Biological Molecules

Question 1

What chemical elements do carbohydrates, proteins and lipids contain

Answer 1

Carbohydrate: carbon oxygen and lipids
Protein: carbon, oxygen, nitrogen and some small amounts of other elements
Lipids: carbon, oxygen and hydrogen

Question 2

Carbohydrates

Answer 2

Long chain of simple sugar
When 2 glucose molecules join together maltose is formed
Lots of these molecules join together starch, glycogen or cellulose can form

Question 3

Proteins

Answer 3

Long chains of amino acids
About 20 different amino acids
When they’re joined together protein is formed

Question 4

Fats (lipids)

Answer 4

Made up of triglycerides
1 glycerol molecule chemically bonded to 3 fatty acid chains
fatty
Lipids are didvded into fats (solid at room temp) and oils (liquids at room temp)

Question 5

What is the test for glucose (reducing sugar)?

Answer 5

Benedict’s solution
Positive test will show a color change from BLUE to ORANGE or BRICK RED

Question 6

What is the test for starch ?

Answer 6

Iodine solution
A positive test will show a color change from BROWN/ORANGE to BLUE-BLACK

Question 7

What is the test for PROTEINS ?

Answer 7

biurret solution
Positive test will show color change from BLUE to VIOLET/PURPLE

Question 8

What is the test for PROTEINS ?

Answer 8

biurret solution
Positive test will show color change from BLUE to VIOLET/PURPLE

Question 9

What is the test for lipids (fats and oils)?

Answer 9

Ethanol
Positive test will show cloudy emulsion- negative result colourless

Question 10

What are enzymes?

Answer 10

Proteins that function as biological catalysts

Question 11

What are they?

Answer 11

-Catalysts that speed up rate of chemical reactions without being changed or used up
-proteins
-biological catalyst (made in living cells)

Question 12

Why are they necessary

Answer 12

Beacause living cells they maintain reaction speeds of all - metabolic reactions at a rate that can sustain life
E,g
If digestive enzymes are not produced it would take 2-3 weeks to digest a meal with enzymes it takes around 4 hours

Question 13

How do they work

Answer 13

1. Enzyme and substrate randomly move around in solution
2. Enzyme and its complementary shape randomly collide with substrate fitting into active site of enzyme- enzyme complex forms, reaction occurs
3. A product forms from substrates which is then released from active site. Enzyme maintains unchanged and will go on to catalyze further reactions

Question 14

Enzyme effect of temperature on amylase

Answer 14

Method:
1. Heat starch solution to a set temperature
2. Add iodine to well of a spotting tile
3. Amylase is added to starch solution and mixed well
4.every minute, droplets of solution are added to new well of iodine solution
5. Continue until iodine stops turning. Lue black (meaning there no more starch left in solution as amylase broke it all down
6. Record time taken for reaction to be completed
7. Repeat experiments at different temp
8. The quicker it is completed the faster enzyme is working

Question 15

Effect of pH on amylase

Answer 15

method:
1. Place single drops of iodine solution in row on the tile
2.use syringe to place amylase in the test tube
3. Add buffer solution to test tube using syringe
4. Use another test tube and add starch solution to amylase and buffer solution, start stopwatch whilst kixing using pipette
5. After 10 s, use a pipette to place drop of mixture on the first drop of iodine, which should turn blue-black
6. Wait 10s place another drop of mixture of drop of iodine
7. Repeat every 10 s until iodine solution remains orange-brown
8. Repeat experiment at different pH values the less time it take iodine solution to remain orange-brown the quicker starch has been digested, the better enzyme works on THAT pH

Question 16

What happens if you exceed the maximum temperature amylase can resist ?

Answer 16

It will denature and starch will not be broken down

Question 17

Are enzymes specific ?

Answer 17

Specific to particular substrate the active site of enzyme, where substrate attaches, is a complementary to the substrate

Question 18

Why?

Answer 18

Proteins that have a specific 3D shape, known as the LOCK AND KEY

Question 19

What happens after the reaction?

Answer 19

Products leave enzymes active site as they no longer fit and it is free to take up other reactions

Question 20

Enzymes structure

Answer 20

Proteins with specific shale held in place by forces in the bonds of amino acids

Question 21

When do enzymes work best

Answer 21

At their optimum temperature- in human body it would be 37ºC

Question 22

What happens if you heat enzymes beyond its optimum temperature or exceed in pH

Answer 22

Bonds holding enzyme will break and it will lose its shape —>denaturation

Question 23

Is denaturation reversible?

Answer 23

Once denaturation occurs its irreversible, they can’t regain their proper shape and activity stops

Question 24

Do enzymes denature in low temperatures

Answer 24

No, they just work more slowly . The more energy molecules have the faster they move and the number of collisions with substrate molecules increases leading to faster rate of reaction

Question 25

What happens if ph is not at its optimum?

Answer 25

If ph is too high or too low bonds holding amino acids together can get destroyed, changing shape of active site, so substrate no longer fit into it, reducing rate of reaction
And moving it too far from optimum ph will cause enzyme to denature