Protein Synthesis PDF

Why Do Cells Make Proteins? Eating a donut raises blood sugar…. The body produces the hormone INSULIN which lowers blood sugar Eating yogurt r...

Why Do Cells Make Proteins? Eating a donut raises blood sugar…. The body produces the hormone INSULIN which lowers blood sugar Eating yogurt requires the breakdown of lactose … The body produces the enzyme LACTASE which digests lactose Prevention of tumors in DOGS! (and ….humans) …. The canine cells produce TUMOR SUPPRESSOR genes to prevent tumor growth Making muscle … Muscle growth requires the synthesis of ACTIN and MYOSIN protein filaments Making COVID antibodies ….. Injection of COVID vaccines stimulates the synthesis of the viral SPIKE PROTEIN Biology 1 Lecture: Protein Synthesis Differences between DNA and RNA Protein Synthesis Deoxyribonucleic acid (DNA): primary information bearing molecule in living Codon = Three base things. sequence of mRNA that Codes for proteins codes for a specific De-oxy = one less oxygen on sugar (ribose) amino acid Ribonucleic acid (RNA): transfers genetic code from DNA in the nucleus to protein-forming system in the cytoplasm Uracil instead of Thymine How Cells Make Proteins Players Involved in Protein Synthesis DNA contains information specifying the amino acid PROTEIN SYNTHESIS requires the following types of RNA sequences required to build proteins. RNA Polymerase Enzyme PROTEIN SYNTHESIS requires a TWO-STEP rRNA (Ribosomal RNA) process: mRNA (Messenger RNA) tRNA (Transfer RNA) ○ TRANSCRIPTION: Genetic information is transferred from DNA to RNA ○ TRANSLATION: Synthesis of a polypeptide chain; mRNA codons are read in triplets RNA Polymerase Enzyme Protein Synthesis Overview Protein Synthesis:Transcription Transcription (occurs in the cell's nucleus) Big Picture: What Genetic information is transferred from DNA to RNA happens during this phase? What are the leading Deoxyribonucleic Acid (DNA) players in this role? RNA polymerase enzyme Messenger Ribonucleic Acid (mRNA) Main Steps in Transcription Initiation: RNA polymerase binds to DNA to unwind the double helix. Once unwinded, RNA reads the DNA bases to create the complementary sequence of bases for mRNA. Elongation: Building the nucleotides needed for the mRNA strand. Termination: Refers to the ending of transcription and when the mRNA strand is completed and detaches from the DNA  Protein Synthesis:Translation How Do We Know Which Amino Acid to Translation (occurs outside the nucleus in the cytoplasm) Incorporate into a Polypeptide? Big Picture: What happens The transferred genetic information from RNA is during this phase? assembled to create a protein. Translation begins when the ribosome arrives at the first START CODON AUG = Methionine (Met) What are the leading Ribosomes, ribosomal RNA (rRNA), and transfer RNA players in this role? (tRNA) Main Steps in Translation Translation ends when the ribosome reaches a STOP Initiation: mRNA attaches to a ribosome which initiates the CODON - UAA, UAG, or UGA recruitment of the first tRNA which typically carries the first amino acid methionine (Met) to begin translation Elongation: The ribosome continues to read the mRNA chain, and the amino acids are brought to the ribosome by tRNAs which link together to form a chain bonded by peptide bonds. Termination: Completion and release of the polypeptide chain (protein); stop codons within the mRNA is read (UAA, UAG, or UGA). Question - 1 Mutation: a permanent Mutations Starting DNA Incorrect base pairing Q: Indicate all of the TRUE statements: change in the base Mutation sequence of DNA a. Transcription occurs in the nucleus and the purpose is to make an mRNA transcript from a DNA May result in production template (gene) of a nonfunctional protein Completely random b. Translation occurs on the ribosome inside the nucleus Point mutation c. Translation begins when the ribosome arrives at the first start codon - AUG d. The molecule responsible for bringing amino acids to the ribosomes in tRNA e. The purpose of transcription is to make chains of amino acids Ser deletion Gly Phe His Ala Leu Base Types of Mutations Different Types of Point Mutations Normal gene Name Point mutation: Definition Example Consequence - When one base pair in the mRNA Original DNA sequence DNA is substituted for Original polypeptide Protein Met Lys another, or when one is Change in nucleotide that Change in genetic code but Silent does not change amino acid inserted or deleted. Base substitution not the resulting protein specified by codon Change in nucleotide that Change in primary structure Point Missense changes amino acid specified of protein mutation by codon Met Lys Nonsense Change in nucleotide that Premature termination, Base Deletion results in early stop codon incomplete polypeptide Missing Frame shift Addition or deletion of Reading frame is shifted, Frameshift mutation nucleotide massive missense Met Lys Sickle Cell Anemia Gene Regulation Sickle cell anemia: genetic Gene regulation: control of gene disorder caused by a single expression (protein production) point mutation that results Self regulating in a change in the structure Proteins that regulate gene expression are of hemoglobin transcribed and translated Missense mutation Three forms of gene regulation 1. Transcription factors Promoters and enhancers 2. Micro-RNAs 3. Alternative splicing Genomic Vaccines ……A Brief Reminder from Question - 2: Agree or Disagree? Why? Unit I mRNA vaccines inject cells with pieces of the viral spike protein that is normally found on the surface of SARS-CoV 2, the virus that causes COVID-19 How Does an mRNA Vaccine Work? Your Job is to Translate the Following Sequence: mRNA CUA UGU CUU GAA GCG GAU AUU ACU CUG UUU GUG UGA Amino Acid Sequence What Occurs When You Get the COVID Maria’s Story …. Vaccine? The following is a generalization of what occurs with the Pfizer and Moderna mRNA vaccine March 4th 2021: Maria and her coworkers (all essential workers) took the day off to get vaccinated. Maria received the Pfizer mRNA vaccine Minutes after the COVID vaccination: ○ Based upon vaccination and CDC recommendation, Maria was allowed to gather indoors with fully Muscle cells take up DNA/mRNA and undergo extensive protein synthesis of the viral SPIKE PROTEIN. vaccinated people without masks and without social distancing 15-30 minutes after the COVID vaccination: December 1st 2021: The first case of the Omicron variant in the U.S. is detected by the California and San Patients are asked to wait for an observation period to watch for any possible allergic reaction Francisco Departments of Public Health 12hr – 2 days later: February 5th 2022: Maria tests positive for COVID after experiencing sore throat and fever Patient may feel sore and experience fatigue – these are typical symptoms of local inflammation and the infiltration of white blood cells to the local area (More on this….when we go into immunity!) THESE ARE SIGNS THAT YOUR IMMUNE SYSTEM is WORKING! Question - 3 What are COVID Variants? COVID Variants are different versions of an original viral strain The more that SARS-CoV2 spreads (via infection), the greater the chance that it’s genetic material will change - or mutate - creating new variants or strains If Maria was vaccinated in March 2021, why did she Question becomes: test positive for COVID on February 2022? ○ Is the variant more infectious? ○ Is the variant more transmissible? ○ Does our immune system recognize the new variant? What are Mutations Silent Mutation MUTATIONS results in changes in the DNA SEQUENCES – there are many types of mutations, we will focus on three main mutation types: SUBSTITUTION, INSERTION, and DELETION The outcome of these mutations can result in the following: SILENT MUTATIONS, MISSENSE MUTATIONS, and NONSENSE MUTATIONS SILENT MUTATION: Nucleotide change still results in the SAME AMINO ACID - no effect on the protein product Missense Mutation Nonsense Mutation MISSENSE MUTATION: Nucleotide change results in a different amino acid – Can (or cannot) effect the overall NONSENSE MUTATION: Nucleotide change results in pre-mature STOP CODON. This results in a TRUNCATED protein and its function PROTEIN (much shorter polypeptide) COVID Variants mRNA Sequencing of COVID Variants Spike Gene Delta Variant mRNA March 2021: In the U.S. over 60% of positive COVID cases were caused by the Delta Variant UUA UCC GCG UUG CGA GGG AGG UUC GAC December 2021: In the U.S. over 99% of positive COVID cases were caused by the Delta variant Omicron BA.1 Variant mRNA UUU UGC GCG UUA CGC CGG GAG GUU Mid January 2022: In the U.S. over 95% of positive COVID cases were caused by the Omicron BA.1 variant CG_ Question -4 Spike Protein Delta Variant mRNA Binding site 34 Mutations in the binding site UUA UCC GCG UUG CGA GGG AGG UUC GAC Omicron BA.1 Variant mRNA UUU UGC GCG UUA CGC CGG GAG GUU CG_ 30 nonsynonymous mutations, 3 deletions, and 1 insertion Question - 5 The Biology of Omicron Variant WHAT MUTATIONS DOES OMICRON HAVE? Omicron’s spike protein has at least 30 amino acid substitutions, three small deletions, and one small insertion Suggested that some mutations may aid in viral transmission Provide an Explanation to Maria Why She got IS IT MORE TRANSMISSIBLE THAN THE DELTA VARIANT? Early indications are that omicron is more transmissible than previous variants Infected with COVID even as a Vaccinated Although its has been suggested that omicron is more transmissible, it causes less severe disease Individual “ Significant increase in protection vs Omicron from mRNA boosters” “Pfizer expects Omicron coronavirus vaccine to be ready by March” NPR:The Science Behind The Historic mRNA Vaccine