BIO EXAM 2 REVIEW 50 questions multiple choice questions one extra credit question evenly distributed over the different topics Lecture 9 The main thing difference between eukaryote and prokaryote Eukaryote know organelles and what they do how the move things through membrane energy production endomembrane system mitochondria vesicle transport lysosomes are garbage bucket of the cell etc Difference between plant and animal cells plant cells have cell wall and chloroplast in addition to mitochondria Don t worry about the filament system and cytoskeleton Lecture 10 Membranes and transport Membrane structure biological membranes of phospholipids Hydrophobic tails hydrophilic heads Creates a barrier against movement of substance through the membrane Be aware that there are lots of proteins located in the membranes transport proteins extremely important class of those membranes proteins that span the membrane are integral protein membranes Biological membranes are semipermeable smaller molecules and uncharged go through easier than large or charged molecules Passive transport across membranes and osmosis Things to move form outside to inside is diffusion passive process where molecules move form high concentration to low concentration move across concentration gradient Because biological membranes are semipermeable strict permeability to solutes Instead of solute moving water moves to equalize the solute concentration across the membrane osmosis KNOW WHICH WAY WATER WILL MOVE IN OSMOSIS This much sugar on outside and inside what s going to happen Hypotonic less concentrated hypertonic more concentrated isotonic equal Lecture 11 Transport across the membrane Virtually everything that moves across the membrane moves membrane with help of integral membrane proteins doesn t actually move across membrane O2 N2 and CO2 are small uncharged and can pass freely through membrane everything else is mediated through protein Diffusion two types of proteins that participate channels and carriers Channels are pores that have molecular dimensions that allow a particular thing to move across membrane Channels are very specific Proteins move across membrane through flip flop mechanism these are carriers Channels and carriers are highly specific those transfer potassium but no sodium etc Channel that water moves through is aquaporin channel for water Active transport against concentration gradient requires energy energy comes form ATP ATP hydrolyzed into ADP and used to move things across membrane Passive transport energy yielding transport spontaneous Active transporters Sodium potassium ATPase in animal cell moves sodium out potassium in 3 sodiums out for every 2 potassiums in so there s a charge asymmetry creates a voltage across membrane called membrane potential Proton ATPase found in everything else protons are pumped out pH is lower outside than inside negative voltage this is used to move other things called cotransport ATP energy is used to create ion gradients and voltage across membrane use energy to move other substances amino acids and sugars enter animal cells by going through a cotransport protein with a binding site for amino acid and sodium and pulls both of them across the membrane Drawing sodium in with negative voltage and moving other things along with it All this is about small stuff little molecules bigger than ATP then these transport mechanisms don t work Things bigger than ions or sugars move across the membrane by endo or exocytosis Big things is endocytosis Phagocytosis food particles example bacteria Pinocytosis little vesicles on surface cell drinking Receptor mediated where proteins bind specific substances on the cell and pulls them into the cell through formation of vesicles Lecture 12 Two types of chemical reactions catabolic and anabolic Catabolic take complex substances and break them down release energy energy yielding respiration Anabolic build them up to more complex ones need energy photosynthesis Most energy conversions have to do with energy in cleaving of bonds FIRST law of thermodynamics energy is not destroyed SECOND law of thermodynamics increasing chaos increase in entropy some energy released is not available to do work but lost in the form of heat If free energy of reaction is negative direction of reaction is releases energy negative delta g spontaneous Positive delta g requires energy anabolic reactions Exergonic energy is released Endergonic energy is taken up Can couple unfavorable nonspontaneous reactions to hydrolysis of ATP and push these reactions forward Lecture 13 Reactions take place in cells even if spontaneous and have negative delta G have to be helped along by catalyst speed up without being used up All chemical reactions in cells are controlled by an enzyme Each enzyme is specific for controlling one particular reaction Enzymes catalyse specific chemical reactions speed up chemical reactions lower activation energy need input of energy to get reaction going even if spontaneous Enzymes bind to substrates and energy needed to start reaction is greatly reduced speeds up rate in which reaction will occur Table sugar is full of energy but the breakdown of sugar into CO2 and water is spontaneous but has high activation energy reaction is slow slow because of the activation energy its not useful in recent time Enzymes depend on 3D shape Activation site that binds the substrates and may have additional site Additional things like cofactors Familiar with temperature and pH Operate at optimal pH and temperature which corresponds in natural environment At pH above of below optimal for enzyme rate of reaction goes way down enzymes denature Temperature high temperature beyond optimum denaturation below optimum chemical reactions depend on temperature stop going faster Lecture 14 Regulation of enzymes redox reactions respiration Enzyme regulation activity of enzyme controlled by cells controlled by substances that inhibit or promote binding to site other than active site allosteric site Changes 3d shape of enzyme and can be positive of negative depending on nature of reaction Can close active site and inhibit the enzyme activity Enzymes are regulated through end product inhibition Substance will feed back and bind to allosteric site after going through enzyme glycolysis is an example End product of respiration feeds back and regulates that enzyme regulates ATP and ADP Enzyme is inhibited by ATP product and activated by ADP Have plenty of ATP don t
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