DNA and Protein Synthesis - History of DNA

Unit 7 Test Study Guide: DNA and Protein Synthesis 1)​ HISTORY OF DNA DISCOVERIES: a)​ Give a brief description of the following scientists’ contributions to the discovery of DNA. i)​ Miescher (1868) Found that the chemical make-up of cell nuclei consisted of half proteins and half of “something else” ii)​ Frederick Griffith (1928) His research led to the concept of transformation – one strain of bacteria takes in the DNA of a different bacteria and makes the proteins from that DNA code. iii)​ Avery, MacLeod, McCarty (1944) Discovered that genes are composed of DNA iv)​ Sutton (early 1900s) Used grasshopper chromosomes to verify that chromosomes were a basis for heredity. v)​ Franklin and Wilkins (1952) Used X-Ray diffraction/crystallography to examine the structure of DNA – showed that DNA was a double helix! vi)​ Chase and Hershey (1952) Used radioactive markers and found that viruses have DNA vii)​ Chargaff (1952) Developed the base-pairing rule for DNA. (% A = % T and % C = % G) viii)​Watson and Crick (1953) Developed the double helix model of the structure of DNA b)​ What is the human genome project? When did it occur? Occurred 1990-2003. This project sequenced (mapped out) the DNA on all 46 human chromosomes. 2)​ DNA Structure a)​ What is the monomer of DNA? Nucleotide b)​ Name the 3 parts of a nucleotide. Deoxyribose sugar, phosphate, nitrogenous base c)​ What are the 4 nitrogen bases? Adenine, Thymine, Guanine, Cytosine d)​ What is the difference between purines and pyrimidines? Purines have two rings, pyrimidines have one e)​ What is Chargaff’s rule? %A = %T and %C = %G f)​ Why is DNA called a double helix? Because its 3D structure is similar to a twisted ladder – there are two strands that twist in a helix shape g)​ What are the structures that make up the DNA backbone? Deoxyribose and phosphate. That make up the rungs? Nitrogenous bases h)​ What kind of bond holds the strands of DNA together? Hydrogen bonds 3)​ Prokaryotic vs. Eukaryotic DNA PROKARYOTES EUKARYOTES WHERE IS DNA LOCATED In the cytoplasm In the nucleus AMOUNT OF DNA One plasmid (one ring of DNA) Multiple chromosomes WHAT IS THE SHAPE OF DNA A ring shape Linear chromosomes 4)​ DNA Replication a)​ What is replication? The process of copying DNA b)​ When does replication happen? During S-phase of interphase c)​ List the steps of DNA Replication, including the necessary enzymes to make the process happen. i)​ Enzyme helicase unzips the double helix ii)​ Enzyme DNA polymerase builds the new DNA strand iii)​ Enzyme ligase zips up the two strands, hydrogen bonds reform d)​ Why is DNA a semi-conservative process? Each DNA molecule is made of one old and one new strand 5)​ Protein Synthesis a)​ What is protein synthesis? The process of making proteins using an mRNA template b)​ Name three reasons why protein synthesis is necessary for living organisms: i)​ Proteins help with a cell’s structure and function ii)​ Enzymes help catalyze chemical reactions iii)​ An organism’s physical characteristics are the result of proteins 6)​ DNA vs. RNA Structure DNA RNA Number of Strands and shape Two, double helix One, single helix Nitrogen bases A, T, C, G A, U, C, G Type of 5-Carbon Sugar Deoxyribose Ribose Phosphate group? Yes Yes 7)​ Types of RNA a)​ mRNA: Messenger RNA – based off the DNA, it carries the genetic code out of the nucleus to a ribosome in the cytoplasm i)​ What is a codon? A three letter sequence found on mRNA b)​ tRNA: Transfer RNA – brings amino acids to the ribosome during translation i)​ What is an anticodon? A three letter sequence found on tRNA, complementary to codons on the mRNA c)​ rRNA: Ribosomal RNA – forms the ribosome 8)​ DNA & RNA Base-pairing rules a)​ In DNA: i)​ A pairs with: T ii)​ C pairs with: G iii)​ G pairs with: C iv)​ T pairs with? A b)​ DNA RNA: i)​ A pairs with: U ii)​ C pairs with: G iii)​ G pairs with: C iv)​ T pairs with: A 9)​ Central Dogma of Biology: Use the diagram to identify the appropriate answers a)​ b)​ c)​ d)​ e)​ A: Replication B: DNA C: Transcription D: mRNA E: Translation f)​ F: Protein/Polypeptide 10)​Protein Synthesis a)​ Why does the cell need mRNA? To take the genetic code to a ribosome in the cytoplasm – DNA cannot leave the nucleus b)​ What is transcription? The process of creating a complementary mRNA sequence based on the DNA c)​ What is translation? The process of making proteins based on the mRNA code d)​ What is the function of RNA polymerase? Make mRNA molecules e)​ List the 3 steps of Translation i)​ Initiation ii)​ Elongation iii)​ Termination f)​ Number of amino acids used by cells? 20 g)​ What happens to a protein after it leaves the ribosome? It will go to the ER for additional processing or the Golgi body to be shipped to another location 11)​Codon Chart Practice: a)​ Name the amino acid being coded for: i)​ AUG: Met ii)​ UCG: Ser iii)​ UAC: Tyr iv)​ UGA: Stop b)​ Name the codon: i)​ Valine (Val): There are multiple – GUU, GUC, GUA, GUG ii)​ Methionine (Met): AUG iii)​ Stop: UGA iv)​ Tryptophan (Trp): UGG 12 Mutations- Genetic information is altered when changes in the DNA sequence, called mutations, occur. Changes in the DNA sequence of a single gene are called Point mutations. Identify each of the following mutation Deletion Duplication Inversion Translocation