Biological Molecules ‘what you need to know!’. MONOMER – single repeating units that……...
-
Upload
asher-dominick-willis -
Category
Documents
-
view
215 -
download
0
Transcript of Biological Molecules ‘what you need to know!’. MONOMER – single repeating units that……...
Biological Molecules
‘what you need to know!’
MONOMER – single repeatingunits that……
……are joined together to formPOLYMER.
POLYMER
MONOMER
POLYMERISATION
PolymersPolysaccahrides
Proteins
Lipids
MonomersGlucose
etc.
Amino acids
Glycerol & fatty acids
CARBOHYDRATES
CARBOHYDRATES
MONOSACCAHRIDES
DISACCAHRIDES
POLYSACCAHRIDES
MONOSACCHARIDES
- A single sugar unit
- Sweet and soluble
- Contain carbon, hydrogen & oxygen
- Classified according to the number of carbons a molecule has.
MONOSACCHARIDES
TRIOSE – 3 carbons
PENTOSE – 5 carbons
HEXOSE – 6 carbons
MONOSACCHARIDES – which is which?
MONOSACCHARIDES – which formula?
Molecular formula – C6H12O6 or
C3H12O6 or C5H10O5
Structural formula –
C6H12O6 C3H12O6 C5H10O5
You decide!
Triose or Pentose or Hexose
Pentose and hexose sugarsexist in two forms:
Straight chain forms
Ring forms
HydrogenCarbon
Oxygen C6H12O6
GLUCOSE comes in 2forms, this one;
Here this H is abovethe carbon.
This is called α (alpha) glucose.
Here this H is belowthe carbon.
This is called β (beta) glucose.
Both these molecules are glucose.
Both have a molecular formula of C6H12O6.
But they are structurally different.
Structural Isomers
Biological role of monosaccharides
As an energy source…..
•A large amount of energy is stored between the C-H bonds•This is released to form ATP•ATP is the energy currency of the cell
As building blocks…..
•Repeated glucose molecules build up; starch & glycogen•Ribose (5C) forms part RNA•Deoxyribose (5C) forms part DNA
Forming a disaccharide……MALTOSE
Two α glucose molecules C1 & C4 meet.OH (hydroxl grp) from C1 & H from C4 react.Water is expelled.A condensation reaction.This can be reversed by adding water.
Polysaccharides
• Polymers with subunits of monosaccharides• Repeated condensation reactions• Normally 1000’s of monomers • Polysaccharides are not sugars
STARCH CELLULOSE GLYCOGEN
Starch• Polymer of glucose.• Plant storage polysaccharide.• Made up of two types of substances;1)Amylose 2) Amylopectin
Amylose• Condensation reactions between α
glucose (1-4 links).
• Forms from 1000s of condensation reactions.
• Coiled springs are formed.
Spiral structure of amylose; part of starch.
StarchMade up of two types of substances;1)Amylose 2) Amylopectin
Amylopectin• Condensation reactions between α
glucose (1-4 links).
• Branches of 1-6 links also exist.
• Coiled springs with a branched structure are formed.
1-4 links form a helicalstructure
1-6 links form a branchstructure
Amylopectin
Mostly 1-4 links.Some 1-6 links.
Starch grains are a mixture of amylose & amylopectin
Starch is a polysaccharide
Starch it is a insoluble store of glucose
Starch is only found in plant cells, the animal equivalent is called GLYCOGEN.
GLYCOGEN is the storage polysaccharide in animals
It has 1-4 links
and 1-6 links
Cellulose
• Present in plant cell walls.
• Has a slow decomposition.
• It is the most abundant organic molecule on the planet!!
• It is mechanically very strong.
• It is a polymer of β glucose
Cellulose
• C1-4 links make up this polysaccharide.
• If C1 and C4 are to react, one glucose molecule needs to flip through 180o.
• It is this subtle difference that make cellulose so strong!
• This structure has H bonds holding it together
70 chains of β glucose combine to form a MICROFIBRIL.
Lots of MICROFIBRILS are held together to form FIBRES.