Resources. How to Use This Presentation. Chapter 10. Objectives. Table of Contents. Griffith s Discovery of Transformation. Griffith s Experiments

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1 How to Use This Presentation To View the presentation as a slideshow with effects select View on the menu bar and click on Slide Show. To advance through the presentation, click the right-arrow key or the space bar. From the resources slide, click on any resource to see a presentation for that resource. From the screen click on any lesson to go directly to that lesson s presentation. You may exit the slide show at any time by pressing the Esc key. Chapter Presentation Transparencies Visual Concepts DNA, RNA, and Protein Synthesis Table of Contents Objectives Relate how Griffith s bacterial experiments showed that a hereditary factor was involved in transformation. Summarize how Avery s experiments led his group to conclude that DNA is responsible for transformation in bacteria. Describe how Hershey and Chase s experiment led to the conclusion that DNA, not protein, is the hereditary molecule in viruses. Griffith s Experiments Griffith s experiments showed that hereditary material can pass from one bacterial cell to another. Griffith s Discovery of Transformation The transfer of genetic material from one cell to another cell or from one organism to another organism is called transformation.

2 Transformation Avery s Experiments Avery s work showed that DNA is the hereditary material that transfers information between bacterial cells. Hershey-Chase Experiment Hershey and Chase confirmed that DNA, and not protein, is the hereditary material. The Hershey-Chase Experiment Hershey and Chase s Experiments Objectives Evaluate the contributions of Franklin and Wilkins in helping Watson and Crick discover DNA s double helix structure. Describe the three parts of a nucleotide. Summarize the role of covalent and hydrogen bonds in the structure of DNA. Relate the role of the base-pairing rules to the structure of DNA.

3 DNA Double Helix Watson and Crick created a model of DNA by using Franklin s and Wilkins s DNA diffraction X-rays. DNA Nucleotides DNA is made of two nucleotide strands that wrap around each other in the shape of a double helix. DNA Nucleotides, continued Structure of a Nucleotide A DNA nucleotide is made of a 5-carbon deoxyribose sugar, a phosphate group, and one of four nitrogenous bases: adenine (A), guanine (G), cytosine (C), or thymine (T). DNA Nucleotides, continued Bonds Hold DNA Together Nucleotides along each DNA strand are linked by covalent bonds. Complementary nitrogenous bases are bonded by hydrogen bonds. Complementary Bases Hydrogen bonding between the complementary base pairs, G-C and A-T, holds the two strands of a DNA molecule together.

4 Complementary Base Pairing Objectives Summarize the process of DNA replication. Identify the role of enzymes in the replication of DNA. Describe how complementary base pairing guides DNA replication. Compare the number of replication forks in prokaryotic and eukaryotic cells during DNA replication. Describe how errors are corrected during DNA replication. How DNA Replication Occurs DNA replication is the process by which DNA is copied in a cell before a cell divides. How DNA Replication Occurs, continued Steps of DNA Replication Replication begins with the separation of the DNA strands by helicases. Then, DNA polymerases form new strands by adding complementary nucleotides to each of the original strands. DNA Replication DNA Replication

5 How DNA Replication Occurs, continued Replication Forks Increase the Speed of Replication Each new DNA molecule is made of one strand of nucleotides from the original DNA molecule and one new strand. This is called semi-conservative replication. DNA Errors in Replication Changes in DNA are called mutations. DNA proofreading and repair prevent many replication errors. DNA Errors in Replication, continued DNA Replication and Cancer Unrepaired mutations that affect genes that control cell division can cause diseases such as cancer. Objectives Outline the flow of genetic information in cells from DNA to protein. Compare the structure of RNA with that of DNA. Flow of Genetic Information The flow of genetic information can be symbolized as DNA RNA protein. Describe the importance of the genetic code. Compare the role of mrna, rrna,and trna in translation. Identify the importance of learning about the human genome.

6 RNA Structure and Function Comparing DNA and RNA RNA has the sugar ribose instead of deoxyribose and uracil in place of thymine. RNA is single stranded and is shorter than DNA. RNA Structure and Function, continued Types of RNA Cells have three major types of RNA: messenger RNA (mrna) ribosomal RNA (rrna) transfer RNA (trna) RNA Structure and Function, continued mrna carries the genetic message from the nucleus to the cytosol. rrna is the major component of ribosomes. trna carries specific amino acids, helping to form polypeptides. Types of RNA Transcription During transcription, DNA acts as a template for directing the synthesis of RNA.

7 Transcription Genetic Code The nearly universal genetic code identifies the specific amino acids coded for by each threenucleotide mrna codon. Translation Translation: Assembling Proteins Steps of Translation During translation, amino acids are assembled from information encoded in mrna. As the mrna codons move through the ribosome, trnas add specific amino acids to the growing polypeptide chain. The process continues until a stop codon is reached and the newly made protein is released. Translation: Assembling Proteins, continued The Human Genome The entire gene sequence of the human genome, the complete genetic content, is now known. To learn where and when human cells use each of the proteins coded for in the approximately 30,000 genes in the human genome will take much more analysis.

8 Multiple Choice 1. For which of the following is DNA responsible? A. directing RNA to make lipids B. directing RNA to produce glucose C. encoding information for making proteins D. encoding information for changing the genetic code 1. For which of the following is DNA responsible? A. directing RNA to make lipids B. directing RNA to produce glucose C. encoding information for making proteins D. encoding information for changing the genetic code 2. Where is RNA found? F. only in proteins G. only in the nucleus H. only in the cytoplasm J. in the nucleus and cytoplasm 2. Where is RNA found? F. only in proteins G. only in the nucleus H. only in the cytoplasm J. in the nucleus and cytoplasm 3. What is the basic unit of DNA called? A. sugar B. nucleotide C. phosphate D. nucleic acid 3. What is the basic unit of DNA called? A. sugar B. nucleotide C. phosphate D. nucleic acid

9 4. Which of the following nucleic acids is involved in translation? F. DNA only G. mrna only H. DNA and mrna J. mrna and trna 4. Which of the following nucleic acids is involved in translation? F. DNA only G. mrna only H. DNA and mrna J. mrna and trna The table below shows the percentage of bases in some organisms. Use the table to answer the questions that follow. 5. What is the ratio of purines to pyrimidines for these organisms? A. about 1:1 B. about 1:2 C. about 1:3 D. about 1:4 The table below shows the percentage of bases in some organisms. Use the table to answer the questions that follow. 5. What is the ratio of purines to pyrimidines for these organisms? A. about 1:1 B. about 1:2 C. about 1:3 D. about 1:4 The table below shows the percentage of bases in some organisms. Use the table to answer the questions that follow. 6. Within each organism, which nucleotides are found in similar percentages? F. A and T, G and C G. A and C, G and T H. A and C, G and U J. A and G, T and U The table below shows the percentage of bases in some organisms. Use the table to answer the questions that follow. 6. Within each organism, which nucleotides are found in similar percentages? F. A and T, G and C G. A and C, G and T H. A and C, G and U J. A and G, T and U

10 7. mrna : uracil :: DNA : A. guanine B. thymine C. adenine D. cytosine 7. mrna : uracil :: DNA : A. guanine B. thymine C. adenine D. cytosine The model below represents a DNA molecule undergoing DNA replication. Use the model to answer the question that follows. 8. Which part of the model represents DNA helicase? F. 1 G. 2 H. 3 J. 4 The model below represents a DNA molecule undergoing DNA replication. Use the model to answer the question that follows. 8. Which part of the model represents DNA helicase? F. 1 G. 2 H. 3 J. 4 Short Response DNA is made up of two strands of subunits called nucleotides. The two strands are twisted around each other in a double helix shape. Explain why the structure of a DNA molecule is sometimes described as a zipper. Short Response, continued DNA is made up of two strands of subunits called nucleotides. The two strands are twisted around each other in a double helix shape. Explain why the structure of a DNA molecule is sometimes described as a zipper. Answer: DNA is often described as a zipper because the two strands of DNA look like each lengthwise half of a zipper and the bases and hydrogen bonds between the strands look like the teeth of a zipper.

11 Extended Response DNA can be damaged by mistakes made during its replication. The mistakes are called mutations. Part A Explain eukaryotic DNA replication. Part B Explain how a mutation during replication can affect a protein that is synthesized. Extended Response, continued Answer: Part A During DNA replication, each strand serves as a template. DNA replication begins when helicase enzymes separate the DNA strands. DNA polymerases add complementary nucleotides to each of the original DNA strands. The DNA polymerases are then released. Two DNA molecules identical to the original DNA molecule result. Part B When mistakes in DNA replication occur, the base sequence of the newly formed DNA differs from that of the original DNA, changing the original code on the DNA. When the mutated DNA is transcribed, the sequence of bases on the mrna is incorrect. Translating the incorrect mrna can result in an incorrect amino acid which can affect the protein s structure and ultimately its function. DNA Nucleotides RNA Structure and Function Genetic Code