Biological Molecules Quiz

Large Biological Molecules

• Four main classes of large biological molecules: carbohydrates, lipids, proteins, and nucleic acids.
• Macromolecules are formed by joining small organic molecules, characterized by their large size and thousands of atoms connected by covalent bonds.
• Molecular structure directly relates to function.

Macromolecules as Polymers

• Polymers are long-chain molecules made of similar building blocks called monomers.
• Carbohydrates, proteins, and nucleic acids are primary examples of polymers in biology.

Polymer Synthesis and Breakdown

• Dehydration synthesis (condensation reaction) combines monomers by removing a water molecule.
• Hydrolysis is the reverse process, breaking polymers into monomers by adding water.
• Enzymes act as organic catalysts to accelerate these chemical reactions.

Diversity of Polymers

• Cells contain thousands of different macromolecules that vary among and within species.
• A small set of monomers can create an immense variety of polymers.

Carbohydrates: Fuel and Structure

• Carbohydrates consist of sugars and their polymers, with monosaccharides as the simplest form.
• Common monosaccharide: glucose (C6H12O6).
• Polysaccharides are formed from linked monosaccharides via glycosidic linkages.
• Disaccharides are produced through dehydration reactions joining two monosaccharides.

Polysaccharides

• Serve two main roles: storage and structural functions determined by monomer types and glycosidic linkages.
• Storage polysaccharides include starch (for plants) and glycogen (for animals).
• Structural polysaccharide: cellulose, a key component of plant cell walls with specialized glycosidic linkages.
• Chitin provides structural support in exoskeletons of arthropods and fungal cell walls.

Lipids: Diverse Hydrophobic Molecules

• Lipids do not form polymers and are primarily hydrophobic due to hydrocarbon composition.
• Phospholipids self-assemble in water, forming bilayers crucial for cell membranes.
• Steroids, including cholesterol, consist of four fused ring structures and play a role in cell membrane integrity.

Proteins: Multifunctional Polymers

• Proteins constitute over 50% of cellular dry mass, serving various functions: structural support, transport, signaling, and catalysis.
• Amino acids are monomers that combine to form proteins (polypeptides).
• Types of proteins include enzymatic, structural, storage, transport, hormonal, receptor, contractile, and defensive.

Protein Structure

• Proteins exhibit four levels of structure: primary, secondary, tertiary, and quaternary.
• Secondary structure includes alpha-helices and beta-pleated sheets formed by hydrogen bonds.
• Tertiary structure is formed by interactions among R groups, while quaternary structure involves multiple polypeptide chains.
• Changes in DNA sequence can alter protein structure and function, illustrated by sickle-cell disease.

Disorders Related to Carbohydrates

• Carbohydrate deficit disorders arise from insufficient carbohydrate intake/metabolism, causing various health issues such as:
  • Hypoglycemia: symptoms include weakness and confusion due to excessive insulin or inadequate intake.
  • Ketoacidosis: leads to nausea and fruity breath, primarily in diabetics.
  • Glycogen Storage Disease: varies in symptoms based on enzyme deficiencies resulting in hypoglycemia.
  • Starvation: results in extreme weight loss and muscle wasting.
  • Ketosis: marked by fatigue and nausea due to low carbohydrate availability.
  • Lactic Acidosis: muscle pain and fatigue from lactic acid accumulation.
  • Hypoglycemic Shock: severe blood sugar drop causing confusion and seizures.

Disorders Related to Lipids

• Abnormal lipid levels cause cardiovascular and metabolic disorders, including:
  • Hyperlipidemia: often asymptomatic; can lead to cardiovascular disease.
  • Atherosclerosis: caused by lipid buildup in arterial walls, leading to chest pain.
  • Familial Hypercholesterolemia: early heart disease due to genetic factors affecting cholesterol metabolism.
  • Obesity: excess body fat linked to high caloric intake and low physical activity.
  • Lipid Storage Disease: genetic conditions causing defective lipid metabolism, with varying symptoms.

Diagnosis and Treatment

• For carbohydrate disorders: blood tests for glucose levels, dietary management, and enzyme replacement therapy (for GSD).
• For lipid disorders: lipid panels and imaging tests for atherosclerosis are key diagnostic tools.

Test your knowledge on the structure and function of large biological molecules, including carbohydrates, lipids, proteins, and nucleic acids. This quiz will help you understand how macromolecules are formed and their importance in living organisms.