Biochemistry Lab - 03 The Cell

BIOCHEMISTRY LABORATORY • MODULE 3 - THE CELL LESSON 1 - TYPES OF CELLS TYPES OF CELL • • Types of Cell • • • Prokaryotic Cell o These are unicellular organisms that do not develop or differentiate into multicellular forms. They are identical and capable of independent existence. o They lack a nucleus and membranous organelles. o Include all bacteria and archaea (archaebacteria). Eukaryotic Cell o These cells contain a nucleus and membrane-bound compartments, called organelles, in which specific metabolic activities take place. o Include fungi, animals, and plants as well as some unicellular organisms. ORGANELLES • Endoplasmic Reticulum o Concerned with intracellular transport o Smooth Endoplasmic Reticulum ▪ Agranular – no attached ribosomes ▪ Site for synthesis of cholesterol & phospholipids ▪ Involved in transport of fatty acids and other lipids o Rough Endoplasmic Reticulum ▪ Granular – with ribosomes ▪ Receives proteins that synthesized by ribosomes. ▪ More extensive that sER • Mitochondrion o Motile o Also known as the powerhouse because they release energy for the cell o ATP generation happens in the MATRIX. o Undergoes self replication in a manner similar to bacterial cell division . o Contains a DNA PARTS OF A EUKARYOTIC CELL • • • Cell membrane –controls what gets in and out of the cell Cytoplasm – It is the living substance of the cell o Cytosol - It is the fluid portion of the cell. o Organelles – small, membrane-bound compartments. o Mitochondrion – It is the powerhouse of the cell o Endoplasmic Reticulum – responsible for intracellular transport o Golgi body - modifies, packages & transports proteins o Lysosome – Suicide bag of the cell o Peroxisome – Detoxifies the cell Nucleus - A rounded structure at the center of the cell that controls the metabolic activities. It contains the DNA PLANT CELL VS. ANIMAL CELL • Cell Membrane o Also called plasma membrane or plasmalemma o Semi-permeable o All membranes are phospholipid bilayers with embedded proteins Cytoplasm o Jelly-like matrix that surrounds the nucleus and is bounded by the cell membrane. o Contains dissolved nutrients, helps break down waste products, and moves material around the cell. o The living substance of the cell Cytosol o The fluid portion of a cell's cytoplasm. o It contains water, free proteins, and other substances. o Where a major part of cellular metabolism takes place. o It also contains the cytoskeleton. Structurally, plant and animal cells are very similar because they are both eukaryotic cells. However, plant cells are usually larger than animal cells. They also contain structures that are absent in a typical animal cell, such as chloroplasts, plastids cell wall and large vacuoles. On the other hand, there are organelles found in an animal cell that are absent in plant cells. These incudes centrioles, lysosomes (rarely seen in plant cells), microvilli, cilia, and filaments. PARTS OF THE CELL (PPT) • Major Parts of the Cell o Cell membrane o Cytoplasm o Nucleus • • BIOCHEML - M3 • 1 • • Golgi Complex o Stacked, flattened membranes o Transports substance to and from the cell o Modifies, packages and transports protein o Produces lysosomes Lysosomes o Simple tiny spherical sac-like structures. o Surrounded by a single membrane and contains powerful enzymes capable of digesting or breaking down all organic materials. o Known as suicide bags • cell as part of the same organism or foreign. Some proteins work like fasteners, binding cells together so they can function as a unit. Other membrane proteins serve as communicators, sending and receiving signals from other cells. Parts of the Cell Membrane: o Phosphate head ▪ Polar ▪ Hydrophilic o Fatty Acid Tail ▪ Non-polar ▪ Hydrophobic o Proteins ▪ Transmembrane Proteins ▪ Integral Proteins ▪ Peripheral Proteins CELL MEMBRANE (PPT) • • Peroxisome o Breaks down hydrogen peroxide into water & oxygen. o Detoxification of alcohol and other toxic compounds o Formed by budding off the endoplasmic reticulum • • Nucleus o A rounded structure at the center of the cell o Controls the metabolic activities. o Frequently the largest structure in the cell. o Contains the DNA • Cell Membrane o Phosphate head ▪ Polar ▪ Hydrophilic o Fatty Acid Tail ▪ Non-polar ▪ Hydrophobic ▪ Saturated Fatty Acid ▪ Unsaturated Fatty Acid o Proteins ▪ Transmembrane Proteins ▪ Integral Proteins ▪ Peripheral Proteins • Types of Transport o Active ▪ Requires energy ▪ Goes against the concentration gradient LESSON 2 - THE CELL MEMBRANE THE CELL MEMBRANE • • The cell membrane serves as a clear boundary between the cell’s internal and external environment. It is also called plasma membrane or plasmalemma. It is semipermeable with a framework of fat-based molecules called phospholipids, which prevent hydrophilic substances from entering or escaping the cell. All membranes are phospholipid bilayers with embedded proteins. Some of these proteins act as gatekeepers, determining what substances can and cannot cross the membrane. Others function as markers, identifying the Function of the Cell Membrane o Delimits the cell from its surroundings o Controls what gets in and out of the cell. o Provides attachment for the skeleton of the cell. o Receives and sends out stimuli. o Provides binding sites and receptors for enzymes and other substances. o Allows cell-to-cell recognition. o Forms specialized junctions with cell membrane of adjacent cells Proteins are Crucial to Membrane Function BIOCHEML - M3 • 2 o Passive ▪ Does not require energy ▪ Goes with the concentration gradient • • • Simple Diffusion o Diffusion is the random movement of molecules from an area of high concentration to low concentration o Requires NO energy • o • • Molecules that Diffuse through Cell Membranes ▪ Oxygen – Non-polar so diffuses very quickly. ▪ Carbon dioxide - polar but very small so diffuses quickly. ▪ Water - polar but very small so diffuses quickly. Osmosis o Osmosis is the diffusion of water across a membrane o Moves from HIGH water concentration to LOW water concentration Diffusion Across a Membrane • • • • Cells in Solutions o Isotonic - solution whose solute concentration is the same as the solute concentration inside the cell. o Hypotonic - solution whose solute concentration is lower than the solute concentration inside a cell o Hypertonic - solution whose solute concentration is higher than the solute concentration inside a cell. Cytolysis & Plasmolysis Facilitated Diffusion o Does not require energy o Uses transport proteins to move high to low concentration o Molecules will randomly move through the pores in Channel Proteins. o Examples: Glucose or amino acids moving from blood into a cell. Types of Transport Proteins o Channel Proteins - embedded in the cell membrane & have a pore for materials to cross o Carrier Proteins - can change shape to move material from one side of the membrane to the other Active Transport o Requires energy or ATP o Moves materials from LOW to HIGH concentration o AGAINST concentration gradient o Example: SodiumPotassium Pump. Active Transport Exocytosis o Molecules are moved out of the cell by vesicles that fuse the with the plasma membrane. o This is how many hormones are secreted and how nerve cells communicate with each other Active Transport--Endocytosis o Large molecules move materials into the cell by one of three forms of endocytosis. ▪ Pinocytosis ▪ Receptor-mediated endocytosis ▪ Phagocytosis BIOCHEML - M3 • 3