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POWERPOINT® LECTURE SLIDE PRESENTATION by LYNN CIALDELLA, MA, MBA, The University of Texas at Austin Additional text by J Padilla exclusively for Physiology 31 at ECC UNIT 1 4 Energy and Cellular Metabolism HUMAN PHYSIOLOGY AN INTEGRATED APPROACH DEE UNGLAUB SILVERTHORN Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings FOURTH EDITION Enzymes: Types of Reactions Types 1. Oxidation-reduction Description Energy extraction +/- electrons or H+ 2. Hydrolysis-dehydration Breakdwon/synthesis +/- water 3. Addition-subtraction+/- or exchange exchange function groups to substrates 4. Ligation Joins molecules using ATP Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Chemical Reactions: Overview Activation energy is the energy that must be put into reactants before a reaction can proceed A+BC+D Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 4-3 Enzymes: Speed Up Reactions Enzymes lower the activation energy of reactions Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 4-8 Enzymes: Overview Speed up the rate of reactions- they reduce the activation energy making easier for a reaction to occur. They may also perform reactions that would not otherwise take place. Isozymes Catalyze same reaction but under different conditions such as in different tissue cells May be activated, inactivated, or modulated Proenzymes and zymogens are synthesized as inactive and undergo proteolytic reactions to activate Coenzymes usually vitamins, are needed for proper function, can carry atoms removed at the active site Chemical modulators, temperature, and pH also affects enzyme activity Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings ENZYMES Metabolism is defined as the many chemical reactions that occur in organisms Few metabolic reactions occur without the assistance of enzymes Enzymes are made up of proteins and have the following characteristics They function at an optimal pH and Temperature They are denatured or deactivated if exposed to extreme pH and temperature They only bind a specific molecule They only perform one specific reaction While they change the reactants into new products enzymes themselves are not changed during a reaction They can be re-used multiple times They may be permanently or temporarily inhibited Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings The Enzyme Substrate Complex Enzymes can be recycled This is a key characteristic of enzymes Substrate (sucrose) 1 Enzyme available with empty active site 2 Substrate binds Active site to enzyme Enzyme (sucrase) Fructose Glucose 4 Product are released Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings 3 Substrate is converted to products Figure 5.9 Cofactors and competitive Inhibition Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2-19 Allosteric Modulation Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2-20a Physical Regulators Temperature- each protein has a adequate temperature for it’s function. Outside of the range it may be denatured of inactivated. pH- each protein has a adequate temperature for it’s function. Outside of the range it may be denatured of inactivated. Concentration of protein –amounts in body vary over time to control physiological processes Up-regulation – programmed production of protein Down regulation – programmed removal of protein Concentration of ligand – determines the magnitude of the reponse if the protein concentration is the same. Reaction rates – speed up as ligand concentration increases up until saturation is reached. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings A Review of DNA & RNA Structure Nucleic Acids are ____? What does DNA stand for? How does DNA compare to RNA? Why is RNA needed? Cap End Tail Start of genetic message Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Visual Summary 3.3 Figure 10.17 Nucleotides, DNA, and RNA Nucleotides are the monomers of nucleic acids. DNA and RNA have different nucleotides . In DNA A –T and C-G pair up. There is no pairing in RNA but RNA nucleotides pair up with DNA nucleotides Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Synthesis: Protein The major steps required to convert the genetic code of DNA into a functional protein are done by enzymes We have20 different amino acids made from 4 nitrogenous bases Gene 1 GENE ACTIVATION Regulatory proteins Constitutively active Regulated activity Induction Repression 2 TRANSCRIPTION mRNA 3 mRNA PROCESSING Alternative splicing siRNA Interference mRNA “silenced” Processed mRNA Nucleus • rRNA in ribosomes • tRNA • Amino acids 4 TRANSLATION Cytoplasm Protein chain 5 POST-TRANSLATIONAL MODIFICATION Folding and cross-links Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Cleavage into smaller peptides Addition of groups: • sugars • lipids • —CH3 • phosphate Assembly into polymeric proteins Figure 4-24 Transcription and Translation What is the language of nucleic acids? In DNA, it is the linear sequence of nucleotide bases When DNA is transcribed, the result is an RNA molecule RNA is then translated into a sequence of amino acids in a polypeptide Triplets of bases are called codons and they specify all of the amino acids DNA molecule Gene 1 Gene 2 Gene 3 DNA strand Transcription RNA Translation Codon Polypeptide Amino acid Figure 10.10 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings The Genetic Code The genetic code is the set of rules relating nucleotide sequence to amino acid sequence Use the RNA sequence in codons to determine the corresponding amino acid Figure 10.11 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Synthesis: Protein Gene 1 GENE ACTIVATION Constitutively active Regulatory proteins Regulated activity Induction Repression 2 TRANSCRIPTION mRNA Nucleus Cytoplasm Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 4-24, steps 1–2 Synthesis: Protein Gene 1 GENE ACTIVATION Regulatory proteins Constitutively active Regulated activity Induction Repression 2 TRANSCRIPTION mRNA 3 mRNA PROCESSING Alternative splicing Processed mRNA siRNA Interference mRNA “silenced” Nucleus Cytoplasm Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 4-24, steps 1–3 Synthesis: Protein Gene 1 GENE ACTIVATION Regulatory proteins Constitutively active Regulated activity Induction Repression 2 TRANSCRIPTION mRNA 3 mRNA PROCESSING Alternative splicing Processed mRNA siRNA Interference mRNA “silenced” • rRNA in ribosomes • tRNA • Amino acids 4 TRANSLATION Nucleus Cytoplasm Protein chain 5 POST-TRANSLATIONAL Folding and Cleavage into Addition of groups: Assembly into MODIFICATION • sugars cross-links smaller peptides polymeric • lipids proteins • —CH3 • phosphate Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 4-24, steps 1–5 Protein: Transcription Transcription factors bind and activate promoter region RNA polymerase RNA nucleotides RNA polymerase binds and “unwinds” DNA mRNA created from sense strand mRNA is processed by RNA interference Newly made RNA Alternative splicing Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Direction of transcription Template strand of DNA Figure 10.13a RNA polymerase DNA of gene Transcription of an entire gene Promoter DNA Initiation Terminator DNA Three stages Initiation of transcription RNA Elongation Area shown in part (a) Elongation of RNA Strand Termination of transcription Termination Growing RNA Completed RNA (b) Transcription of a gene RNA polymerase Figure 10.13b Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings The Processing of Eukaryotic RNA DNA The eukaryotic cell processes the RNA after transcription RNA processing includes Cap RNA transcript with cap and tail Tail Introns removed Exons spliced together Adding a cap and tail Removing introns Transcription Addition of cap and tail mRNA Splicing exons together Coding sequence Nucleus Cytoplasm Figure 10.14 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Translation: The Players Translation is the conversion from the nucleic acid language to the protein language There are three types of RNA mRNA is messenger RNA, it is created during transcription tRNA is transfer RNA it carries the amino acid and an anticodon rRNA is ribosomal RNA, it forms the units of the ribosome Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Transfer RNA (tRNA) tRNA Amino acid attachment site Acts as a molecular interpreter Carries amino acids Matches amino acids with codons in mRNA using anticodons Hydrogen bond RNA polynucleotide chain Anticodon Anticodon Figure 10.15 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Ribosomes Ribosomes Are organelles that actually make polypeptides Are made up of two protein subunits Next amino acid to be added to polypeptide Growing polypeptide Contain ribosomal RNA (rRNA) tRNA mRNA A fully assembled ribosome holds tRNA and mRNA for use in translation (b) Figure 10.16b Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Intiation of Translation Translation is divided into three phases Initiation Elongation Termination The first phase brings together The mRNA The first amino acid with its attached tRNA The two subunits of the ribosome Met Initiator tRNA mRNA Start codon 1 Small ribosomal subunit Large ribosomal subunit A site Initiation The process of initiation is the assembly stage and is signaled by the codon AUG that matches the anticodon UAC P site 2 Figure 10.18.1 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Formation of a polypeptide chain Amino acid The process of elongation The anticodon of an incoming tRNA pairs with the mRNA codon Polypeptide P site Anticodon mRNA A site Codons The ribosome catalyzes bond formation between amino acids 1 Codon recognition Elongation A tRNA leaves the P site of the ribosome 2 Peptide bond formation The ribosome moves down the mRNA New peptide bond mRNA movement 3 Translocation Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 10.19 Termination RNA Polymerase 1 Transcription Nucleus RNA transcript DNA Elongation continues until the ribosome reaches a stop codon The stop codon signals all the pieces that come together at initiation to disassemble The end result is a polypeptide Intron 2 RNA processing Amino acid CAP Tail mRNA Intron Enzyme 3 Amino acid attachment Ribosomal subunits 4 Initiation of translation Stop codon Anticodon Codon 6 Termination Elongation Copyright © 2007 Pearson Education, Inc., publishing as Benjamin5Cummings Protein: Transcription and Translation DNA 1 Transcription 2 mRNA processing RNA polymerase Nuclear membrane Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 4-27, steps 1–2 Protein: Transcription and Translation DNA 1 Transcription 2 mRNA processing RNA polymerase Nuclear membrane 3 Attachment of ribosomal subunits Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 4-27, steps 1–3 Protein: Transcription and Translation DNA 1 Transcription 2 mRNA processing RNA polymerase Nuclear membrane Amino acid tRNA 4 Translation Growing peptide chain Incoming tRNA bound to an amino acid Lys Asp 3 Attachment of ribosomal subunits Outgoing “empty” tRNA Phe Trp Anticodon mRNA AA G A C C G AU UU C UG G A A A Ribosome Each tRNA molecule attaches at one end to a specific amino acid. The anticodon of the tRNA molecule pairs with the appropriate codon on the mRNA, allowing amino acids to be linked in the order specified by the mRNA code. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 4-27, steps 1–4 Protein: Transcription and Translation DNA 1 Transcription 2 RNA polymerase mRNA processing Nuclear membrane Amino acid tRNA 4 Translation Growing peptide chain Incoming tRNA bound to an amino acid Lys Asp Outgoing “empty” tRNA 3 Attachment of ribosomal subunits Phe Trp Anticodon mRNA AA G A C C G AU UU C UG G A A A Ribosome mRNA 5 Termination Ribosomal subunits Completed peptide Each tRNA molecule attaches at one end to a specific amino acid. The anticodon of the tRNA molecule pairs with the appropriate codon on the mRNA, allowing amino acids to be linked in the order specified by the mRNA code. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 4-27, steps 1–5 Protein: Post-Translational Modification Protein folding Creates tertiary structure Cross-linkage Strong covalent bonds disulfide Cleavage Addition of other molecules or groups Assembly into polymeric proteins Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings