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The following four slides relate to Chapter 4 and will be discussed in that context
Chemical modifcations of bases in DNA can lead to permanent changes in the
sequence of bases due to mispairing
The events that may take place after base
mispairing. Any permanent change in a base
sequence is called a mutation
The information in very similar (homologous) DNA molecules can be exchanged
by homologous recombination systems. Non-homologous recombination
systems also exist. Recombination takes place in all organisms.
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B-
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Homologous recombination
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B+
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A more detailed view of the mechanism of homologous recombination by
”strand invasion”
Slides on metabolism starts her
Glycolysis is a wide-spread pathway for utilization of glucose. It generates
chemical energy in the form of ATP and NADH. It ends with pyruvate, which
can be degraded further to CO2 in the citric acid cycle (Krebs cycle)
To enter the Krebs cycle pyruvate is first converted to acetyl CoA
Molecular formulas of some important compounds coupled to metabolism
Some enzymes require additional factors to function. Coenzymes
are examples of such factors, and refer to complex organic or
metalloorganic compounds that act as transient carriers of
specific functional groups. So coezymes are NOT enzymes!
Simple factors such as metal ions are called cofactors.
Oxidation-reduction reactions with FAD
How NAD is converted from oxidized (NAD+) to reduced form (NADH)
The Krebs cycle is a circular process involving many enzymes
A simplified view of the energy-generating steps of the Krebs cycle
Overview of glycolysis plus the citric acid cycle
plus transfer of energy from reduced carriers
(NADH, FADH2) to ATP via the electron transport
system, which involves a series of proteins that
can carry out the energy transfer reactions. Note
the role of atmospheric oxygen in this!
A summary of the total energy gains from conversion of glucose to ATP
The citric acid cycle is coupled to amino acid synthesis, and the amino acids
are required for protein synthesis. There are numerous other such connections
inside living cells (see fatty acids on the figure), and together they form very
complex metabolic networks
This overview of the metabolic networks show why we now need computers, particulary
if we want to predict cell behaviour! In recent years these needs have led to the
development of ”Systems Biology”, which involves mathematical analysis and modelling
of living cells. Hint: think about this figure by considering our previous discussions
about Km and Vmax values of enzymes,and membranes and uptake systems