BIO 116 1st Edition Lecture 5Outline of Last Lecture I. Phospholipid BilayerII. Osmosisa. Plantb. AnimalIII. Membrane Transporta. Passiveb. ActiveIV. Prokaryotic CellsV. Eukaryotic Cellsa. Cytosolb. Microtubulesc. Intermediate Filamentsd. Actin Filaments e. Motor Proteins f. Nucleusg. EROutline of Current Lecture II. Endomembrane System ContinuesA. Golgi Apparatus B. LysosomesC. VacuolesD. Plasma MembraneIII. Semi- Autonomous Organellesa. Mitochondria and ChloroplastsIV. Protein SortingV. Multicellularitya. Benefits and RisksVI. Transition to MulticellularityThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. Creation of the ECMCurrent LectureEndomembrane System- the organelles within the cell that have their own membranes (continued from past lecture).Golgi apparatus: found near the endoplasmic reticulum (ER) Functions: secretes vesicles, processes and sorts proteins. The pathway for a protein is as follows Nucleus ER Golgi Apparatus. Lysosomes: Break down things within the cell, using acid hydrolases, that are no longer functioning so the new one can take its place. Can also recycle worn out organelles through endocytosis. Vacuoles: often used as storage, found within plant and animal cells Plants: Generally very large. Swells or contracts to provide turgor pressure which helps to maintain cell structure. Very important to plant cell.Animals: Not generally as big or as important. Stores some material and controls turgor pressure. Plasma membrane: the phospholipid bilayer that keeps the inside of the cell in, and the outsideout. Channels: proteins with channels that allow certain materials in and out of the cell Receptors: proteins that help the cell communicate with other cells Cell adhesion: there are three types, relates to how multicellular organisms are formed Anchoring- holds cells to each other usingcadherins (proteins) OR holds cells to the ECM (discussed later) using integrins (proteins). Tight- prevents leakage between cells in areas such as the stomach or intestines using occluding and claudin (proteins). Gap- portals between cells that allow communication and the sharing of ions, nutrients, ect. These are formed by connnexon (protein) that allows anything small enough to pass through. Semi- Autonomous Organelles-Mitochondria and Chloroplasts- storage and energy for the cell. Both are believed to have evolved from bacteria that a cell engulfed. Most of the DNA from that bacteria has now moved to the nucleus of the cell in order to give the cell more control over its functions. Protein sorting: how do proteins end up where they need to be The amino acid sequence decides everything about the protein.Some proteins have ER sorting signals, this causes the proteins to be synthesized there. If they have a retention signal they stay there. If not, they are sent to the golgi in vesicles. Then, some have retention signals to stay in the golgi or signals that get them sent to lysosomes, the plasma membrane, or outside the cell. Other proteins are made entirely in the cytosol and then are given chaperone signals that transport it in unfolded form to either the mitochondria’s membrane or the nucleus’s membrane. Once there, they are released and allowed to form. Some have more chaperones to help complete this process. Chapter 10: MulticellularityIt’s important to realize that life was not always cellular. It took billions of years for the earth cool down enough after the Big Bang (14 bya- 14 billion years ago) for prokaryotes to develop (3.8 bya) and then for photosynthetic prokaryotes (3 bya) to evolve. They began to produce O2 which allowed eukaryotic cells (2 bya) to develop, finally giving way to multicellular life (1 bya). The O2 is used as a garbage bag for waste, it’s where cells dump electrons. Finally, complex animals developed (500 mya- 500 million years ago), then plants and insects (400 mya), and lastly mammals (200 mya). Benefits of multicellularity: cells can specialize to do certain functions within the wholeRisks: for the organism to survive, all cells must survive; for the cells to survive, all the other cells must also survive = cells are now very dependent TransitionCells had to develop:ECM- extracellular matrix in order to provide support for tissues (groups of cells with the same function), strength (protection of the cell), organization, and signaling (communication betweencells)Structural Proteins Fibronectin and Laminin: connects cells to the ECM and organizes the ECMAdhesive ProteinsElastin: gives ECM the ability to stretch and recoil Collagen: forms fibrous networks for the ECM, provides tensile strength, 25% of human’s protein is collagen*forms as a triple helix of strands *there are 27 different types, need to know 4 of the sites of collagen synthesis:1) tendons, ligaments, bones, and skin: rigid and thick, there’s lots of it2) cartilage, disks, between vertebrae: more flexible than type one, allows joints to move smoothly3) arteries, skin, internal organs, around muscles: thin, mesh like, allows elasticity in tissues4) skin, intestines, kidneys, around capillaries: meshwork that helps organize and support cell