MMBIO 240 - Week 2 Notes
MMBIO 240 - Week 2 Notes MMBIO 240
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This 4 page Class Notes was uploaded by Eric Walls on Sunday September 11, 2016. The Class Notes belongs to MMBIO 240 at Brigham Young University taught by Nielsen, Brent in Fall 2016. Since its upload, it has received 20 views. For similar materials see Molecular Biology in Biology at Brigham Young University.
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Date Created: 09/11/16
MMBIO 240 – Week 2 07/09/2016 Ch. 3 DNA • DNA is the carrier of genetic information. It is made up of long chains ofnitrogenous bases (Thymine(T), Adenine(A), Guanine(G), and Cytosine(C))whose order is a code for the creation of proteins. Thesebases arelinked together by a phosphate-sugar backbone • The combination of a nitrogenous base,a deoxyribose sugar,and a phosphate group is calleda nucleotide. • When a nucleotide is missing a phosphate group, itis calleda nucleoside.(Thenames of the nucleosides are Cytidine (C),Adenosine (A), Guanosine (G),Thymidine (T)) • Bases pairoffwith eachother (Awith T,G with C),thus forming a double stranded DNA molecule. Reactions between the phosphate-sugar backbone then causethe molecule to fold in on itselftoform a helixstructure RNA RNA’s composition and structure is very similarto that of DNA’s,there are only a few key differences: • RNA uses Uracil (U)as a replacement for Thymine (T) • RNA’s backbone contains ribose sugar,not deoxyribose sugar. • RNA will typicallystaysinglestranded, however, becauseof intramolecular reactions between component of RNA’s backbone, itcan fold in on itselfto form secondary structures. What can modify DNA and RNA structure? • Nucleosides Cytidine, Guanosine, and Adenosine can all be methylated. • Methylation –Theaddition of a methyl group to a molecule • RNA canalsobe methylated (the sugarnot the base) • Guanosine canloseits amino acidto generate inosine. Changes to structure will affectthe function of the molecule, either helping or hurting it. Proteins • Proteins arelong chains of amino acids,Amino acidsequence is determined by RNA basesequence • Several modifications can alteramino acids which help to regulate the activity of the entire protein -Methylation (addition of a methyl group) -Phosphorylation (addition of a phosphate group) -Fatty acidmodification -Glycosylation(addition of a sugar) -Hydroxylation (addition of a hydroxyl group) Ch 3.2-3 Chemical Bonds and Interactions • Covalent bondsareformed when two atoms share a pair of electrons. Both atoms now have an outer electron shell which is filled,The atomic radii overlap, creating a very strong bond • Ionic bondsareformed when an electron is transferred completely from one atom to another. This leaves one atoms positively charged, and the other negativelycharged. They are attracted to eachother becauseof the difference of charges, however they do not come as closeas atoms in a covalent bond. Ionic bonds are not as strong as Covalent bonds. • Electronegativity istheinclinationof an atomto draw electrons to itself(thus forming bonds). Elements in grow more electronegative left right and bottom top on the periodic table • Polar bondshaveun-even charges (i.e.water) • Non-Polar Bondshavenonet difference incharge across the molecule • Van der WaalsInteractions–weakinteractions causedby fluctuation in charges of neighboring atoms. • Hydrophobic Effect–Thegrouping together of hydrophobic molecules. This is caused becauseof the tendency ofwater to push awaynonpolar groups, causing them to group together. (likeoil inwater) • Hydrogen Bonds–bonds between two molecules of opposite charge, one of which is a Hydrogen Enzymes • Enzymesare proteins that catalyze specific chemical reactions • Reactions require a certain amount of Activation Energy tostartthe reaction, enzymes normally lower this amount. • Free Energy is theamount of energy ina systemthat is availableto be used. • If the changein free energy (ΔG) is negative,then the energy in the system has increasedand the reaction is considered to be favorable. If ΔG is positive then energy has been consumed in the reaction, the reaction is unfavorable. Laws of Thermodynamics • Energy can never be created or destroyed; in other words the energy of a systemis conserved. • All spontaneous processes takeplacewith an increaseindisorder, calledentropy, of the system. • Free energy (G)is energy that is availabletodo work. • Free-energy change(ΔG) is negativein spontaneous reactions. Ch. 4 Amino Acids (Prof. Nielsenonly barely started this section,further notes on ch.4will be availablenextweek) -All work done in our bodies is done by proteins -Proteins are made up of 20 different amino acids that link into polypeptide chains -Proper folding,which is determined by amino acidsequence, is essential toprotein function -There are 4 levels ofprotein folding 1 level,Amino Acid sequence 2 –alpha helix,beta sheets 3 –folded polypeptide chain 4- assembledsubunits (multiple polypeptides) Amino acids chaperones monitor folding and keep inappropriate interaction from happening (just like chaperones at dances) Amino Acids are made up of--- -An Amino Group -A Central Carbon -A Carboxyl Group -A Hydrogen Molecule -An R-group (which determines the Amino Acids identity) -There are 4 groups of Amino acids Nonpolar, aliphatic R-groups- nonpolar hydrocarbon R-groups Polar, uncharged R-groups –polar, easilyassociatedwithwater molecules Polar, negatively charged R-groups – has a negative charge(likes to be w/ water) Polar, positively charged R-groups –has a positive charge (likes tobe w/ water) Nonpolar, aromatic R-groups – largering structure R groups, unipolar (hydrophobic) (buries itselfinsidethe protein) (In test,we will seelistofamino acids,but we will need to be ableto label the group names)
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