BIOl 1441 1st Edition Lecture 9 Outline of Last Lecture I Proteins a Side groups b Levels of protein structure II Nucleic acids a Structure Outline of Current Lecture I Microscopy II Cell classification III Cell size IV Cell organelles Current Lecture The Importance of Cells All organisms are made of cells The cell is the simplest unit of life Cell structure is correlated to cellular function All cells are related by their descent from earlier cells Fundamental themes in biology 1 Structure Function 2 Cells respond to their environment These 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 I II III Microscopy a Discovery of microscope in 16th century enabled us to study cells their components b Light microscope visible light to magnify an image i Passes light through a specimen then through glass lenses ii Lenses refract bend light magnifying the image c Light Microscopy i Magnification ratio of an object s image size to its real size 1 Multiple objective lens 4x times ocular lens 10x 40x ii Resolution measure of the clarity of the image 1 Minimum distance 2 points can be separated and still be distinguished as 2 points 2 Shorter wavelength better resolution iii Minimum resolution 200 nanometers nm iv Magnify effectively to 1 000 times the size of the actual specimen v Various techniques enhance contrast and enable cell components to be stained vi Most cellular organelles too small to be resolved d Electron Microscopy i Scanning electron microscopes SEMs focus a beam of electrons onto the surface of a specimen 1 Provides 3D image ii Transmission electron microscopes TEMs focus a beam of electrons through a specimen 1 Mainly to study the internal ultrastructure of cells iii Electrons shorter wavelength than visible light better resolution clarity 1 Resolution 2 nm much smaller Prokaryotic Eukaryotic Cells classify by whether or not they have a nucleus a Basic features of all cells i Plasma membrane ii Cytosol fluid inside cell iii Genetic information iv Ribosomes make proteins v Cytoplasm interior of cell 1 Used interchangeable with cytosol Prokaryotes vs Eukaryotes No nucleus Nucleus Cell wall No cell wall No membrane bound organelles Membrane bound Smaller Larger Simple Complex bacteria IV V plants animals fungi protists Cell Size plasma membrane limits a Logistics of carrying out cellular metabolism sets limits on the size of cells b Needs a certain level of metabolic ability to support all reactions taking place inside i Large cell high level of metabolism ii Small cell lower level of metabolism c Cell can only grow to the extent that it can support itself d Increase size increase volume surface area e Volume increases MORE than the surface area not proportional surface area only increases a little i Smaller object has a greater surface to volume ratio than a larger object ii High surface to volume facilitate exchange of materials between cell and its environment f Area calculated in square units l x w g Volume calculated in cubic units l x w x h Cell Organelles a Plasma Membrane Selective barrier that allows sufficient passage of oxygen nutrients waste to service the volume of the cell i Surface area must be sufficiently large to accommodate volume explains microscopic size ii Larger organisms do not have larger cells they have MORE cells iii Function exchange material with surroundings need a lot of surface area 1 Intestinal epithelial cell microvilli 2 Long thin projections 3 Increase surface area not volume b Nucleus i Nucleus contains DNA only genomic 1 Some genes mitochondria chloroplast ii Nuclear envelope encloses the nucleus separating it from the cytoplasm 1 Double membrane phospholipid bilayer iii Nuclear lamina lines inside of the nuclear membrane 1 Netlike array of protein filaments maintains the shape iv Nuclear matrix framework of fibers extends throughout the nuclear interior v Chromosomes DNA in discrete units coiled super tight only right before division vi Chromatin complex of proteins and DNA 1 Human Cell 46 Chromosomes 2 BOTH CHROMOSOMES AND CHROMATIN HAVE PROTEIN AND DNA CLASSIFIED ON HOW TIGHTLY THEY ARE COILED vii Nucleolus 1 Ribosomal RNA rRNA is synthesized 2 rRNA is assembled into large small subunits 3 DNA mRNA Protein c Ribosomes i Make proteins using DNA as directions 1 Makes all the same proteins but in different locations depending on what type of protein ii Made of rRNA and protein iii Ribosomes carry out protein synthesis in two locations 1 In the cytosol free ribosomes 2 On the outside of the endoplasmic reticulum ER bound ribosomes d Endomembrane System i Components of the endomembrane system 1 Nuclear envelope 2 Endoplasmic reticulum 3 Golgi apparatus 4 Lysosomes 5 Vacuoles 6 Plasma membrane ii Components are either continuous or connected via transfer by vesicles iii Endomembrane System Functions 1 Synthesize proteins 2 Transport proteins into membranes organelles 3 Transport proteins out of cell 4 Metabolism movement of lipids 5 Detoxification of poisons e Endoplasmic Reticulum ER i Accounts for more than 1 2 the total membrane in many eukaryotic cells ii Consists of tubules and sacs cisternae iii There are two distinct regions of ER 1 Smooth ER which lacks ribosomes 2 Rough ER with ribosomes iv ER membrane is continuous with the nuclear envelope v ER lumen cisternal space vi Smooth ER lacks ribosomes 1 Synthesizes lipids 2 Phospholipids 3 Steroids sex hormones a Testes ovaries lots of smooth ER b Most important steroid cholesterol 4 Metabolizes carbohydrates 5 Stores calcium muscles f 6 Detoxifies drugs liver a Make more soluble secrete i Add a hydroxyl group vii Rough ER bound ribosomes 1 Produces secreted proteins a Hormone insulin from pancreas cells 2 Polypeptide chain goes into ER lumen through a pore in ER membrane a Folded into native conformation PROTEIN FOLDING b Secreted proteins glycoproteins c Protein covalently bonded to a carbohydrate 3 Secretory proteins distributed by transport vesicles a Depart ER wrapped in membranes from transitional ER b Transport vesicles vesicles moving from one area of cell to another 4 Makes membranes 5 Polypeptide grows from ribosome inserted into ER membrane a Anchored by hydrophobic portions b Transferred in transport vesicles Golgi Apparatus not as big as rough ER i Products of ER modified and stored sent out ii Cells involved in secretion lots of golgi iii Flattened membrane sacs cisternae iv