Lecture
Notes – 8 September 2003
The
stuff of life
Proteins—polymer
of amino acids
20
different kinds
Function
of proteins
·
messengers
·
structure
·
enzymes
Structure
Amino
acids have an amine group at one end and a carboxyl group at the other end.
When a bond is formed between the two ends, water is produced. Proteins have a
primary (which aa are part of the chain), a secondary and tertiary (the final
form the chain takes—for example haemoglobin is globular protein.
carbohydrates
polymer
of smaller units like
fructose
glucose
sucrose
Two
important polymers are cellulose and starch
Bond
between units is formed between the carbon atoms at the end of the unit.
fats
and fatty acids and lipids
nucleic
acids—macromolecules formed from the nucleotides, ACGT
two
major forms
RNA
DNA
water-H2O
minerals
The
elements of life--CHONS
Origin
of the earth was 4.3 billion years bp
Most
likely had a reducing atmosphere
CO2
NOx
H2O
NH3
Miller-Urey
exoeriment showed that one can get amino acids from non-organic activity
Where
did living forms evolve?
Living
things store materials in a sack, therefore we need to understand the structure
and function of the cell membrane
Semi-permeable
membrance
Use
of coacervates as models of what early life forms might have been like.
Life
forms must have developed metabolic activity
AMP
+ high enrgy phosphates = ADP
ADP
+ high energy phosphate = ATP
ATP
> ADP + energy
How
do membranes work to get materials into the cell?
straight
movement of materials through the membrane via concentration gradients
active
transport—use of energy to moved material across the membrane
pinocytosis—cell
drinking of fluid at the outside of the membrane
Whatever events that took place were affected by natural selection. Creatures that could pass effective features along to offspring were selected with respect to creatures that lacked such features.