Dr Harran Module 2

Question 1

What are macromolecules?

Answer 1

Large organic molecules that are not polymer’s but have bonded components

Question 2

What is Glycerol made of?

Answer 2

3 carbon chain with 3 hydroxyl (-OH) groups, hence tri-glyceride

Question 3

What does glycerol look like?

Answer 3

H
|
H-C-OH
|
H-C-OH
|
H-C-OH
|
H

Question 4

What does a triglyceride look like?

Answer 4

3 chains of fatty acids and glycerol

Question 5

What is an unsaturated or kinky fatty acid?

Answer 5

A fatty acid carbon chain that contains a C=C

Question 6

What is the bond in a triglyceride called?

Answer 6

An ester bond

Question 7

Why do saturated an unsaturated fats look physically different?

Answer 7

Because, due to their regular structure, saturated fats can pack up tightly, so often are solid like butter or lard whereas unsaturated fatty acids, due to the kink of the C=C bond, cannot pack as tightly so are more likely to be liquid like vegetable oil

Question 8

What are the functions of a triglyceride?

Answer 8

1. Energy Source - Can be broken down in respiration by hydrolysing the ester bond, and then glycerol and fatty acids can broken into CO2 and H2O. This produces more H2O than the respiration of sugar
2. Energy Store - Because of their insolubility and high proportion of H atoms, triglycerides can produce x2 more energy than glucose and can be stored without affecting a cells water potential
3. Insulation - Adipose tissue can act as an insulator and in nerve cells acts as a heat insulator
4. Buoyancy - Fat < dense than H2O so used by aquatic mammals to keep afloat
5. Protection - Humans have fat around delicate organs to absorb shock

Question 9

What is glucose used for in plants? (crops)

Answer 9

Cellulose cell walls
Respiration (aerobic)
Oils and fats
Proteins (actually amino acids+nitrate ions)
Starch (Amylose+Amylopectin)

Question 10

What is a phosolipid?

Answer 10

A glycerol molecule with 2 fatty acid carbon chains and one hydrophilic phosphate group

Question 11

What does mono-unsaturated mean?

Answer 11

A fatty acid one C=C double bond. Poly-unsaturated is therefore where there are many C=C double bonds

Question 12

What is a bacterial cell wall made of?

Answer 12

A phospholipid bi-layer with peptidoglycan within the hydrophobic centre, so bacteria are described as having a lipid rich outer layer

Question 13

What can phospholipids form in water?

Answer 13

Due to the fatty acid tails being hydrophobic, and the phosphate group (containing a number of hydroxyl groups, so being polar and attracted to water) being hydrophilic, phospholipids form structures like micelles, lysosomes and phospholipid bi layers when exposed to water

Question 14

What is a phospholipid bi layer?

Answer 14

The structure that allows the membrane to form boundaries between two watery environments as phospholipids arrange themselves with their hydrophobic tails facing in and their hydrophilic heads pointing outwards. The membrane is fluid, meaning that the lipids flow around each other to allow certain molecules past the membrane, e.g. CO2 or O2. This type of membrane makes up 20-80% of membranes in organelles

Question 15

What is cholesterol?

Answer 15

It is a steroid alcohol that is based around a 4 carbon ring, making it a lipid that is not based upon fatty acids or glycerol. It is a hydrophobic and philic molecule allowing it to sit in the hydrophobic middle of a phospholipid bi layer. From there it regulates the fluidity of the membrane, allowing certain needed molecules through

Question 16

What does HDL and LDL mean?

Answer 16

HDL: Means that a consumed cholesterol contains a high density of lipoproteins and is better for the body LDL: Means a cholesterol consumed contains a low density of lipoproteins, so in high quantities is worse for the body than HDL cholesterol

Question 17

What is a condensation reaction?

Answer 17

When two molecules bond through the loss of a water molecule.

Question 18

What is hydrolysis?

Answer 18

Hydrolysis is the separation of two molecules by the addition of a water molecule.

Question 19

Why is water a liquid at room temperature?

Answer 19

Know this script: -Hydrogen is bound to oxygen via a covalent bond -Oxygen has more protons in its nucleus than Hydrogen, so attracts the shared pair of electrons more strongly -This is because O is more electronegative -This leaves H with a δ+ charge and O with a δ- charge -This makes water a polar molecule -Hydrogen bonds are weak electrostatic interactions between the δ+ H and the δ- O of 2 water molecules

Question 20

What are some features of water?

Answer 20

-High latent heat of vaporization, large amount of energy needed to from a liquid to a gas, e.g. sweat cools you without dehydrating you
-High specific heat capacity, large amount of energy needed to raise the temperature by 1*C, so aquatic animals have a thermally stable habitat
-Ice is less dense than water, so can float creating a habitat for organisms like penguins
-Ice insulates the water below it keeping it a liquid so aquatic organisms do not freeze
-It is an effective solvent due to its polarity. This makes it a good reaction and transport medium, e.g. the blood
-The H bonds allow adhesion and cohesion amongst H2O molecules, e.g. water travelling up the xylem vessel in a plant
-Because of adhesion, water has a high surface tension creating a habitat for some organisms like the pond skater
-Water is transparent so allows underwater plants to photosynthesise
-Water has a high density so allows objects to float providing support for aquatic organisms

Question 21

What does an amino acid look like?

Answer 21

Amino acids have an amine group on one side and a carboxylic acid group on the other. There is also an R group attached to the central carbon.

Question 22

How many amino acids are there?

Answer 22

Over 200, but 20 in proteins. Animals can make some, but have to ingest others, essential aa’s, whereas plants can make all of them if they have a steady supply of nitrates.

Question 23

Why are amino acids amphoteric?

Answer 23

Amino acids are amphoteric because they contain both acidic and basic groups in the same molecule, so at low pH’s they accept H^+ ions as bases and at high pH’s they release H^+ ions as acids.

Question 24

What is the primary structure of a protein?

Answer 24

It is the sequence of amino acids in a polypeptide chain. It is held together by peptide bonds that are created through a condensation reaction.

Question 25

What is the secondary structure of a protein?

Answer 25

It is where the polypeptide folds into either an α helix structure or a β pleated sheet. This is held together with hydrogen bonds, the α helix between the -NH and the -CO 4 places ahead in the chain, and the β pleated between the -NH and the -CO much further ahead in the strand.

Question 26

What is the tertiary structure of a protein?

Answer 26

It is the 3D shape of the protein, including bending, that shows whether or not the protein is fibrous or globular. It is maintained by hydrogen bonds, ionic bonds between R groups and disulphide bridges between cysteine sulphur R groups. It also contains hydrophobic/philic interactions.

Question 27

What is the quaternary structure of a protein?

Answer 27

The quaternary structure appears when two or more polypeptide chains are joined together, and form a different and final 3D shape, like haemoglobin. Not all proteins have this. It is held together with Ionic, Hydrogen and disulphide bonds as well as hydrophobic or philic interactions.

Question 28

What are fibrous proteins?

Answer 28

Fibrous proteins usually contain a repetitive sequence of amino acids. Because of this it forms insoluble fibre-like polypeptide chains that take on a structural function in the body such as collagen, elastin and keratin.

Question 29

What are globular proteins?

Answer 29

Proteins with a specific 3D shape. They are soluble as the hydrophilic R groups arrange themselves so that they are on the outside of the protein. Because of their solubility they usually take on a more functional role, e.g. haemoglobin, Insulin/hormones, enzymes....

Question 30

What are carbohydrates?

Answer 30

A group of molecules containing C, H and O.

Question 31

How do you draw β glucose?

Answer 31

1. draw the hexose back-bone, with 5 C's and an O 2. follow the up down rule for the placement of the hydroxyl groups 3. add the H's at the other ends of the hydroxyl groups 4. to draw α glucose, reverse the first hydroxyl group

Question 32

What is a glycosidic bond?

Answer 32

When two monosaccharide rings are bonded via a condensation reaction.

Question 33

What are the 3 different uses of carbohydrates?

Answer 33

1. Energy storage- polysaccharides are an energy store as monosaccharides can be hydrolysed off the main chain 2. Energy source- for instance glucose is used in aerobic respiration and the production of ATP 3. Structural support- the polysaccharide cellulose is used in cell walls to keep the cell turgid and strong

Question 34

What are some examples of disaccharides?

Answer 34

α glucose + α glucose - maltose, α glucose + fructose - sucrose, α glucose + β glucose - lactose, β glucose + β glucose - cellobiose (component of cellulose)

Question 35

What are the 2 types of polysaccharides?

Answer 35

- Homopolysaccharide, made of only one type of monosaccharide - Heteropolysaccharide, made of more than one type of monosaccharide

Question 36

Why are polysaccharides good energy stores?

Answer 36

-They are stored as densely packed granules, so don't take up much space in the cell -They hold monosaccharides in chains, so that they can be hydrolysed and used when needed for respiration -Some are branched meaning that they are more compact and have more ends, so more monosaccharides can be removed at once -Polysaccharides are less soluble than their monomers, and so do not affect the cells water potential and disrupt normal cell functions

Question 37

What enzymes are responsible for hydrolysing polysaccharide chains?

Answer 37

Amylase is responsible for hydrolysing 1-4 glycosidic bonds and glucosidase for 1-6 glycosidic bonds.

Question 38

What is amylose? (plants)

Answer 38

A long polysaccharide of α glucose monosaccharides, bonded with 1-4 glycosidic bonds, found in starch. It coils in a helix shape, held together by hydrogen bonds on the inside of the molecule, so it is less soluble.

Question 39

What is amylopectin? (plants)

Answer 39

A long, branched chain of alpha glucose found in starch containing 1-4 and 1-6 alpha glycosidic bonds. It is therefore more compact than amylose, and because of the branches is less helical.

Question 40

What is glycogen? (animals)

Answer 40

It is a branched polysaccharide of α glucose, like amylopectin, but containing many more branches. This makes glycogen very compact and useful for animals when lots of glucose is needed for respiration due to intensive movement, as the branches allow lots of glucose to be removed as there a many ends. The 1-4 bonded chains are also smaller than the equivalent in starch, so glycogen is less likely to form a helix.

Question 41

What does amphipathic mean?

Answer 41

A molecule that contains both hydrophilic and hydrophobic parts.