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Chapter 5


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BIOL 1000
Nicole Nivillac

Chapter 5 NOTES LECTURE NOTES Permeability: - Main function to allow things to pass through -> molecules/signals - Integral -- > interacts with hydrophobic and hydrophilic - Peripheral  does not interact with these molecules ^ - Difference: different percentage of proteins and phospholipids (almost 50% difference) - 75% proteins and 25% phospholipids in mitochondria membrane - Green proteins do not interacts with hydrophobic regions whereas the integral ones interact - Peripheral are found inside a cell – do not interact with hydrophobic core part at all! - Polar: like water (hydrophilic) non-polar: do not like water (hydrophobic) - Their side chains make them polar and non-polar - Non polar region will become embedded with the hydrophobic portion – important - Taking out integral protein, will change the membrane entirely - Difference between monotopic and polytopic is that they have 2 grey parts: one interacts with - one portion of the bilayer  monotopic - Polytopic covers the entire layer (transmembrane protein) cuz it transmembranes the entire membrane – green coils are transmembrane protein  integral membrane protein - Peripheral do not interact with hydrophobic part - Integral are made of beta plates. Alpha helices are embedded in #1. #2 has beta sheets embedded #3 called beta barrel - Yellow amino acids are hydrophilic and blue amino acids are hydrophobic (in hydrophobic region because there is a long stretch of hydrophobic amino acids) - Proteins are folded the same time as translation Diffusion - Passive: high to low concentration – down concentration gradient - No energy is required - Facilitated: protein helps transports - ^ faster movement of transportation - ^ works with concentration gradient - ^ specific towards particles transporting - ^ carrier protein  carry protein – more conformation change - Look at concentration gradient when determining transport path - Channel proteins: always goes from high to low concentration gradient - Passive: high to low concentration gradient - Weak gradient will make transport slow. Whereas 99 particles versus 1 will make transport fast - Gated channel proteins: have a gate - ^ high to low concentration - Gate opens and closes - More you have, more efficient and fast it transports - Plasma membrane have charge across them - ^ positive out and negative inside - Gradient and charge help with transportation (they both stimulate ions to go inside) - Positive inside  repels positive and positive (arrow represents driving force) - Doesn’t really reach equilibrium but reaches rest - Charges are electrical portion and there are gradient portion - Carrier protein: shape matters since the molecule has to fit in the protein and then a conformation change occurs Osmosis - Movement of WATER only - Movement of water depends on solute concentrations - Can move through aquaporins (FAST transportation) - Dependent of water concentration on the outside to the inside - Move from LOW TO HIGH concentration - Less solute relative to the bag  solution hypotonic to the cell and OPPOSITE  hypertonic QUESTION: The inside of a cell has a high solute concentration than the surrounding. The surrounding solution is hypotonic to the cell because water is going in the cell. - Hyponatraemia happened to a lady who held in her urine Active Transport: - LOW TO HIGH concentration - Helps to transport ions against concentration gradient so passive processes can happen - Outside: overall positive charge. Inside: overall negative charge - Main contributor to negative charge of chlorine ion is - Active transport maintains the ratio of concentration of ions (high to low ions and vice versa) - PRIMARY  directly used ATP for movement - SECONDARY  DOES NOT USE ATP DIRECTLY BUT USES IT INDIRECTLY- symport provides kinetic energy to drive molecules through (MORE EFFICENT THAN PRIMARY ACTIVE TRANSPORT) - ^ antiport – goes opp direction of where the driving ion went - ^ always has 3 high affinity sites for Na + and 2 sites for K+ when exposed to cytosol - High to low  driving ion Vesicles - When something is wrong with the plasma membrane, mucous is not produced in lungs efficiently. Cilia cant sweep thick mucous. Transporter has one amino acid missing, missing 3 nucleotides. October 17, 2013 – BIO NOTES Test – Chapters: 4 5 6 7 - - Symport is the same as co-transport. - Primary active transport uses ATP directly - Exchange diffusion – uses two molecules going in opp. Direction - Electrical gradient does not affect the glucose diffusion because it doesn’t have a charge. - Target cells are determined depending on if the cells have receptors (taking in the molecules) of the same molecule shape. - Every process involves protein kinases. - Peripheral proteins does not cross the membrane, does not interact with hydrophobic portion. Sits on the surface. - GDP is bound to inactive protein and triggers activation of protein when GDP is removed. GTP replaces it on the protein. - Taking signal molecules off will cause stop signaling and will return to inactive conformation. - To remove cAMP by PDE which converts it to AMP and will also stop signaling. - Adenylyl cyclase removal will have cell activated but repeated signals will occur. It will not messengers to activate messengers. G protein will be the main regulator then. TEXTBOOK NOTES: 5.3 – Membrane Proteins - Unique proteins have their own different functions 4 Major Functional Categories: 1. Transport – Many substances cannot freely diffuse through the membrane. Instead a protein may provide a hydrophilic channel that allows movement of a specific compound 2. Enzymatic Activity – A number of enzymes are membrane proteins. The best example of this is the enzymes associated with the respiratory and photosynthetic electron transport chains 3. Signal Transduction – Membranes often contain receptor proteins on their outer surface that bind to specific chemicals such as hormones. Receptors trigger changes on the inside surface of the membrane that lead to transduction of the signal through the cell 4. Attachment/recognition- Proteins exposed to both the internal and external membrane surfaces act as attachment points for a range of cytoskeleton elements, as well as components involved in cell-cell recognition Integral Membrane - These are membrane proteins that are embedded in the phospholipid bilayer - Some posses one region of the hydrophobic region of membrane but most of them interact with the entire membrane bilayer (called transmembrane proteins) - ^ these are exposed to the aqueous environment on both sides of the membrane - To interact with hydrophobic core of membrane, integral proteins consist of non-polar amino acids coiled into alpha helices - Transmembrane proteins have amino acids with 17 to 20 amino acids - Since these proteins ^ cover the entire membrane, many of them consist of polar amino acids since they are exposed to the aqueous environment of the other side of membrane Peripheral Membrane Proteins - The second major group of proteins - Positioned on the surface of a membrane and do not interact with the hydrophobic core of the membrane - Held by non-covalent bonds (hydrogen and ionic bonds) - Most of these prote
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