06/08/2014
1. Based on carbon compounds
– Organic Chemistry
PreDent 2014
2. Depends on chemical
reactions occurring in aqueous
environment
Biological Molecules and Concepts
“Chemistry dictates biology”
Docent Rachael Sugars
Oral Facial Diagnostics and Surgery
Dept. Dental Medicine
3. More complex in the cell than
any other chemical system
4. Dominated and co-ordinated
by complex polymeric molecules
Rachael.Sugars@ki.se
5. Tightly regulated
Small molecules and macromolecules
Small molecules
Macromolecules
1
06/08/2014
Polymerisation
Key concepts:
1.
2.
3.
4.
5.
Importance of carbon
Importance of water
Importance of selectively permeable membrane
Importance of synthesis by polymerisation
Importance of self-assembly
“The macromolecules that are
responsible for most of the
form and order characteristic of
living systems are generated by
the polymerisation of small
organic molecules”
Becker et al., 2009
Synthesis of biological macromolecules
2
06/08/2014
Self-assembly
Figure 2-33 Essential Cell Biology (© Garland Science 2010)
Figure 2-32 Essential Cell Biology (© Garland Science 2010)
Main families of organic molecules in cells
Figure 4-7 Essential Cell Biology (© Garland Science 2010)
Figure 2-15 Essential Cell Biology (© Garland Science 2010)
3
06/08/2014
Sugars – Monosaccharide's (aka carbohydrates)
e.g. Glucose
(CH2O)n
n = 3 – 7 C atoms
In equilibrium between linear
and ring form
(e.g. DNA and RNA = pentoses)
Central role as an energy form
Defined as:
Aldosugars – terminal carbonyl
Ketosugars – internal carbonyl
Condensation reaction
Polymers
Glycogen in animal cells
Starch in plant cells
Oligosaccharides
Covalent bond = glycosidic bond
2 monomers = disaccharides
Between –OH on one sugar and –
OH on another
Oligosaccharides = trisaccharides,
tetrasaccharides etc
Water released and bond formed
Other biological macromolecules
use this process
Polysaccharide = 1000’s monosaccharide
units
Proteins and nucleic acids
4
06/08/2014
Fatty acids
Properties
Consists of:
Saturated
2 hydrophobic hydrocarbon
chains (non-polar)
Hydrophilic carboxylic acid
group (polar)
No double bonds between C
Pack together tightly
Meat and diary
Unsaturated
Linked to other fatty acids via the
carboxylic acid group
Termed amphipatic
Double bonds produce kinks in
chains
Prevents close packing
Plant oils
Figure 2-19 Essential Cell Biology (© Garland Science 2010)
Major classes of
lipids
Formation of membranes
Thin sheets enclosing all cells
Phospholipids
2 chains
Lipid bilayer
Figure 2-20 Essential Cell Biology (© Garland Science 2010)
22
5
06/08/2014
Amino acid structure
Carboxyl group
Amino group
Hydrogen atom
Side chain (R group)
Attached to α-carbon
20 amino acids
Proteins
Dehydration or condensation
1 C and 1 N directly linked
H20 excluded
Peptide bond
Each addition lengthens the sequence
Figure 4-3 Essential Cell Biology (© Garland Science 2010)
Figure 4-1 Essential Cell Biology (© Garland Science 2010)
6
06/08/2014
Polypeptide chain
Protein organisation
Figure 4-2 Essential Cell Biology (© Garland Science 2010)
Nucleotides
Short term carriers of energy
Nucleic acids
Figure 2-24 Essential Cell Biology (© Garland Science 2010)
7
06/08/2014
Nucleic Acids
DNA vs RNA
DNA
RNA
A=T
A=U
G=C
G=C
Double strand
Single strand
2’ C has H
2’ C has OH
Long
Short
mRNA
tRNA
rRNA
DNA is made
from 4
nucleotide
building bocks
Figure 5-2 Essential Cell Biology (© Garland Science 2010)
Figure 5-6a Essential Cell Biology (© Garland Science 2010)
DNA Double helix
Anti-parallel strands
Hydrogen bonds
8
06/08/2014
Study questions!
9