Biological molecules

Question 1

What elements are carbohydrates made out from

Answer 1

Carbon Hydrogen Oxygen

Question 2

What chemical element are proteins made from

Answer 2

Carbon Hydrogen Oxygen Nitrogen sometimes sulphur

Question 3

What elements are in lipids

Answer 3

Carbon Hydrogen Oxygen

Question 4

What do most molecules in organisms contain

Answer 4

carbohydrates,
Protein and lipids

Question 5

Describe the structure of Carbohydrates

Answer 5

These larger molocules are made from smaller molecules

Question 6

Describe the structure for fats

Answer 6

Most fats(lipids in the body are made up from triglycerides )
Their basic unit is one glycerol molecule bonded to three fatty acid chains
The fatty acids vary in size and structure
Lipids are divided into fats( solids a room tempreture) and liquids(liquids at room tempreture)

Question 7

Describe what proteins are

Answer 7

Proteins are formed from long chains of amino acids
-There are 20 different amino acids
-When amino acids join together they form proteins
-Examples of proteins include enzymes and Haemoglobin

Question 8

Describe the structure and shape of proteins

Answer 8

Different proteins have different amino acid sequences resulting in them being a different shape
-Even a small change in the Amino acid sequence will result in a completly different Protein
-The shape of a protein depends on its function for example
-Enzymes have a specifically shaped active site - this is where a specific substrate molocule fits in order for a reaction to take place
-If the shape of the active site does not match the shape of the molecule fits into it, the reaction will not take place
-Antibodies are proteins produced by certain types of white blood cells that attach to antigens on the surface of pathogens
-The shape of the antibody must match the shape of the antigen so it can then attach itself and send a signal for destruction

Question 9

What food samples do you need to do before testing

Answer 9

-Break up the food using a pestle and mortar
-Transfer to a test tube and add distilled water
-Mix the food up with water by stirring with a glass rod
-Filter the mixture using a funnel and filter paper collecting the soloution
-Proceed with the test

Question 10

Test for glucose

Answer 10

-Add benedict’s soloution to the sample soloution in the test tube
-Heat in boiling water bath for 5 minutes
-take it out of the test tube bath
-A positive solution should show a change from blue to orange

Question 11

Test for Starch

Answer 11

-You can use iodine to test for the presence of Starch in a soloution
-Add drops of iodine soloution to the food soloution
-A positive test should show a change from orange to brown

Question 12

Test for protein

Answer 12

-Add drops of Biuret soloution to the food sample
-A positive test will turn from blue to violet

Question 13

Test for lipids

Answer 13

-Mix the food sample with 4cm3 of ethanol
-Allow the sample to dissolve in the ethonal
-Strain the ethonal soloution into another test tube
-Add the ethonal soloution to an equal soloution to an equal volume of cold distilled
Water
-A positive test should show a cloudy emulsion forming

Question 14

What are important hazards concerned with the food samples

Answer 14

Iodine irritant to the eyes. Ethanol highly flammable keep away rom Bunsen burner.
The Bunsen burner itself is a hard due to the open flame

Question 15

What are enzymes

Answer 15

-Enzymes are proteins that act as biological cataylst to speed up the rate of a chemical reaction without being changed or used up in the reaction
They are biological because they are made in living cells

Question 16

Explain what enzymes do

Answer 16

-Enzymes are necessary for all living organisms as they maintain reaction speed of all metabolic reactions(chemical reactions that take place in cells) at a rate that can sustain life
-Enzymes are specific to one particular substrates at the active site of the enzyme. Where the substrate attaches , is a complementary shape to the substrate
-When the substrate moves into the enzyme’s active site they become known as the enzyme-substrate complex

Question 17

How does tempreture effect enzyme activity

Answer 17

Enzymes work fastest at their optimum tempreture
-In the human body that is 37
Heating to high tempretures beyond the optimum will break the bonds
That hold the enzyme together and it will lose its shape
-this is called denaturation
-Substrates cannot fit into denatured enzymes as the shape of their Active site has been lost
-Denaturation is irreversible once they are denatured they cannot regain
Their shape and their active site and they do not work

Question 18

What is the effect of tempreture on enzyme activity

Answer 18

Increasing the tempreture toward the optimum increases the activity of the enzymes
As the more kinetic energy the molecules have the faster they move and the number
Of collisions with the substrate molecules increases, leading to a faster rate of reaction
-This means that lower tempretures do not denature enzymes they just have kinetic energy
And move more slowly not as efficient

Question 19

How does pH effect enzyme activity

Answer 19

The optimum pH for most enzymes is 7
-Some enzymes produced in acidic conditions like to stomach
Have a pH of 2

-if the pH is too high or low, the bonds that hold the amino acids chain
Together to make a protein can be disrupted/ Denatured
-This will change the shape of the active site so that the substrate can no longer fit into it reducing the rate of activity
-Moving too far away from the pH can cause the enzyme to denature and activity will stop