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Dalhousie University
BIOL 1010

Biology: The Eukaryotic Cell 9/10/2013 10:35:00 AM Essential cell activities:  Obtain energy  Exhibit selective permeability  Interpret and use information in DNA  Separate chemical reactions from one another  Reproduce  ACRONYM: ESOIR Discovery of Cells  1660 – microscopes  ―cells‖ term coined by Robert Hooke o took a piece of cork thinly sliced and examed in and saw the ―cells‖ which remineded of him of the monestary where monks lived, better known as cells, hence the term.  1670s – Anton van Leeuwenhoek  made many microscopes and looked at everything; he sold cloth (merchant) he used microscopes for thread count o first to see sperm cells and bacteria (he drew them)  1838 – Schleiden and Schwann  all organisms composed of one or more cells. Structural unit of lie  1855 – Virchow  cells can only arise by division from a pre existing cell Two Types of Cells:  Prokaryotes  no membrane bound nucleus/ no membrane bound anything o PRO meaning BEFORE / KARYOTES meaning NUCLEUS o Bacteria and archaea  Eukaryotes  compartmentalized o Protists, fungi, animals and plants o EU meaning TRUE A Bit About Sizes:  1000 microns in 1mm  Our eye balls can only see around 200 microns  most eukaryoteic cells are between 10 and 100 microns Endomembrane System:  Nucleus: largest organelle in the cell o red blood cells don‘t have nuclei unless a bird or fish o Chromatin = DNA + Proteins o There is some DNA outside the Nucleus, but for the most part is is capped inside. o Nucelus has two membranes o Nuclear Envelope has two sides: facing outside of nucleus and facing DNA hence, ENVELOPE o DNA  RNA ( mRNA, tRNA, rRNA) o DNA  In nucleus = transcription ---- RNA In cytoplasm = translation ----- Protein o Nuclear Lamina – kind of like a cement, protection of nucleus o Nucleolus : RNA is made, and combines with proteins to make ribosomes To send message, use mRNA, tRNA deciphers the code, and rRNA is ribosomal RNA  Ribosomes: large and small subunits o rRNA and protein o make protein o found free in cytosol  attached to membrains (endoplasmic reticulum and nucleus)  mitochondria and chloroplasts  Endoplasmic Reticulum: rough / smooth o Rough because ribosomes are attached  They make proteins for protein synthesis:  Proteins to be exported out of cell  To be incorporated into membranes  To be importaed into other organelles  An address is put on when the synthesis happens and the ribosomes move to the membraine based on that address o Smooth because no ribosomes—DUH  TWO main functions: lipid synthesis and detoxification (add OH groups to make the stuff more soluble; the liver does this)  Golgi Apparatus: o Each stack – not connected to each other; each stack is called a cisternae o Formed from ER vesicles o Cis, medial and trans cisternae (POLARITY) o Vesicles o FUNCTIONS: manufacturing (adding sugars), sorting, storing, and shipping SSS&M ;) o Cisternal Maturation Model  Lysosome o Come from the Golgi o Vesicles  hydrolytic enzymes (breaking water or substances, NOM NOM NOM) - acidic pH o Intracellular digestion  PHAGOCYTOSIS (cell eating)  Lysosomes do not eat themselves (the membranes they do eat is sugar coated, like candy= yummy for them! It‘s like why we don‘t eat our own stomach its acidic, mucus and produces ulcers, so same idea)  AUTOPHAGY (self eating) – its like anorexia  when the body has nothing left to eat and there is no food, it will start to eat itself to survive to gain protein  Mitochondrua o Energy synthesis (ie ATP synthesis) o Outer and inner membranes, matrix, intermembrane Space and Ribosomes: 2 membranes are not continuous; the inner membrane goes backwards and forwards to form cristae  Inside the inner membrane is the matrix (jelly like material full of proteins, containing ribosomes and DNA)  Mitochondrial DNA: CIRCULAR and all maternal  mother‘s mitochondria. o Endosumbiont Theory: membrane of larger cell + membrane of smaller cell  double membrane  Cytoskeleton: Microfilaments (7nm thick), microtubules (25 nm thick), intermediate filaments (10-14 nm thick) o Made up of proteins o Intermediate filaments: Required to keep a firmness and structure of cell o Functions: mechanical support (structure to cell) and movement/motility (only microfilaments and microtubules) o Microfilaments: made of protein actin (made up of amino acids)  assemble like rod like structure and is two fibers about 40% of protein in cell is active  where the cell moves, forms fibers that run the length of the cell (stress fibers) and not all actin are the same; works with the protein myosin  Functions of Microfilaments:  Changes cell shapes  Move organelles organelles are attached and they move by the motoral  Cell division (cytokinesis)  Muscle contraction: actin forms the tracks; discovered by Huxley o Microtubules: hollow tubes  tubulin alpha tubulin and beta tubulin  at the centre, the microtubules radiate from the negative end (or the centre)  centrosome = mtoc microtubule operation centre  act as railway tracks for motility within the cell  MOLECULAR MOTORS/ KINESIN = move towards outside of cell ―+‖ end directed movement  MOLECULAR MOTORS / DYNEIN = move towards inside of cell ―-― end directed movement  At the centrosome is the microtubules organizing centre of the cell. Nine groups of microtubules, each one has three  Grow from the centrosome out towards the cell membrane  Microtubules form cilia and flagella  When you‘re hungry and you eat a lot, ―went down the wrong tube‖, those pieces trapped in the cilia and it queues and makes you cough it back.  The internal structure is called the Axoneme ―9+2‖ pattern  Nine doublet microtubules + two single microtubules in centre  Cilia and flagella attached to the cell at the BASAL BODY ―9+0‖ pattern  Membrane around the cilia or flagella; motor molecule dynein allows them to move;  The dynein molecules only move a small distance and cause the flagella to bend; o Intermediate Filaments  Intermediate in size  Stabilize cell structure  Very strong, resist tension  No motility, no motor moleculles  Variety of different proteins  KERATIN: finger nails, horns (hard keratins); soft keratins are good for skin  it allows you to go swimming without dissolving its like a waterproofing  Tissues: nerve cells, blood cells all have intermediate filaments o Extracellular Matrix is found on the OUTSIDE of the cell  Outside the cell – cell membrane – inside the cell  The ECM is mainly composed of glycoproteins (protins attached to sugar chains)  collagen is an example of a glycoprotein (wrinkly skin is caused by collagen going bad)  Proteoglycans: lots of sugar but very little protein; also for cushioning layer; water layer to outside of the cell (fibernectin linked up to proteoglycans)  Functions: cell migration; coordinate cell bejaviour  Cells connected to other cells via Junctions o Tight junctions  fuze the membranes of two cells together to prevent any liquid or food from going between the cells. o Desmosomes  proteins that use calium to connect the cells; like carrots going theough the cell; desosomes provide strength to cells ‗  o Gap junctions  connect two cells and allow cells to communicate as a tissue; they play major part in heart: electrical stimuli to help the heart beat; sends signals to heart to help beat heart through communication through junction  Small hole between cells so tiny signaling molecules can ove between the two cells Clicker Questions/ Answers 9/10/2013 10:35:00 AM The medial cisternae of the golgi complex are primarily formed from what?  the maturation of the cis, cisternae An amino acid with a hydrophibic side chain will most likely to be found where in the protein?  Tucked inside What kind of macromolecule is omega 3  Lipid What organelle makes cholesterol?  Smooth ER Which of the following is NOT a component of membraines?  They are all (look it up) Whcich statement is false regarding NA/K pump Is Glycolysus aerobic or anaerobic?  Anaerobic If pyruvate is ozidezed do you expect that electrons and hydrogens will be added or removed?  Removed  Lecture 3: Macromolecules: 9/10/2013 10:35:00 AM 1. Carbohydrates (ie sugars) 2. Lipids (ie fats) 3. Proteins 4. Nucleic Acids (dr right will cover) Monomer #1 +Monomer #2  NEW POLYMER!  ALSO PRODUCES h2o  Many macromolecules are formed via condensation reactions (also called dehydration reactions)  Condensation reactions are catalyzed by enzymes o The substraint molucules grab on to the active side and swueeze together and the bond is formed; after the thing is squeezed the enzyme is released and can be reused Long Polumer  Shorter Polymer and Monomer + H2O Carbohydrates: carbon, Hydrogen, oxygen  Molar ration of 1:2:1 (CH2O)n o N+ number of carbons  Monosaccharides are the monomer for carbohydrates (ie:glucouse) o Glucose: C6H12O6  Disaccharides: two monosaccharides linked o (ie glucose + glucose = maltose) o Glucose + Fructose = Sucrose o Glucose + Galactose = Lactose (found in milk)  Polysaccahardes = hundreds oor thousands of monosaccharides linked together  used to store carbohydrates o Example: Glycogen  can be stored for 6 hours o Important storage molecule because our brain loves it! Without it in our bloodstream, our brain can‘t function and we go brain dead! o When you eat to the point of fullness, your body wants to break down the food and your body produces insulin and because you ate so much, you produced so much insulin, your brain gets tired, making you want to sleep! :o cool!!! o Ex2: STARCH! --> amylose and amylopectin  Pasta, noodles, bread, potatoes, and rice o Ex3: Cellulose  trees, grass  Starch and cellulose are both long chains of glucose  Cellulose is beta linkage and starch is alpha linkage; our bodies can produce enzymes to break it down but our bodies do not for cellulose  Why can cows digest grass? (CLICKER)  Cows have a digesting enzyme for it.  The cellulose is modified in one of their stomachs  They can’t bacteria in their gut does it!! Correct Lipids: Fats, Phospholipids, steroids  Hydrophobic – don‘t like water  Water is a polar molecule  uneven distribution of electron clouds has a partial negative charge (delta); the hydrogens are positively charged, referred to being polar o How water sticks to warer  look in text book  Hydrocarbon‘s are not charged  they are non polar and hydrophobic  Hydrophillic and hydrophobic do NOT mix  Hydrocarbon chain with a carboxy group on end is called a fatty acid  at one end you have a carboxyl group  Glycerol molecule is removed by dehydration reaction and we get a covalent bond, referred to as an ester o When three of those accids are cobined, we create triglycerol  Good to have a little, because it‘s a storage fat, so it adds insulation; insulates our organs  Stored in cells  Saturated vs Unsaturated Fats: refers to whther there are double bonds in the hydrocarbon or not o Saturated = no double bonds o Unsaturated = double bonds o Most animal fats are saturated o Unsaturated: double bonds form a kink in one of the tails and doesn‘t allow the two bonds to link and forms an oil (like olive oil) when it happens its polyunsaturated o Cis isomer: the two Xs are on the same side, so it will form a bend o Trans isomer: the two Xs are on opposite sides  so trans has no bend o Hydrogenated vegetable oil‘s DO NOT
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