SNS Biology - The Basis of Life

Question 1

Coacervate Droplets

Answer 1

A cluster of colloidal molecules surrounded by a sheel of water

Question 2

Categories of Organisms

Answer 2

1. Autotroph anaerobes - eg chemosynthetic bacteria
2. Autotroph aerobes - eg green plants, plankton
3. Heterotroph anaerobes - eg yeast
4. Heterotroph aerobes - eg animals, amoebas

Question 3

Organic Compounds

Answer 3

• Made by living systems
• contain carbon
• Include carbohydrates, lipids. proteins, nucleic acids

Question 4

Inorganic Compounds

Answer 4

• Componunds that don’t contain carbon
• Include salts, HCl

Question 5

Lipids

Answer 5

• Like carbohydrates, composed of C, H and O but H:O ratio much greater than 2:1 - contain much more H than O
• Consists of three fatty acids and single glycerol frmed by dehydration reaction

Question 6

Lipid Derivatives

Answer 6

1. Carotenoids
2. Phospholipids
3. Porphyrins
4. Steroids
5. Waxes

Question 7

Lipids Derivatives

Phospholipids

Answer 7

• Contain glycerol, two fatty acids, a phosphate group and a N containgin alcohol
• eg lecithin, cephalin

Question 8

Lipid Derivatives

Waxes

Answer 8

• Esters of FAs and monohydroxylic alcohols
• Form protective coatings
• eg lanolin

Question 9

Lipid Derivatives

Steroids

Answer 9

• Have 3 fused cyclohexan rings and one fused cyclopentane ring
• eg Cholesterol, sex hormones, corticosteroids

Question 10

Lipid Derivatives

Carotenoids

Answer 10

• FA-like carbon chains containing conjugated double bonds and carrying 6-membered carbon rings at each end
• The pigments that produce red, yellow, orange and brown colours in plants and animals
• Two subgroups - carotenes, xanthophylls

Question 11

Lipid Derivatives

Porphyrins

Answer 11

• Or tetrapyrroles
• Contain four joined pyrrole rings
• Often complexed with a metal
• eg haemoglobin, chlorophyll

Question 12

Proteins

-Structure and Classification

Answer 12

1. Albumins and globulins - primarily globular, act as carriers or enzymes and are usually found in the serum
2. Chromoproteins - protein bound to pigmented molecules
3. Conjugated proteins - contain a simple protein portion plus at least one nonprotein fraction
4. Lipoproteins - protein bound to lipid
5. Metalloproteins - protein complexed with a metal ion
6. Mucoproteins - protein bound to carbohydrate
7. Nucleoproteins - protein bound to nucleic acids (DNA or RNA). In the case of DNA, the protein is combined with either histone or protamine
8. Scleroproteins - fibrous, structural roles, eg collagen
9. Simple proteins - composed only of AAs

Question 13

Proteins

Functions

Answer 13

1. Antibodies
2. Enzymes
3. Hormones
4. Structural proteins
5. Transport proteins

Question 14

Enzymes

Models For Substrate Binding

Answer 14

1. Lock and Key
2. Induced Fit

Question 15

Enzymes

Reversibility

Answer 15

• Most enxymatic reactions are reversible - the product can be decomposed by the same enzyme
• For example, an enzyme that synthesises maltose from glucose can also hydrolyse maltose back to glucose

Question 16

Enzyme Action

1. Temperature
2. pH
3. Concentration

Answer 16

1. As temp increases, rate of enzyme action increases until optimum temp, beyond this decreases
2. Also has an optimal pH. For many human enzymes, is 7.2. Exceptions are pepsin (2) and pancreatic enzymes (8.5)
3. Increasing substrate conc increases until saturation point is reached - Vmax

Question 17

Enzyme Action

Examples

Hydrolysis

Answer 17

Digest large molecules into smaller components

1. Lactase - hydrolyses lactose into glucose and galactose
2. Proteases - proteins into AAs
3. Lipases - Lipids to FAs and glycerol

Question 18

Enzyme Action

Examples

Synthesis

Answer 18

Can be catalysed by the same enzymes as hydrolysis reactions, but the direction of reaction is reversed

These reactions occur in various parts of the cell, eg protein synthesis on the ribosomes, glycogen production

Question 19

Enzymes

Cofactors

Answer 19

Many enzymes require non-protein components for activity

Can be metal ions or small organic groups called coenzymes

Cofactors that bind to the enzyme via covalent bonds are called prosthetic groups

Question 20

Cell Biology

Cyclosis

Answer 20

Process by which transport occurs within the cytoplasm

Is the streaming movement of cytoplasm within the cell

Question 21

Cell Biology

Autolysis

Answer 21

Form of apoptosis

Rupture of the lysosomal membrane and release of hydrolytic enzymes

Question 22

Osmosis

1. Hypertonic
2. Hypotonic

Answer 22

1. When the cytoplasm of a cell has a lower conc of nonpenetrating solutes than the extracellular medium, the extracellular medium is hypertonic to the cell. Water will flow out of the cell - plasmolysis
2. Extracellular medium less concentration than the cell cytoplasm. Water will flow into the cell, causing it to swell and lyse

Question 23

Circulation

Intracellular

Answer 23

1. Brownian Movement - Spreading movement of suspended particles throughout the cell cytoplasm via kinetic energy created by collisions
2. Cyclosis (streaming) - circular movement of cytoplasm around the cell transport molecules
3. Endoplasmic Reticulum - provides channels throughout the cytoplasm and provides a direct continous passageway from the plasma membrane to the nuclear membrane

Question 24

Circulation

Extracellular

Answer 24

1. Diffusion - if cells are in direct/close contact with the external environment, diffusion can serve as a means of transport of food and oxygen from the environment into the cell. In larger, more complex organisms, diffusion is important for the transport of materials between cells and the interstitial fluid that bathes the cells
2. Circulatory System - complex animals whose cells are too far from the external environment to transport materials by diffusion require a circulatory system