biological molecules

• How does hydrogen bonds form between water molecules?

  What is polar oxygen is more electronegative than hydrogen so attracting electron density in covalent bond, more strongly
• What are 7 Biologically important properties of water?

  - Reaches maximum density at 4°C.

  - High surface tension

  - Incompressible

  - metabolite/covalent for chemical reactions in the body

  -High latent heat of vaporisation

  -high specific, heat capacity

  -Cohesion between molecules
• What is the incompressible nature of water important to the organisms?

  - Provides turgidity to plant cells

  -Provides a hydrostatic skeleton for some small animals
• Ice floats on water, why is this important for organisms?

  Ice is less dense than water, because H bonds, hold molecules in fixed positions further away from each other

  
  

  - acts as a habitat
• Why is the high surface tension of water important for organisms?

  Slows water loss due to transpiration in plants.

  Water rises unusually high in narrow tubes, lowering demand on root pressure.

  Some insects can 'skim' across the surface of water.
• Why is water an important solvent for organisms?

  Polar universal solvent dissolves and transports charged particles involved in intra and extracellular reactions
• Why are the high specific heat capacity and latent of vaporisation of water, important for organisms?

  Acts as a temperature buffer which enables endotherms to resist fluctuations in core temperature to maintain optimum enzyme activity.

  Cooling effect when water evaporates from skin surface as sweat/ from mouth when panting.
• Elements found in carbohydrates

  C, H, O
• What are the elements found in lipids?


  C, H, O
• What are the elements found in proteins?

  carbon, hydrogen, oxygen, nitrogen
• What are the elements found in nucleic acids?


  C, H, O, N, P
• What's the difference between alpha glucose and beta glucose?

  Alpha glucose has the hydroxyl group on the bottom of the first carbon while beta glucose has the hydroxyl group on top. Alpha glucose is more commonly found in polysaccharide chains.
• Describe the properties of glucose

  -small and water soluble - easily transported in the bloodstream

  -complimentary shape to auntie portable co-transport for absorption in guts

  -Complementary shape for enzymes for glycolysis - respiratory substrate
• Structure of Ribose


  A pentose monosaccharide five carbon
• What type of bond forms when monosaccharides react?

  (1,4 or 1,6) glycosidic bond

  ● 2 monomers = 1 chemical bond = disaccharide.

  ● Multiple monomers = many chemical bonds = polysaccharide.
• Name 3 disaccharides. Describe how they form.

  condensation reaction forms glycosidic bond between 2 monosaccharides

  ● maltose: glucose + glucose

  ● sucrose: glucose + fructose

  ● lactose: glucose + galactose

  all have molecular formula C12H22O11
• What is starch?


  Is a storage polymer of alpha glucose in plants cells

  
  

  - in soluble

  -large
• What can start to be made up of?

  Amylose and amylopectin
• What's the difference between amylose and amylopectin

  Amylose

  - 1,4 glycosidic bonds

  -single-stranded

  Amylopectin

  1, 4 and 1,6 glycosidic bonds

  - branched
• What is the function of glycogen?

  It's a main storage polymer of alpha glucose and animal cells
• What's the main structure of glycogen?

  1,4and 1,6. Glycosidic bonds

  - branched

  - insoluble - no osmotic effects

  -Compact
• How do triglycerides form?

  condensation reaction between 1 molecule of glycerol & 3 fatty acids forms ester bonds
• Contrast saturated and unsaturated fatty acids.

  Saturated:

  ● contain only single bonds

  ● straight-chain molecules have many contact points

  ● higher melting point = solid at room temperature

  ● found in animal fats

  Unsaturated:

  ● contain C=C double bonds

  ● 'kinked' molecules have fewer contact points

  ● lower melting point = liquid at room temperature

  ● found in plant oils
• Relate the structure of triglycerides to their functions

  ● High energy:mass ratio = high calorific value from oxidation (energy storage).

  ● Insoluble hydrocarbon chain = no effect on water potential of cells & used for waterproofing.

  ● Slow conductor of heat = thermal insulation e.g. adipose tissue.

  ● Less dense than water = buoyancy of aquatic animals.
• Describe the structure and function of phospholipids

  Amphipathic: glycerol backbone attached to 2 hydrophobic fatty acid tails & 1 hydrophilic polar phosphate head.

  ● Forms phospholipid bilayer in water = component of membranes.

  ● Tails can splay outwards = waterproofing e.g. for skin.
• Are phospholipids and triglycerides polymers?

  No; they are not made from a small repeating unit. They are macromolecules.
• Describe the structure and function of cholesterol


  Steroid structure of 4 hydrocarbon rings. Hydrocarbon tail on one side, hydroxyl group (-OH) on the other side.

  Adds stability to cell surface phospholipid bilayer by connecting molecules & reducing fluidity.
• What is the general structure of an amino acid?

  amino group, R group, carboxyl group
• How do polypeptides form?

  Condensation reactions between amino acids form peptide bonds (-CONH-). There are 4 levels of protein structure.
• Define primary structure of a protein

  ● Sequence, number & type of amino acids in the polypeptide.

  ● Determined by sequence of codons on mRNA.
• Define secondary structure of a protein

  Hydrogen bonds form between O 𝛿- (slightly negative) attached to ‒C=O & H 𝛿+ (slightly positive) attached to ‒NH.
• What are the two types of secondary protein structure?

  alpha helix and beta pleated sheet
• Define tertiary structure of a protein

  3D structure formed by further folding of polypeptide

  - disulphide bridges

  - ionic bonds

  - hydrogen bonds
• Define quaternary structure of a protein

  ● Functional proteins may consist of more than one polypeptide.

  ● Precise 3D structure held together by the same types of bond as tertiary structure.

  ● May involve addition of prosthetic groups e.g metal ions or phosphate groups.
• Describe the structure of globular proteins

  Spherical and compact

  - hydrophobic R groups, face, outwards and hydrophobic R groups face inwards usually water-soluble
• Describe the function of Gobular proteins

  Involved in metabolic processes, e.g. enzymes, such as amylase, insulin and haemoglobin
• Describe the structure of haemoglobin

  - Globular conjugated protein with a prosthetic group

  - Two. Alpha chains to beta chains for prosthetic Haem groups.

  -Water soluble also dissolves in plasma

  - Iron haem group forms, coordinated bonds with O2

  -Tertiary structure changes, so it is easier for subsequent O2 molecules to bind
• What is the structure of fibrous proteins?

  - Repetitive sequences organised, long, strong structures, not folded into 3-D shapes

  - inSoluble molecules
• What is the function of fibrous proteins?

  structural (strength and support)
• Keratin


  Long stranded molecules found in hair, feathers and nails

  -High proportion of cysteine amino acid

  -Many strong diphosphate bonds, which determine flexibility