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BU BIOL 118 - lecture 150204

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Monomers and Polymers- macromolecules include proteins nucleic acids carbohydrates- All are polymers (made of monomers)- Join by condensation reaction- when two monomers bond they lose a H and an OH whichmake water and then the two monomers have a place to bond- When a protein breaks you need a H and an OH to go where the bond was so that the monomers can be neutral charge again- In amino acids it’s called peptide bonds; the COOH group bonds with the NH3 group. It’s a very strong bond and not very flexibleProtein Structure- - Primary structure- the sequence of amino acids. Not actually the shape of the protein. The list of amino acids starts with the N terminus ( the amine group NH3). If you changethis at all it can cause huge problems like sickle cell anemia. Normal red blood cells looklike tiny red donuts but with sickle cell anemia the cells look like a crescent moon. The red blood cells don’t move as much and can’t carry as much oxygen. The benefit of this is you won’t get malaria.- Secondary structure- beta pleated sheets/ alpha helices/ others caused by hydrogen bonding between amino acid backbones. Beta pleated sheets are usually with short non-polar side chain amino acids because they don’t get in the way of the sheet. They kind oflook like an accordion.- Tertiary structure- when you have some of the overall shape. The folding is dependant onthe shape and charge of the amino acids. Polar side chains like to stay with polar side chains and also be on the outside where there’s water. Non-polar side chains like to stay together and stay on the inside of the protein away from water. The shape can also depend on Van der Waals forces between non-polar bits and hydrogen bonds in the side chains. Disulfide bonds (salt bridges) also make the shape. It’s just a bond between twosulfurs in the side chains of amino acids. It’s a very stable bond.- QuateRNAry structure- sometimes proteins are made of several subunits that all have their own primary secondary structureText table 3.1THINGS THAT DENATURE PROTEINS: temperature change, pH changeProtein function- crucial to most tasks required for cells to exist- Catalysis- enzymes speed up chemical reactions- Defense- antibodies and complement proteins attack pathogens- Movement- motor and contractile proteins move the cell or molecules with in the cell- Signaling- proteins convey signals between cells ex. hormones- Structure- define cell shape and comprise body structures ex. collagen- Transport- carry materials ; membrane proteins control molecular movement into and out of the cell ex. Lipoproteins in blood stream (cholesterol is one)Nucleic Acids (chapter 4)- 3 components: phosphate (2- charge), sugar (ribose, 5 carbons, number of oxygen atoms vary), nitrogenous base- DNA is more stable than RNA because of the fewer oxygens- Purines- adenine and guanine- Pyrimidines- cytosine and thymine and uracil. Pyrimidines have a y in them in DNA - Links between the nucleic acids is a phosphodiester link- DNA builds from 5’ to 3’ because that’s how RNA polymerase- You can’t have bonds other than c-g or a-t/a-u because the hydrogen bonds won’t line up and the nucleic acids won’t be able to bond and stick together- If the DNA strands are not anti-parallel then the hydrogen bonds won’t line up and the DNA won’t stay togetherDNA replication- the DNA splits apart and DNA polymerase comes and makes new DNA by filling in the other half of the strand so you don’t really have to do any guess workRNA structure- usually single stranded but sometimes it will loop around and make a two stranded helix with itself and there will be a loop at one end- Also can have a tertiary structure unlike DNA- Tetradymena RNA makes a ribozyme- Pretty reactive and can be a catalyst for reactionsCarbohydrates- made of monosaccharides (one sugar unit)- Glucose, food, lactose, galactose- 2 inteRNAl structures: carbonyl(C=O) and hydroxyl(OH)- If the CO is on the end of the chain it’s an aldose- If the CO is in the middle of the chain it’s a ketose- Most names for carbs end in –ose- Carbs can be linear or ring shaped- They usually bond at the H and HO groups that stick out from the ring of the carbPolysaccharide types- Glycogen- animal storage for carbs, in muscle and liver, carb loading- you can train your body to store a little extra glycogen by overloading on carbs pretty often - Starch- plant storage for carbs, lots of glucoses bonded together in a helix- Cellulose- beta glycosidic link unlike starch and glycogen (they have alpha links) UNDIGESTABLE fiber in food is usually cellulose. Structure is a lot of parallel strands makes cell walls often- Chitin- cell walls of fungi, insects, and crustaceans (lobsters)- Peptidoglycan- cell walls in bacteriaCarb function- diverse functions in cells- Structural support- Identity- protein tags that identify cells/ foreign bodies lots of these are trans-membrane proteins so they stick out of the cell, the tag proteins are called oligosaccharides ex. Blood type markers- Energy- starch/glycogen both store


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