Go to Section: Interest Grabber Order! Genes are made of DNA, a large, complex molecule. DNA is composed of individual units called nucleotides. Three of these units form a code. The order, or sequence, of a code and the type of code determine the meaning of the message. Section On a sheet of paper, write the word cats. List the letters or units that make up the word cats. 2. Try rearranging the units to form other words. Remember that each new word can have only three units. Write each word on your paper, and then add a definition for each word. 3. Did any of the codes you formed have the same meaning? 4. How do you think changing the order of the nucleotides in the DNA codon changes the codon’s message?

Go to Section: Section Outline 12–1DNA A.Griffith and Transformation 1.Griffith’s Experiments 2.Transformation B.Avery and DNA C.The Hershey-Chase Experiment 1.Bacteriophages 2.Radioactive Markers D.The Components and Structure of DNA 1.Chargaff’s Rules 2.X-Ray Evidence 3.The Double Helix Section 12-1

Go to Section: Percentage of Bases in Four Organisms Section 12-1 Source of DNAATGC Streptococcus Yeast Herring Human Streptococcus Yeast Herring Human

Go to Section: Disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Heat-killed, disease- causing bacteria (smooth colonies) Control (no growth) Heat-killed, disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Dies of pneumoniaLives Live, disease-causing bacteria (smooth colonies) Dies of pneumonia Section 12-1 Figure 12–2 Griffith’s Experiment

Go to Section: Disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Heat-killed, disease- causing bacteria (smooth colonies) Control (no growth) Heat-killed, disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Dies of pneumoniaLives Live, disease-causing bacteria (smooth colonies) Dies of pneumonia Section 12-1 Figure 12–2 Griffith’s Experiment

Go to Section: Bacteriophage with phosphorus-32 in DNA Phage infects bacterium Radioactivity inside bacterium Bacteriophage with sulfur-35 in protein coat Phage infects bacterium No radioactivity inside bacterium Figure 12–4 Hershey-Chase Experiment Section 12-1

Go to Section: Bacteriophage with phosphorus-32 in DNA Phage infects bacterium Radioactivity inside bacterium Bacteriophage with sulfur-35 in protein coat Phage infects bacterium No radioactivity inside bacterium Section 12-1 Figure 12–4 Hershey-Chase Experiment

Go to Section: Bacteriophage with phosphorus-32 in DNA Phage infects bacterium Radioactivity inside bacterium Bacteriophage with sulfur-35 in protein coat Phage infects bacterium No radioactivity inside bacterium Section 12-1 Figure 12–4 Hershey-Chase Experiment

Go to Section: PurinesPyrimidines AdenineGuanine CytosineThymine Phosphate group Deoxyribose Figure 12–5 DNA Nucleotides Section 12-1

Go to Section: Hydrogen bonds Nucleotide Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Figure 12–7 Structure of DNA Section 12-1

Go to Section: Interest Grabber A Perfect Copy When a cell divides, each daughter cell receives a complete set of chromosomes. This means that each new cell has a complete set of the DNA code. Before a cell can divide, the DNA must be copied so that there are two sets ready to be distributed to the new cells. Section 12-2

Go to Section: Interest Grabber continued Section On a sheet of paper, draw a curving or zig-zagging line that divides the paper into two halves. Vary the bends in the line as you draw it. Without tracing, copy the line on a second sheet of paper. 2.Hold the papers side by side, and compare the lines. Do they look the same? 3.Now, stack the papers, one on top of the other, and hold the papers up to the light. Are the lines the same? 4.How could you use the original paper to draw exact copies of the line without tracing it? 5.Why is it important that the copies of DNA that are given to new daughter cells be exact copies of the original?

Go to Section: 12–2Chromosomes and DNA Replication A.DNA and Chromosomes 1.DNA Length 2.Chromosome Structure B.DNA Replication 1.Duplicating DNA 2.How Replication Occurs Section 12-2 Section Outline

Go to Section: Chromosome E. coli bacterium Bases on the chromosome Prokaryotic Chromosome Structure Section 12-2

Go to Section: Figure Chromosome Structure of Eukaryotes Chromosome Supercoils Coils Nucleosome Histones DNA double helix Section 12-2

Go to Section: Figure 12–11 DNA Replication Section 12-2 Growth Replication fork DNA polymerase New strand Original strand DNA polymerase Nitrogenous bases Replication fork Original strand New strand

Go to Section: Interest Grabber Information, Please DNA contains the information that a cell needs to carry out all of its functions. In a way, DNA is like the cell’s encyclopedia. Suppose that you go to the library to do research for a science project. You find the information in an encyclopedia. You go to the desk to sign out the book, but the librarian informs you that this book is for reference only and may not be taken out. Section Why do you think the library holds some books for reference only? 2. If you can’t borrow a book, how can you take home the information in it? 3. All of the parts of a cell are controlled by the information in DNA, yet DNA does not leave the nucleus. How do you think the information in DNA might get from the nucleus to the rest of the cell?

Go to Section: 12–3RNA and Protein Synthesis A.The Structure of RNA B.Types of RNA C.Transcription D.RNA Editing E.The Genetic Code F.Translation G.The Roles of RNA and DNA H.Genes and Proteins Section 12-3 Section Outline

Go to Section: fromtoto make up Concept Map Section 12-3 also calledwhich functions toalso called which functions to can be RNA Messenger RNA Ribosomal RNA Transfer RNA mRNACarry instructions rRNA Combine with proteins tRNA Bring amino acids to ribosome DNARibosomeRibosomes

Go to Section: RNA DNA RNA polymerase Figure 12–14 Transcription Section 12-3 Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only)

Go to Section: Figure 12–17 The Genetic Code Section 12-3

Go to Section: Figure 12–18 Translation Section 12-3

Go to Section: Figure 12–18 Translation (continued) Section 12-3

Go to Section: Interest Grabber Determining the Sequence of a Gene DNA contains the code of instructions for cells. Sometimes, an error occurs when the code is copied. Such errors are called mutations. Section 12-4

Go to Section: Interest Grabber continued Section Copy the following information about Protein X: Methionine— Phenylalanine—Tryptophan—Asparagine—Isoleucine—STOP. 2.Use Figure 12–17 on page 303 in your textbook to determine one possible sequence of RNA to code for this information. Write this code below the description of Protein X. Below this, write the DNA code that would produce this RNA sequence. 3.Now, cause a mutation in the gene sequence that you just determined by deleting the fourth base in the DNA sequence. Write this new sequence. 4.Write the new RNA sequence that would be produced. Below that, write the amino acid sequence that would result from this mutation in your gene. Call this Protein Y. 5.Did this single deletion cause much change in your protein? Explain your answer.

Go to Section: 12–4Mutations A.Kinds of Mutations 1.Gene Mutations 2.Chromosomal Mutations B.Significance of Mutations Section 12-4 Section Outline

Go to Section: Substitution Insertion Deletion Gene Mutations: Substitution, Insertion, and Deletion Section 12-4

Go to Section: Deletion Duplication Inversion Translocation Figure 12–20 Chromosomal Mutations Section 12-4

Go to Section: Interest Grabber Regulation of Protein Synthesis Every cell in your body, with the exception of gametes, or sex cells, contains a complete copy of your DNA. Why, then, are some cells nerve cells with dendrites and axons, while others are red blood cells that have lost their nuclei and are packed with hemoglobin? Why are cells so different in structure and function? If the characteristics of a cell depend upon the proteins that are synthesized, what does this tell you about protein synthesis? Work with a partner to discuss and answer the questions that follow. Section 12-5

Go to Section: Interest Grabber continued Section Do you think that cells produce all the proteins for which the DNA (genes) code? Why or why not? How do the proteins made affect the type and function of cells? 2.Consider what you now know about genes and protein synthesis. What might be some ways that a cell has control over the proteins it produces? 3.What type(s) of organic compounds are most likely the ones that help to regulate protein synthesis? Justify your answer.

Go to Section: 12–5Gene Regulation A.Gene Regulation: An Example B.Eukaryotic Gene Regulation C.Development and Differentiation Section 12-5 Section Outline

Go to Section: Regulatory sites Promoter (RNA polymerase binding site) Start transcription DNA strand Stop transcription Typical Gene Structure Section 12-5

Video Contents Videos Click a hyperlink to choose a video. Griffith’s Experiment DNA Replication DNA Transcription Protein Synthesis Duplication and Deletion Translocation and Inversion Point Mutations

Internet Interactive test Articles on genetics For links on DNA, go to and enter the Web Code as follows: cbn For links on DNA replication, go to and enter Web Code as follows: cbn For links on protein synthesis, go to and enter the Web Code as follows: cbn Go Online

Section 1 Answers Interest Grabber Answers 1. On a sheet of paper, write the word cats. List the letters or units that make up the word cats. The units that make up cats are c, a, t, and s. 2. Try rearranging the units to form other words. Remember that each new word can have only three units. Write each word on your paper, and then add a definition for each word. Student codes may include: Act; Sat; Cat 3. Did any of the codes you formed have the same meaning? No 4. How do you think changing the order of the nucleotides in the DNA codon changes the codon’s message? Changing the order of the nucleotides changes the meaning of the codon.

Section 2 Answers Interest Grabber Answers 1.On a sheet of paper, draw a curving or zig-zagging line that divides the paper into two halves. Vary the bends in the line as you draw it. Without tracing, copy the line on a second sheet of paper. 2.Hold the papers side by side, and compare the lines. Do they look the same? Lines will likely look similar. 3.Now, stack the papers, one on top of the other, and hold the papers up to the light. Are the lines the same? Overlaying the papers will show variations in the lines. 4.How could you use the original paper to draw exact copies of the line without tracing it? Possible answer: Cut along the line and use it as a template to draw the line on another sheet of paper. 5.Why is it important that the copies of DNA that are given to new daughter cells be exact copies of the original? Each cell must have the correct DNA, or the cell will not have the correct characteristics.

Section 4 Answers Interest Grabber Answers 1.Copy the following information about Protein X: Methionine—Phenylalanine— Tryptophan—Asparagine—Isoleucine—STOP. 2.Use Figure 12–17 on page 303 in your textbook to determine one possible sequence of RNA to code for this information. Write this code below the description of Protein X. Below this, write the DNA code that would produce this RNA sequence. Sequences may vary. One example follows: Protein X: mRNA: AUG-UUU-UGG-AAU- AUU-UGA; DNA: TAC-AAA-ACC-TTA-TAA-ACT 3.Now, cause a mutation in the gene sequence that you just determined by deleting the fourth base in the DNA sequence. Write this new sequence. (with deletion of 4th base U) DNA: TAC-AAA-CCT-TAT-AAA-CT 4.Write the new RNA sequence that would be produced. Below that, write the amino acid sequence that would result from this mutation in your gene. Call this Protein Y. mRNA: AUG-UUU-GGA-AUA-UUU-GA Codes for amino acid sequence: Methionine— Phenylalaine—Glycine—Isoleucine—Phenylalanine—? 5.Did this single deletion cause much change in your protein? Explain your answer. Yes, Protein Y was entirely different from Protein X.

Section 5 Answers Interest Grabber Answers 1.Do you think that cells produce all the proteins for which the DNA (genes) code? Why or why not? How do the proteins made affect the type and function of cells? Cells do not make all of the proteins for which they have genes (DNA). The structure and function of each cell are determined by the types of proteins present. 2.Consider what you now know about genes and protein synthesis. What might be some ways that a cell has control over the proteins it produces? There must be certain types of compounds that are involved in determining what types of mRNA transcripts are made and when this mRNA translates at the ribosome. 3.What type(s) of organic compounds are most likely the ones that help to regulate protein synthesis? Justify your answer. The type of compound responsible is probably a protein, specifically enzymes, because these catalyze the chemical reactions that take place.