Topic 1

Question 1

HYDROXYL

- OH

Answer 1

Readily form hydrogen bonds
Polar, water soluble
Found in alcohols and carbohydrates

Question 2

CARBONYL
 \ /
 C
 II
 O

Answer 2

Carbon-oxygen double bond
Contribute to making molecules water soluble
Polar, water soluble
Lipids
All carbohydrate molecules have one carbonyl group in addition to hydroxyl groups

Question 3

CARBOXYL 
     O
    //
- C 
    \\
     OH

Answer 3

Weak organic acid
Consists of a carbon atom dble bonded to an oxygen molecule and sgle bonded to a different oxygen molecule
2nd oxygen also bonded to a hydrogen molecule
Polar, water soluble (hydrphilic), acidic
Common in many biological molecules, incl.amino acids and fatty acids

Question 4

AMINO ACIDS
      H
     /
- N
     \
      H

Answer 4

Nitrogen atom bonded to 2 hydrogen 
Hydrophilic
Building blocks of protein
One of the most important classes of molecules found in living things
Slightly polar, weak base, water soluble
Proteins

Question 5

SULPHYDRYL

- S - H

Answer 5

Aka a thiol group
Sulphur bonded to hydrogen
Forms disulphide bridges, stabilises protein structure
Mainly found in proteins

Question 6

PHOSPHATE
     O
      I
O - P - O
      I
     O

Answer 6

Phosphorus bonded to 4 oxygen molecules
Found in DNA and RNA and in certain lipids
Involved in the biological storage and release of energy
Oxygen makes it polar and hydrophilic
Very polar, very water soluble
*Phosphates important - involved in signalling pathways, initiate reactions by binding to other molecules, key component in cellular wall formation
ATP, ADP, AMP - all amino phosphates

Question 7

What are the four classes of important organic molecules?

Answer 7

Carbohydrates (1 carbon : 2 hydrogen : 1 oxygen)
Lipids
Proteins
Nucleic acids

Question 8

Explain the difference between monosaccharides, disaccharides and polysaccharides

Answer 8

These are the three major carbohydrate groups.
Monosaccharides - simple sugars composed of a single unit (eg. glucose)
Disaccharides - formed by covalent bonds of two monosaccharides (eg. sucrose)
Polysaccharides - covalent bonding of several monosaccharides (eg. glycogen - polymer chain of glucose sub-units)

Question 9

What are functional groups?

Answer 9

Specific groups of atoms or bonds within molecules that are responsible for the characteristic chemical reaction of those molecules

Question 10

List the six important functional groups

Answer 10

Hydroxyl
Carbonyl
Carboxyl
Amino acid
Sulfhydryl
Phosphate

Question 11

What is the basic functioning unit of the body?

Answer 11

Cell

Question 12

List the four primary biomolecules

Answer 12

Carbohydrates
Lipids
Proteins
Nucleotides

Question 13

When is an atom most stable?

Answer 13

When orbits occupied by electrons

Question 14

What is the octet rule?

Answer 14

Tendency to fill outermost shell with 8 electrons

Question 15

What makes an element chemically reactive?

Answer 15

Partially filled outer shells - can then form chemical bonds with other atoms

Question 16

What is a chemical bond?

Answer 16

An attractive force between atoms

Question 17

Briefly describe the covalent bond

Answer 17

Two atoms share an electron
Non-polar = share equally
Polar = share unequally
To do with electronegativity (degree to which atom attracts electrons)

Question 18

What makes carbon so versatile?

Answer 18

Contains 4 electrons in its outer shell so can potentially form covalent bonds with 4 molecules at a time

Question 19

How is a polar bond formed?

Answer 19

The different electronegativity of atoms means that electron is more attracted to one than the other and it is shared unequally

Question 20

Explain a non-polar bond

Answer 20

Atoms share electrons equally

Question 21

What happens to the electrons when they are shared by oxygen and hydrogen?

Answer 21

Electrons are drawn closer to the oxygen atom because it has a higher electronegativity than hydrogen. Polar covalent bond is formed. Oxygen becomes slightly more negatively charged. Hydrogen becomes slightly more positively charged.

Question 22

What is a hydrogen bond?

Answer 22

A bond formed due to attraction between a positively charged hydrogen atom and a negatively charged oxygen atom

Question 23

Explain how ionic bonds are formed

Answer 23

Electronegativity of an atom is so strong that it takes an electron rather than sharing it

Question 24

How do cations differ from anions?

Answer 24

Cations are positive ions and anions are negative ions

*Ions are atoms which have lost acquired electrons
*Ions are atoms that have a positive or negative charge because the no. of electrons is not equal to the number of protons
Proton = +ve
Electron = -ve

Question 25

What type of bond is hydrophilic and what type is hydrophobic?

Answer 25

Polar covalent bond is hydrophilic Non-polar covalent bonds are hydrophobic This is because polar molecules are electrically attracted to water molecules

Question 26

What are the CHNOPS elements? 6 most common elements found in biomolecules (more than 25 overall)

Answer 26

``` Carbon Hydrogen Nitrogen Oxygen Phospherus Sulphur ```

Question 27

What are fatty acids?

Answer 27

Simplest of the fats Chain of carbon atoms (mostly 16 or 18) at its core, carboxyl acid (COOH) alpha end Can be saturated or unsaturated depending on dble bonds

Question 28

Distinguish between saturated fatty acids and unsaturated fatty acids

Answer 28

Saturated - carbons linked in chain by single bonds, the two open bond sites become occupied by hydrogen atoms, when all bonding sites filled by hydrogen atoms it becomes 'saturated' (eg. animal fats - solid at room temp.) Unsaturated - have some dble bonds between carbons causing bends or kinks, therefore cannot bond to as many hydrogen molecules and are 'unsaturated' (less compact, liquid at room temp.)

Question 29

Explain how the following lipid structures differ: - Triglycerides - Phospholipids - Eicosanoids - Steroids

Answer 29

Triglycerides - glycerol molecule containing 3 hydroxyl groups that combine with the carboxyl groups of 3 fatty acids, nonpolar, hydrophobic Phospholipids - glycerol combines with 2 fatty acids, one of which is unsaturated, phosphate group attaches to 3rd carbon of glycerol (polar head, hydrophilic) and the two fatty acids form the tail (non-polar, hydrophobic), form phospholipid bilayer Eicosanoids - signaling molecules made by oxidation of 20-carbon fatty acids, exert complex control over many bodily systems; mainly in inflammation or immunity, and as messengers in the central nervous system. Steroids - 4 fused rings of carbon atoms, two main functions: important components of cell membranes that alter membrane fluidity (cholesterol) and signaling molecules that activate steroid hormone receptors.

Question 30

What is a peptide bond?

Answer 30

A covalent bond between amino acids, by condensation reaction (reaction that releases water).

Question 31

What are the components of an amino acid?

Answer 31

....

Question 32

What structure makes amino acids different?

Answer 32

The variable or function group R - different chemical characteristics arise here.

Question 33

Explain the difference between primary, secondary, tertiary and quaternary proteins

Answer 33

....

Question 34

What is the basic structure of a nucleotide?

Answer 34

....

Question 35

How do pyrimidines and purines differ?

Answer 35

....

Question 36

Explain how phosphates form different nucleotides

Answer 36

....

Question 37

Explain the concept of complementary base pairing

Answer 37

....