Week 2 notes- Chapter 3
Week 2 notes- Chapter 3 EXSC 223 001
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This 5 page Class Notes was uploaded by Chase Heffron on Friday September 4, 2015. The Class Notes belongs to EXSC 223 001 at University of South Carolina taught by Thompson in Summer 2015. Since its upload, it has received 179 views. For similar materials see Anatomy and Physiology 1 in Physical Education at University of South Carolina.
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Date Created: 09/04/15
First assignment posted on Blackboard Submit as PDF Important terms are underlined Larger topics and more important concepts are bolded Chapter 3 continued Plasma membrane phospholipid bilayer Cholesterol makes the membrane more solid in warm conditions exible in cooler conditions Glycolipid phospholipid that has essentially had sugar added to it These are attached sugar groups to the membrane Integral membrane Proteins these are involved in transport functions channels carriers Unique in that they have hydrophobic and hydrophilic components Hydrophilic portion sticks out center portion is hydrophobic Peripheral proteins sit either on the outside or inside of membrane typically smaller hydrophilic Enzymes or intracellular signaling molecules Glycoprotein when a protein has a sugar attached to it Most proteins on the outside of the cell are glycosylated Play a key role in distinguishing you from foreign substances in your body Serve as an ID tag that are specifically recognized by other cells During a tissue transplant your body tries to destroy foreign tissue because it does not recognize the glycoproteins Fuzzy coat on outside of cell membrane this is called the glycocalyx branching sugar groups attached to proteins facing extracellular space Transport and Digestion Substances moved through membrane in 3 ways Passive Transport Active Transport Vesicular Transport Passive Transport simple diffusion fat soluble molecules can cross membrane simply by diffusion Small fat soluble molecules lipids ex Oxygen and steroids can cross through the membrane to narrow the concentration gradient Facilitated Transport Done through an integral protein Channel proteins allow one or a couple ions cross through at a time These channels are usually specific to ions Carrier proteins will allow lipid soluble molecules glucose amino acids to cross through Osmosis is the diffusion of water through the membrane Water molecules cross through aguaporiens Diffusionmovement of a solute from area of high concentration to area of low concentration Passive process Our cells purposely allow concentration gradients Larger the concentration gradient the faster the rate of diffusion The smaller the particle the faster the rate The higher temperature the faster the rate Osmosis the movement of water from low to high solute concentration when separated by semipermeable membrane In both diffusion and osmosis the area of high concentration becomes diluted Isotonic solutions with the same solute concentration to that of cytosol A saline solution is isotonic same solute concentration as blood Movement of water across the membrane is essentially zero in an isotonic solution Hypertonic solution that has a higher than normal salt concentration Water inside cell will move outside cell in a hypertonic solution Hypotonic solution that contains lower than normal saline Water ows into cell in hypotonic solution In extreme conditions can cause the cell to rupture Active Transport movement through the cell membrane that requires energy atp Substances or molecules are being moved against a concentration gradient Sodium potassium pump integral protein that has sites where sodium and potassium can bind to the protein Requires ATP for it to move these ions so this is a form of active transport This pump helps establish a gradient Sodium is pumped out of the cell into the interstitial uid Potassium is pumped in Job of this pump to put these ions there Pump picks up 3 sodium ions Phosphorylation changes the shape of the protein and the pump releases the sodium ions into interstitial uid Then 2 potassium ions move into the cell when the phosphate is released 3 to 2 sodium to potassium ratio Secondarv active transport Indirectly requires ATP By establishing a sodium gradient with the sodium potassium pump the gradient can be used to move substances through the membrane Using the sodium gradient glucose is moved across the membrane through proteins called cotransporters svmports Vesicular Transport energy dependent form of transport Three types of transport associated with this Endocytosis Transcytosis exocytosis Exocytosis exit occurs when the vesicle docks with membrane and releases contents into the extracellular uid Involves two sets of proteins One set on the inside of the cell and complementary proteins on the vesicle These are called tSNAREs and vSNAREs VSNAREs are associated with the vesicle and t with the plasma membrane Could be eliminating waste or releasing something that it created These proteins allow vesicles to dock bond to membrane and temporarily become part of the membrane This allows membrane to open up With the membrane open the contents of the vesicle are released into the extracellular uid The vesicle can also undock Increase in calcium causes exocytosis to occur and decrease triggers the vesicle to undock Endocytosis bring in Vesicle forms It s common to have proteins called clathrin that aids in the formation of vesicles This protein is recycled Phagocytosi process where a white blood cells forms a vesicle around substances in the extracellular uid Pseudopods help white blood cells fold around captured material to form a vesicle Pinocytosis cell takes in random sample of uid outside the cell through endocytosis Receptor Mediated Endocvtosis RME Receptors that target specific material in the extracellular uid such as ions or proteins and concentrates substances in protein coated vesicles Ligand a molecule that binds to something In RME whatever binds to the receptor is the Ligand Receptors are recycled Transcytosis across to be continued next week Cytoskeleton Just like the human body cells have skeletons too Microtubule largest of the cytoskeletal elements Made of protein tubulin Gives cells a distinct shape Also serves as an important highway for vesicles to move around the cell Flagella are the result of a specific protein causing microtubules to move Intermediate filament toughest most fibrous cytoskeletal element Designed to withstand high tensile force pulling Associated with membrane structure called desmosomes Intermediate Filaments goes from the membrane and ties onto microtubules in the cell When stress is put on the intermediate filaments the stress is distributed throughout the cell Actin microfilament filaments made of protein actin This actin forms a twisting filament This type of filament follows the inside of the membrane The microfilament binds to internal portions of peripheral and integral proteins Helps stabilize membrane by holding this in place Microfilament also helps cells moves Cilia is powered by microfilaments Vesicular transport continued Myosin motor protein Protein that can walk along a microtubule This is an ATP dependent process Myosin can also attach between filaments and move filaments back and forth This is how agella s move back and forth to propel sperm cells or other cells with agella Centrioles Microtubules emanate from centrioles Play a key role in mitosis Read in book 8991 cellular extensions before exam Specialized membrane proteins help cells hold on to each other Tight J unction consists of small membrane proteins that link to adjacent cells Can think of these as rivets that holds membranes together Each junction is not very strong Where there are tight junctions there are usually a lot of them These junctions create a water tight seal between cells Desmosome high stress connection between two cells 3 major components to these On the cytosol side of the protein there are intermediate filaments that tie into a protein on the inside of the membrane On the other side of the protein between the two cells there are linker proteins Sugar on the outside of the cell helps bind the linker proteins The intermediate filaments distribute the stress within the cell from pulling on the desmosome Gap J unction series of proteins call connexon that forms between two cells These allow cells to communicate They are seen in the heart Not resistant to stress Cell communication Cells communicate via some sort of signaling molecules Cells secrete hormones chemical signals to communicate These chemical messengers bind to receptors that are usually integral proteins and glycoproteins on cell membranes When the chemical messenger binds to the protein it changes the shape of the protein How does a chemical stimulate a cell to do something These chemicals bind to a receptor which changes shape and activates another protein called a g protein associated with gtp The g protein activates effector protein by causing its shape to change The effector catalyzes reactions that produce second messengers in the cell and the secondary messengers carry out the cell instructions Mitochondria unique in that they have two membranes An inner membrane and an outer membrane The inner membrane is called cristae The intermembrane space is the space between the two membranes filled with a uid just like cytosol The space inside the second membrane is known as the matrix also filled with a cytosol like substance Mitochondria have their own DNA This DNA codes for 13 proteins that are associated with ATP resynthesis It is thought that the mitochondria is an example of a bacteria and eukaryotic cells that formed a symbiotic relationship Cells can change the number of mitochondria Mitochondria are maternal passed down through the mother Mitochondria resynthesizes ATP Aerobic metabolism specific to mitochondria Oxygen that you breathe is used in the mitochondria Building and Breaking things down within the cell Building DNA I RNA I Protein The process of making an RNA copy of DNA is known as Transcription mRNA and splicing are invloved Translation is the process of reading the RNA and making the protein Some proteins require modification which occurs after the RNA translates the protein rRNA tRNA modification packaging and secretion are involved Ubiquitin proteasome Pathwav the process where we can target and eliminate specific proteins RNA and DNA differ by one OH group On the second carbon in RNA there is a hydroxyl group and DNA on the second carbon there is a hydrogen DNA because it doesn t have this hydroxyl group forms a double helix RNA is typically single stranded RNA can form extremely complex shapes DNA is where genes are stored RNA is what ribosomes are made of Another difference between RNA and DNA is that RNA contains Uracil U and DNA contains Thymine T Protein called RNA polymerase that binds to promoter region and makes a copy of DNA That subsequent copy produces PremRNA It is Pre because it needs to be spliced After splicing the RNA attaches to a ribosome and is translated into proteins Transcription 3 stages initiation elongation and termination Initiation RNA polymerase binds to a region of the DNA called the promoter When the polymerase is binded it separates the two strands of DNA Elongation polymerase has unwinded the double stranded DNA and has made a copy of one strand the template strand and allows the DNA to rewind behind it RNA is complementary to the template strand This is the strand of DNA that was copied Termination This tells the polymerase to stop The mRNA transcript is the item that will be translated Once it has been edited and spliced a ribosome is going to read it A ribosome is mostly RNA with some proteins They are the primary organelle associated with translation The ribosome reads the mRNA transcript in codons triple base pairs different codons code for different amino acids EX UUU and UUC codes for phenylalanine AUG is the start codon for the ribosome to start reading the RNA UGA UAA UAG are stop codons