BIOLOGY 315 1st Edition Lecture 2 Outline of Last Lecture I. Introductiona. Levels of Structureb. ScaleII. Directional Termsa. Anatomical Positionb. Body PlanesIII. Studying Cells and Tissuesa. Preservationb. Sectioningc. StainingOutline of Current Lecture I. Light Microscopy vs Electron MicroscopyII. The Cella. The Parts of the Average Celli. 3 basic partsCurrent LectureI. Light Microscopy vs Electron Microscopya. Light microscopy (LM)i. Used for viewing cells within tissues ii. Sharper image at lower magnificationiii. Color stainedb. Electron microscopy (EM)i. Sharper image at higher magnificationsii. Used for viewing structures within a cell, organellesiii. Always black and whiteiv. Requires better fixatives because the smallest structures must be preserved v. Uncolored stains are heavy metal salts (osmonium tetroxide, uranyl acetate, lead citrate) act as fixativesvi. Shoots a beam of electrons through a sectioned specimenvii. Electron beams have much shorter wavelength than light, so resolution is much higherII. The CellThese 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. Smallest living part in the bodyb. About 200 different major cell typesc. Cells of different types have different functionsi. Although all cells share the same organelles, different organelles predominate in different cell typesd. The Average Celli. 3 basic parts: plasma membrane, cytoplasm, and nucleusii. Plasma Membrane (plasmalemma)1. Outer cell membrane, consists of proteins and lipids2. 3 layer (trilaminar) in EM, but really only bilayer (formed by phospholipid molecules)3. Cholesterol: lipid in the membrane used to stabilize the membrane so it won’t break into little sacs4. Proteins span the width of the membrane5. Coat of sugar chains, the glycocalyx or cell coata. Makes cells sticky for temporary adhesion to other cellsb. Acts as a fingerprint for each cell, because each cell has a different arrangement of sugars in the glycocalyxc. Thick enough to protect the plasmalemma and the cell6. Function: a. Interference between the inside and outside of cellb. Determines what gets in and what goes outi. Pumps and Channels in the membranec. Receptors: receive chemical signals from outside the cell, cell-to-cell communicationd. Protection7. Unit membrane: bi-layered membranes within the cell form walls of some organellesiii. Cytoplasmic components1. Cytosol (cytoplasmic matrix)a. Shapless part of the cytoplasm, occupies the empty spacesbetween organelles b. Made up of water, ions, other small molecules, and enzymes that direct the cell’s biochemical reactionsc. Makes up ½ of the volume of cytoplasm2. Organelles:a. Ribosomesi. Small dark circles in EM picturesii. Consist of 2 subunits, looks like cap and body of an acorniii. Made of RNA bound to proteiniv. Function: synthesize all cell’s proteins, assemble amino acids into protein chainsv. Some free in the cytosol and others attached to RERb. Rough (or granular) endoplasmic reticulum (RER)i. Structure: 1. stacked, membrane-walled envelopes (cistern), some are tubes or little spheres2. form extensive network of cavities throughout in cytoplasm, which are lined bythe unit membrane3. covered by ribosomes4. well developed in the cells that make and secrete proteinsii. Function:1. Makes protein products that will be secreted from the cell2. Makes all the external and internal unit of membranes of cells3. Membrane Factoryiii. Move readily between the RER and Cytosolc. Smooth (Agranular) Endoplasmic Reticulum (SER)i. Network of branched membrane-walled tubules (not flattened envelopes like RER)ii. No attachment to ribosomesiii. Continuous with RERiv. Usually involved in lipid metabolism (making or breaking down fats)v. Gathers calcium ions from the cytosol and stores themvi. Most cell types have very little SERd. Mitochondrion (plural: mitochondria)i. Structure: 1. Most complex organelle2. Drawn bean-shaped, but actually really longand rod shaped3. Covered by 2 unit membranes a. Inner forms shelf-like folds called cristae, increases the membrane area of the mitochondriai. Inbetween the cristae= matrix granules4. Have own RNA, DNA, ribosomes and self replication ii. Function: 1. Generate the energy needed for the cell, by breaking down sugars in the presence of oxygen to form carbon dioxide and water2. Occur in matrix, Kreb’s cycle, and the cristae3. Furnish ATP to do the work for the cell4. # of mitochondria present in a cell type is proportional to the cell’s metabolic level5. Mitochondria concentrated in parts where metabolism is highestiii. both mitochondria and endoplasmic reticulum store calciume. Lysosomesi. Structure:1. Membrane-walled sacs containing enzymes of digestive function2. Usually appear dark in EM3. Filled with cellular debris that are digestedii. Function:1. Break down worn-out organelles2. “cell’s cleanup crew”3. Destroy material that has been ingested by the cell (such as bacteria)4. Phagocytosis: “cell digesting”5. Phagocytic cells have many lysosomes in their cytoplasmf. Golgi apparatusi. Structure: 1. Near the nucleus2. Stack of hollow membrane-walled disks, cupped in each other3. Constantly changing4. Convex face (cis face) formed by vesicles coming from RER5. Other vesicles are constantly splitting off of the concave face (trans face)ii. Function:1. Concentrates and modifies secretory proteins that have been made in RER2. Acts as a sorting and packing house for the products made in the RER3. Lysosomes form by budding off of the Golgi