General Biology Lab 5 Notes PDF

Stage: 1 - Lab: 5 General Biology Humam Saadi The Structure and Function of Cellular Organelles Cell Theory The cell is the smallest unit of life. All organisms are composed one or more cells. New cells arise from previously existing cells. The Nature of Cell...

Stage: 1 - Lab: 5 General Biology Humam Saadi The Structure and Function of Cellular Organelles Cell Theory The cell is the smallest unit of life. All organisms are composed one or more cells. New cells arise from previously existing cells. The Nature of Cells Each cell has four common components: 1. Plasma membrane 2. Region containing DNA 3. Cytoplasm 4. Mitochondria Two fundamental types: Prokaryotic: (No Nucleus, No organelles, Small 100nm-5µm) 1 Eukaryotic: (True Nucleus, Membrane bound, organelles, 10-100um, some are larger). Cell Wall - Provides support - Gives shape - Protection of internal structures - Prevent loss of water Composition - Cellulose, Pectin, hemiocellulose - Callose, structural proteins - Layers: o Primary cell wall o Secondary cell wall o Middle lamella (pectin-rich) 2 Cell Membranes and Transport [Plasma Membrane (Fluid mosaic model)] Protein molecules bobbing in phospholipid sea Proteins determine membrane’s specific functions Movement of a substance A. Passive Transport Molecules transfer from an area of high concentration to an area of low concentration and does not require energy, which is in 3 types: 1. Diffusion: Movement of a substance (solute) from an area of high concentration to an area of low concentration. 2. Osmosis: Movement of H2O across a Semi-permeable membrane. 3. Facilitated Diffusion: Molecules that can’t go through the lipid bilayer must pass through proteins 3 B. Active Transport: Molecules transfer from an area of low concentration to an area of high concentration and does require energy. Structure of the Cell Membrane Phospholipids Most abundant lipid Polar/hydrophilic head (attracted to water), Pair of nonpolar/hydrophobic tails (repelled by water). Phospholipid bilayer: - Polar heads, outside & inside - Nonpolar tails in the interior Cytoplasm Viscous fluid containing organelles, components of cytoplasm, interconnected filaments & fibers. - Fluid = cytosol - Organelles (not nucleus) - storage substances Cytoskeleton Filaments & fibers Made of 3 fiber types (Microfilaments, Microtubules, Intermediate filaments) 4 3 functions: - Mechanical support - Anchor organelles - Help move substances Nucleus  Large, round structure usually located near The center of the cell.  It is the control center for all cell activities.  DNA is stored here!  Double membrane Contains – Chromosomes – Nucleolus Nuclear Envelope [Separates nucleus from rest of cell, Double membrane, has pores] DNA Hereditary material – Chromosomes: [DNA, Proteins]. – Chromatin Nucleolus Most cells have 2 or more Directs synthesis of RNA Forms ribosomes 5