Chapter 1- Biological molecules Flashcards
Explain covalent bonding
Where atoms share a pair of electrons in their outer shells. The outer shell of both atoms are filled and a molecule is formed.
Explain ionic bonding
ions with opposite charge attract to each other.
for example Na+ attracts to Cl- to form sodium chloride.
Explain hydrogen bonding
- when electrons aren’t evenly distributed but spend more time in one position
- this makes this region more negatively charged than the rest of the molecule.
- a weak electrostatic bond is formed
What are monomers
Individual molecules which can bond together to form a polymer
What are polymers
- long chains of monomer sub-units.
- they are formed in a process called polymerisation
- glycosidic bonds from a condensation reaction
Outline condensation reactions
- A molecule of water is formed
- glycosidic bond is formed
- e.g polysaccharides are formed from monosaccharide glucose is an example of condensation reaction.
Outline hydrolysis reactions
- addition of water break the bonds that link sub-units
- i.e polymer gets hydrolysed into monomers
- e.g starch can be hydrolysed into glucose
Definition of metabolism
All the chemical processes that take place in living organisms
Describe the mole
- The SI unit for measuring the amount of a substance and is abbreviated to mol
-One mol contains the same number of particles as there are in 12g of carbon-12 atoms - 12g of carbon-12 atoms contains 6.022x10^23 also known as Avogadro constant.
Define:
-monosaccharide
-disaccharide
-polysaccharide
- 1 single monomer
- 2 monomers joined in a condensation reaction
- a large amount of monomers combined by a condensation reaction.
how many isomers does glucose have
2:
- alpha glucose
-beta glucose
How to test for reducing sugars
- add benedicts reagent which is an alkaline solution of copper (II) sulfate
- when heated with benedicts reagent, if there’s a positive result, a insoluble red precipitate is formed.
- glucose + glucose =
- glucose + fructose =
- glucose + galactose =
- maltose
- sucrose
- lactose
Test for starch
- add iodine solution to a sample
- presence of starch is indicated by a blue-black coloration
Describe starch
- polysaccharide
- found in form of small grains in many parts of plants
- made up of chains of alpha-glucose
- linked by glycosidic bonds in condensation reactions
outline 3 features and 1 function of starch
ANY 3 FROM:
- insoluble so doesn’t affect water potential
- large so doesn’t diffuse out of cells
- compact so a lot can fit in a small place
- when hydrolysed it forms a-glucose which is both easily transported and readily used in respiration
- branched meaning glucose monomers are released very rapidly
+ main role is to act as energy storage
In which organisms is glycogen found
Animals and bacteria but never in plants
Structure and function of glycogen
very similar to starch but:
- has shorter chains
- is more highly branched
Functions include being a major carbohydrate storage product of animals. This helps for animals which have a higher metabolic rate as they would have a higher respiratory rate so require more energy.
Structure / function of cellulose
- different from starch and glycogen because it is made from monomers of b-glucose
- has straight, unbranched chains which run parallel to each other
Functions are: - to add strength to a cell
- form rigidity to plant cell walls
-prevents the cell from bursting as water enters into it by osmosis
Properties of lipids
- contaibn: carbon, hydrogen and oxygen
- insoluble in water
- soluble in organic solvents such as alcohols and acetone
What are the two main groups of lipids
- triglycerides
- phospholipids
Roles of lipids
- source of lipids when oxidised
Structure of an amino acid
- central carbon attached to 4 different chemical groups:
- amino group (NH2)
- carboxyl group (COOH)
- hydrogen atom (H)
- R group
Describe the primary structure of proteins (polypeptides)
- through condensation reactions
- many AA monomers join through polymerisation
- resulting in many hundreds of AA’s called a polypeptide
- the sequence of AA forms the primary structure of proteins
What are catalysts
catalysts alter the rate of a chemical reaction without undergoing permanent changes themselves
What is the activation energy
the minimum amount of energy required to start a reaction
Describe the induced fit model
- the active site forms as the enzyme and substrate interact ( enzyme-substrate complex) i.e the enzyme can mould itself around the substrate
- when these are bonded, it puts strain on the substrate molecule which in effect lowers the activation energy
Name some factors affecting enzyme action
- temperature
- pH
- concentration
Describe inhibitors
substances that directly or indirectly interfere with the functioning of the active site resulting in reduced activity
Describe:
-Competitive inhibitors
- Non-competitive inhibitors
- bind to the active site of the enzyme
- bind to the enzyme at a place other than the active site
