SNS Biology - The Basis of Life Flashcards
Coacervate Droplets
A cluster of colloidal molecules surrounded by a sheel of water
Categories of Organisms
- Autotroph anaerobes - eg chemosynthetic bacteria
- Autotroph aerobes - eg green plants, plankton
- Heterotroph anaerobes - eg yeast
- Heterotroph aerobes - eg animals, amoebas
Organic Compounds
- Made by living systems
- contain carbon
- Include carbohydrates, lipids. proteins, nucleic acids
Inorganic Compounds
- Componunds that don’t contain carbon
- Include salts, HCl
Lipids
- 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
Lipid Derivatives
- Carotenoids
- Phospholipids
- Porphyrins
- Steroids
- Waxes
Lipids Derivatives
Phospholipids
- Contain glycerol, two fatty acids, a phosphate group and a N containgin alcohol
- eg lecithin, cephalin
Lipid Derivatives
Waxes
- Esters of FAs and monohydroxylic alcohols
- Form protective coatings
- eg lanolin
Lipid Derivatives
Steroids
- Have 3 fused cyclohexan rings and one fused cyclopentane ring
- eg Cholesterol, sex hormones, corticosteroids
Lipid Derivatives
Carotenoids
- 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
Lipid Derivatives
Porphyrins
- Or tetrapyrroles
- Contain four joined pyrrole rings
- Often complexed with a metal
- eg haemoglobin, chlorophyll
Proteins
-Structure and Classification
- Albumins and globulins - primarily globular, act as carriers or enzymes and are usually found in the serum
- Chromoproteins - protein bound to pigmented molecules
- Conjugated proteins - contain a simple protein portion plus at least one nonprotein fraction
- Lipoproteins - protein bound to lipid
- Metalloproteins - protein complexed with a metal ion
- Mucoproteins - protein bound to carbohydrate
- Nucleoproteins - protein bound to nucleic acids (DNA or RNA). In the case of DNA, the protein is combined with either histone or protamine
- Scleroproteins - fibrous, structural roles, eg collagen
- Simple proteins - composed only of AAs
Proteins
Functions
- Antibodies
- Enzymes
- Hormones
- Structural proteins
- Transport proteins
Enzymes
Models For Substrate Binding
- Lock and Key
- Induced Fit
Enzymes
Reversibility
- 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
Enzyme Action
- Temperature
- pH
- Concentration
- As temp increases, rate of enzyme action increases until optimum temp, beyond this decreases
- Also has an optimal pH. For many human enzymes, is 7.2. Exceptions are pepsin (2) and pancreatic enzymes (8.5)
- Increasing substrate conc increases until saturation point is reached - Vmax
Enzyme Action
Examples
Hydrolysis
Digest large molecules into smaller components
- Lactase - hydrolyses lactose into glucose and galactose
- Proteases - proteins into AAs
- Lipases - Lipids to FAs and glycerol
Enzyme Action
Examples
Synthesis
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
Enzymes
Cofactors
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
Cell Biology
Cyclosis
Process by which transport occurs within the cytoplasm
Is the streaming movement of cytoplasm within the cell
Cell Biology
Autolysis
Form of apoptosis
Rupture of the lysosomal membrane and release of hydrolytic enzymes
Osmosis
- Hypertonic
- Hypotonic
- 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
- Extracellular medium less concentration than the cell cytoplasm. Water will flow into the cell, causing it to swell and lyse
Circulation
Intracellular
- Brownian Movement - Spreading movement of suspended particles throughout the cell cytoplasm via kinetic energy created by collisions
- Cyclosis (streaming) - circular movement of cytoplasm around the cell transport molecules
- Endoplasmic Reticulum - provides channels throughout the cytoplasm and provides a direct continous passageway from the plasma membrane to the nuclear membrane
Circulation
Extracellular
- 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
- Circulatory System - complex animals whose cells are too far from the external environment to transport materials by diffusion require a circulatory system
