Anabolic and catabolic reactions are integrated through a group of common intermediates. Such integrated metabolic pathways are referred to as amphibolic pathways.
Energy Source Light (Phototrophs) Chemicals (Chemotrophs) Light generates high energy electrons by exciting chlorophyll electrons Organism oxidizes chemicals to get high energy electrons Type of chemical Organic molecules Inorganic molecules Type of process used: Fermentation Cellular Respiration uses: uses: uses: Glycolysis Glycolysis Krebs Cycle Electron Transport Chain Electron Transport Chain Chemiosmosis Chemiosmosis Makes ATP by: Makes ATP by: Makes ATP by: Makes ATP by: Photophosphorylation
The sugars composing nucleotides are derived from either the pentose phosphate pathway or the Entner-Doudoroff pathway. Carbon and nitrogen atoms from certain amino acids (aspartic acid, glycine, glutamic acid) form the backbones of the purines and pyrimidines. Includes DNA, RNA, ATP, NAD, NADP, FMN, and FAD.
Amino acids are required for protein biosynthesis. All amino acids can be synthesized either directly or indirectly from intermediates of carbohydrate metabolism, particularly from the Krebs cycle. Transamination or amination reactions: Organic acids + an amine group = amino acid. Not all organisms can do this. Some require preformed amino acids.
Glucose (and other simple sugars - monosaccharides) may be synthesized from intermediates in glycolysis and the Krebs cycle. Monosaccharides can be linked together to make polysaccharides. Glycogen is formed from ADPG (ATP + glucose 6-phosphate = adenosine diphosphoglucose) in bacteria and from UDPG in animals (UTP + glucose 6-phosphate = uridine diphosphoglucose). UDPNAc is the starting material for the biosynthesis of peptidoglycan (UTP + fructose 6-phosphate = UDP-N-acetylglucosamine).