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Proteins Proteins Review Proteins are composed of C, H, O, N and sometimes S Proteins are made of amino acids Proteins are held together by peptide bonds (covalent bonds between amino acids) Proteins are coded for by the sequence of DNA nucleotides Proteins are the building blocks of all materials Proteins can be enzymes (catalysts for reactions) Proteins Pre-Production: Understanding DNA and RNA DNA (deoxyribonucleic acid) RNA (ribonucleic acid) • Double helix strand of nucleotides • Bases A, T, C, G • Contained in the nucleus • Deoxyribose sugar • Single strand of nucleotides • Bases A, U, C, G • RNA does not have thymine, it has uracil • Several types in cell • Ribose sugar Proteins Pre-Production: Understanding DNA and RNA DNA RNA Proteins Pre-Production: Understanding DNA and RNA RNA: types RNA: Types • mRNA: messenger RNA, carries code of DNA as codons to ribosomes • tRNA: transfer RNA, brings amino acids and matches it to codons using anti-codons • mRNA • tRNA Checkpoint #1 1. Create a Venn diagram for DNA and RNA 2. You already know how DNA replication occurs. With that in mind, what predictions could you make about how mRNA is formed from DNA? In other words, how does the code of DNA become a strand or RNA? 3. Name and describe two types of RNA involved in protein synthesis? 4. Using your macromolecule notes, give examples and functions of at least three proteins. Production: Transcription • RNA molecules are made by copying part of the nucleotide sequence • RNA polymerase – enzyme that helps match complementary RNA nucleotides to DNA nucleotides • During transcription, RNA polymerase splits the DNA and matches complementary nucleotides to form a strand of mRNA (messenger RNA). Production: Transcription • What do you notice about the DNA to RNA base pairs? Production: Transcription • Instead of Thymine, RNA has Uracil. •A–U • C–G Production: Transcription • mRNA forms a “language” to become protein. Three mRNA nucleotides together from a codon and that will be used for translation • UCGCACGGUUUC UCG – CAC – GGU – UUC (Three Codons) Production: Transcription • Each codon represents a specific amino acid • There are 20 amino acids • What would the codon AUG stand for? • What do you notice is different about this codon? Production: Translation • During translation the cell uses information from messenger RNA to produce proteins. • The ribosome moves along the mRNA strand and matches tRNA (transfer RNA) anticodons to the codons of the mRNA • Each tRNA is carrying the specific amino acid coded for by the mRNA • The ribosomes assists with forming peptide bonds between the amino acids so a long chain (polypeptide) is formed Production: Translation Further resources • Listen to Bozeman explain it! • https://www.youtube.com/watch?v=h3b9ArupXZg • Text page reference: Page 300-306 • Short animation: http://www.dnalc.org/resources/3d/12transcription-basic.html Checkpoint #2 1. 2. 3. 4. 5. What happens during transcription? What happens during translation? What is the codon and anticodon? What roles do mRNA and tRNA play in protein synthesis? Using the genetic code, identify amino acids that have the following messenger RNA strand codes: UGGCAGUGC 6. Challenge: determine the amino acid sequence coded for by the DNA strand AATTCGGCTACG Post-Production • Proteins are long chains of amino acids held together by peptide bonds. They form polypeptide chains. • Proteins have 4 levels of structure 1. Primary Structure: sequence of amino acids 2. Secondary Structure: hydrogen bonding twists strand into a helix 3. Tertiary Structure: folding of the helix 4. Quaternary Structure: individual peptides are linked to one another Post-Production • Protein Folding Protein Types • Structural – keratin (hair, nails) • Movement – actin and myosin in muscles • Defense – antibodies in bloodstream, venom • Storage – albumin in egg whites nourish an embryo • Signaling – insulin promotes glucose uptake • Catalyzing reactions – amylase in saliva digests carbohydrates Structural proteins Proteins: Enzymes • Enzymes • Make it easier for reactions to occur • Act as catalysts to speed up a reaction • They lower the activation energy (energy necessary for the rxn. to occur) • Lock and Key Model • Makes enzymes only work for specific reaction • Important in controlling reactions of the body Ex.: amylase, catalase, lactase • “Enzymes are proteins that end in –ase” Enzyme Structure – Lock and Key Proteins: Enzymes • Insulin Denaturing Proteins • Denature: when the shape of the protein gets permanently changed • Enzyme can’t function any longer • Caused by: change in pH or temp • Cold = usually slows enzymes down • Hot = denatures enzymes • Too acidic or basic = usually denatures enzymes *Important to maintain homeostasis! Denaturing Proteins Checkpoint #3 1. If a codon changed from UUU to UUC, what effect would that have on the overall protein? 2. Explain the importance of the proteins hemoglobin and insulin. 3. Why do you think it is important for enzymes to function with a lock and key model? 4. A child goes to the doctor with an extremely high fever. Explain why the doctor is very concerned and what might he/she do for treatment. 5. Outline the four levels of structure for proteins.