Components of DNA. Components of DNA. Aim: What is the structure of DNA? February 15, DNA_Structure_2011.notebook. Do Now.

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1 Aim: What is the structure of DNA? Do Now: Explain the Hershey Chase experiment and what was its conclusion? Homework Read pp P.299 3,4,6.7 Do Now Paperclip Combos Material: 8 paperclips, 2 each of 4 different colors Procedure: * Chose one letter to represent each color 1.Place any two paper clips side by side. Record the sequence from left to right. 2.Create new pairs of paper clips to produce as many different sequences as you can. Record the sequences. 3.Next place 3 paper clips side by side to form a triplet. Record. 4 Make as many triplets of different combinations as you can and record them. Go to website, verderbz.com Through the links, visit one of the websites related to DNA. Write a 1 paragraph review of it. Mar 9 9:51 PM Mar 10 10:52 AM Components of DNA Structure a polymer monomer units of DNA are nucleotides polymer is known as a "polynucleotide." each nucleotide consists of a 5 carbon sugar (deoxyribose) + a nitrogen containing base attached to the sugar + a phosphate group four different types of nucleotides found in DNA, differing only in the nitrogenous base four nucleotides are given one letter abbreviations as shorthand for the four bases: A,C,G.T Mar 9 10:47 PM Mar 9 10:48 PM Components of DNA Adenine and guanine are purines. Purines are the larger of the two types of bases found in DNA Mar 9 10:48 PM Mar 9 10:56 PM 1

2 Cytosine and thymine are pyrimidines. The deoxyribose sugar of the DNA backbone has 5 carbons and 3 oxygens. The carbon atoms are numbered 1', 2', 3', 4', and 5' Mar 9 10:57 PM Mar 9 10:59 PM FYI: A nucleoside is one of the four DNA bases covalently attached to the C1' position of a sugar. The sugar in deoxynucleosides is 2'-deoxyribose The four different nucleosides of DNA are deoxyadenosine (da), deoxyguanosine (dg), deoxycytosine (dc), and (deoxy)thymidine (dt, or T). DNA backbone is a polymer with an alternating sugar phosphate sequence. The deoxyribose sugars are joined at both the 3' hydroxyl and 5' phosphate groups to phosphate groups in ester links, also known as "phosphodiester" bonds. Mar 9 11:01 PM Mar 9 11:07 PM Features of the 5' d(cgaat) structure: Alternating backbone of deoxyribose and phosphodiester groups Chain has a direction (known as polarity), 5' to 3' from top to bottom Oxygens (red atoms) of phosphates are polar and negatively charged A, G, C, and T bases can extend away from chain, and stack atop each other Bases are hydrophobic DNA Double Helix DNA is a normally double stranded macromolecule. Two polynucleotide chains, held together by weak thermodynamic forces, form a DNA molecule. Mar 9 11:10 PM Mar 9 11:12 PM 2

3 LE 3 2/15 Aim: What is the structure of DNA? (Cont) Do Now: What are the base pairs of DNA? Homework: LE1 only: 1. Take home Quiz to be Collected P #1 16 Answers only (1, 2,3 etc) LE3 2. Read pp P. 299 #1, 2 Describe the Hershey Chase Experiment Mar 10 8:47 PM Feb 15 10:01 AM LE 1 2/15 Feb 15 8:43 AM Feb 15 7:21 AM DNA I Structure Features of the DNA Double Helix Two DNA strands form a helical spiral, winding around a helix axis in a right handed spiral The two polynucleotide chains run in opposite directions The sugar phosphate backbones of the two DNA strands wind around the helix axis like the railing of a sprial staircase The bases of the individual nucleotides are on the inside of the helix, stacked on top of each other like the steps of a spiral staircase. Strands are complementary to each other, not identical a. Sugar Phosphate backbone b. Complementary pairs of nitrogenous bases A always pairs with T C always pairs with G A T (Adenine Thymine) C G (Cytosine Guanine) Bases bonded together by hydrogen bonds II Function a. sequence of these bases encodes instructions b. some parts DNA are control centers for turning genes on and off c. some parts have no function, d. some parts have a function not yet understood e. other parts of DNA are genes that carry the instructions for making proteins these proteins build an organism and carry out life function ex: hemoglobin in red blood cells insulin Mar 9 11:14 PM Mar 10 9:28 PM 3

4 Base Pairs A forms 2 hydrogen bonds with T on the opposite strand, G forms 3 hyrdorgen bonds with C on the opposite strand. How does a DNA Molecule copy itself? DNA REPLICATION Genes (the chemicals of heredity) are composed of DNA. Whenever new cells are made in either meiosis or mitosis, then new genes made of DNA are produced for the new cells. DNA Replication means the duplication of DNA that is identical to the original double stranded DNA. Results in two, double stranded DNA molecules One old strand + one new strand This replication of DNA must be exact, or a mutation of an incorrect sequence of nucleotides will occur. DNA Replication occurs in 3 steps: **Many proteins are involved 1. DNA double helix unwinds (enzyme Helicase) and "unzips", forming two template strands as the bases (ACTG) come apart 2. Spare nucleotides (in the nucleus of the cell) attach themselves to the broken rungs to repair the break (DNA polymerase) (Recall DNA is a Polymer) Each repairing nucleotide is identical to the one broken. 3. As each broken rung is repaired, two ladders form, that is 2 identical strands of DNA. The repairing is really the process of replication. Mar 9 11:15 PM Mar 10 10:10 PM Aim: How does DNA send its genetic information out of the nucleus? Do Now: What it called when DNA copies itself? Homework 1. Complete the Transcription Lab 2. Quiz Wednesday DNA, RNA, Protein Synthesis 2. Read pp , p.310 1,2,3,4 Feb 15 7:26 AM Mar 12 8:56 AM Aim: How does DNA send its genetic information out of the nucleus? Do Now: What it called when DNA copies itself? Homework 1. Complete the Transcription Lab 2. Quiz Wednesday DNA, RNA, Protein Synthesis 2. Read pp , p.310 1,2,3,4 Transcription: DNA to RNA The nucleus controls all activity of the cell via the information contained in DNA DNA never leaves the nucleus. In order to get the information to the cell it uses Messenger RNA, which is complementary to DNA Transcription: the process by which mrna, a single stranded nucleic acid is formed using DNA as a template. Usually copies only a portion of the DNA Carries instructions for making a protein from a gene & delivers to the ribosome Nitrogenous Bases pair similarly to DNA except that T is replaced by U (Uracil) DNA mrna A U T A C G G C Complete the following: DNA Strand: CGCGATCATGTGAAC MRNA: GCGCUAG Mar 12 8:56 AM Mar 11 8:47 AM 4

5 How does DNA direct Protein synthesis? Translation:Making Proteins mrna to trna Translation the process by which mrna leaves the nucleus and provides the template for protein synthesis in the ribosome Translates the mrna sequence into a specific sequence of amino acids trna have amino acids attached to them and bring them to the ribosome Codon a triplet of three nitrogenous bases that codes for a specific amino acid, or to stop/ start the transcription LE3 3/12/2010 Feb 15 2:16 PM Mar 10 9:44 PM LE3 3/12/2010 Mar 16 1:50 PM Mar 12 9:29 AM Translation:Making Proteins mrna to trna Protein Synthesis is diected by DNA and its use of mrna & trna to carry the information from the nucleus to the cell cytoplasm & ribosomes Translation the process by which mrna leaves the nucleus and provides the template for protein synthesis in the ribosome Translates the mrna sequence into a specific sequence of amino acids trna have amino acids attached to them and bring them to the ribosome Codon a triplet of three nitrogenous bases that codes for a specific amino acid, or to stop/ start the transcription Mar 10 9:44 PM Mar 16 9:05 AM 5

6 Transcription & Translation DNA TCGATTGCA mrna trna Amino Acid Mar 10 9:45 PM Mar 16 9:08 AM 1. DNA 2. nucleotide 3. purines 4. genes 5. pyrimidines 6. DNA helicase 7. DNA polymerase 8. DNA replication DNA & RNA Vocabulary Practice Match the term/ word to its definition a. represented by adenine and guanine b. enzyme that separates the DNA helix by breaking the hydrogen bonds that link the nitrogenous bases c. instructions for inherited traits d. the process by which DNA is copied e. represented by thymine and cytosine f. consists of a phosphate, a five carbon sugar, and a nitrogenous base g. enzyme that adds nucleotides to exposed nitrogenous bases h. name given for deoxyribonucleic acid a. codon b. gene expression c. RNA d. transcription e. translation 1 The process in which RNA is made from the information in DNA 2 Includes transcription and translation 3 A three nucleotide sequence that encodes an amino acid or a start/stop signal 4.A type of nucleic acid that includes three major types 5.A process that occurs at ribosomes where proteins are made from the information found in RNA RNA Review Mar 10 9:45 PM Mar 11 10:51 PM 6