Understanding the Role of DNA, RNA, and Proteins in Living Organisms - Prof. Chantilly A. , Study notes of Human Biology

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The molecules of life work in a specific order: DNA → RNA → Protein → Function Molecules DNA – Deoxyribonucleic acid RNA – Ribonucleic acid Protein–Made of amino acids These three molecule work together to coordinate all of our body’s activities DNA Genetic information Stored in the nucleus Organized into 23 pairs (46 total) chromosomes & many thousands of genes Molecular structure

• Double helix
• Nucleic acids (sugar + phosphate + base)
• 4 different bases (A, T, C, G) = rungs of ladder
• Specific base‐pairs (A/T, C/G) What would the opposite DNA strand read? GAATTCATTGTT DNA Replication = Duplicating DNA, making a copy of DNA Occurs during mitosis when an exact genetic copy needs to be made for the daughter cells (and meiosis) Semiconservative replication
• The original strands do not stay together Protein (enzymes) helpers involved
• “unzipping” protein (topoisomerase)
• DNA polymerase
• Ligase (reconnecting pieces) Mutations can occur during replication Point mutations
• Single base pair changes
• Change of sequence C A TTC to C T TTC
• Removal of one nucleotide CA T TC to CATC
• Addition of an extra nucleotide CATTC to CATTTC “Mutations” are NOT always “bad”
• Responsible for evolution
• “Heroes” “X‐men” (science fiction but….) Techniques to work with DNA DNA extraction
• Cheek cells
• Any organism cell PCR (polymerase chain reaction)
• Making many copies of a piece of DNA
• DNA replication in a tube
• Karry Mullis, 1993 Nobel Prize Gel Electrophoresis
• Separating molecules by size
• Big things move slower, small things move faster Gel Electrophoresis Gel
• Agarose (seaweed)

• Molecules move through “obstacles” Gel Box & Power supply
• Electricity (voltage) pushes molecules according to charge (DNA is negative) Loading a gel
• Putting liquid (with molecules) into wells Running a gel
• Applying voltage to molecules and forcing them to move RNA DNA → RNA is called transcription RNA ‐ Most of the time, DNA serves as a template to make RNA Made of bases A, C, G, U Single stranded There are three main types of RNA ‐Messenger RNA (mRNA) ‐Ribosomal RNA (rRNA) ‐Transfer RNA (tRNA) mRNA (messenger RNA) ‐Is a copy of only one gene ‐Made by the process of transcription and by RNA polymerase ‐Genes initially contain exons and introns ‐mRNA copies both exons and introns and then cuts the introns out What would the mRNA sequence be from the following DNA sequence? ATCGA RNA polymerase attaches to the promoter. (A promoter is a region right before the start of a gene.) Without RNA Polymerase, no transcription occurs. This situation occurs when a gene is “OFF”. When RNA Polymerase attaches to a promoter, transcription occurs. This situation occurs when a gene is “ON”. RNA → Protein is called translation Biotechnology Using the molecules of life to make a product (molecular biology)
• Diagnostic tools
• Pharmaceuticals
• Agriculture
• Environment Use of DNA specifically is termed genetic engineering Genetic Engineering Recombinant DNA
• DNA from two different sources (organisms) Manipulating DNA to create transgenic organisms Using those organisms to make a protein of interest
• Research (green fluorescent protein)
• Market (insulin) Green Fluorescent Protein (GFP) is naturally found in jellyfish and other aquatic life GFP (Red, too) •A useful tool for researchers

Step 6 •Mitosis

• We’ll let the bacteria grow overnight •DNA replication every time the bacteria divides •Every bacteria has a copy of the plasmid Translation Making protein from mRNA Done by the ribosome (part protein, part rRNA) & tRNA’s The ribosome reads the genetic code off of mRNA The Genetic Code •Codons are made of 3 bases (on mRNA) •Codons specify an amino acid •Amino acids are building blocks of proteins •20 amino acids •“Start codon” and “Stop codon” Translation •Involves the mRNA, ribosome (protein and rRNA) and tRNA •The ribosome’s job is the bring the correct tRNA and mRNA together and then link the amino acids into a chain •mRNA has codons, tRNA has anticodons and carries an amino acid •The ribosome reads from the start to the stop codon Mutations from DNA may affect proteins Point mutations
• Single base pair changes Can result in
• No change at all (multiple codons for one amino acid)
• Protein still functions
• Protein does not function as well
• Protein does not function at all

• Protein functions better Gene Activity •Genes can be “on” or “off”
• “on” = being made into protein = RNA polymerase is bound to promoter – mRNA ‐ protein
• “off” = not being made into protein = RNA polymerase is NOT bound to promoter – no mRNA •Gene activity changes during development •Gene activity changes every day in response to environment •Certain genes are always on in some tissues or always off Step 5 = Genetic Transformation •Inserting new DNA into a host cell
• New DNA = GFP gene
• Host cell = E.coli •This will change E.coli ’s traits
• Before… •Eats LB •Sensitive to antibiotics (ampicillin) •Do not glow in UV light
• After… Step 6 •Mitosis
• We’ll let the bacteria grow overnight •DNA replication every time the bacteria divides •Every bacteria has a copy of the plasmid Recombinant DNA technology •Bioremediation
• cleaning up toxic waste •BST and milk production in cows •“Cloned” cattle •Vaccines •Genetically modified foods
• “Golden‐rice”
• Most of the corn we eat? •Alternative sources of energy •Treatments or cures… Concerns •Long‐term effects? •Disrupting environment? •Can insects/diseases adapt more quickly than we can make the technology? •Will the public “trust” the products? Human Genome Project •Genome = all of an organism’s DNA •Human and other Sequences are complete •Sequence information does not provide functional information
• What do proteins actually do?
• How are the genes controlled? On/Off •Future may hold more information for diagnosing, treating, or preventing diseases