BIOL 101 Unit 2 Study Guide

Biomolecules

Overview of Biomolecules

  • The four classes of large biological molecules (biomolecules) are:

    • Carbohydrates

    • Proteins

    • Lipids

    • Nucleic acids

Monomers and Polymers

  • Definition of Monomer: A monomer is a small, simple molecule that can join together with other similar molecules to form larger structures known as polymers.

  • Definition of Polymer: A polymer is a large molecule that is composed of repeated subunits (monomers) linked together in a chain.

  • Example: Draw a glucose molecule (monomer) and a starch molecule (polymer).

Lipids

Chemical Properties of Lipids

  • All lipids are hydrophobic, meaning they do not mix well with water.

Fatty Acids

  • Definition of a Fatty Acid: A fatty acid is a long hydrocarbon chain with a carboxylic acid group (-COOH) at one end.

  • Drawing Example: Draw a simple fatty acid structure, e.g., octanoic acid (C8H16O2).

Trans vs. Cis Fatty Acids

  • Cis Fatty Acid: The hydrogen atoms are on the same side of the double bond, leading to a bend in the structure.

  • Trans Fatty Acid: The hydrogen atoms are on opposite sides of the double bond, resulting in a straighter structure.

Classes of Lipids

Fats and Oils

  • Function: Energy storage, insulation, and protection of organs.

  • Structure: Composed of glycerol and fatty acids.

Phospholipids

  • Function: Form biological membranes (phospholipid bilayer).

  • Structure: Composed of two fatty acids, a phosphate group, and a glycerol molecule.

Steroids

  • Function: Hormonal regulation and structural components of cell membranes.

  • Structure: Composed of four fused carbon rings with various functional groups attached.

Carbohydrates

Types of Carbohydrates

  • Monosaccharide: A simple sugar; example is glucose (C6H12O6).

  • Polysaccharide: A complex carbohydrate; examples include:

    • Starch: Energy storage in plants.

    • Glycogen: Energy storage in animals.

    • Cellulose: Structural component in plant cell walls.

    • Chitin: Structural component in fungal cell walls and exoskeletons of arthropods.

Proteins

Structure and Function of Proteins

  • Amino Acids: Building blocks of proteins, consisting of an amino group, a carboxyl group, and a side chain (R group).

  • Protein Structure: Proteins have four levels of structure:

    • Primary Structure: Sequence of amino acids.

    • Secondary Structure: Local folding into alpha helices and beta sheets.

    • Tertiary Structure: Overall 3D shape of a polypeptide.

    • Quaternary Structure: Assembly of multiple polypeptide chains.

Protein Folding

  • Definition of “Folded”: Refers to how a protein achieves its functional shape.

  • Denatured: A protein that has lost its functional shape due to various conditions such as heat or pH changes.

  • Conditions leading to denaturation: High temperatures, extreme pH levels, and high concentrations of polar substances.

Nucleic Acids

DNA and RNA

  • Flow of Genetic Information: The flow of genetic information is from DNA → RNA → protein.

Structure and Function Comparison

  • DNA:

    • Strands: Double-stranded.

    • Monomers: Deoxyribonucleotides (composed of deoxyribose, phosphate group, and nitrogenous bases).

    • Sugar: Deoxyribose.

  • RNA:

    • Strands: Single-stranded.

    • Monomers: Ribonucleotides (composed of ribose, phosphate group, and nitrogenous bases).

    • Sugar: Ribose.

Cells and Membrane Transport

General Features of Cells

  • All cells share common features: plasma membrane, cytoplasm, and genetic material (DNA).

Types of Cells

  • Prokaryotic Cells: Simple, unicellular organisms without a nucleus (e.g., bacteria).

  • Eukaryotic Cells: Complex cells with a nucleus and organelles (e.g., plant and animal cells).

  • Comparison of Plant and Animal Cells:

    • Plant cells have a cell wall, chloroplasts, and central vacuoles; animal cells do not.

Organelles and Their Functions

  • Nucleus: Contains the genetic material and controls cell activities.

  • Endoplasmic Reticulum (ER):

    • Rough ER: Studded with ribosomes; synthesizes proteins.

    • Smooth ER: Lacks ribosomes; synthesizes lipids.

  • Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion.

  • Transport Vesicles: Carry materials between organelles.

  • Mitochondria: Powerhouse of the cell; produces ATP through cellular respiration.

  • Chloroplasts: Site of photosynthesis in plant cells.

  • Central Vacuole: Stores nutrients and waste products; provides turgor pressure in plant cells.

Biological Membranes

Components of Biological Membranes

  • Phospholipid Bilayer: Composed of hydrophilic heads and hydrophobic tails.