Chemical Digestion

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Chemical Digestion

• Ms. Lowrie
• Advanced Biology 11

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Enzymes

• Biological catalysts
• Cause reactions
• Made in ribosomes proteins
• Named after organic compound they breakdown
• End in ase
• Ex. lipase breaks down lipids

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Enzymes (cont.)

• Activity effected by
• pH
• Depends on enzyme location
• Temperature
• Usually 37C
• If too high may alter shape of enzyme
• If too low may slow down movement

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Review Organic Compounds

• Carbohydrates
• Polysaccharides/starch are composed of
• Simple sugars (monosaccharides)
• Proteins are composed of
• Amino acids
• Lipids are composed of
• Fatty acids glycerol

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6.3 - Ingestion

• Salivary amylase
• Polysaccharides (starch) TO disaccharides
• FYI amylose polysaccharide
• Bolus pushed into esophagus
• Enters stomach

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Chemical Digestion
Enzyme Produced by Place of reaction Breaks down Into
Salivary amylase Salivary glands Mouth Polysaccharides Disaccharides
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6.4 Stomach

• Gastric juices contain
• Mucus
• Pepsinogen
• Hydrochloric acid (HCl)
• Kills microbes
• Converts pepsinogen to pepsin

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6.4 Stomach

• (using HCl)
• Pepsinogen Pepsin
• (inactive) (active)
• Protein digestion
• Long-chain TO short-chain proteins
• Chyme moves to small intestine

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Chemical Digestion
Enzyme Produced by Place of reaction Breaks down Into
Pepsin Stomach Stomach Long-chain proteins Short-chain proteins
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6.5 Small Intestine/Pancreas

• Pepsin (from stomach)
• Inactivated by secretin
• All three organic compounds finish chemical
  digestion here!
• Absorbed into villi

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6.5 Protein

• Trypsinogen from pancreas enters small intestine
• (using enterokinase)
• Trypsinogen Trypsin(inactive) (active)

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6.5 Protein

• Trypsin
• Long-chain TO short-chain proteins
• Similar to pepsin!

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6.5 Protein

• Erepsin
• Released into small intestine
• From small intestine pancreas
• Short-chain proteins TO amino acids

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Chemical Digestion
Enzyme Produced by Place of reaction Breaks down Into
Trypsin Pancreas Small Intestine Long-chain proteins Short-chain proteins
Erepsin Pancreas Small Intestine Small Intestine Short-chain proteins Amino acids
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6.5 Carbohydrates

• Pancreatic amylase
• Released into small intestine
• From pancreas
• Disaccharides TO monosaccharides
• With help from maltase (a disaccharidase)
• From small intestine

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Chart
Enzyme Produced by Place of reaction Breaks down Into
Pancreatic amylase Pancreas Small Intestine Disaccharides Simple sugars
Maltase Small Intestine Small Intestine Disaccharides Simple sugars
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6.5 Lipids

• Pancreatic lipase
• Released into small intestine
• From pancreas
• Lipid droplets TO fatty acids glycerol
• Also
• Phospholipase
• Breaks down phospholipids

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Chart
Enzyme Produced by Place of reaction Breaks down Into
Pancreatic Lipase Pancreas Small Intestine Lipid droplets Fatty acids Glycerol
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Why is bile not included?

• Not chemical digestion
• Chemical bonds arent broken
• Mechanical digestion
• Fat is made smaller
• Broken into smaller fat droplets

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Review Carbohydrates

• Polysaccharides (starch)
• by salivary amylase
• Disaccharides
• by pancreatic amylase maltase
• Simple Sugar
• diffuses into
• Capillary

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Review Lipids

• Fat
• by bile (mechanical)
• Fat Droplets
• by pancreatic lipase
• Fatty acids Glycerol
• diffuses into
• Lacteal

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Review Protein

• Protein (long-chain protein)
• by pepsin trypsin
• Short-chain protein
• by erepsin
• Amino Acids
• diffuses into
• Capillary

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Text Questions

• Practice
• 3 (pg 212)
• 2 (pg 216)
• 2 to 4, 6 (pg 218)
• Section
• 3, 7 (pg 222)

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Fill in the Blanks
Alimentary canal Accessory organs Digestion Digestion Absorption
Alimentary canal Accessory organs Mechanical Chemical Absorption
Mouth Salivary glands
Esophagus
Stomach
Small Intestine Liver (gallbladder) Pancreas
Large Intestine
Rectum/Anus
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Pancreatic lipase amylaseTrypsinErepsin
Bile