12 5 12 Biology Final Exam Dec 5 ATP Adenosine triphosphate energy money for the cell o Broken down into ADP phosphate Phosphate is used to create a phosphorylated intermediate This is how the cell captures the energy released when you hydrolyze ATP o Uses the purine adenine GTP guanosine triphosphate o Uses the purine Guanine o Identical to ATP o Initiation of translation uses a GTP as an energy source to complete the assembly of the transcription initiation complex Elongation o First step The initiation complex has a codon in the A site a transfer RNA with an anticodon that is complementary to that codon goes into the A site Once it is there a bond transfer occurs connecting a transfer RNA to a polypeptide is broken and an AA is bonded to another The amino acid in the P site has nothing attached to it and the AA in the A site has the polypeptide attached to it Used a GTP Another GTP is used That energy is used to eject the transfer RNA that was in the P site which goes back into the cytoplasm where it is recharged with its AA again Transfer RNA s are constantly used and then recharged The transfer RNA with a polypeptide that was in the A site is then ejected and moved to the P site A new transfer RNA is brought into the A site and the same process is repeated again Occurs in milliseconds Elongates the strand of amino acids in the polypeptide by adding one AA at a time Once at the end of the messenger RNA a stop Codon appears in the K site There is no transfer RNA that has an anticodon complementary to the stop codon To make sure a transfer RNA cant get in there a protein called a release factor slides in to block the A site Preventing RNA from accidentally sliding in there One the release factor bonds to the A site o The bond that bonded the polypeptide to the 3 prime position is broken and the completed polypeptide is released 12 5 12 o Transfer RNA is ejected from the P site another GTP molecule is used to separate out the two components of the ribosome and messenger RNA Everything is used over and over again Prokaryotes transcription and translation is coupled both happen at the same time o There is no nucleus so the DNA is translated into a messenger RNA molecule The instant the RNA molecule is starting to be produced a ribosome grabs onto the messenger RNA and a polypeptide begins being produced Moving proteins to specific destinations in the cell o Ribosomes can be free or bound o Free Found in the cytoplasm cytosol Proteins produced function in the cytoplasm of the cell Ex enzymes of glycolysis o Bound Attached to the endoplasmic reticulum Produce proteins for Secretion from the cell o Transport vesicles Transporting a protein or anything to be secreted from the cell The transport vesicles fuse with the plasma membrane of the cell and release that secretion Proteins that function in the endomembrane system Signal Peptide 20 AA in lengeth o All proteins that are going to be secreted or are going to be part of the endomembrane system begin with the same 20 AA AA are always the same o Signal recognition particle Like a SNURP SNURPS ribonucleoproteins Complex of RNA in proteins Grabs onto a signal peptide and transports the ribosome and mRNA to a protein in the plasma membrane in the endoplasmic reticulum Translation continues The protein produced during translation either goes to the inside of the ER or stays on the plasma membrane of the ER 12 5 12 Mutations change in the base sequence of a gene o Caused by mistakes by DNA polymerases They have proofreading ability so mistakes are rarely made 1010 almost perfect o Mutagen a thing that causes a mutation Chemical base analog Benzene common mutagen similar in structure to the bases of DNA The DNA polymerases might mistake benzene for adenine Chemicals that can fool polymerases Radiation X Rays UV Ultra Violet Light Can cause two thymine s which are right beside of each other to for a covalent bond together Thymine Thymine Dimer bad When replication occurs the daughter strand will get another nucleotide other than A to bond to it Mutated Daughter Strand o Point Mutation Involves a single nucleotide change When one of the bases is change commonly substitutions but can be insertions or deletions Substitution point mutations substitutes one nucleotide for another Missense a single AA change Nonsense Involves creating a stop codon in the wrong Silent no AA change place Sickle Cell Anemia is an example of a Missense serious Most common in people from Africa and the middle east Abnormal form of hemoglobin The red blood cell will be sickle shaped Causes pain and tissue damage because it clogs the small blood vesicles Silent point mutation GGC to GGU codon They both code for Glycine as a result of changing GGC to GGU there is no mess up Silent mutations exist because the genetic code is unambiguous and redundant Missense Point mutation One amino acid change in the final protein Sickle cell Nonsense mutation Creates a stop codon prematurely A protein product wont be produced at all or it will be so small it doesn t have a normal function 12 5 12 Insertions and deletions Much more serious than substitutions They always cause a frame shift AAACCCGGGUUU normal AAAUCCCGGGUUU U was inserted between A C 1st Codon is still AAA Normal but the 2nd is now UCC instead of CCC 3rd is CGG instead of GGG 4th is now GUU instead of UUU Codons downstream of the insertion or deletion are always all changed The protein will either be vastly different and not function or the frame shift will cause a stop codon very quickly Chapter 18 Last Chapter Gene Regulation turning genes on or off Prokaryotes o Genes Constitutive Genes that are always on Ex glycolysis Inducible Genes that are normally off but can be turned on Repressible Genes that are normally on but can be turned off o Operons Page 1 of final a group of related structural genes and their controlling elements Almost always exclusively in prokaryotes Lactose Operon Inducible Three related genes A B C Controlling elements promoter operator and terminator Promoter Operator Gene A Gene B Gene C Terminator Line is a strand of DNA they re all on a DNA molecule