MAIC - Week 01 Lecture 2 - Module Introduction_IT ARP (1)

Introduction

This document outlines the structural features and functions of key biological molecules, focusing on lipids, proteins, carbohydrates, and energy carriers within cells.

Intended Learning Outcomes

  • Understand the structural features of lipids, proteins, carbohydrates.

  • Recognize the major energy carriers in the cell.

Atoms, Ions, and Molecules

  • Atoms consist of a positively charged nucleus surrounded by negatively charged electrons, resulting in a neutral charge.

  • Molecules are formed from one or more atoms joined by covalent bonds; akin to snapping Lego blocks together, thus requiring energy to break them apart.

  • An ion results from atoms that have gained or lost electrons, leading to a net charge.

Chemical Reactions

The Simplest Chemical Equation

  • Example: C + O2 → CO2

  • Key rules for balancing chemical equations:

    • Atoms must be equal on both sides.

    • Charges must balance.

    • Oxidation is the loss of electrons; reduction is the gain of electrons.

A Slightly Harder Chemical Equation

  • The basic respiration equation: C6H12O6 + 6O2 → 6CO2 + 6H2O + energy

  • This involves multiple smaller reactions rather than a single step to produce energy.

Global Map of Cellular Metabolism

  • Cellular metabolism involves series of reactions, usually catalyzed by enzymes, handled stepwise to manage energy conversion efficiently.

Major Biomolecules

  1. Proteins

  2. Fats (Lipids)

  3. Carbohydrates

  4. Nucleic Acids

Lipid Molecules

  • Triglycerides consist of glycerol (3-carbon alcohol) and 3 fatty acids, which may be saturated or unsaturated.

  • Fats yield more energy per gram than other biomolecules due to lower oxygen content, leading to energy storage primarily in fat.

Common Fatty Acids in Animals

  • Saturated fatty acids: Palmitate (C16:0), Stearate (C18:0)

  • Unsaturated fatty acids: Oleic acid (C18:1)

  • Categories based on location of double bonds:

    • n-3 (first double bond 3 carbons from CH3)

    • n-6 (first double bond 6 carbons away)

Phospholipids

  • Common head groups include phospho-choline, phospho-ethanolamine, and phospho-serine; fatty acids can be saturated or unsaturated.

Cholesterol

  • Essential for membrane strength and fluidity; regulated by the liver, with excess being toxic.

Proteins

Amino Acids and Proteins

  • Proteins are formed from polymerized amino acids with structures ranging from primary to quaternary.

  • Amino Acids: Characterized by an amine group, carboxyl group, and unique side chain (20 types).

Peptide Bonds

  • Formed via a condensation reaction between the amine of one amino acid and the carboxyl of another, leading to peptide formation.

Role of Amino Acid Side Groups

  • Side groups determine protein shape and functionality, affecting binding sites and catalytic properties in enzymes.

Enzyme Functionality

  • Enzyme binding sites formed by amino acid side chains facilitate specific interactions with substrates, often utilizing energy from ATP hydrolysis.

Carbohydrates

Simplest Carbohydrates

  • Basic formula: Cn(H2O)m, with examples like glucose (C6H12O6).

  • Hydroxyl groups enhance solubility in water.

Monosaccharides and Polysaccharides

  • Monosaccharides (single sugar units) combine to form disaccharides (e.g., sucrose from glucose and fructose) and polysaccharides (e.g., starch and glycogen).

Nucleotides and Nucleic Acids

Composition of Nucleotides

  • Nucleotides consist of a base (A, C, T, G), sugar (ribose), and phosphate, functioning in DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

Polymerization of Nucleotides

  • Nucleotides are joined by phosphodiester bonds formed via condensation reactions.

Chirality in Biological Molecules

  • D and L designations indicate chirality; most amino acids are L-type while sugars are predominantly D-type.

Cofactors and Coenzymes

  • Cofactors can include metal ions or organic molecules (coenzymes) essential for enzyme activity.

  • Coenzymes assist enzyme functions and may be recycled during reactions.

Commonly Used Coenzymes

  • ATP, Coenzyme A (CoA), Flavin adenine dinucleotide (FAD), and Nicotinamide adenine dinucleotide (NAD).

Energy Carriers

  • ATP serves as the primary energy currency, while FAD and NAD also transport energy across cellular processes.

Oxidation and Reduction in Energy Transfer

  • Oxidation involves the loss of electrons and energy release; reduction is the gain of electrons, often leading to energy storage in the form of NADH.

Summary

  • A thorough understanding of the structures of lipids, carbohydrates, proteins, and nucleotides, as well as the bonds that connect them and the roles of coenzymes, oxidation, and reduction, is crucial for mastering this module.

Reading List

  • Alberts et al., "Essential Cell Biology" Chapter 2 (pages 39-80).