MCB 450 1st Edition Final Exam Study Guide Lectures 20 26 Lecture 20 April 14 I Be able to identify the repeated steps of fatty acid degradation a Oxidation by flavin adenine dinucleotide FAD b Hydration c Oxidation by nicotinamide adenine dinucleotide NAD d Thiolysis by coenzyme A II Be able to describe ketone bodies and their role in metabolism a Alternative fuel source formed from acetyl CoA and fatty acid degradation b Acetoacetate 3 hydroxybutyrate beta hydroxybutyrate and acetone c Don t generate as much ATP as fatty acids but are water soluble so are more easily transported in the blood d Synthesized in the mitochondria present in the liver e Will be used heavily in the event of starvation instead of glucose f III Excess production of ketone bodies in diabetics can cause death if not treated Know how fatty acid are synthesized a Acetyl CoA is transferred to the cytoplasm in the form of citrate which is cleaved to yield acetyl CoA and oxaloacetate b Activation of acetyl CoA to malonyl CoA c Fatty acid is synthesized two carbon atoms at a time in a five step elongation cycle IV Understand the regulation of fatty acid metabolism a Acetyl carboxylase is a key regulator i Responds to changes in the cell environment ii Is switched off by phosphorylation and is activated by dephosphorylation iii Glucagon and epinephrine switches off fatty acid synthesis and inactivates acetyl carboxylase iv Insulin activates acetyl carboxylase and allows for the accumulation of fatty acids as triacylgylcerols Lecture 21 April 16 I Know the components and structure of nucleic acids a Composed of sugars phosphates and bases b Bases i Adenosine guanine thymine cytosine and uracil c Backbone of DNA and RNA is formed by phosphodiester linkages d RNA contains a hydroxyl group while DNA contains only a hydrogen II Be able to explain how we know replication is a semi conservative process a Semiconservative one strand of the parent DNA strand is combined with a newly synthetized daughter strand b We know this due to an experiment done by Meselson and Stahl i Used density gradient equilibrium sedimentation III Understand DNA melting and annealing a DNA melting i The dissociation of the double helix ii Also called denaturation iii Occurs at a melting temperature defined as the temperature when half the helical structure is lost b DNA annealing i When the temperature is lowered below the melting temperature separated complementary strands of nucleic acids can spontaneously reassociate to form a double helix ii A renaturation process IV Be able to describe how DNA is packaged into cells a Form supercoils to fit into the nucleus of cells Lecture 22 April 21 I II III IV Understand the overall aspects of DNA replication in prokaryotes a Replicated by polymerases b Topoisomerases prepare the double helix for unwinding c The new DNA strand is assembled directly on a preexisting DNA template d The polymerases require a primer to start synthesis e The polymerases also are able to correct mistakes in DNA synthesis by removing mismatched nucleotides f One strand of DNA is made continuously and the other strand is synthesized in fragments Know the properties of the two polymerases responsible for DNA replication in E coli a DNA Polymerase III i Two copies of it Know the differences between prokaryotic and eukaryotic replication a Eukaryotic replication is more complex b More challenging in three ways i Sheer size many more base pairs to replicate ii Multiple chromosomes must be replicated opposed to only one chromosome iii Prokaryotic chromosomes are circular and eukaryotic chromosomes are linear 1 Linear chromosomes are subject to shortening Understand telomerase mode of action a The enzyme that maintains the length of the telomeres by adding nucleotides to the leading strand b Prevents cell death because the telomeres are shortened too much c This is the mechanism that occurs in cancer cells and allows those cells to replicate continuously Lecture 23 April 23 I II Know the steps of prokaryotic transcription a Initiated at promoter sites on the DNA template b RNA polymerase unwinds the template double helix c Elongation takes place at transcription bubbles that move along the DNA template d The nascent RNA chain contains stop signals that end transcription Understand transcription regulation of Lac operon III a Lac operon controls lactose degradation b In the absence of lactose the lac repressor binds very tightly to the operator and therefore blocking the bound RNA polymerase from using the DNA as a template Be able to describe the general differences between prokaryotic and eukaryotic transcription a Eukaryotes have three types of RNA polymerases b Eukaryotes very extensively process nascent RNA destined to become mRNA c In eukaryotes transcription and translation take place in different cellular compartments Lecture 24 April 28 I II III IV Be able to explain how RNA is processed after transcription in eukaryotes Know the steps involved in splicing a The introns are removed and the exons are linked to form the final mRNA strand b RNA molecules play key roles in directing the alignment of splice sites and in carrying out catalysis c ATP powered helicases unwind RNA duplex intermediates that facilitate catalysis and induce the release of snRNPs from the mRNA Be able to describe the characteristics of the genetic code a The relation between the sequence of bases in DNA and the sequence of amino acids in proteins b Three nucleotides encode an amino acid c The code is nonoverlapping d The code has no punctuation e It has directionality f It is nearly universal Understand the mechanism of tRNA synthetase Lecture 25 April 30 I II III Be able to list the key components of protein synthesis a Initiation b Elongation c Termination Understand the roles of the ribosomes in protein synthesis Know the differences between prokaryotic and eukaryotic translation a Differ in the initiation of protein synthesis b Eukaryotic ribosomes are larger i 80S complex opposed to 70S c In eukaryotes the initiating amino acid is methionine d Eukaryotic mRNA is circular e Differ in elongation and termination f Also differ in organization IV Be able to describe the types of mutations a Point mutations i Silent mutation ii Missense mutation iii Nonsense mutation b Insertion deletion mutations Lecture 26 May 5 I II III Understand how restriction enzymes work a Recognize specific base sequences in double helical DNA and cleave at specific places