Protein Structure and Function

Protein Structure and Function

• Amino Acids: Building blocks of proteins
  • Each contains a central carbon atom, an amino group (−NH₂), a carboxylic acid group (−COOH), and a unique side group determining properties
  • There are 20 different amino acids
• Peptide Bonds: Form when amino acids link via dehydration synthesis
  • Water molecule removed, joining the carboxylic acid group of one amino acid to the amino group of another
• Polypeptides: Long chains of amino acids linked by peptide bonds
  • Length varies from hundreds to thousands of amino acids
• Protein Folding: Polypeptides fold into unique 3D shapes
  • Shape is stabilized by bonds between amino acid side groups
  • Shape determines protein function; some proteins are complexes of multiple polypeptide chains (e.g., hemoglobin has four chains).
• Protein Functions:
  • Transport: Hemoglobin transports oxygen through the bloodstream.
  • Defense: Antibodies bind to foreign invaders for immune defense.
  • Structure: Keratin is found in hair, skin, nails, and fur.
  • Enzymes: Lactase breaks down lactose in the digestive system.
  • Movement: Actin enables muscle contraction.
• Form and Function of Proteins: A protein's amino acid sequence determines its shape and function
  • Even a single amino acid change can significantly affect a protein's function. Example: Sickle-cell disease results from a single amino acid change in one of hemoglobin's polypeptides, leading to misfolded proteins and sickle-shaped red blood cells.
• Core Idea: Proteins are made of amino acids joined by peptide bonds and perform most life functions. Each protein's unique shape is essential to its specific function.
• Key Terms:
  • Amino Acid: Organic molecules that form proteins.
  • Peptide Bond: Covalent bond linking amino acids.
  • Polypeptide: Long chain of amino acids forming proteins.
  • Proteins: Diverse molecules responsible for most biological functions.
• Core Question: What is a polypeptide?
  • A polypeptide is a chain of amino acids joined by many (or "poly") peptide bonds.

Animal Body Structural Hierarchy

• Core Idea: The human body is organized into a structural hierarchy, where individual cells are the building blocks forming progressively larger units. Each level contributes to the body's overall function, illustrating the correlation between form and function.
• Structural Hierarchy:
  • Cell: The fundamental unit of life. Examples: epithelial cells, muscle cells, nerve cells. Contains organelles like the nucleus, mitochondria, cytoplasm, and others.
  • Tissue: An integrated group of similar cells performing a specific function. Example: epithelial tissue forming sheets lining organs.
  • Organ: Composed of two or more types of tissue working together for a specific task. Example: The heart (muscle, nervous, epithelial, and connective tissues).
  • Organ System: Groups of organs working together to perform a broad function. Example: The circulatory system (heart and blood vessels) transports oxygen and nutrients, removes waste.
  • Organism: The entire living being; relies on the coordinated functions of all organ systems. Example: Humans performing exercise depend on the skeletal, muscular, circulatory, and respiratory systems.
• Form and Function: Structure reflects function (e.g., branched lung structures for gas exchange). Conversely, understanding a function clarifies structure.
• Anatomy vs. Physiology:
  • Anatomy: Study of organism's body structures (e.g., heart structure via angiograms).
  • Physiology: Study of organism's body part functions (e.g., heart activity using EKGs).
• Key Takeaways:
  • Each level of the structural hierarchy contributes unique functions.
  • The integration of all levels is essential for organism survival.
• Core Question: The brain is an organ within this hierarchy.
• Key Terms:
  • Anatomy: The study of bodily structures.
  • Physiology: The study of bodily structure functions.

Animal Internal Environment and Homeostasis

• Core Idea: Animal bodies exchange chemicals and energy with the external environment but strive to maintain relatively constant internal conditions (homeostasis). This is achieved through mechanisms like negative feedback, ensuring proper physiological function despite environmental changes.
• Homeostasis Examples:
  • Blood Glucose Regulation: After a meal, blood glucose rises; the pancreas releases insulin, reducing levels to normal. In diabetes, regulation fails: Type 1 diabetes has insufficient insulin production; Type 2 diabetes has insulin resistance.
  • Temperature Regulation: The body maintains ~37°C (98.6°F). If too high: blood vessels widen, sweat glands activate; if too low: blood vessels constrict, muscles shiver.
• Negative Feedback Mechanism: A regulatory process where the result of an action inhibits further occurrence of that action (e.g., thermostat).
• Integumentary System: Key in homeostasis, especially temperature regulation. Components include skin, epidermis, dermis, fat layer, and muscles.
• Diabetes and Homeostasis Breakdown: Homeostasis failure can lead to serious health conditions like Type 1 and Type 2 diabetes.
• Core Question Example: Flushing a toilet demonstrates negative feedback.
• Key Terms:
  • Homeostasis: Maintenance of a steady internal environment.
  • Integumentary System: Organ system with skin, hair, nails; aids in protection and temperature regulation.
  • Negative Feedback: Regulatory mechanism where a process inhibits itself.

Digestive System Health Problems and Nutritional Imbalances

• Core Idea: Digestive system malfunctions or improper nutrition can cause health issues like obesity, malnutrition, and eating disorders.
• Digestive System Malfunctions:
  • Acid Reflux/GERD: Esophageal backflow of stomach acid.
  • Gallstones: Bile crystals obstruct ducts.
  • Constipation: Slow fecal movement.
  • Appendicitis: Bacterial infection of the appendix.
  • Cholera: Infection by Vibrio cholerae (poor sanitation).
  • IBD (Crohn’s/Ulcerative Colitis): Intestine inflammation.
  • Gastric Ulcers: Infection (Helicobacter pylori).
  • Gastric Bypass Surgery: Reduced stomach size, small intestine bypass.
• Nutritional Imbalances:
  • Obesity: High BMI, significant health risks. Obesity rates have risen dramatically since 1960 (one-third of Americans are overweight; another third are obese).
  • Malnutrition: Insufficient calories or nutrients. Severe cases (e.g., fluid accumulation in children).
  • Eating Disorders: Anorexia nervosa (self-starvation) and bulimia (binge-purge cycles).
• Core Question Example: Can someone be obese and malnourished? Yes, high caloric intake but lack of essential nutrients.
• Key Terms:
  • Anorexia Nervosa: Self-starvation eating disorder.
  • Body Mass Index (BMI): Weight-to-height ratio for weight categorization.
  • Bulimia: Binge-purge eating disorder.
  • Malnutrition: Insufficient calorie or nutrient intake.
  • Obesity: High body fat, typically measured using BMI.

Urinary System: Regulation and Waste Disposal

• Core Idea: The urinary system eliminates waste and regulates water/ion concentration in the body. Nephrons filter blood; reclaim needed materials; form urine.
• Functions:
  • Water and Ion Balance: Maintains balance via osmoregulation.
  • Waste Removal: Removes waste like urea, producing urine.
• Structure:
  • Kidneys: Filter blood, reclaim water/substances; filtered blood exits via renal veins.
  • Ureters: Carry urine to the bladder.
  • Urinary Bladder: Stores urine.
  • Urethra: Excretes urine.
• Blood Flow: Enters the kidneys via the renal artery; filtered blood exits via the renal vein.
• Kidney Processes:
  • Filtration: Water and small molecules filter into nephron tubules.
  • Reabsorption: Valuable substances (water, glucose, ions) are reclaimed by surrounding capillaries.
  • Excretion: Concentrated urine forms and travels to the bladder.
• Urine Composition: Primarily water, urea, plus chloride, sodium, potassium, phosphate, sulfate, creatinine, and uric acid.
• Nephron: Functional unit of the kidney, filters blood and forms urine.
• Kidney Malfunctions/Treatment: Kidney failure leads to toxic waste buildup; treated using dialysis or a transplant.
• Core Question: What is the functional unit of the urinary system where urine forms? The nephron.
• Key Terms:
  • Dialysis: Machine-based blood filtration for kidney failure patients.
  • Nephron: Kidney's functional unit for filtration and urine formation.
  • Osmoregulation: Regulation of water/ion concentration.
  • Urinary System: Organ system for water balance and waste excretion.
  • Urine: Liquid waste primarily water and urea.

Explore the fundamentals of protein structure and function in this quiz. Learn about amino acids, peptide bonds, polypeptides, and the significance of protein folding. Test your knowledge on the various roles proteins play in biological systems.