Blood Types and Protein Structures

Blood Types

• Blood types are categorized as A, B, AB, or O.
• The determination of blood type depends on antigens present on red blood cells.
• Antigens: Substances on the surface of red blood cells that determine blood type.
• Example: A person with blood type A has antigen A on their red blood cells.
• These antigens are glycoproteins.
• Blood type B has antigen B.
• Blood type AB has both A and B antigens.
• Blood type O has neither A nor B antigens.
• Rh factor determines positive or negative blood type. If present, the blood type is positive; if absent, it is negative.

Protein Classification

• Proteins are classified based on how they are held together, referring to their structure.
• The classification includes primary, secondary, tertiary, and quaternary structures.

Primary Structure

• The primary structure is a linear sequence of amino acids linked by peptide bonds.
• Analogy: Like beets (amino acids) on a string.

Secondary Structure

• The secondary structure involves twisting or pleating of the amino acid chain, stabilized by hydrogen bonds.
• Two main patterns: alpha helix and pleated sheets.
• The arrangement and bonding differentiate these patterns.

Tertiary Structure

• The tertiary structure is a complex three-dimensional shape of a polypeptide chain.
• Globular proteins (e.g., in blood) are often tertiary structures.
• Fibrous proteins (e.g., hair) also exhibit tertiary structure.

Quaternary Structure

• The quaternary structure is present in proteins with two or more polypeptide chains.
• Example: Hemoglobin, a globular protein with four polypeptide chains.
• Some proteins have prosthetic groups, which are non-protein structures covalently bonded (e.g., heme group in hemoglobin).
• The complexity of bonding between polypeptides determines the structure.

Protein Denaturation

• Protein denaturation is the destruction of the protein's shape.
• Enzyme-Substrate Model: An enzyme (key) with a unique shape matches a substrate.
• Denaturation alters the enzyme's shape, preventing it from functioning correctly.
• Causes of Denaturation: High temperature (fever) or extreme pH levels.
• Denaturation is often irreversible, leading to loss of function.
• Example: Fever can cause protein denaturation.
• Blood pH must be maintained around 7.37; significant deviations can cause denaturation.

Energy in Living Organisms

• Living organisms require energy for various functions:
  • Powering muscles.
  • Pumping blood.
  • Absorbing nutrients.
  • Exchanging respiratory gases.
  • Synthesizing new molecules.
  • Establishing cellular concentrations.
• The ultimate source of energy is the sun.
• Plants convert solar energy into food through photosynthesis, which is then consumed by humans and animals.
• Energy exists in different forms: sound, chemical, mechanical, radiant.

Definition of Energy

• Energy is the capacity to do work.
• It is often invisible but can be observed through its effects on matter.
• ATP (Adenosine Triphosphate): The energy currency of the body.
  • ATP is produced through metabolic pathways (e.g., breakdown of glucose).
  • Utilized ATP must be replenished to avoid fatigue.

Potential vs. Kinetic Energy

• Potential Energy: Energy of position (e.g., ions moving across a plasma membrane).
• Kinetic Energy: Energy of motion.

Molecules for Chemical Energy Storage

• Energy is stored in the chemical bonds of molecules:
  • Triglycerides (Fat): Long-term energy storage in adipose tissue.
  • Glucose: Another molecule that stores energy.
  • Glycogen: A carbohydrate converted from glucose for energy storage.
  • ATP: Stored in all cells, produced continuously, and used immediately.
  • Proteins: Also store energy.

Forms of Energy

Electrical Energy

• Movement of charged particles.
• Neurons transmit signals using electrical energy.
• The propagation of nerve impulses involves charged ions moving across the plasma membrane.

Mechanical Energy

• The force of contraction and relaxation (e.g., heart pumping blood).
• Involves the movement of a structure or substance due to an applied force.

Sound Energy

• Sound waves vibrate the tympanic membrane in the ear.
• Stimulates sensory receptors for hearing.

Radiant Energy (Solar Energy/Light)

• Light comes in the form of radiation (UV, visible light).
• Photoreceptors (rods and cones) in the retina convert light into electrical signals.
• Electromagnetic spectrum includes gamma rays, X-rays, UV light, visible light, etc.
  • High electromagnetic energy (gamma rays, X-rays) can cause DNA mutations.
  • Visible light is used for seeing.

Laws of Energy (Thermodynamics)

• First Law: Energy cannot be created nor destroyed; it can only be converted from one form to another.
• Second Law: During energy transformation, some energy is converted into heat.
  • This conversion is not controllable and results in wasted energy.

Thermodynamics

• Thermodynamics is the study of energy transformation.
• Examples:
  • Burning a candle converts chemical energy to light and heat.
  • Retinal cells convert light energy into electrical energy.
  • Chemical energy from food is converted into mechanical energy.

Metabolism

• Metabolism is the sum of all chemical reactions in the body.
• Includes anabolism (building) and catabolism (breaking).

Chemical Reactions

• Occur when chemical bonds in existing molecules are broken or new bonds are formed.
• Chemical Equation: Representation of reactions.
• Reactants: Substances before the reaction.
• Products: Substances formed after the reaction.

Classification of Chemical Reactions

• Based on changes in chemical structure:
  • Decomposition: Breaking down large molecules (e.g., disaccharides into monosaccharides).
  • Synthesis: Building larger molecules from smaller ones (e.g., protein synthesis).
  • Exchange Reactions: Atoms, molecules, ions, or electrons are exchanged between chemicals (A + BC -> AC + B).
• Based on changes in chemical energy:
  • Exergonic: Energy is released.
  • Endergonic: Energy is consumed.
• Based on reversibility: irreversible or reversible.

Oxidation-Reduction (Redox) Reactions

• Most chemical reactions in the body are redox reactions.
• Oxidation: Loss of electrons.
• Reduction: Gain of electrons.
• The substance that loses electrons is oxidized; the one gaining electrons is reduced.
• Redox reactions involve either losing or gaining electrons.

Reaction Rate and Activation Energy

• Enzymes: Speed up chemical reactions (catalysts).
• Catalyst: Speeds up chemical reactions.
• Difference between Enzyme and Catalyst:
  • Enzymes are biological molecules made of proteins, used in metabolic reactions.
  • Catalysts can be inorganic and are used in chemistry labs.
• How Enzymes Work: Enzymes lower the activation energy required to start a chemical reaction.

Enzymes Decrease Activation Energy

• Enzymes decrease the activation energy, increasing the reaction rate.
• They do not get involved in the reaction but facilitate it.
• Enzymes can be reused and recycled.

Enzyme Structure and Location

• Enzymes have a unique shape (lock and key model).
• They can be located in the interstitial fluid, on the membrane, or inside the cell.
• Enzymes are produced by protein synthesis.
• Some remain within the cells (e.g., DNA polymerase).
• Some are embedded on the plasma membrane.
• Some are secreted.

Molecules and Ions for Enzyme Function

• Cofactors and coenzymes (e.g., NAD, FAD) are required for normal enzyme function.

Factors Affecting Speed

• Temperature and concentration impact the speed and rate of reactions.

Protein Denaturation

• High temperature or fluctuation in pH can mess with the shape of the protein.
• pH and Temperature are detrimental to the unique geometry of proteins that dictate function.

Chemical Equations and Variables

• H_2O : Chemical formula of water to be known and used in various equations.
• 
  abla : A greek symbol that may stand for a gradient.
• NAD : Nicotinamide Adenine Dinucleotide
• FAD : Flavin Adenine Dinucleotide
• ATP : Adenosine Triphosphate

Important Notes From Transcript

• No questions on upcoming quiz from outside PowerPoint.
• Students should review PowerPoint for preparation.