Discussion 4 Problem Solving I MCB 150 Problem Solving I 1 Name the organelles in a typical animal cell that we have discussed in MCB 150 and identify their primary function s 1 Mitochondria Powerhouse of the cell breaks down glucose into 2 Golgi Apparatus Modifies sorts and packages lipids and 3 Rough ER Takes in proteins made by ribosomes ribosomes ATP for energy proteins for use post office never enter just threads the protein through and is part of the secretory pathway 4 Smooth ER Detoxes and makes lipids 5 Lysosome Bonfire or composter for waste 6 Nucleus Stores genome 7 Ribosome Protein factory 2 Draw a very crude evolutionary tree showing humans E coli a bacterium and Methanococcus jannaschii an archaea dating back to their most recent common ancestor 3 Asymmetry semi permeability and fluidity are the three major properties of biomembranes Explain them using no more than two sentences for each property Asymmetry means that two leaflets in a bilayer can differ in composition and lipid identity does not mean they have different total amounts of lipids though just that the lipids on each leaflet can differ 1 Discussion 4 Problem Solving I MCB 150 Semi permeability means that the bilayer chooses and only allows certain molecules through Charged and big molecules like sugar or Na cannot enter while smaller uncharged molecules like O2 and even H20 whose polar and slightly bigger can Fluidity means how easy it is for the phospholipids in the bilayer to move around fluidly and not be gel like Tail length and number of kinks C C determine it and environmental situations like temperature and things like Cholesterol can help modulate it to be either more gel like or fluid to hit the target fluidity level 4 With the scale of life being so vast explain why cell size remains within a fairly narrow range Because cells want a certain volume to surface area ratio and because as volume increases surface area does as well but at a slower rate So cells may have more internal rooms but not as many exits and entrances to let stuff in or out 5 Compare and contrast the three major glucose polymers described in lecture Cellulose No branching pin straight used for structure monomers joined together at 1 4 b Glucose bonds most common organic polymer in the world Starch Some branching joined together at 1 4 a Glucose bonds branching happens at the 1 6 a Glucose bonds made by plants used for energy Glycogen Lots of branching branches also at 1 6 a Glucose bonds branching also happens at the 1 6 a Glucose bonds in animal muscle tissue used for energy as well 6 Compare and contrast the two main types of nucleic acids Two main nucleic acids are RNA and DNA and their structural differences are that RNA has an OH at the 2 Carbon and DNA has only an H at the 2 Carbon Additionally they have the same purine nitrogenous bases but differ in pyrimidine bases where RNA has 2 Discussion 4 Problem Solving I MCB 150 Uracil and DNA has Thymine RNA also is single stranded by DNA is double stranded 3
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