Macronutrients, Enzymes, and Digestive System Review

Macronutrients

Key Terms

• Steroids/Cholesterol
• Proteins
• Amino Acids
• Carbohydrates
• Mono/di/polysaccharides
• Dehydration synthesis
• Triglycerides
• Phospholipids
• Saturation/unsaturated fat
• Lipids
• Hydrolysis
• Polypeptide
• Coagulation

Macronutrients

• Lipids
• Proteins
• Carbohydrates

Makeup of Carbohydrates

• Carbon, hydrogen, and oxygen atoms.

Carbohydrate Types

Common Disaccharides and Formation

• Sucrose: Glucose + Fructose = Table Sugar
• Lactose: Glucose + Galactose = Milk Sugar
• Maltose: Glucose + Glucose

Common Polysaccharides

• Glycogen: Storage form of glucose in animals.
• Starch: Storage form of glucose in plants.
• Cellulose: Structural component of plant cell walls.

Dehydration Synthesis and Hydrolysis

• Dehydration Synthesis: Removes a water molecule to join monomers.
• Hydrolysis: Adds a water molecule to break polymers into monomers.

Makeup of Lipids

• Carbon, hydrogen, and oxygen.

Saturated vs. Unsaturated Fatty Acids

• Saturated Fatty Acids:
  • Carbon chain consists of only single bonds.
  • Allows for a more compact shape.
  • Solid at room temperature.
• Unsaturated Fatty Acids:
  • Contain at least one double bond in the carbon chain.
  • Creates a "kink" in the chain.
  • Cannot pack as tightly.
  • Liquid at room temperature.

Types of Lipids

Triglycerides

• Formed by joining three fatty acids to a glycerol molecule through dehydration synthesis.
• Can be saturated (derived from animals, fats) or unsaturated (derived from plants, oils).
• Function: Energy storage.
  • Excess energy is stored as triglycerides.
  • Broken down into carbon or fatty acids.
  • Provide insulation and protect body mass during periods of low caloric intake.

Phospholipids

• Structurally similar to triglycerides.
• One fatty acid tail is replaced by a phosphate group.
• Essential component of cell membranes.
• Amphipathic nature (hydrophilic and hydrophobic ends).

Cholesterol

• Lipid without fatty acid chain.
• Can produce vitamin D and produce hormones such as estrogen, testosterone, etc.
• Synthesized in the liver.
• Helps to maintain cell membrane structure.
• Can build up in arteries, leading to cardiovascular issues.

Protein Structure

1. Primary: Amino acid chains with linear arrangement.
2. Secondary: Amino acid chains coiled or folded due to hydrogen bonding.
3. Tertiary: The coiled molecule is further folded into a 3D shape.
4. Quaternary: Two or more proteins interact.

Denaturation and Coagulation

• Denaturation: Change in the shape of a protein due to physical or chemical factors.
  • Caused by physical or chemical factors.
  • Causes protein to unfold or uncoil, or change shape.
  • Changes protein's physical properties.
• Coagulation: Permanent change in the protein's shape.
  • Example: Egg white turning opaque when cooked.

Macronutrient Tests

• Iodine solution:
  • Tests for: Polysaccharides
  • Positive result: Dark blue/black color
• Biuret test
  • Turns blot when protein is detected.

Enzymes

• Made of protein.
• Act as catalysts to regulate chemical reactions.

Factors Influencing Enzyme Activity

• Temperature:
  • Enzymes have optimal temperatures.
  • Activity decreases at high temperatures (above 37^{\circ}C) due to denaturation.
• pH:
  • Enzymes have optimal pH ranges.
  • Pepsin thrives in low pH (acidic) environments.
  • Trypsin thrives in high pH (basic) environments.
• Substrate concentration:
  • Enzyme activity increases with substrate concentration until saturation is reached.
  • Enzyme binds to the substrate.

Digestive System

• Organs with food moving through them are:
  • Esophagus
  • Stomach
  • Large Intestine
  • Small Intestine
  • Rectum
• Accessory organs:
  • Salivary glands
  • Liver
  • Gallbladder
  • Pancreas

Macronutrient Movement Through Digestive Organs

Mouth

• Mechanical digestion: Chewing/mixing food with teeth/tongue.
• Chemical digestion: Salivary glands contain amylase (enzyme) which breaks down starch into disaccharides.

Esophagus

• Movement of food bolus by peristalsis (waves of contraction and relaxation).
• Walls contain mucus glands to lubricate food for easier passage.

Stomach

• Mechanical Digestion: Stomach churns up food
• Peristaltic contractions.
• Chemical Digestion: Stomach secretes gastric juice.
  • Gastric juice aids in food breakdown.
  • (HCl) kills bacteria in food.
  • Mucus protects the lining of the stomach

Small Intestine

• Peristaltic contractions.
• Major organ for nutrient absorption into bloodstream. Proteins, disaccharides and lipids are absorbed into the blood stream.
• Duodenum, jejunum, and ileum are major sections.

Large Intestine

• Colon and rectum function by absorbing water and electrolytes.
• No digestion of macronutrients.

Rectum

• Stores waste material from the colon.
• Prepares for defecation.
• Does not perform chemical digestion or absorption of macronutrients.