Microbiology 1010 – Lecture Notes
2.7 Membrane Structure (Continued…)
o Ether linkages in phospholipids of Archaea (Figure 2.16)
o Bacteria and Eukarya that have ester linkages in phospholipids
In the case of this, they must have a way to withstand the high temp. The tails are held together
by vaderval forces. A degree of saturation between the two tails – which causes a kink.
To offset melting, often times, they will have a different linkage in their membrane and a fat as a whole.
o Archaeal lipids lack fatty acids; have isoprenes instead
o Major lipids are glycerol diethers and tetraethers
(Figure 2.17a, b)
o Can exist as lipid monolayers, bilayers, or mixture (Figure 2.17 d, e)
31 Microbiology 1010 – Lecture Notes
The whole fatty acid isn’t possible when we have an ether linkage.
They have an isoprene units.
There is a continuum instead of a separation between the two phospholipid bilayer = more heat
is needed to destruct the tetra membrane.
Need to have vanderwale forces that keep the two phosphiillipds the most linear as possible… This
increases the amount of heat needed to destruct is higher = able to stay stable at higher temps.
Membrane Structure (Continued…)
In contrast to lipid bilayers, lipid monolayer membranes are extremely heat resistant
Commonly found in hyperthermophilic Archaea (grow best at temperatures above 80 C) o
The cell had ports made of the proteins (have an element of specificity) . Sometimes they are coupled
for some energy etc.
Permeability barrier (Figure 2.18)
o Polar and charged molecules must be transported
Transport proteins accumulate solutes against the concentration gradient
Holds transport proteins in place
Generation of proton motive force
Hydrophilic or charged ions that will need a transporter of some sort.
The proteins give permeability to the proton because it’s charger it can’t just go through the membrane.
The order of proteins for the ETC IS NOT random….orders itself in positive relativity. (Ex. E-won’t leave
NADH unless the protein is more positive).
32 Microbiology 1010 – Lecture Notes
Carrier-mediated transport systems
Show saturation effect
The number of solute molecules is increasing as the number of transporters.. Until all transporters
are used and it plateaus.
It doesn’t have any requirement for other assistance and the direction of the movement to high to
low concentration. Releasing energy storing in the gradient.
Nutrient Transport (Continued…)
Three major classes of transport systems in
prokaryotes o Simple transport
o Group translocation
o ABC system
All require energy in some form, usually proton motive force or ATP
33 Microbiology 1010 – Lecture Notes
For bacteria, they have to have a way for getting nutrients which often times requires a specific
transporter to exist (Ex. Lactose).
When we talk about simple transport: it moves material right though a channel. There is NRG required
and most often used form of NRG is a proton modem force.
Group trans = chemical molecules will donate phosphate and will chemically change the substrate.
ABC= periplasmic space, is the first challenge. It needs to meet the actually transporter protein. So
the chaperon grabs the material and brings it to the correct port to bring the material into the cell.
Not a passive process.
Nutrient Transport (Continued…)
Three transport events are possible: unip