Structure/Function%20of%20Cell%20Components

1
(No Transcript)
2
Structure/Function of Cell Components

• Living things are made of
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids
• CHNOPS
• Carbon
• Hydrogen
• Nitrogen
• Oxygen
• Phosphorous
• Sulphur

3
Basic Chemistry
Strong Bonds

• Atoms make bonds
• Ionic loss/gain of electrons
• Covalent electrons are shared
• Polar covalent unequal sharing of the electrons
• Makes the atoms have a partial charge (polarity)
• Hydrogen bonds
• Between a polar covalently bonded hydrogen atom
  (e.g. to N or O) and another polar covalently
  bonded atom e.g. oxygen in a carbonyl group.
• Polar covalent bonds, only a partial charge so
  relatively weak
• Van der waals forces
• Induced polarity (e.g. in C-H bond)
• Hydrophobic Interactions
• Non-polar groups tend to cluster together (away
  from water)
• Polar groups tend to move towards water

Weak Bonds
4
CARBOHYDRATES
5
Carbohydrates

• C, H, O
• (CH2O)n
• Monosaccharides - one monomer
• Form rings in solution
• Disaccharides - two monomers
• Polysaccharides - many monomers
• Monomers contain
• 5 Carbon atoms - pentose
• 6 carbon atoms - hexose

6
Carbohydrates

• Saccharides can exist in solution as linear
  molecules or rings.
• They interconvert between the two forms, but at
  equilibrium, 99 will be ring

7
Structural Variation in Carbohydrates

• Special carbons
• Carbon atoms 1-5 are chiral (optically active)
  i.e. OH and H groups on the C atoms can be
  ordered differently.
• For C atoms 2-4 the arrangement of OH and H
  groups determines the monosaccharide .
• Orientation of OH on Carbon 5 (in Hexoses)
  confers D (dextro rotatory) or L (laevorotatory)
  forms
• D points right
• L points left
• Orientation of OH on Carbon 1 (in Hexoses)
  determines ? (down) or ? (up)

8
Numbering
6
5
4
1
2
3
9
The molecules are isomers, they differ in the
orientation of H and OH on C2-4.
10

Note Fructose differs in the position of the
carbonyl important in forming rings
11
? down, ? up
The OH group on the carbon next to the oxygen (C1)
12
Forming Rings
1
Rings form between C1 and C5. An O atom acts as
a bridge (hence the 6 member ring).
2
Complex rearrangement
3
4
5
6
13
Disaccharides

• Two monosaccharides join together with a
  glycoside bond
• Dehydration (condensation) reaction (elimination
  of water)
• e.g. maltose (2 x glucose)
• ? -D-glucose joined to ? -D-glucose
• join at the C1 (?) and C4 atoms
• ?1-4 glycoside bond

14
(No Transcript)
15

• ? 1,4, glycosidic bond - cellobiose

? 1,2 glycosidic bond -sucrose
? 1,6, glycosidic bond
16
(No Transcript)
17
Polysaccharides

• 3 major ones of interest
• Starch
• Glycogen
• Cellulose

18
(No Transcript)
19
(No Transcript)
20
STARCH

• Comprised two components
• Soluble part (20) - AMYLOSE
• Continouous unbranched chain of glucose units (up
  to 300) joined by ?1-4 glycoside bonds.
• Insoluble part (80) AMYLOPECTIN
• Shorter ?1-4 chains (24-30), with ?1-6 branching

Starch, being insoluble exerts no osmotic
pressure, so is useful as a storage polysaccharide
21
GLYCOGEN

• Animal storage polysaccharide
• Similar to amylopectin,
• Lower molecular weight
• More highly branched
• ?1-4 chains (up to 10), with ?1-6 branching

22
CELLULOSE

• Linear polymer of glucose units (up to 2800)
• ? 1,4, glycosidic bonds
• Cellulose fibre - parallel strands held together
  by hydrogen bonds

23
(No Transcript)
24
(No Transcript)