DNA Structure and Replication Worksheet Answers

Unit 4: Molecular Genetics DNA Structure and Replication Reviewing Key Concepts Matching On the line provided, match the letter of the scientist(s) with the description of his or their conclusions. a. Avery c. Watson and Crick b. Griffith d. Hershey and Chase __D___ 1. Concluded that the genetic material of a bacteriophage (bacteria virus) is DNA __A___ 2. Concluded that DNA was the factor that cause one bacterium to transform into another. __B___ 3. Concluded that bacteria could be transformed from harmless to disease-causing by an unknown factor. __C___4. Figured out the structure of DNA. Multiple Choice. 5. The primary function of DNA in cells is to a. serve as a storage form for unused nucleotides b. occupy space in the nucleus to keep the nucleus from collapsing c. store information that tells the cells which proteins to make. d. Serve as a template for making long, spiral carbohydrates 6. In the eukaryotic cell, DNA is stored in a. The vacuole c. The nucleus b. The cytoplasm d. The rough endoplasmic reticulum 7. According to the rules of base-pairing Guanine binds to which nitrogenous base? a. guanine b. adenine c. thymine d. cytosine 8. The double helix has ____________ bonds between the base-pairs and ___________ bonds along the backbone. a. Hydrogen, covalent c. Ionic, hydrogen b. Covalent, hydrogen d. Covalent, Ionic 9. Interpreting Graphics On the lines corresponding to the numbers on the diagram identify the following parts of the DNA molecule: nucleotide, sugar, phosphate, base pair, nitrogenous base. A. Phosphate Group B. Sugar C. Nitrogenous Base D. Base-pair E. Nucleotide Reviewing Key Skills 10. Using Analogies A double helix looks like a twisted ladder. Which parts of the nucleotide would be analogous to the rungs of a ladder? To the sides of the ladder? The base pairs are similar to the rungs of the ladder. The phosphates and the sugars are along the sides. 11. You have over 200 different types of cells in your body. Do these cells have the same DNA or different DNA? ______same_______________________________________________ Unit 4: Molecular Genetics 12. Explain why Adenine pairs with Thymine and why Guanine pairs with Cytosine 1) Adenine and Thymine both form 2 hydrogen bonds while Guanine and Cytosine form 3 hydrogen bonds. 2) A purine (A and G) always bonds with a pyrimidine (T and C). 13. Calculating Use Chargaff’s rules to determine the approximate percentage of thymine, guanine and cytosine in a DNA molecule, if 28% of the nucleotides in the molecule contain adenine. 28% Adenine, 28% Thymine, 22% Cytosine, 22% Guanine_ 14. Write the complimentary sequence to the following DNA strand A A T T C G A T C C G T A T T A G G T T A A G C T A G G C A T A A T C C Summarizing Replication: 15. Complete the following chart DNA Replication Location Purpose Product nucleus Make identical copies of the DNA for new cells Two new DNA helices Enzymes and their functions Helicase – unzips the DNA helix DNA Polymerase – builds the new DNA strand & proofreads DNA Ligase – forms covalent bonds along the backbone & proofreads 15. Identifying Structures Use the image below to answer the following questions a. Which color shows the original strands? (White or Black) white b. Which color shows the new strands? (White or Black) black 16. Why is it important that exact copies of DNA are produced during replication? The new DNA is for new cells produced by cell division. It is important that each of these cells have accurate and complete copies of the DNA so that they may function properly. 17. Critical Thinking Why is it advantageous to have weak hydrogen bonds between complementary base pairs and strong covalent bonds between phosphate and deoxyribose groups in a DNA molecule? The weak hydrogen bonds allow the two strands to be pulled apart during replication. The covalent bonds along the sides keep the strands from falling apart. If the base-pairs were connected by covalent bonds then they would not be able to be separated for replication. If the side chains had hydrogen bonds than they would fall apart during replication and the DNA would be permanently damaged. 18. Place the following sequence of events in order. __2_ helicase binds to the double helix and separates the two strands __4_ Ligase forms bonds along the backbones and proofreads to check for errors _6__ cell continues with its preparations for cell division. _5__ two new DNA strands are made _1__ cell decides it needs to carry out cell division _3__ DNA polymerase binds to each strand builds the new strand Unit 4: Molecular Genetics RNA and Protein Synthesis Reviewing Key Concepts 1. For each of the following statements indicate whether it is true of DNA, RNA or both. a. Never leaves the nucleus ____DNA___ h. Single stranded _____RNA___ b. Travels to the cytoplasm ____RNA___ i. Contains the sugar ribose _____RNA___ c. Made in the nucleus ____BOTH_____ j. Contains the sugar deoxyribose ___DNA___ d. Made up of nucleotides ___BOTH____ k. Has thymine _____DNA___ e. Short term information storage _RNA_ l. Has uracil _____RNA___ f. Long term information storage _DNA_ m. Contains a phosphate group __BOTH_____ g. Double stranded _____DNA___ Summarizing Transcription 2. Complete the following chart. Transcription Location Nucleus Purpose Produce RNA for the production of proteins Product RNA (mRNA, rRNA, tRNA) Enzyme and its functions RNA Polymerase: opens the DNA helix, makes the new strand of RNA. Identifying Structures 3. Label the RNA and DNA in this image. 4. Which process is shown in this image? 5. What would be the nucleotide sequence of the RNA that is transcribed from DNA with a nucleotide sequence of G C T A A T C C G C G A U U A G G C 6. Arrange the following steps in transcription in the correct order by writing the numbers 1-5 in the spaces before the steps. __3____ The two chains of the DNA molecule separate near the promoter. __2____ RNA polymerase binds to the promoter on the template chain of DNA. __5____ RNA polymerase reaches the termination signal and releases the DNA and RNA molecules __1____ RNA polymerase attaches to the first DNA nucleotide of the template chain. __4____ Complementary RNA nucleotides are added to the newly forming RNA molecule. 7. After the RNA it contains sections called introns and sections called exons. What are introns and exons? Introns are the sections of the RNA which are removed from mRNA before the mRNA travels out of the nucleus. The exons are the sections of the RNA that are kept and connected back together to form the final mRNA. Unit 4: Molecular Genetics Identifying structures. 8. Which process is shown in the image below? translation Polypeptide chain Amino acid 9. Label the image with the following terms: mRNA, ribosome, tRNA, polypeptide chain, amino acid, codon, anticodon. tRNA ribosome anticodon mRNA codon 10. Complete the following table Translation Location Purpose Product Cytoplasm Make proteins protein Enzyme and its functions Ribosome: uses the mRNA to build polypeptide chains 11. How does the cell control protein expression? By turning off and on Transcription. 12. Place the following terms, in order, to show the flow of information: DNA, Protein, Replication, RNA, Transcription, Translation, Trait Trait 13. Sentence Completion. Use the word bank below to fill in the blanks. Word Bank: amino acid, anticodon, codon, mRNA, polypeptide chain, ribosome, rRNA, tRNA a. _mRNA___ is a temporary copy genetic information that travels from the nucleus to the ribosome in the cytoplasm. b. _tRNA__ brings the correct amino acid to ribosome c. _ribosome___ is the enzyme that makes the polypeptide chain d. __polypeptide_ will fold up to become the protein e. proteins are made up of many _amino acids__ bonded together f. _codon__ are three consecutive nucleotides g. _anticodon___ is the part on the tRNA that matches to the complimentary sequence on the mRNA h. The ribosome is made of up __RNA__ and proteins. DNA, RNA, Protein Synthesis Worksheets 4