The Cytoplasmic Membrane & Transport PDF

Group 1: THE CYTOPLASMIC MEMBRANE AND TRANSPORT  01 table of MEMBRANE STRUCTURE Composition of Membranes contents: Membrane Proteins Archaeal Membranes 02 MEMBRANE FUNCTION Permeability Tran...

Group 1: THE CYTOPLASMIC MEMBRANE AND TRANSPORT  01 table of MEMBRANE STRUCTURE Composition of Membranes contents: Membrane Proteins Archaeal Membranes 02 MEMBRANE FUNCTION Permeability Transport Proteins 03 NUTRIENT TRANSPORT Transport Event and Transporters Simple Transporters and Group Translocation Periplasmic Binding Proteins and the ABC System Membrane structure Membrane structure It is structurally weak and confers little protection from osmotic lysis, but it is an ideal structure for its major function on the cell: selective permeability. Cytoplasmic membrane surrounds the cytoplasm and separates it from the environment  Composition of membrane 1. General structure: phospholipid bilayer 2. Common fatty acids found are those with 14 to 20 carbon atoms 3. only 8−10 nanometers wide but is still visible in the transmission electron microscope 4. In transmission electron microscope, it appears as two dark lines separated by a light line 5. Unit membrane 6. Although it appears rigid in diagram, it is actually somewhat fluid, having a consistency approximating that of a low-viscosity oil 7. Hopanoids is the sterol-like membrane that strengthens most bacteria cytoplasmic membranes.  MEMBRANE proteins Membrane proteins have hydrophobic regions that span the membrane and hydrophilic regions that contact the environment and the cytoplasm.  MEMBRANE proteins The outer surface of the cytoplasmic membrane faces the environment and this interacts with proteins that bind substrates or process larger molecules for transport into the cell in gram-negative bacteria. The inner surface of the cytoplasmic membrane touches the cytoplasm and interacts with proteins and other molecules.  Types Integral proteins that are firmly embedded in the membrane. of Membrane proteins that have one portion anchored in the Peripheral membrane and in extramembrane regions that proteins point into or out of the cell. Lipoproteins: molecules that contain a lipid tail that anchors the protein into the membrane Peripheral membrane proteins interact with integral membrane proteins in important cellular processes such as energy metabolism and transport. Source: https://www.creative-biolabs.com/blog/index.php/membrane-protein-overview/  ARCHAEAL MEMBRANES Bacteria contain fatty acids on the cell membrane, whereas archaea contain phytanyl. The lipids of Archaea contain ether bonds between glycerol and their hydrophobic side chains instead of ester linkages that bond fatty acids to glycerol found in the lipids of Bacteria and Eukarya. Archaeal lipids are formed from Isoprene multiple units of the five-carbon hydrocarbon isoprene.  ARCHAEAL MEMBRANES Bacteria contain fatty acids on the cell membrane, whereas archaea contain phytanyl. The cytoplasmic membrane of Archaea is formed from either glycerol diethers (20-carbon side chains called a phytanyl group composed of 5 isoprene units) or diglycerol tetraethers (40-carbon side chains).  ARCHAEAL MEMBRANES Some archaeal membranes are lipid monolayers instead of bilayers. In the tetraether lipid, the ends of the phytanyl side chains that point inward from each glycerol molecule are covalently linked, forming a lipid monolayer membrane. Lipid monolayer membranes are extremely resistant to heat. They are widely distributed among hyperthermophilic Archaea.  ARCHAEAL MEMBRANES Archaeal lipids can also contain rings within the hydrocarbon side chains or sugars. Crenarchaeol, a lipid found in Thaumarchaeota species, contains four 5-carbon (cyclopentyl) rings and one 6-carbon (cyclohexyl) ring. The predominant membrane lipids of many Euryarchaeota species are glycerol diether glycolipids.  Understanding the Role and Mechanisms of the Cytoplasmic Membrane Function and Permeability  Membrane Function The cytoplasmic membrane is crucial for maintaining the cell’s integrity. Acts as a barrier between the cell’s interior (cytoplasm) and the external environment. Supports vital cellular functions such as selective permeability, protein anchoring, and energy conservation. Primary Functions of the Cytoplasmic Membrane Primary Functions of the Cytoplasmic Membrane Primary Functions of the Cytoplasmic Membrane  Membrane Permeability The cytoplasmic membrane is a selective barrier. Substances in the Cytoplasm: Salts, sugars, amino acids, nucleotides, etc. Hydrophobic Nature: Acts as a tight barrier, preventing the diffusion of most substances. Even small ions like protons (H⁺) cannot diffuse freely. Diffusion and Transport: Water: Can freely pass through due to its small size and polar nature. Aquaporins: Specialized proteins that speed up water movement. Larger Molecules: Require transport proteins to move across the membrane. transport proteins Transport proteins transport molecules that cannot be moved by simple diffusion across a membrane. Cell membrane transport proteins facilitate selective passage of external molecules. Each transport protein is specific for a certain molecule.  2 types of transport proteins A channel protein is a unique arrangement of amino acids that embeds in the cell membrane, creating a hydrophilic pathway for water and small, polar ions. As with all transport proteins, each channel protein has a size and shape that excludes all but the chANNEL proteins most specific molecules. image1.slideserve.com/2595404/transport-proteins-l.jpg  2 types of transport proteins Carrier proteins transport substances from one side of a biological membrane to the other. Many carrier proteins are found in a cell's membrane, but they can also be found in the membranes of internal organelles like mitochondria, chloroplasts, and nucleolus. cARRIER proteins image1.slideserve.com/2595404/transport-proteins-l.jpg  nutrient transport is an important process for cells to acquire the necessary molecules for growth, metabolism, and maintenance Transport Events and Transporters THE THREE CLASSES OF TRANSPORT SYSTEMS. Simple transport Group translocation ABC transport system THE THREE DIFFERENT TRANSPORT EVENTS UNIPORT ANTIPORT SYMPORT THREE TRANSPORT MECHANISMS Simple transport consists only of a membrane spanning transport protein, Group translocation employs a series of proteins in the transport event, and ABC transport systems consist of three components. a substrate-binding protein membrane integrated transporter ATP-hydrolyzing protein THE THREE DIFFERENT TRANSPORT EVENTS Uniporters are proteins that carry a substance unidirectionally across the membrane, either in or out. Symporters are cotransporters; they transport a molecule along with a second substance. Antiporters are proteins that transport one substance into the cell while simultaneously transporting a second substance out of the cell.  Lysosomes Peroxisomes They contain enzymes that degrade They contain digestive enzymes that hydrogen peroxide and toxic break down molecules and unwanted compounds, thereby protecting the cellular materials. cell from oxidative damage. They facilitate cellular digestion, by Additionally, they play a role in the disposing of waste, recycling synthesis and degradation of lipids nutrients, and defending against and bile acids, regulating lipid pathogenic invasions. metabolism and overall homeostasis.  simple transporters and group translocation  Simple Transporters and Group Translation Simple transporter also called lac permease enables E.coli to metabolize disaccharide sugar lactose and lactose to be transported into cells of E.coli. Proton motive force drives the transport event. Group translocation differ from simple transporter because: Energy rich organic compounds serve as driving force in transport events rather than proton motive force. During the transportation process, the transported substance is being chemically modified.  Simple Transporters and Group Translation Phosphotransferase system (PTS) is responsible for transportation of sugars such as glucose, mannose and fructose.  periplasmic binding proteins and the abc system Periplasm and ABC Transport System Periplasm: A space in gram-negative bacteria between the cytoplasmic membrane and the outer membrane. Periplasmic Binding Proteins: Play a key role in the transport of substances. ABC Transport Systems: Utilize periplasmic binding proteins, membrane transporters, and ATP-hydrolyzing proteins to move substances across the membrane. "ABC" stands for ATP-binding cassette, a structural feature of these transport proteins.  Structure of Periplasm Location: Located in between the cytoplasmic membrane and the outer membrane in gram-negative bacteria. Contents: The periplasm contains various proteins, including those involved in transport. Function: Acts as a zone where substances can be processed before entering the cell.  ABC Transport System Components of ABC Systems: Periplasmic Binding Proteins: Bind substrates with high affinity. Membrane Transporters: Span the membrane to form a channel for the substrate. ATP-Hydrolyzing Proteins: Provide energy by breaking down ATP. Diversity: Over 200 different ABC transport systems identified in prokaryotes. Function: Transport organic compounds, inorganic nutrients, and metals into the cell.. High Substrate Affinity of Periplasmic Binding Proteins High Affinity: Capable of binding substrates even at very low concentrations (e.g.,