Chemistry & Macromolecules

Introduction to Atoms and Molecules

Chemistry forms the foundation of microbiology, as all living organisms are composed of atoms and molecules. Understanding the structure and interactions of atoms is essential for grasping the molecular basis of life.

• Atom: The smallest unit of matter that retains the properties of an element.

• Molecule: A group of atoms bonded together.

The Elements of Life

Living organisms are primarily composed of a few key elements, which are essential for biological processes.

• C: Carbon

• H: Hydrogen

• O: Oxygen

• N: Nitrogen

• P: Phosphorus

• S: Sulfur

Chemical Bonds

Types of Chemical Bonds

Atoms interact through their valence electrons to form chemical bonds, which are crucial for the structure and function of biological molecules.

• Ionic Bonds: Formed by the transfer of electrons from one atom to another, resulting in oppositely charged ions that attract each other.

• Covalent Bonds: Formed when two atoms share one or more pairs of electrons.

• Hydrogen Bonds: Weak attractions between a slightly positive hydrogen atom and a slightly negative atom (often oxygen or nitrogen).

Chemical Reactions

Synthesis and Decomposition Reactions

Chemical reactions involve the making or breaking of bonds between atoms. These reactions are fundamental to metabolism in cells.

• Synthesis (Anabolism): Atoms, ions, or molecules combine to form new, larger molecules. Example: Formation of proteins from amino acids.

• Decomposition (Catabolism): A molecule is split into smaller molecules, ions, or atoms. Example: Breakdown of glucose during cellular respiration.

Water and Its Properties

Importance of Water

Water is an inorganic, polar molecule that acts as a universal solvent in biological systems. Its polarity allows it to dissolve many substances, facilitating chemical reactions in cells.

• Solvent: Polar substances dissociate in water, forming solutes.

Acids, Bases, and pH

Acid-Base Balance

Acids and bases are substances that alter the concentration of hydrogen ions (H+) and hydroxide ions (OH-) in solution. The pH scale measures the acidity or alkalinity of a solution.

• Acids: Release H+ in solution.

• Bases: Release OH- in solution.

• pH:

• Most organisms grow best between pH 6.5 and 8.5.

Organic Molecules and Functional Groups

Functional Groups

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules.

• Examples: Hydroxyl (-OH), Carboxyl (-COOH), Phosphate (-PO42-), etc.

Macromolecules

Formation and Breakdown of Macromolecules

Macromolecules are large, complex molecules essential for life. They are polymers made from smaller units called monomers. The formation and breakdown of macromolecules involve dehydration synthesis and hydrolysis reactions.

• Dehydration Synthesis: Joins monomers by removing water.

• Hydrolysis: Breaks polymers into monomers by adding water.

Carbohydrates

Structure and Function

Carbohydrates serve as energy sources and structural components in cells. They are composed of carbon, hydrogen, and oxygen in the general formula (CH2O)n.

• Monosaccharides: Simple sugars (e.g., glucose).

• Disaccharides: Two monosaccharides joined together (e.g., sucrose).

• Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose).

Lipids

Simple and Complex Lipids

Lipids are hydrophobic molecules that include fats, phospholipids, and steroids. They are important for energy storage, membrane structure, and signaling.

• Simple Lipids (Fats/Triglycerides): Composed of glycerol and fatty acids.

• Complex Lipids: Contain additional elements, such as phosphorus in phospholipids.

• Steroids: Such as cholesterol, are components of eukaryotic cell membranes.

Proteins

Structure and Function

Proteins are polymers of amino acids and perform a vast array of functions, including catalysis (enzymes), transport, signaling, and structural support.

• Amino Acids: 20 different types, each with a unique R group.

• Peptide Bonds: Link amino acids via dehydration synthesis.

• Levels of Structure: Primary, secondary, tertiary, and quaternary.

Nucleic Acids

DNA and RNA

Nucleic acids store and transmit genetic information. They are polymers of nucleotides, each consisting of a sugar, phosphate group, and nitrogenous base.

• DNA (Deoxyribonucleic Acid): Double-stranded, contains deoxyribose, bases are A, T, G, C.

• RNA (Ribonucleic Acid): Single-stranded, contains ribose, bases are A, U, G, C.

ATP: The Energy Currency of the Cell

ATP (adenosine triphosphate) is a nucleotide that stores and provides energy for many cellular processes.

• Structure: Adenine base, ribose sugar, and three phosphate groups.

• Function: Hydrolysis of ATP releases energy used by cells.

*Additional info: ATP is not shown in the provided images, but is a critical nucleotide for cellular energy transfer.*