Biological Molecules

Question 1

Definition of a polymer

Answer 1

large complex molecules composed of land chains of monomers

Question 2

Definition of a monomer

Answer 2

small basic molecular units that can join together to form a polymer

Question 3

Explain the test for non-reducing sugars ( 2parts)

Answer 3

Part 1- add dilute hydrochloric acid to the sample and then heat in a water bath till boiling, finally to nutralise add sodium hydrocarbonate
Part 2- then carry out the test for reducing sugars

Question 4

Why is part 1 for the testing of non-reducing sugars needed

Answer 4

to break down the sample into monosaccharides

Question 5

explain/draw the structure of a fatty acid

Answer 5

1- C double bond O
2-OH
3- R

Question 6

what bond is formed between a fatty acid and a glycerol molecule

Answer 6

ester bond

Question 7

What type of reaction is needed when joining a glycerol molecule and a fatty acid

Answer 7

condensation reaction

Question 8

what is released when a glycerol molecule and a fatty acid to joined together

Answer 8

H2O
Water

Question 9

properties of triglycerides and explain why
(2 main properties)

Answer 9

1- energy storage -because of the long hydrocarbon tails contains lots of chemical energy
2- insoluble in water- because of the hydrophilic heads and hydrophobic tails

Question 10

Test for lipids

Answer 10

emulsion test -shake the testing sample with ethanol then poor the solution into water if lipids are present a milky/white ppt will be present

Question 11

what are the 3 functional groups in an amino acid

Answer 11

Carboxyl group(COOH)
Amine/Amino group(NH2)
R group

Question 12

structure of an amino acid

Answer 12

R

                    |      

           H3N-C-COOH 

                     | 

                     H

Question 13

explain the 4 structure of proteins

Answer 13

Primary Structure- sequence of amino acids in a polypeptide chain

Secondary Structure- hydrogen bonds form between the amino acids and coil into A-helix or B-pleated sheets

Tertiary Structure- more folding and more hydrogen bonding is used with the addition of ionic bonds, disulfide bridges, final 3D structure is formed

Quaternary Structure- where several different polypeptide chains are bonded/assembled together. proteins final 3D structure

Question 14

Go into detail about the bonds formed in the tertiary structure of a protein formation

Answer 14

additional hydrogen bonding is formed and ionic bonding is then started,
attraction between positivity and negativity charges parts of the molecule
Disulfide bridges- covalent bonds between sulfur atoms ( strong bonds)

Question 15

Test for proteins

Answer 15

Biuret test- test need to be alkaline so add drops of sodium hydroxide to the testing sample
then add copper sulfate solution , if proteins are present the solution will turn purple, the test stays blue if its an negative result.

Question 16

What is formed when a substrate fits into an enzymes active site, and what happens for substrate molecules being joined together and for an enzyme that is catalysing

Answer 16

enzyme - substrate complex which lowers activation energy
1) for substrate molecules joining together - lowers activation anergy because reducing repulsion between molecules so they can bond more easily
OR
2) or an enzyme that is catalysing- fitting into the active site buts a strain on the bonds holding the molecules together so the substrate molecules can break apart more easily.

Question 17

describe enzyme properties
also what would happen if the tertiary structure is altered

Answer 17

enzyme structures are related to their tertiary structure . this is because only one complementary substrate will fit into the active site. each enzyme has a different tertiary structure so they all have a different active site. so if the substrate is not complementary an enzyme substrate complex wont be formed and the reaction wont be catalysed. if the tertiary structure is altered the shape of the active site will change , so the substrate cant fit and a complex would be formed

Question 18

what are competitive inhibitors

Answer 18

molecules that have similar shape to substrate molecules , they compete with the substrate molecules to combine to the active site BUT no reaction takes place. substrate concentration need to increase for the rate to increase

Question 19

Non- Competitive inhibitors

Answer 19

binds to the enzyme AWAY from its active site. which cause the enzyme to change its shape so substrate molecules can no longer bind. increasing substrate concentration will have little to no effect.

Question 20

what is the function of RNA

Answer 20

transfer the genetic information form the DNA to the ribosomes.

Question 21

1- How are 2 nucleotides bonded together
2-Through what type of reaction
3- what is the bond formed

Answer 21

1- bonded through the phosphate of one group and the sugar of another ,
2- condensation reaction is needed.
3- ester bonds (phosphodiester bonds)

Question 22

the chain of phosphates and sugars are knows as what

Answer 22

sugar-phosphate backbone

Question 23

name 4 ways in which the structure of an RNA molecule differs from a DNA molecule

Answer 23

• ribose sugar
  -uracil replaces thymine
  -only forms a SINGLE polynucleotide strand
  -RNA strands are much shorter

Question 24

what are the 5 properties of water

Answer 24

1- important metabolite
2- good solvent
3- high latent heat of vaporisation
4- can buffer/resist changes in temperature
5-very cohesive

Question 25

how is water a
important metabolite?
good solvent ?
has a high latent heat vaporisation ?
can buffer/ resist changes in temperature ?
very cohesive ?

Answer 25

1- it is included in a lot of metabolic reactions , such as condensation reaction and hydrolysis reactions
2- some substances dissolve in it and many reaction stake place in it 3- lots is heat is needed to have water change form a liquid to a gaseous state. this is useful because we can use water water loss through evaporation to cool down w/o losing to much water - this is because when water evaporates it carries AWAY heat energy from the surface allowing the body to lower its temperature
4- hydrogen bonds give water high specific heat capacity- useful because water does not experience rapid temp. changes , help the body maintain constant internal body temperatures
5- cohesive- they stick together because they are polar ,strong cohesion helps water flow which is good for transporting substances , strong cohesion also means that water has a high surface tension when it comes into contact with air which allows some animals to be able to walk on water.