Ch. 3: Biomolecules

Overview of Biomolecules

Biomolecules are organic molecules that are essential for life. They include carbohydrates, proteins, lipids, and nucleic acids. Each type of biomolecule has unique structures and functions within living organisms.

• Organic Compounds: Molecules containing carbon atoms bonded to hydrogen, often with oxygen, nitrogen, or other elements.

• Functional Groups: Specific groups of atoms within molecules that determine the chemical properties and reactions of those molecules (e.g., hydroxyl, carboxyl, amino, phosphate).

• Polymerization: The process by which monomers (small molecules) join to form polymers (large molecules).

• Dehydration Synthesis: A chemical reaction that joins two molecules by removing a water molecule. This is how polymers are formed from monomers.

• Hydrolysis: The reverse of dehydration synthesis; a water molecule is added to break a bond in a polymer, resulting in smaller molecules.

• Macromolecules: Large, complex molecules such as proteins, nucleic acids, carbohydrates, and lipids.

• Monomer: A small molecule that can join with others to form a polymer.

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

• Monosaccharide, Disaccharide, Polysaccharide: Types of carbohydrates classified by the number of sugar units.

Carbohydrates

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen, typically with a hydrogen:oxygen ratio of 2:1. They serve as energy sources and structural components in cells.

• Monosaccharides: Simple sugars (e.g., glucose, fructose) that are the monomers of carbohydrates.

• Disaccharides: Two monosaccharides joined by a glycosidic bond (e.g., sucrose, lactose).

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

• Formula for Glucose:

• Carbohydrate Structure: Carbohydrates can be linear or branched, and their structure determines their function (e.g., energy storage vs. structural support).

• Examples: Starch (plant energy storage), glycogen (animal energy storage), cellulose (plant cell wall structure).

Proteins

Proteins are polymers made of amino acids. They perform a wide variety of functions, including catalyzing reactions (enzymes), providing structure, and regulating processes.

• Amino Acids: The monomers of proteins, each containing an amino group, a carboxyl group, a hydrogen atom, and a unique side chain (R group).

• Peptide Bond: The covalent bond formed between amino acids during protein synthesis.

• Protein Structure: Proteins have four levels of structure: primary (amino acid sequence), secondary (alpha helices and beta sheets), tertiary (3D folding), and quaternary (multiple polypeptide chains).

• Functions: Enzymes, structural proteins, transport proteins, antibodies, etc.

Lipids

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

• Saturated vs. Unsaturated Fats: Saturated fats have no double bonds between carbon atoms (solid at room temperature), while unsaturated fats have one or more double bonds (liquid at room temperature).

• Trans Fats: Unsaturated fats with trans double bonds; associated with negative health effects.

• Phospholipids: Major components of cell membranes, with hydrophilic heads and hydrophobic tails.

• Example: Cell membrane structure is based on a phospholipid bilayer.

Ch. 4: Cell Structure and Function

Overview of Cell Theory

The cell theory is a fundamental concept in biology that describes the properties of cells, the basic unit of life.

• Three Parts of Cell Theory:

  1. All living things are composed of one or more cells.

  2. The cell is the basic unit of structure and function in living things.

  3. All cells arise from pre-existing cells.

Cell Types and Organelles

Cells are classified as prokaryotic or eukaryotic. Eukaryotic cells contain membrane-bound organelles, while prokaryotic cells do not.

• Prokaryotic Cells: Lack a nucleus and membrane-bound organelles (e.g., bacteria).

• Eukaryotic Cells: Have a nucleus and membrane-bound organelles (e.g., plants, animals, fungi, protists).

Major Organelles and Their Functions

How Organelles Work Together

Organelles interact to carry out the functions necessary for cell survival. For example, the nucleus provides instructions for protein synthesis, ribosomes build proteins, the ER and Golgi apparatus modify and transport them, and mitochondria provide the energy required for these processes.

• Example: The endomembrane system (nucleus, ER, Golgi, vesicles) coordinates the production and transport of proteins and lipids.

Summary Table: Prokaryotic vs. Eukaryotic Cells

Additional info: Some details, such as the specific chemical structure of functional groups or the full list of organelles, were inferred based on standard General Biology curricula.