Ch 18- Biosynthesis Flashcards
Another name for biosynthesis
Anabolism
What is biosynthesis?
Building of complex molecules
Essential elements for biosynthesis
CHON, etc
What processes are used to obtain energy?
ATP hydrolysis, NADPH oxidation, ion flow down transmembrane concentration gradient
How to obtain substrates
Glycolysis and TCA cycle
What is secreted? Biosynthesis
Antibiotics, toxins, quorum signals, biofilm matrix
PEP + CO2 → Oxaloacetate
Anaplerotic reactions
Why does the TCA cycle reverse?
for reduction of CO2 and regenerate acetyl-CoA and sugars
Reductive TCA cycle uses
4-5 ATP for 4-5 molecules of CO2 and one oxaloacetate
What are the reducing agents?
NADPH or NADH
Who uses the Acetyl-CoA pathway?
Anaerobic soil bacteria, autotrophic sulfate reducers, methanogens
What happens in the acetyl-CoA pathway
2 CO2 molecules converge pathways to form the acetyl group of acetyl CoA
What is the reducing agent for acetyl-CoA pathway?
H2
Who uses the 3-hydroxypropionate cycle?
Thermophiles: Chloroflexus and Sulfolobus
What happens during 3-hydroxypropionate cycle
Acetyl-CoA condenses with CO2 and reduced by 2NADPH to 3-hydroxypropionate
Overall outcome of 3-hydroxypropionate cycle
3 CO2 molecules are fixed into one molecule of pyruvate»substrate for biosynthesis
What is nitrogen fixation?
Conversion of atmospheric nitrogen into ammonia
N2»NH4+
How much ATP is consumed during N2 fixation?
40 ATP
The four reduction cycles through nitrogenase
Uses ATP, FeMo, 2e- ,and H2 to reduce in N2 Fixation
Why does Nitrogen Fixation require regulation?
It uses a lot of energy
O2 and NH4+ regulate expression of which gene?
nif gene (encode nitrogenase)
Other nif regulators are:
sigma factor 54 and NtrB-NtrC signal transduction system
How do bacteria assimulate NH4+?
2-oxogluterate»glutamate or
glutamate»glutamine
Transamination is
The transfer of ammonia to two metabolites
How do glutamate and glutamine contribute to biosynthesis?
Make amino acids
Purines and pyrimidines are built onto which structure?
Ribose 5-phosphate substrate
ATP»AMP
Purine is made from
Iosine
AMP and GMP
Pyrimidine is made from
Uracil
CMP and TMP
