Week 3 of Notes
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This 6 page Class Notes was uploaded by Danielle Francy on Saturday March 5, 2016. The Class Notes belongs to Bio 190 at Towson University taught by Joseph Velenovsky in Fall 2015. Since its upload, it has received 26 views. For similar materials see Intro Biology for Health Professions in Biology at Towson University.
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Date Created: 03/05/16
Week 3 of Notes ***Chitin: ● The exoskeleton of insects and crustaceans ● Structural polysaccharide ● Cell wall of fungi Lipids: ● Hydrophobic because of fatty acids ● Nonpolar ● Glycerol alcohol found on top of lipid ● Polarhydroxyl groups ● Overall name for lipid with three tails= fat/triglyceride ○ Kinked fatty acid tail ○ Unsaturated ○ Kinks prevent tight molecular packing Trans Fat: ● All bonds are ‘cis’ in direction ● Can change the double bonds ● long term energy storage Mono vs Poly Unsaturated Fat: ● Single double bonds ● Multiple double bonds ● ***Top group is cholinetwo tails ● Choline, phosphate, and glycerol=very hydrophilic Cholesterol: ● Steroid four rings ● Animal cell membranes ● Cholesterol is the four rings plus the extra top pieces ● Can read more about this in 1.11.3 and 4.1 of our book ***Cell Theory: ● All things are composed of cells ● All cells come from other cells Cells: ● Need surface area large enough to service the volume of a cell ● Active cells have a huge amount of traffic across their outer surface (oxygen, nutrients, waste, etc) ● Need surface area/volume ratio that is favorable to functions ● Cell site governed by the ability to perform cellular functions Plasma Membrane: ● Not the same as phospholipid bilayer ● When you add proteins, it will become a plasma membrane ● Regulates traffic in the cell ● Nonpolar O2 CO2 ● Ions and polar molecules ● Channel proteins ● Pumps ● Semipermeable Functions of Plasma Membrane: 1. Limiting boundary ● Separate and protect cell from its environment 2. Transport (in and out) 3. Identification and recognition 4. Communication ● Receptor protein empty ○ ex. insulin Prokaryotic Cells: ● Bacteria and archaea ● No membrane enclosed nucleus ● Nucleoid ● Cell walls ● Membrane enclosing the cytoplasm= plasma membrane ● Protects and maintains shape=cell wall ● No lysosomes ● ex. Penicillin ● Much smaller than eukaryotic cells ● DNA is circular; no limiting membrane; nucleoid ● Very few organelles ● Ribosomes are smaller than ribosomes in eukaryotes Eukaryotic Cells: ● Organelles ● Membrane bound ● Animal or human cells ● Not in animal cells: ○ Central vacuole ○ Chloroplast ○ Cell wall ○ Plasmodesma ● Larger in size than prokaryotic cells ● DNA is linear and paired; within membrane; true nucleus ● Many organelles; most enclosed in 12 membranes ● Ribosomes are larger than those of prokaryotes Cytoskeleton: 1. Microfilament 2. Intermediate filament 3. Microtubule Microfilament: ● Structure holding the cell together ● How the cell moves ● Thinnest fiber ● ***Composed of Actin ● Solid rods ● Mainly globular proteins (Actin); twisted double chain ● ***3D network just inside the plasma membrane ● Supports cell’s shape ● Muscle Cells (Actin and Myosin) Intermediate Filament: ● ***Fibrous subunits ● Various fibrous proteins ● Supercoil into thicker cables ● ***Reinforce cell shape and anchor organelles ● Nucleus is held in this way ● Generally permanent (microfilaments can be disassembled and reassembled elsewhere) Microtubule: ● Tubulin subunits ● Globular proteins called tubulin proteins ● Elongate by the addition of tubulin proteins(2 subunits) ● Can be disassembled and reused elsewhere ● Microtubule organizing center near the nucleus ● ***Centrioles (cellular division)= where microtubules come from ● Support and shape for cells ● Train tracks for organelles ● Guide chromosomes during cellular division ● Main component of cilia and flagella Extracellular Matrix(ECM) ● Tissues and protection ● Main component= glycoproteins long polysaccharide and complex ● Strong and abundant=collagen fibers ● ECM attaches to cell ● Influence each other ● Integrin directly affects/influences cellular behavior Tight Junctions: ● Neighboring cells and digestive tract. ● Water tight seal ● Looks like the adjacent membranes are sewn together ● Forms a watertight seal between two membranes ● Prevent passage of material between the cells ● Seen in intestinal epithelium where they prevent the passage of gut contents between gut lining cells Anchoring Junctions(aka desmosomes): ● Plasma membrane pressed and knit ● Screws fasten cells together into sheets ● Composed of Intermediate filaments ● Common in skin and heart muscle ● Stretching or mechanical stress ● Connect the intermediate filaments of the cytoskeletons of adjacent cells(desmosomes) ● May also anchor a cell’s intermediate filaments to the ECM ● Provide mechanical strength to the tissue by connecting many cells firmly together ● Seen between keratinocytes in the skin epidermis, where the multiple layers of dead, but firmly connected keratinocytes form the barrier that separates you from the environment Gap Junctions: ● Communicating junctions ● Allow small molecule ions in the cell ● Form pores that provide direct connection between the cytoplasm of adjacent cells ● Allow flow of molecules and ions from one cell to the next ● Permit communication between adjacent cells that coordinate the tissue’s reaction to stimuli Plasmodesmata: ● Keeps plants upright ● Cellulose and other polysaccharides and proteins ● Primary cell wall is thin and flexible ● Some cells add secondary cell wall ● Lignin ● Pectin glues cells together(polysaccharide) ● Plasmodesmata prevents isolation ● Water, nutrients, and chemicals Diffusion: ● Concentration gradient ● Movement of atoms/ions/molecules down their concentration gradient ○ From area of high concentration to area of low concentration ○ No external energy input needed ○ Energy for net movement comes from potential energy of concentration gradient ○ If 2 or more components are present, each moves down its own concentration gradient(generally in opposite directions) Passive Transport: ● O2 ● Ions and polar molecules Osmosis: ● Selectively permeable membrane ● Permeable to water, not solute(salt) ● Low water, high solute ● High water, low solute ● Water molecules cluster around solute molecules ● Fewer water molecules on the right side ● Movement of water molecules from high concentration to low concentration through a membrane Tonicity: ● RBC in plasma(isotonic) ● Osmoregulation ● Turgid is good(normal) for plant cell ● The amount of solute in a solution ● If one solution has the same amount of solute as another solution; the two solutions are isotonic to each other ● If one solution contains more solute than another solution, it is hypertonic to the other solution ● If one solution contains less solute than another solution, it is hypotonic to the other solution ● Isotonic ○ Same=normal ● Hypertonic ○ More=shriveled ● Hypotonic ○ Less=burst