digestion and synthesis - chapter 12

PHR 3200

three stages of nutrient breakdown

1. digestion: break down of large food molecules into smaller molecules

2. formation of shared intermediates: nutrients feeds into pathways to produce acetyl- CoA and other intermediates

3. oxidation and ATP synthesis: citric acid oxidize acetyl group, oxidative phosphorylation produces ATP

carbohydrate digestion

• due to salivary amylase

• continues in small intestine (pancreatic amylase)

• digestive carbs into monosaccharides

starch

plant glucose storage

Glycogen

animal glucose storage

protein digestion

• broken into small peptides by protease

• digestive in stomach and then small intestines

  • breaks down protein into amino acids

  • transporters absorb amino acid and peptides into intestinal cells

protease

breaks down proteins

Lipid digestion

• Lipases hydrolyze triacylglycerols into fatty acids

• pancreatic lipase breaks lipids into fatty acids and glycerol

• intestinal cells absorb product