Chapter 1 - Biological Molecules Flashcards
Monomer
Smaller units which can create larger molecules
Polymer
Made from lots of monomers bonded together
Examples of monomers
Glucose, amino acid and nucleotides
Examples of polymers
Starch, cellulose, glycogen, protein, DNA & RNA
Condensation reaction
Joining two molecules creating a chemical bond and removing water
Hydrolysis reaction
Breaks a chemical bond between two molecules and involves the use of water
What do carbohydrates contain?
Carbon, hydrogen and oxygen
Name three monosaccharides?
Glucose, fructose and galactose
What is sucrose made of?
Fructose
What is maltose made of?
Glucose
What is lactose made of?
Galactose
What are the three polysaccharides?
Starch, cellulose and glycogen
Where is the OH for alpha glucose?
Both on the bottom
Where is the OH on beta glucose?
Bottom and top
What is the bond between two monosaccharides?
Glycosidic bond
How do you join two monosaccharides?
Condensation reaction
Where is starch found?
Plants
Where is glycogen found?
Animals
What is the structure and function of starch?
Branched (amylopectin vs amylose) - many ends for attack for rapid release of alpha glucose
Insoluble so doesn’t affect water potential and osmosis
Large and insoluble - doesn’t diffuse out of the cell
Coiled into helixes to make it compact
Hydrolysed in to alpha glucose which is useful for respiration
Function : store of glucose
Structure and function of glycogen
Insoluble, coiled
More highly branched than starch - glucose is released/ hydrolysed more rapidly (advantageous for animals respiring)
Storage polysaccharide - stored in animals fat as an energy store
Structure and function of cellulose
Beta glucose chains (using hydrogen bonds which form cross links between adjacent chains) form microfibrils form into parallel groups called fibres - major component of plant cell walls due to structural strength
Straight, unbranched, no coils
Large and insoluble - won’t affect water potential
What do all polysaccharides have in common?
They are large and insoluble so won’t affect the water potential
What is a triglyceride made of?
1 glycerol and 3 fatty acids
What is a phospholipid made of?
1 glycerol, 2 fatty acid chains and a phosphate group
How are triglycerides formed?
3 condensation reactions between glycerol and 3 fatty acids.
1 water molecule is lost between the fatty acid and the part of the glycerol is attaching to = 3 condensation reactions and 3 waters lost.
3 ester bonds formed
What is the bond between glycerol and fatty acids?
Ester bonds
What are the two types of fatty acids you can get?
Saturated - the hydrocarbon chain has only single bonds between carbons
Unsaturated - the hydrocarbon chain has 1 or more double bonds between carbon atoms
Properties of triglycerides
- Low mass so a lot can be stored without increasing the mass and preventing movement.
- Insoluble - triglycerides do not affect water potential and osmosis. This is because they are large and hydrophobic, making them insoluble in water.
- Metabolic water source due to high ratio of hydrogen to oxygen atoms. Triglycerides release water if oxidised. This is essential of animals in the desert, such as camels.
- Energy storage - high ratio of energy storing carbon hydrogen bonds compared to the number of carbon atoms a lot of energy is stored in the molecule
How are phospholipids made?
Two condensation reactions to make 2 ester bonds.
What structure of phospholipid make them attract water and repel fats?
Hydrophilic head due to negative charge on phosphate group.
Are the fatty acid tails hydrophobic or hydrophilic?
Hydrophobic
Are the heads of phospholipids hydrophobic or hydrophilic?
Hydrophilic
How do phospholipids make bilayers?
They have too charged regions because they are polar
In water they are positioned so that the heads are exposed to the water and the tails are not.
This forms a phospholipid biosphere membrane structure which makes up the plasma membrane around cells
What are the roles of lipids?
Cell membranes around cell and organelles (phospholipids)
Waterproofing of plants: cuticles on leaves, animals: oils from sebaceous glands of the skin
Insulation of heat: layer of fat under the skin (blubber) and electricity: insulators in the myelin sheath around nerves.
Protection: around delicate organs like kidneys and the heart
Energy (more than twice as much as carbohydrates) when lipids oxidised (also release of water)
Structure of phospholipids related to properties
Forms of phospholipid bilayer in cell membranes.
Creates a hydrophobic barrier between inside and outside of cell.
Phosphate heads maintain the structure of the membrane.
Phosphate heads can attach to carbohydrates forming glycolipids
Useful in cell signalling (antigens on the cell surface)
What are the monomers in proteins?
Amino acids