Chemistry of Biology & Biological Molecules

Introduction

Understanding the chemistry underlying biological systems is essential for grasping how molecules interact and function in living organisms. This section covers foundational concepts such as atoms, ions, molecules, chemical bonds, water's role in life, macromolecules, nucleic acids, carbohydrates, and lipids.

Graphs in Biology

Graphing and Data Analysis

Graphs are vital tools for visualizing and interpreting biological data. They help summarize results and reveal patterns.

• Dependent Variable: The variable measured or observed in an experiment; it depends on changes made to the independent variable.

• Reading a Graph: Key steps include identifying axes, understanding the scale, and interpreting data points.

• Scatterplots vs. Bar Graphs: Use scatterplots when both variables are continuous; use bar graphs when the independent variable is categorical.

Atoms, Ions, and Molecules

Atomic Structure and Properties

Atoms are the basic units of matter, composed of subatomic particles. Their arrangement and interactions form molecules essential for life.

• Atomic Number: The number of protons in an atom, which defines the element.

• Common Elements in Life: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Sulfur (S), and Phosphorus (P) make up most biological matter.

• Electronegativity: The tendency of an atom to attract electrons in a chemical bond.

Chemical Bonds

Types of Chemical Bonds

Chemical bonds hold atoms together in molecules. The main types are covalent, polar covalent, and ionic bonds.

• Covalent Bonds: Strong bonds formed by sharing electrons.

• Ionic Bonds: Formed by the attraction between oppositely charged ions.

• Polar Covalent Bonds: Result in molecules with partial positive and negative regions.

Life Depends on Water

Properties and Interactions of Water

Water is essential for life due to its unique chemical properties, including polarity and hydrogen bonding.

• Electrostatic Interactions: Interactions between charged or partially charged regions of molecules.

• Hydrogen Bonding: A type of electrostatic interaction where a hydrogen atom covalently bonded to an electronegative atom (like oxygen) is attracted to another electronegative atom.

• Hydrophobic Substances: Repel water and do not dissolve; examples include oils and fats.

• Hydrophilic Substances: Attract and dissolve in water; examples include salts and sugars.

Functional Groups in Organic Molecules

Role and Types of Functional Groups

Functional groups are specific groups of atoms within molecules that determine their chemical properties and reactions.

• Influence on Molecules: Functional groups affect solubility, reactivity, and interaction with other molecules.

Macromolecules: Polymers of Life

Structure and Formation of Polymers

Macromolecules are large molecules made by joining smaller units called monomers. The four major types are proteins, nucleic acids, carbohydrates, and lipids.

• Polymer: A large molecule made of repeating monomer units.

• Condensation Reaction: Monomers are joined by removing water ().

• Hydrolysis: Polymers are broken down by adding water ().

Nucleic Acids

Structure and Function

Nucleic acids (DNA and RNA) are polymers of nucleotides, which store and transmit genetic information.

• Nucleotide Structure: Each nucleotide consists of a sugar, a phosphate group, and a nitrogenous base.

• DNA Bases: Adenine (A), Thymine (T), Cytosine (C), Guanine (G)

• RNA Bases: Adenine (A), Uracil (U), Cytosine (C), Guanine (G)

• Sugar in DNA: Deoxyribose

• Sugar in RNA: Ribose

Carbohydrates

Monosaccharides and Polysaccharides

Carbohydrates are energy-rich molecules classified as simple sugars (monosaccharides) or complex carbohydrates (polysaccharides).

• Hydrophilic vs. Hydrophobic: Most sugars are hydrophilic due to their polar hydroxyl groups.

• Energy Storage: Starch stores energy in plants; glycogen stores energy in animals.

Lipids

Types and Properties

Lipids are hydrophobic molecules important for energy storage, membrane structure, and signaling.

• Types of Lipids: Fats, oils, phospholipids, steroids, waxes

• Fatty Acid: A long hydrocarbon chain with a carboxyl group; can be saturated (no double bonds) or unsaturated (one or more double bonds).

• Saturated vs. Unsaturated: Saturated fatty acids have straight chains and pack tightly; unsaturated fatty acids have kinks due to double bonds, making them more fluid.

Summary Table: Key Biological Molecules

Additional info: Academic context and definitions have been expanded for clarity and completeness. All tables have been reconstructed and missing details logically inferred based on standard biology curriculum.