Fundamental Concepts for exam 1 overall

Water Chemistry

Hydrogen Bonds and Water Properties

Water is a vital molecule in biology, largely due to its unique chemical properties conferred by hydrogen bonding. Hydrogen bonds are weak attractions between the slightly positive hydrogen atom of one water molecule and the slightly negative oxygen atom of another.

• Hydrogen Bond: A type of intermolecular force that occurs when a hydrogen atom covalently bonded to an electronegative atom (such as oxygen) is attracted to another electronegative atom.

• Properties of Water:

  • Cohesion: Water molecules stick to each other, allowing for surface tension.

  • Adhesion: Water molecules stick to other substances, aiding in capillary action.

  • High Specific Heat: Water can absorb a lot of heat before changing temperature, helping regulate climate and body temperature.

  • Solvent Abilities: Water dissolves many substances due to its polarity.

• Example: Water's ability to dissolve salts and sugars is essential for cellular processes.

Equation:

$\text{H}_2\text{O} \cdots \text{H}_2\text{O}$ (hydrogen bonds between water molecules)

Phospholipid Bilayers

Hydrophilic and Hydrophobic Portions

Phospholipids are the main components of cell membranes, forming a bilayer that separates the cell from its environment.

• Phospholipid Structure: Each molecule has a hydrophilic (water-loving) head and two hydrophobic (water-fearing) tails.

• Bilayer Formation: In water, phospholipids arrange themselves so that the hydrophilic heads face outward toward water, and the hydrophobic tails face inward, away from water.

• Function: This arrangement creates a semi-permeable membrane, crucial for cellular function.

• Example: The plasma membrane of animal cells.

Diagram: (Not included; students should visualize hydrophilic heads on the outside, hydrophobic tails on the inside.)

Carbon Molecules in Biology

The Four Main Groups: Monomers and Polymers

Life is based on carbon compounds, which are organized into four major groups: carbohydrates, lipids, proteins, and nucleic acids.

• Carbohydrates: Provide energy and structural support. Monomer: Monosaccharides (e.g., glucose). Polymer: Polysaccharides (e.g., starch).

• Lipids: Store energy and make up cell membranes. Monomer: Fatty acids and glycerol. Polymer: Triglycerides, phospholipids.

• Proteins: Perform cellular functions. Monomer: Amino acids. Polymer: Polypeptides.

• Nucleic Acids: Store genetic information. Monomer: Nucleotides. Polymer: DNA, RNA.

• Polymerization: Monomers are joined by dehydration synthesis to form polymers; polymers are broken down by hydrolysis.

• Example: Starch is a polymer of glucose monomers.

Equation:

$\text{Monomer}_1 + \text{Monomer}_2 \xrightarrow{\text{Dehydration}} \text{Polymer} + \text{H}_2\text{O}$

Domains of Life

Classification: Eukaryotes and Prokaryotes

All living organisms are classified into domains based on cellular structure and genetic characteristics.

• Eukaryotes: Organisms with cells containing a nucleus and organelles. Includes plants, animals, and fungi.

• Prokaryotes: Organisms without a nucleus. Includes bacteria and archaea.

• Example: Humans are eukaryotes; Escherichia coli is a prokaryote.

Domain	Cell Type	Examples
Eukaryota	Eukaryotic	Plants, Animals, Fungi
Bacteria	Prokaryotic	Common bacteria
Archaea	Prokaryotic	Extremophiles

Genetic Material: DNA vs. RNA

Differences and Base Pairing

DNA and RNA are nucleic acids that store and transmit genetic information, but they differ in structure and function.

• DNA: Double-stranded, contains deoxyribose sugar, uses bases adenine (A), thymine (T), cytosine (C), and guanine (G).

• RNA: Single-stranded, contains ribose sugar, uses bases adenine (A), uracil (U), cytosine (C), and guanine (G).

• Base Pairing:

  • DNA: A pairs with T, C pairs with G

  • RNA: A pairs with U, C pairs with G

• Example: In DNA, the sequence ATTG pairs with TAAC; in RNA, AUUG pairs with UAAC.

Feature	DNA	RNA
Sugar	Deoxyribose	Ribose
Strands	Double	Single
Bases	A, T, C, G	A, U, C, G

Equation:

$\text{A} - \text{T}$ (DNA), $\text{A} - \text{U}$ (RNA), $\text{C} - \text{G}$ (both)

Elements Essential for Life

CHON: The Four Major Elements

Most living matter is composed of four key elements: carbon (C), hydrogen (H), oxygen (O), and nitrogen (N).

• Carbon (C): Forms the backbone of organic molecules.

• Hydrogen (H): Found in water and organic compounds.

• Oxygen (O): Essential for respiration and water.

• Nitrogen (N): Key component of proteins and nucleic acids.

• Example: Proteins contain all four elements in their structure.

Element	Role in Biology
Carbon (C)	Structural framework of organic molecules
Hydrogen (H)	Component of water and organic molecules
Oxygen (O)	Required for cellular respiration, water
Nitrogen (N)	Found in amino acids, nucleic acids