introduction to metabolism l.
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Introduction to metabolism. Chapter 3. Objectives. Recognize the difference between a macro and a micronutrient. Recognize the role of antioxidants Be able to describe the role of enzymes and how enzymes work Be able to explain the difference between Active and passive transport

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  • Recognize the difference between a macro and a micronutrient.
  • Recognize the role of antioxidants
  • Be able to describe the role of enzymes and how enzymes work
  • Be able to explain the difference between Active and passive transport
  • Be able to explain simple diffusion, osmosis, facilitated diffusion, Pumps, and exo/endocytosis
  • One’s diet is important to one’s physical wellbeing
  • The foods we eat supply our body will energy and building materials
  • Energy is stored in the macromolecules we consume
  • Building materials are extracted from the macromolecules we consume
  • Different foods have different types of materials
sources of energy
Sources of energy
  • Carbohydrates, lipids, and proteins are sources of energy for the body
  • Energy is stored in the electrons associated with C-H bonds
  • Lipids contain the most of these bonds per gram and so have the highest number of Calories
  • A food Calorie contains sufficient energy to elevate 1 liter of water by 1 degree Celsius
  • Energy from foods is converted to ATP: Cell energy
building materials
Building Materials
  • Building materials may be consumed directly or synthesized from materials through metabolic pathway
  • A metabolic pathway is a series of chemical steps that lead to molecules being converted to different forms
  • “Essential” means must be eaten
  • Materials needed in very small amounts
  • Vitamins: fine tune body chemistry
  • Minerals: structural materials
  • Water vs. Fat soluble
role of antioxidants
Role of Antioxidants
  • Metabolism occasionally produces free radicals that negatively affect body chemistry
  • Antioxidants are molecules that eliminate free radicals preventing damage to the cells
  • Term used to describe all the chemical reactions occurring in an organism
  • Break down chemistry is called catabolism
  • Buildup (synthesis) chemistry is called anabolism
  • Most chemistry is assisted by proteins called enzymes
  • Enzymes are proteins
    • Specific because of conformational shape
  • Enzymes are catalysts
    • Catalyst: chemical that changes the rate of a reaction without being consumed
    • Recycled
  • Enzymes reduce the activation energy of a reaction
    • Amount of energy that must be added to get a reaction to proceed
activation energy
Activation Energy
  • Activation energy is the amount of energy that must be supplied to get reactants to form products
    • is usually supplied by heat
  • Prevents reactions from “just happening”
how enzymes function
How Enzymes Function
  • Enzymes are substrate specific
    • Substrate: any molecule to which an enzyme will bind
  • Although an enzyme can be a large protein, only a specific region of the enzyme interacts with the substrate
    • Active Site: region of enzyme that “reacts” to substrate
  • As enzyme and substrate bind, the enzyme shape is modified to better fit the substrate
    • Induced fit occurs as a result of the enzyme substrate complex
enzyme activity
Enzyme activity
  • The rate at which an enzyme can function is dependant on several factors including:
    • Temperature
    • pH
  • The rate of reaction is also influenced by the concentration of the substrate or enzyme
  • Some enzymes utilize inorganic or organic molecules as helpers
    • Cofactor: inorganic molecule (mineral)
    • Coenzyme: organic non-protein molecule (vitamin)
how do macromolecules enter the cell
How do macromolecules enter the cell?
  • The plasma membrane borders every cell in our body
  • Materials have to cross the border to enter the cell
  • This is called membrane transport
  • There are active and passive means of moving materials
  • Active mechanisms requires ATP, passive mechanisms do not
plasma membrane composed of both lipid and protein
Plasma membrane composed of both lipid and protein
  • Lipids: mostly phospholipids arranged as a bilayer
  • Proteins: vary in form, some proteins help move molecules
what moves
What moves….
  • Passively
    • Through the lipid bilayer (simple diffusion)
      • Hydrophobic (nonpolar) molecules (O2, lipids)
      • Small uncharged polar molecules (CO2, H2O)
    • Through a protein (facilitated diffusion)
      • Hydrophilic (polar) molecules
      • Ions (+ or – charged particles)
  • Actively (pump or exo/endocytosis)
    • Requires a protein and ATP
      • Hydrophilic molecules
passive transport mechanisms
Passive Transport Mechanisms
  • Simple Diffusion: the movement of a substance from higher concentration to lesser concentration
  • Osmosis: the diffusion of water (solvent) across a membrane
    • influenced by total solute concentration
the importance of osmoregulation
The Importance of Osmoregulation
  • Living things must balance water uptake and loss
  • If cells lose water they crenate (shrivel)
  • If cells gain water they lyse
facilitated diffusion
Facilitated Diffusion
  • Involves transport proteins moving a solute along a concentration gradient
  • May be specific
  • May be saturated (can only work so fast) or inhibited
  • Assist the physical process of diffusion
active transport pumps
Active Transport: Pumps
  • Moves solute uphill and requires energy
  • Always requires transport proteins
  • Major factor that allows the cell to regulate the concentration of solute within the cell
  • May result in an imbalance of solute across a membrane that the cell can utilize
exocytosis and endocytosis
Exocytosis and Endocytosis
  • Exocytosis involve the movement of macromolecule out of the cell by the fusion of membrane bound vesicles to the plasma membrane
  • Endocytosis involves the movement of macromolecule into the cell by the pinching of the plasma membrane into membrane bound vesicles
    • Phagocytosis
    • Pinocytosis

Exocytosis and Endocytosis

  • Phagocytosis: ingestion of large particle
  • Pinocytosis: ingestion of small mixed solutes