Lecture 2: The Cell & its Organelles (PDF)

Department of Biology CAS, UP Manila Lecture 2 The Cell & its Organelles Kimberly B. Benjamin Instructor, Bio 110 Lecture Outline 01 Overview of the Cell 02 Cell Organelles 03 Eukaryotic versus Prokaryotic cell 04 Plant versus Animal cell 05 Cellular regulation How does the intern...

Department of Biology CAS, UP Manila Lecture 2 The Cell & its Organelles Kimberly B. Benjamin Instructor, Bio 110 Lecture Outline 01 Overview of the Cell 02 Cell Organelles 03 Eukaryotic versus Prokaryotic cell 04 Plant versus Animal cell 05 Cellular regulation How does the internal organization of eukaryotic cells allow them to perform the functions of life? Prokaryotic versus Eukaryotic Cell Cell Organelles specialized structures within a cell that perform distinct functions necessary for the cell's survival, growth, and reproduction. Each organelle has a specific role, much like the organs in a body, and they work together to ensure the cell functions properly 1. Plasma Membrane: the dynamic barrier Provide ⚬ fixed environment inside the cell enabling incompatible 9processes to occur simulta?neously in a single cell ⚬ structural support for a cell Participate ⚬ cell’s metabolism because many enzymes are built right into the membranes ⚬ transport of ions and molecules across the membrane Protect ⚬ regulates the passage of materials into and out of the cell 03 2. Nucleus: the information center Cache/Storage and organization ⚬ genetic information (DNA) ⚬ organizes DNA it into a compact structure withthe help of histones Control/Regulation ⚬ controls which genes are turned on or off at any given time, allowing the cell to respond to changes in its environment and to carry out specialized functions. Coordination ⚬ command center of the cell, coordinating various cellular activities such as metabolism, growth, and reproduction Cell Division ⚬ ensures that the genetic material is accurately replicated and distributed to the daughter cells. Create/Synthesize 3. Nucleolus: the ribosome factory Ribosome production ⚬ produce ribosomal RNA (rRNA) and assemble it with proteins to form the subunits of ribosomes. rRNA processing ⚬ processes and modifies rRNA molecules, ensuring they are properly folded and chemically modified before being assembled into ribosomal subunits. Ribosomal subunit assembly ⚬ assembles ribosomal subunits, which are then transported out of the nucleus into the cytoplasm, where they combine to form functional ribosomes. Regulation of cell cycle & stress responses ⚬ regulate the cell cycle and responding to cellular stress 05 4. Ribosome: the protein factories Protein Synthesis ⚬ translate the genetic code carried by messenger RNA (mRNA) into a specific sequence of amino acids, forming a polypeptide chain that will fold into a functional protein. Types ⚬ Free ribosomes ￭ suspended in the cytoplasm ￭ function within the cytosol ⚬ Bound ribosomes ￭ attached to the outside of the endoplasmic reticulum or nuclear envelope ￭ make proteins that are destined for insertion into membranes, for packaging within certain organelles such as lysosomes The Endomembrane System group of membranes and organelles in eukaryotic cells that works together to modify, package, and transport lipids and proteins. includes the nuclear envelope, lysosomes, and vesicles, endoplasmic reticulum and Golgi apparatus, and plasma membrane 4. Endoplasmic reticulum: the biosynthetic factory series of interconnected membranous sacs and tubules that collectively modifies proteins and synthesizes lipids Rough ER ⚬ Protein Synthesis ￭ studded with ribosomes, which are the sites of protein synthesis ⚬ Protein folding & modification ￭ involved in their folding, modification (such as glycosylation), and quality control, ensuring that only properly folded proteins are sent to the Golgi apparatus. ⚬ Production of membrane ￭ contributes to the production of membranes by synthesizing phospholipids and integrating newly synthesized proteins into the ER membrane. 4. Endoplasmic reticulum: the biosynthetic factory series of interconnected membranous sacs and tubules that collectively modifies proteins and synthesizes lipids Smooth ER ⚬ Lipid synthesis ￭ responsible for the synthesis of lipids, including phospholipids, cholesterol, and steroid hormones. ⚬ Detoxification ￭ plays a key role in detoxifying harmful substances, such as drugs and toxins ⚬ Calcium storage ￭ stores calcium ions, which are released into the cytoplasm when needed for processes such as muscle contraction, signal transduction, and enzyme activation ⚬ Carbohydrate and steroid metabolism. ￭ involved in the metabolism of carbohydrates, such as the breakdown of glycogen into glucose. 4. Golgi apparatus: Shipping & Receiving Center as a warehouse for receiving, sorting, shipping, and even some manufactur?ing. Here, products of the ER, such as proteins, are modified and stored and then sent to other destinations Protein modification ⚬ modifies these proteins from ER by adding carbohydrate molecules (glycosylation) and other chemical groups, which are necessary for their proper functioning and destination within or outside the cell. Lipid modification ⚬ processes and modifies lipids that are produced in the smooth ER essential for the cell membrane and other cellular structures Sorting & Packaging ⚬ sorts modified lipids and proteins according to their destination Production of lysosomes ⚬ produce lysosomes, organelles containing enzymes that break down waste materials and cellular debris. Manufacture and secrete Macromolecules ⚬ polysaccharides and cellulose polysaccharides 5. Lysosomes: the digestive compartments is a membranous sac of hydrolytic enzymes that many eukaryotic cells use to digest (hydrolyze) macromolecules. Intracellular digestion ⚬ digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria Autophagy ⚬ cell breaks down and recycles its own components Phagocytosis ⚬ fuse with phagosomes (vesicles containing engulfed particles) and degrade the contents, helping the immune system eliminate pathogens. Programmed cell death ⚬ play a role in apoptosis, a controlled process of cell death that is essential for development and maintaining cellular homeostasis Extracellular digestion ⚬ lysosomes can release their enzymes outside the cell to break down extracellular materials 6. Vacuoles: Diverse Maintenance Compartment membrane-bound organelles found primarily in plant and fungal cells, as well as in some animal cells and protists. Storage ⚬ storage compartments for a variety of substances, including water, nutrients, ions, waste products, and even pigments Maintenance of Turgor Pressure ⚬ the pressure of the cell contents against the cell wall which is essential in maintaining plant’s structure Waste disposal ⚬ store waste products and isolate harmful substances from the rest of the cell, helping to protect the cell from damage. Digestion ⚬ contain enzymes that can break down macromolecules, similar to lysosomes in animal cells The Endomembrane System at-a-glance 7. Mitochondria: Chemical energy conversion sites "powerhouses" of the cell due to their crucial role in energy production. ATP Production Regulation of metabolic activity Apoptosis Calcium Storage and Regulation Synthesis of Certain Molecules Cellular activities like cellular differentiation, cell signalling, cell senescence, controlling the cell cycle and also in cell growth.  8. Chloroplast: Light Energy Capture lens-shaped organelles which are sites of photosynthesis Photosysnthesis ⚬ thylakoid-flattened interconnected sacs ⚬ granum- individual stacks comprising the thylakoid ⚬ stroma-fluid outside thylakoid which contains chloropplast DNA and ribosomes Plastid types ⚬ Chloroplast ⚬ Chromoplast ⚬ Leucoplast ￭ amyloplast ￭ elaioplast ￭ proteinoplast ⚬ Etioplast ⚬ Proplastid  9. Peroxisomes: Oxidation sites metabolic compartment bounded by a single membrane which contain enzymes that remove hydrogen atoms from various substrates and transfer them to oxygen (O2), producing hydrogen peroxide (H2O2) as a by-product. Detoxification and metabolism of harmful substances ⚬ neutralize hydrogen peroxide, a toxic by-product of cellular metabolism ⚬ metabolize other reactive oxygen species (ROS), which are harmful byproducts of cellular metabolism. Fatty acid oxidation ⚬ breakdown of long-chain fatty acids through a process called beta-oxidation. Plasmalogen biosynthesis ⚬ involved in the systhesis of plasmalogen, phospholipid that is a critical component of the myelin sheath in nerve cells, as well as in cell membranes. Glyoxylate Cycle ⚬ involved in the glyoxylate cycle, which is crucial for converting fatty acids into carbohydrates during seed germination Photorespiration ⚬ recycle the byproducts of phtorespiration 10. Cytoskeleton: organelles for support & motility a network of fibers that organizes structures and activities in the cell Structural support and shape maintenance ⚬ provides mechanical strength to the cell, helping it maintain its shape and resist deformation Cell movement ⚬ involved in cell movement through structures like cilia, flagella, and lamellipodia Intracellular transport Cell division Signal transduction Organization of cellular organelles