L2 - Introduction to Biological Molecules Flashcards
How many bonds does carbon form?
4 (tetravalent)
What 3 forms do carbon-based molecules exist as?
- Simple
- Chain
- Ring
Give an example of a simple carbon-based molecule and describe its uses.
- Methane: natural GHG
- Hexane: main constituent of gasoline
- Benzene: aromatic natural constituent of crude oil
What do functional groups do when they attach to carbon-based compounds?
Dictate the function of compounds.
What often occurs in cellular chemical reactions?
Functional group transfer (loss / gain).
What is significant about the breakage of covalent bonds in carbon-based compounds?
Releases energy which can be used to sustain life.
Name the 15 different functional groups and their prefixes / suffixes.
- Alkane: ‘ane’ (C-C)
- Alkene: ‘-ene’ (C=C)
- Alkyne: ‘-yne’ (C≡C)
- Alcohol: ‘-ol’ (-OH)
- Ether: ‘ether’ (-C-O-C-)
- Haloalkane: ‘halo-‘ (-C-X)
- Amine: ‘-amine’ (-C-N-)
- Aldehyde: ‘-al’ (-COH)
- Ketone: ‘-one’ (-C-CO-C-)
- Carboxylic Acid: ‘-oic acid’ (R-COOH)
- Ester: ‘-oate’ (-CO-O-C-)
- Amide: ‘-amide’ (-CO-N-)
- Amino: ‘amino-‘ (R-NH2)
- Thiol: ‘-thiol’ (R-SH)
- Phosphate: ‘phosphate’ (R-PO4)
What is a macromolecule?
Large biological molecule with repeating subunits and many functional groups.
Name the 4 groups of biologically important macromolecules.
- Carbohydrates
- Lipids
- Proteins
- Nucleic acids
How are polymers formed and what conditions are necessary?
- Formed by dehydration synthesis (condensation reaction)
- Water molecule removed when reactants are joined
- Requires energy in the form of ATP
How are polymers broken down and what conditions are necessary?
- Broken down by hydrolysis
- Water molecule added when bonds between reactants are broken
- Energy released from bond is stored as ATP
Why do polymers like starch need to be broken down?
To be easily digested and absorbed across the gut.
What are enzymes?
Biological catalysts that increase the rate of chemical reactions without being used up.
How much of the fresh mass of living organisms does water make up?
60-95%
Describe and explain the 3 main roles of water in living systems.
- Universal solvent and transporter (all body fluids mostly water so can be used as transport medium, water aids movement of chemicals during diffusion)
- Lubricant (in joints and on tissues; moistens epithelial surfaces and acts as shock absorber)
- Regulates body temperature (water requires heat to turn to vapour = sweat absorbs heat from skin when evaporating)
How much of body tissues are water?
62%
Approximately how much water is needed a day?
1.5 L/day
How is hydration status and blood flow tested? Explain the process.
- Capillary Refill Test
1) Pressure applied to nail bed until it turns white (blanched)
2) Pressure removed and hand is held above heart
3) Time taken for blood to return to tissue and nail to turn pink again is measured
What conditions is dehydration associated with?
- Diarrhoea
- Vomiting
- Seizures
(Can be fatal so requires rapid treatment)
How is dehydration treated?
Fluid Replacement Therapy (Oral / Intravenous)
Explain how the polarity of water comes about.
- Oxygen atom had 8 protons in nucleus
- Hydrogen atom has 1 proton in nucleus
- Electron pair shared in each OH covalent bond is more strongly attracted to O nucleus rather than either of the two H nuclei
- Makes water polar with slightly negative pole near O (𝛿-) and slightly positive pole near H (𝛿+)
Describe how hydrogen bonding between water molecule occurs.
𝛿+ near H atoms is attracted to 𝛿- near O on nearby water molecule
Why is water a liquid?
H-bonds are relatively weak and easily broken so molecules of water constantly change ‘partners’ - constant breaking and reforming of hydrogen bonds
Explain water’s role as a powerful solvent, using NaCl as an example.
- Sodium chloride = lattice of sodium (Na+) ions ionically bonded to chloride (Cl-) ions
- 𝛿+ hydrogens are attracted to Cl- ions, while 𝛿- oxygens are attracted to Na+ ions
- So lattice pulls apart and salt dissolves in water
How is water able to act as a universal solvent?
- All polar (charged) molecules / ions are water soluble because they can form H-bonds with water
- Ions / polar molecules can move / interact freely, and take part in cellular chemical reactions
Describe non-polar molecules.
- No electrical charge
- Cannot form H-bonds with water
- Hydrophobic (non-polar molecules repel water molecules)
What is an amphiphilic substance?
Complex molecules that have both hydrophilic and hydrophobic properties.
What is the 3D shape of many biological molecules influenced by?
Hydrophobic forces
Describe the structure of the plasma membrane.
- Phospholipid bilayer
- Hydrophilic (polar) heads point out towards extracellular fluid
- Hydrophobic (non-polar) tails point in toward each other
- Semipermeable membrane
What can easily move through the plasma membrane?
Small molecules and larger hydrophobic molecules
e.g. oxygen, carbon dioxide, water
What is surface tension?
Tension of the surface film of a liquid caused by attraction of particles in the surface layer; so as to reduce surface area.
Describe surface tension.
- Elastic tendency of a fluid surface
- Occurs at liquid-air interfaces
- Results from greater attraction of liquid molecules to each other (cohesion) than to molecules in the air
What are surfactants?
Compounds that lower the surface tension between two liquids.
- Between 2 liquids
- Between a gas and a liquid
- Between a liquid and a solid
What may surfactants act as? (x5)
- Detergents
- Wetting agents
- Emulsifiers
- Foaming agents
- Dispersants
What negative condition can surface tension cause in the body, how does the body react and what happen to babies with this condition?
- Tends to make lung alveoli collapse
- Alveoli secrete surfactants to break down surface
- Premature babies lacking surfactants experience lung collapse (atelectasis)
How can lung alveoli collapse due to surface tension be treated?
Prescribed surfactant inhaler therapy
