Chapter 12 - DNA Biology & Biotechnology.pdf

L A B O R A T O R Y 12 DNA Biology and Technology  DNA Biology and Technology Learning Outcomes Introduction 11.1 DNA Structure and Replication 11.2 RNA Structure 11.3 DNA and Protein Synthesis 11.4 Isolation of DNA Introduction Molecular genetic is the study...

L A B O R A T O R Y 12 DNA Biology and Technology  DNA Biology and Technology Learning Outcomes Introduction 11.1 DNA Structure and Replication 11.2 RNA Structure 11.3 DNA and Protein Synthesis 11.4 Isolation of DNA Introduction Molecular genetic is the study of the structure and function of DNA (Deoxyribonucleic Acid), the genetic material. DNA and RNA (Ribonucleic Acid) are two different nucleic acids found in the cells of every living organism. Introduction DNA and RNA structure are similar because they both consist of long chains of nucleotide units. However, there are a few structural details that distinguish them from each other.  12.1 DNA Structure and Replication DNA Structure lends itself to replication which is a necessary part of chromosome duplication, which precedes mitosis and meiosis. DNA is a polymer of nucleotide monomers. Each nucleotide is composed of three molecules: Deoxyribose (5-carbon sugar), Phosphate and Nitrogen – containing base. 12.1 DNA Structure and Replication 12.1 DNA Structure and Replication Observation: DNA Structure Table 12.1 12.1 DNA Structure and Replication DNA Replication During replication, the DNA molecule is duplicated so that there are two DNA molecules. 12.1 DNA Structure and Replication Observation: DNA Replication 12.1 DNA Structure and Replication Observation: DNA Replication Table 12.2 12.2 RNA Structure Like DNA, RNA is a polymer of nucleotides. RNA is single stranded, whereas DNA is double stranded. 12.2 RNA Structure In an RNA nucleotides, the sugar Ribose is attached to a phosphate molecule and a nitrogen-containing base, C, U, A or G. In RNA, the base uracil replaces thymine as one of the pyrimidine bases. 12.2 RNA Structure Table 12.3  12.2 RNA Structure Observation: RNA Structure Table 12.4  12.2 RNA Structure Observation: RNA Structure Table 12.5 12.3 DNA and Protein Synthesis Protein synthesis requires the processes of transcription and translation. During transcription, which takes place in the nucleus, an RNA molecule called messenger RNA (mRNA) is made complementary to one of the DNA strands. 12.3 DNA and Protein Synthesis This mRNA leaves the nucleus and goes to the ribosomes in the cytoplasm. Ribosomes are composed of ribosomal RNA (rRNA) and proteins in two subunits, and they provide location for protein synthesis to occur. 12.3 DNA and Protein Synthesis During translation, RNA molecules called transfer RNA (tRNA) bring amino acids to the ribosome, and they join in the order prescribed by mRNA. 12.3 DNA and Protein Synthesis Transcription Complementary RNA is made from a DNA template. A strand of mRNA is produced when complementary nucleotides join in the order dictated by the sequence of bases in DNA. Transcription occurs in the nucleus, and the mRNA passes out of the nucleus to enter the cytoplasm. 12.3 DNA and Protein Synthesis Transcription 12.3 DNA and Protein Synthesis Observation: Transcription Table 12.6 12.3 DNA and Protein Synthesis Translation DNA specifies the sequence of amino acids in a polypeptide because every three bases stand for an amino acid. DNA is said to have a triple code. 12.3 DNA and Protein Synthesis Translation The bases in mRNA are complementary to the bases in DNA. Every three bases in mRNA are called a codon. One codon of mRNA represents one amino acid. The sequence of DNA bases serves as the blueprint for the sequence of amino acids assembled to make a protein. 12.3 DNA and Protein Synthesis Translation mRNA leaves the nucleus and proceeds to the ribosomes, where protein synthesis occurs. tRNA transfer amino acids to the ribosomes. Each tRNA has one particular amino acid at one end and a matching anticodon at the other end. 12.3 DNA and Protein Synthesis Observation: Translation 12.3 DNA and Protein Synthesis Observation: Translation Table 12.7 Table 12.8 12.3 DNA and Protein Synthesis Observation: Translation  12.4 Isolation of DNA Experimental Procedure: Isolating DNA 1. Obtain a pair of gloves and wear them when doing this procedure. 2. Obtain a large, clean test tube, and place it in an ice bath. 3. Obtain approximately 4 ml of the filtrate (fruit filtrate) , add it to the test tube while keeping the tube in the ice bath. 4. Obtain and add 2 ml of cold meat tenderizer solution to the test tube, and mix the contents slightly with a stirring rod or Pasteur pipette. Let stand for 10 minutes so the enzyme has time to strip the DNA of protein. 5. You will add two spoon of soap and some salt. 6. Use a graduate cylinder or pipette to slowly add an equal volume (approximately 6 ml) of ice cold 95% ethanol. And tilt it 45angle. “ you should see a distinct layer of ethanol over the white precipitate, the DNA. Let the tube sit for 2-3min. 12.4 Isolation of DNA 7. Insert a glass rod or a Pasteur pipette into the tube until it reachs the bottom of the tube. Gently swirl the glass rod or pipette, always in the same direction. NOTE: you are not trying to mix the two layers, you are trying to wind the DNA onto the glass rod “like cotton candy”. Process spooling the DNA  Detergent (Soap) : break down the fat and proteins that make up the cell membrane. Meat tenderizer: Contain enzymes to strips (break down) the proteins from DNA. Salt : Enables the DNA strands to come closer together (aggregate). Alcohol (ethanol): Precipitates the DNA.