Biological Molecules

Question 1

What is the structure of amino acids

Answer 1

-NH2 (Methyl) group -CH R Group (R determines protein) and -COOH group (Carboxylic acid)

Question 2

How are peptides bonds form

Answer 2

Bond form after condensation of 2 amino acids and OH group from -COOH and H Group from -NH3 are relased and -COO and -NH is fromed between

Question 3

What is the primary structure of a protein

Answer 3

Sequence of a.a bonded by covalent peptide bonds which is the primary structure

DNA of cell determines primary structure of protein

Question 4

What is the secondary structure of protein

Answer 4

Two Types:
Alpha - Helix : every 4th peptide bond and forms H bonds w/ double bond from C and bond from N-H from the same polypeptide chain

Beta - Pleated: Forms H Bonds w/ double bond from C and bond from N-H –> 2 Seperate Polypeptide Chains

Question 5

What are the 4 different bonds that occur in tertiary structure

Answer 5

Ionic Bonds - Negative and Positive R Group attraction
DiSulfide Bonds - Bond between 2 Cytesine(Sulfur) R groups
Hydrogen Bonds - Forms strongly between Polar R-Groups
Hydrophobic Interactions - Between Non Polar R Groups

Question 6

What are 2 types of quaternary proteins

Answer 6

Fibrous and Globular Proteins

Question 7

What is a Globular Protein and what are the featues

Answer 7

Soluble in water and due to Hydrophobic and Hydrophilic interaction in Protein’s Structure –> easily transported in fluid
Conjugated protein
Spherical
3-D Shaped

Question 8

What is an example of a globular protein and explain it

Answer 8

HAEMOGLOBIN

Conjugated Protein –> Non protein group attached to protein Group
Spherical and 3-D

Question 9

Explain the structure of Haemoglobin

Answer 9

Contains 4 PolyPeptide Chains and each has a Prosthetic Haem Group

Each Haem Group contains an Iron Ion

Question 10

State examples of Enzymes and Hormonesand what type of hormone they are

Answer 10

Enzyme - Amylase - Catalyses reaction
Hormone - Insulin - Involved in cell signalling
They are Globular Protein

Question 11

What is a Fibrous Protein and give example

Answer 11

Tough and Rod shaped but Insoluble and strong and Flexible

Examples:
Collagen - Found in connective tissue
Keratin - Flexible and found on skin
**Elasticity - Found in arteries

Question 12

What is celluose

Answer 12

Long chain of Beta Glucose monomers

Question 13

What features does celluose have which makes it a good structural component

Answer 13

1. Unbranched
2. Insoluble in water
3. Unreactive
4. Flexible

Question 14

What are the functions of celluose

Answer 14

1. Main structural component of cell walls
2. Highly tensile strength allows it to be stretched without breaking to withstand turgour pressure
3. Strengthened cell walls to provide support to plant

Question 15

What are the properties of water

Answer 15

1. High latent heat of vapourisation –> Evaporation is a cooling mechanism for example: Sweating
2. High specific heat capacity –> Stable enviornment for aquatic organisms, Organism use less energy on temp. control. Internal temp. of organism changes slowly so enzymes can function properly*
3. Effective Solvent –> Used as an Internal Transport Medium
4. Ice is less dense than water –> As Ice floats on water thus it is forms as an insulation layer and creates a habitat for aquatic organisms at low temps allowing aquatic organisms TO MOVE and water below ice does not freeze

Question 16

Why is Glycogen used in animals

Answer 16

1. Insoluble –> Does not affect water potential of cell
2. Contains branches which means there are lots of end for removing glucose
3. Compact molecule thus stores a lot of energy

Question 17

Starch is a mixture of Amylose and Amylopectin –> what are the similarities and differences between the 2 polysaccharides?

Answer 17

Similarities
Both are Long Chain of Alpha Glucose monomers
Both have 1-4 glycosidic bonds
Differences
Amylopectin has 1-6 Glycosidic Bonds
Amylopectin has Side Branches ( every 20 monomers )

Question 18

What are the structure and function of Triglycerides

Answer 18

Thermal Insulation -> Part of the composition of myelin sheath
Energy Storage –> As triglycerides are Hydrophobic
they do not cause osmotic water uptake in cells thus more cells can be stored
Buoyancy –> The low denstiy of fat tissues increases the ability of animals to float more easily

Question 19

What is the structure of a glycerol monomer

Answer 19

3 Carbon with each only bonded to only 1 OH group and Hs for rest

Question 20

What is the structure for fatty acid tails

Answer 20

-COOH(Carboxyl) group bondend to methyl groups for rest

Question 21

What is the structure for a phosphate group

Answer 21

P in middle bonded to 2 -OH and -2 O

Question 22

Name a reducing sugar

Answer 22

Maltose

Question 23

Name a non-reducing sugar

Answer 23

Sucrose

Question 24

What is the method to test for reducing sugars

Answer 24

1. Use Benedict’s solution and boil solution in a water bath and if sugar is reducing –> BRICK -RED PRECIPITATE FORMS and if none present sample stays blue

Question 25

Name non reducing sugars

Answer 25

ALL MONOSACCHARIDES and some disaccharides (maltose, lactose)

Question 26

How do you test for non-reducing sugars

Answer 26

Sucrose may be present after **failed positive test for reducing sugars** thus you add *hydrochloric acid to get rid of glycosidic bond (**Acid Hydrolysis)*** amd you neutralise it and use litmus paper to test for pH and then **PERFORM BENEDICT'S TEST AGAIN ( if solution goes birck-red, sucrose present)**

Question 27

What are examples of disaccharides

Answer 27

Maltose = Glucose + Glucose Sucrose = Glucose + Fructose Lactose = Glucose + Galactose

Question 28

Why are fibrous protein strong

Answer 28

contains **MANY STRONG HYDROGEN BONDS** between polypeptide chains

Question 29

How is fibrous a tertiary protein

Answer 29

Long chain of A.A Strong --> Provides strength to artery walls Non Polar/Hydrophobic interactions cause it to be insoluble

Question 30

What are the steps for dilution

Answer 30

Take 1cm^3 sample and make up to 10cm^3 Make 4 1:10cm^3 samples Correct value of dilution given between each stage

Question 31

how can structure of glucose allow it to cross from plant to bacterium

Answer 31

-Small hence it can cross membrane - OH/H allows for bond formation