Fatty Acid Synthesis and Ketogenesis

Fatty Acid Synthesis

• Phosphatase activity removal of phosphate (P) from triacylglycerol (TAG) allows TAG synthesis. Lowering phosphatase activity leads to decreased TAG levels.
• Synthesizing an 8-carbon fatty acid from acetyl-CoA requires 3 ATP and 6 NADPH.
• Fatty acid synthesis elongates the chain by 2 carbons per cycle. Each cycle needs 1 ATP for activation and 2 NADPH for reduction.
• 8 carbons = 4 cycles, 3 elongations.
• Fatty acid synthesis doesn't derive from polysaccharide structure; it's based on amino acid sequences.
• Amino acids are the building blocks of proteins.
• Elevated blood insulin stimulates TAG synthesis in the liver, associated with increased glucose.

Ketogenesis

• During fasting, ketogenesis in liver mitochondria utilizes fatty acid oxidation as a starting material.
• Fatty acids are broken down to acetyl-CoA, which then forms ketone bodies.

G-protein Coupled Protein (G-protein) Mutation

• A mutation preventing GTP hydrolysis in the G-protein alpha subunit keeps the cAMP production and PKA activity elevated.

Amino Acid-Derived Reducing Agent

• Glutathione, a peptide from amino acids, is a reducing agent that removes toxic peroxides from cells.

Biotin's Role

• Biotin carries carbon dioxide (CO2) to the catalytic site, where it's transferred to acetyl-CoA to form malonyl-CoA, a crucial step in fatty acid synthesis.

Fatty Acid Synthesis vs. Other Reactions

• Fatty acid synthesis doesn't involve phosphorylation; instead, it involves reduction, condensation, reduction, and dehydration reactions.

Gluconeogenesis Bypass Reaction

• During gluconeogenesis, carbon dioxide (CO2) is used and produced in the conversion of pyruvate to phosphoenolpyruvate (PEP).

Starting Material for Lipid Biosynthesis

• Acetyl-CoA is the starting material for all lipid biosynthesis.

Glucagon and Liver Activity

• Glucagon binding to liver receptors stimulates ATP use for glucose synthesis via gluconeogenesis.

Glycogen Phosphorylase

• Glycogen phosphorylase promotes glycogen breakdown, not inhibition.

Purine and Pyrimidine Biosynthesis

• Nitrogen atoms in purines and pyrimidines don't originate from ribose-5-phosphate; they derive from glutamine, glycine, and aspartate.

Gluconeogenesis Requirements

• Gluconeogenesis in the liver needs chemical energy in the form of ATP or GTP and reducing power in the form of NADH.

PFK-1 and FBPase-1 Regulation

• Fructose 2,6-bisphosphate allosterically activates PFK-1 (stimulating glycolysis) and inhibits FBPase-1 (inhibiting gluconeogenesis).

Glucose Transporter (GLUT) Differences

• GLUTs with higher Kt values transport glucose at lower initial velocities, indicating lower affinity.

High-Density Lipoprotein (HDL)

• HDL has a high percentage of protein and transports cholesterol back to the liver, helping reduce atherosclerosis.

Starch Breakdown Inhibition

• Drugs that inhibit alpha-glucosidase enzymes decrease glucose release from dietary starch. This lowers blood sugar levels.

Glycogen Synthesis

• UDP-glucose is required for glycogen synthesis, acting as an activated glucose carrier.

Polysaccharide Types

• Cellulose is a polysaccharide linked by beta-1,4 glycosidic bonds.

Insulin Receptor Autophosphorylation

• The peptide sequence containing phosphorylated tyrosine residues is found within the beta-subunit of the insulin receptor after autophosphorylation.

Appetite Regulation

• Leptin, released from adipose tissue, binds to receptors in the brain, reducing appetite and increasing energy expenditure.

Reduced Electron Carrier for Fatty Acid Synthesis

• NADPH is the reduced electron carrier vital for fatty acid synthesis.

Common Biosynthesis Regulation

• Feedback inhibition by the end product is a common mechanism for regulating biosynthesis pathways, preventing overproduction.

Elevated Insulin and Liver Cell Activity

• Elevated insulin stimulates glycolysis in liver cells.

Reaction Type (OH to no OH)

• The described reaction is a reduction.

Glycosidic Linkages

• Two monosaccharides joined by a non-reducing alpha-1, beta-2 glycosidic linkage.

Signal Transduction Via Nuclear Receptors

• Nuclear receptors require hormones or ligands that undergo simple diffusion to bind to them after passing across one or more membranes.

Pathway for Nucleotide and NADPH Production

• The pentose phosphate pathway maximizes the production of nucleotides and NADPH before DNA replication.

Cancer Cell ROS Handling

• Cancer cells can manage increased ROS levels through the cycling of the oxidative and non-oxidative phase of the pentose phosphate pathway, increasing NADPH.

Explore the intricate processes of fatty acid synthesis and ketogenesis in this quiz. Focus on the biochemical pathways involved in TAG synthesis, the role of insulin, and the impact of fasting on ketone body formation. Test your understanding of the underlying mechanisms and related mutations in G-protein signaling.