Structural Molecules and Enzymes

Page 1

Structural Carbohydrates

Enzymes

Biological Membranes

Page 2

Structural Carbohydrates

Define and explain the basic structure of carbohydrates

Explain and provide examples of the different types of structural carbohydrate in plants, animals and bacteria

Demonstrate a basic knowledge of the functional role of glycosylation supported by examples

Page 3

Enzymes

Define the terms: enzyme, substrate and product

List advantages of enzymes

Explain the Michaelis-Menten model of enzyme kinetics

Define the terms Vmax, Km, Kd and kcat

Sketch a saturation curve

Explain co-operativity and allosterism in relation to enzymes

Define the differences between the three types of inhibitor and be able to draw Lineweaver-Burk graphs of each

Explain the relationship between enzyme action and activation energy, with reference to transition states and affinity

List the general and specific strategies that enzymes use to lower activation energy

Describe the steps of a serine protease reaction mechanism

Page 4

Biological Membranes

Explain/sketch the structure and molecular composition of a typical biological membrane

Name lipid molecules found in membranes

Explain why lipid bilayers can be described as liquid crystals

Describe the types of membrane proteins including channels, receptors and transporters

Describe membrane protein structural features, with reference to specific amino acid types, alpha helices and beta barrels

Use a hydropathy plot to investigate transmembrane helices

Page 5

Part 1

•Lipids based on glycerol and sphingosine as well as sterols form the major lipid components of biological membranes

•Lipids such as phosphatidylcholine form bilayers in water – the assembly of the bilayer is driven by the hydrophobic effect

•Biological membranes are in the liquid- crystalline phase. The fluid nature of the bilayer, where lipids and proteins are free to move in the plane of the bilayer, is essential for the function of membrane proteins

Page 6

Part 2

•Channels are hydrophilic pores through the membrane

•Channels allow the passage of ions across biological membranes

•Charges at entry to the pore dictate the charge of the ions that can pass

•Passage of ions through the channel can be controlled by a gate

•Direction of ion flow is dictated by the electrochemical gradient of the ion (passive process)

Page 7

Part 3

•Membrane proteins are difficult to crystallise and there are relatively few high resolution structures

•Indirect studies can provide information about the topology of membrane proteins

•Hydrophobicity plots identify possible transmembrane α-helices

•Pores can also be produced in membranes by β-barrel structures