Biology Final Exam Study Materials 1

Biology - Final Exam Study Materials (Semester 1)

• Lipids: Lipids are fatty compounds with various functions in the body. They are hydrophobic (water-fearing), which makes them insoluble in water. Four major types are triglycerides, phospholipids, steroids, and waxes. Triglycerides are found in animal fats and plant oils, consisting of fatty acids and glycerol. Phospholipids are crucial components of plasma membranes, having both hydrophobic and hydrophilic regions. Steroids, like cholesterol and hormones, have a four-fused ring structure. Waxes are found in plant leaves, ear wax, and honeycomb. Saturated fats have no double bonds, which makes them solid at room temperature. Unsaturated fats have at least one double bond, being liquid at room temperature.

Proteins

• Structure: Proteins are polymers made of amino acids bonded together. The unique side chains (R groups) of amino acids give each amino acid distinct chemical properties. The structure of a protein has four levels: primary, secondary, tertiary, and quaternary. The primary structure is the sequence of amino acids. Secondary structure involves folding patterns like alpha-helices and beta-sheets. Tertiary structure is the 3D shape formed by folding, and quaternary structure is formed when multiple polypeptide chains interact. Protein shape is sensitive to the environment. A change in temperature, pH, or other factors can cause a protein to unravel (lose its structure.)

Nucleic Acids

• General Structure: Nucleic acids are polymers of nucleotides, serving as blueprints for proteins and cellular activities. Nucleotides consist of a five-carbon sugar, a phosphate group, and a nitrogenous base. There are two main types: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). DNA and RNA have slightly different sugars and bases. Both are double stranded forming a helix. DNA stores genetic information, while RNA helps in protein synthesis.

Cell Categories

• Prokaryotic vs. Eukaryotic: Biologists classify all life into three domains. Prokaryotic cells are those of bacteria and archaea and lack a membrane-bound nucleus. Eukaryotic cells, those of protists, fungi, plants, and animals, have a membrane-bound nucleus. Eukaryotic cells are typically larger than prokaryotic cells and contain organelles. Prokaryotic cells are simpler in structure, whereas Eukaryotic cells are much more complicated.

Cellular Structures

• Prokaryotic: Key features of prokaryotic cells include a simple structure, a lack of nucleus, circular DNA, and no membrane-bound organelles.
• Eukaryotic: Eukaryotic cells are more complex, have a membrane-bound nucleus, linear DNA, internal membrane-bound organelles like the endoplasmic reticulum, Golgi apparatus, mitochondria, lysosomes, and vacuoles, as well as a plasma membrane and cytosol.

Membrane Structure

• Cell Membrane: The plasma membrane, a thin phospholipid bilayer, separates living cells from their surroundings. It is selectively permeable, allowing some substances to pass through while preventing others. Proteins and cholesterol embedded in the bilayer contribute to its structure and function, forming a fluid mosaic. The surface of most animal cells often contains cell junctions. Plant cells have a cell wall made of cellulose that surrounds the plasma membrane, contributing rigidity and protection..

Microscopes

• Light Microscopes: Uses visible light and glass lenses to magnify up to 1,000x.
• Transmission Electron Microscopes (TEM): Uses an electron beam transmitted through thin samples for high resolution, up to 1,000,000x.
• Scanning Electron Microscopes (SEM): Uses an electron beam to scan the surface of a sample to acquire images of the surface texture, and provides high resolution for surface detail.