Lipids provide important sources of carbon and energy for many microbes. This lesson explains how triglycerides and phospholipids are broken down, how their components enter central metabolic pathways, and why lipid-degrading enzymes can contribute to microbial virulence.
Triglycerides consist of a three-carbon glycerol backbone joined to three fatty acids. They are a form of long-term energy storage in animals. Phospholipids are major components of cell and organelle membranes in organisms other than archaea. Their structure resembles that of triglycerides, but one fatty acid is replaced by a phosphorylated head group.
All flashcards
What are the components of a triglyceride?
A glycerol backbone joined to three fatty acids.
How do lipases differ from phospholipases?
Lipases break down triglycerides; phospholipases break down phospholipids.
What happens during β-oxidation?
Fatty acid chains are shortened by removing two-carbon acetyl groups, while NADH and FADH2 are produced.
How can glycerol enter glycolysis?
It can be phosphorylated to glycerol-3-phosphate and converted to glyceraldehyde 3-phosphate.
How do extracellular and intracellular proteases work together?
Extracellular proteases produce peptides from proteins; after uptake, intracellular proteases break peptides into amino acids.
Quiz questions
How do microbes use extracellular and intracellular proteases to digest proteins?Answer: Extracellular proteases produce peptides, which cells take up and break down further with intracellular proteases.
What indicates gelatinase activity after gelatin broth is refrigerated?Answer: The broth remains liquid because the gelatin has been degraded.
How is caseinase activity detected on skim milk agar?Answer: A clear zone forms around microbial growth where casein has been broken down.
What does deamination do to an amino acid?Answer: It removes the amino group, leaving a carbon-containing molecule that can enter central pathways.
How can cholesterol degradation contribute to Mycobacterium tuberculosis virulence?Answer: Cholesterol breakdown products, including pyruvate, can feed into central metabolism.
Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.