not drawn into cells by osmosis

- compact; so a lot can be stored in a small place

Question 12

how does the structure of glycogen suit it for storage?

Answer 12

it is more highly branched than starch so has more ends that can be acted on by enzymes. it is therefore more rapidly broken down to glucose monomers which are used in respiration. this is important to animals who have a high metabolic rate and therefore a higher respitory rate.

Question 13

what happens when a triglyceride is broken down?

Answer 13

it releases fatty acids so the pH is acidic

Question 14

what happens when a triglyceride is formed?

Answer 14

when a triglyceride is formed a molecule of water is removed as each of the fatty acids join to the glycerol

Question 15

what is an ester bond?

Answer 15

the bond formed between the glycerol and the fatty acid is called an ester bond

Question 16

what is the test for lipids?

Answer 16

• crush the material and mix with ethanol
• pour resulting solution into test tube with water
• a white emulsion shows if a lipid is present

Question 17

what is a triglyceride?

Answer 17

made up of a molecule of glycerol and three fatty acid molecules

Question 18

what is a phospholipid?

Answer 18

has a two fatty acid molecules, a glycerol and a phosphate group

Question 19

what is a phospholipid bilayer?

Answer 19

when phospholipids are mixed with water, they arrange themselves in a double layer with their hydrophobic tails pointing inwards and hydrophobic tails outwards.

Question 20

what is the test for a protein?

Answer 20

• add sodium hydroxide to the test sample.
• add a few drops of dilute copper sulfate solution
• solution turns mauve

Question 21

what is a peptide bond?

Answer 21

a chemical bond formed between two amino acids as a result of condensation.

Question 22

how do amino acids join together?

Answer 22

by condensation reactions

Question 23

what are polypeptides?

Answer 23

joining two amino acids together forms a dipeptide. when these are joined together a polypeptide is formed

Question 24

describe the structure of proteins

Answer 24

polymer of amino acids is joined by peptide bonds in a series of condensation reactions. the primary structure is the order of amino acids. the secondary structure is the folding of thr polypeptide chain due to hydrogen bonding. the tertiary structure is 3-D foldiing due to hydrogen bonding and ionic/disulfide bonds. the quaternary structure is two or more polypeptide chains.