Biological molecules

Question 1

Define monomer.

Answer 1

smaller molecules that combine to make larger molecules.

Question 2

Define polymer.

Answer 2

larger molecule made up of many monomers joined together.

Question 3

What kind of reaction joins two monomers together?

Answer 3

condensation reaction

Question 4

What happens in a condensation reaction?

Answer 4

water is released and a chemical bond is formed.

Question 5

What bond forms when two monosaccharides join together?

Answer 5

glycosidic bond

Question 6

Give 3 examples of monosaccharides.

Answer 6

glucose
fructose
galactose

Question 7

How is starch formed?

Answer 7

Glucose + glucose = maltose + water

Question 8

What is it called when two monosaccharides join by a condensation reaction?

Answer 8

disacharide

Question 9

finish the equations:
Glucose + Glucose =
Glucose + fructose=
Glucose + galactose=

Answer 9

maltose + water
Sucrose + water
Lactose + water

Question 10

What is the difference between alpha and beta glucose?

Answer 10

Hydroxyl group ( OH) on carbon 1 are inverted 180 degrees

Question 11

What is the test for starch?

Answer 11

Add 5ml of sample, add 5 drops iodine, blue black colour means starch is present.

Question 12

What is the test for reducing sugars?

Answer 12

Add 5ml of sample, add 5ml Benedict’s solution, heat in boiling water bath for 5 mins, brick red precipitate present indicates presence of reducing sugar.

Question 13

Give examples of reducing sugars.

Answer 13

maltose, lactose, glucose, fructose, galactose

Question 14

What is the test for non-reducing sugars?

Answer 14

Add 5ml of sample, add 5 drops of HCL and heat, add 1 spatula of sodium hydrogen carbonate to neutralise, add 5ml bennedicts solution, heat, brick red precipitate indicates presence of non-reducing sugar.

Question 15

What is a saturated fatty acid?

Answer 15

contains no carbon carbon double bonds, usually solid at room temperature.

Question 16

Give 5 roles of lipids in the body.

Answer 16

Energy supply, structural components, waterproofing, insulation, protection

Question 17

How is a triglyceride formed?

Answer 17

glycerol and fatty acid joining by a condensation reaction.

Question 18

What is the bond between glycerol and fatty acids?

Answer 18

ester bond

Question 19

Give 3 examples of polysaccharides.

Answer 19

starch, cellulose, glycogen

Question 20

Give 3 examples of disaccharides.

Answer 20

sucrose, maltose, lactose

Question 21

What do all carbohydrates contain?

Answer 21

Carbon, hydrogen, oxygen

Question 22

What is the function of starch?

Answer 22

Store of glucose, provide chemical energy

Question 23

What is the function of cellulose?

Answer 23

Structural strength in the cell wall.

Question 24

What is the function of Glycogen?

Answer 24

Energy store in animals.

Question 25

What are the properties of triglycerides?

Answer 25

Energy storage, metabolic water source, don't effect water potential,

Question 26

What is the structure of glycogen?

Answer 26

Many alpha glucose monomers joined via 1-4 and 1-6 glycosidic bonds. Branched chains.

Question 27

How is the structure of glycogen related to its function?

Answer 27

Insoluble, doesn't affect water potential Compact, lots of glucose stored in a small space. Highly branched, enzymes easily hydrolyse Large, can't diffuse out of cells

Question 28

How is cellulose structured?

Answer 28

Many Beta glucose joined via glycosidic bonds. Long straight unbranched chains Hydrogen bonds between individual chains

Question 29

How does the structure of cellulose relate to it's function?

Answer 29

Long straight and unbranched chains provide rigidity to cell wall Hydrogen bonds, crosslink the chains and add collective tensile strength Microfibrils provide additional strength.

Question 30

What are the differences between phospholipids and triglycerides?

Answer 30

Phospholipids used as a structural component whereas triglycerides used as a store of energy Phospholipids form bilayors in water, triglycerides are insoluble.

Question 31

What is the test for lipids?

Answer 31

Add 5cm3 of ethanol to 2cm3 of sample being tested. Shake to dissolve any lipids in sample Add water and shake Cloudy white emulsion indicates presence of lipids

Question 32

What are the functions of proteins?

Answer 32

Catalysing reactions Transport of substances around body Cell recognition Protection against invasion of foreign bodies

Question 33

What is the bond between amino acids?

Answer 33

Peptide bonds

Question 34

What is the test for proteins?

Answer 34

Add sample Add equal volume of NaOH solution Add a few drops of biuret reagent A purple colour indicates presence of proteins

Question 35

What are enzymes?

Answer 35

Gobular proteins (tertiary structure) that act as catalysts.

Question 36

What is the lock and Key theory?

Answer 36

Enzyme binds with complimentary substrate as each enzyme has a unique active site. Forms an Enzyme substrate complex and products are released.

Question 37

What is the induced to fit theory?

Answer 37

Substrate is not completely complimentary to enzymes unique active site. Active site is induced and moulds to the shape of the substrate to form the enzyme substrate complex. Products are released and the enzyme returns back to its original shape.

Question 38

What is denaturation?

Answer 38

Hydrogen and ionic bonds are broken Tertiary structure is lost Shape of enzymes active site changes Substrate can no longer bind as not complimentary No enzyme substrate complexes form

Question 39

How does temperature effect enzyme activity?

Answer 39

Increased temperature causes more kinetic energy of molecules so more successful collisions and more E.S complexes form meaning higher rate of reaction. Too high a temp breaks hydrogen bonds so enzyme denatures.

Question 40

What are competitive inhibitors? How do you overcome them?

Answer 40

Inhibitor has a similar shape to substrate so bind to enzymes reducing rate of reaction as fewer substrates are able to bind. Increase substrate so there is a higher chance for it to bind.

Question 41

What are non-competitive inhibitors?

Answer 41

Inhibitor binds to enzyme which causes the active site to change shape so this slows down rate as prevents formation of E.S complexes. Cannot be overcome by increase in substrate conc.

Question 42

What is end point inhibition?

Answer 42

When the product can act as a non-competitive inhibitors.