Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How DNA Works Bellringer Unscramble the following words: tpsoneir neesg Now think of three words you associate with each of the above words and use them all in a paragraph that highlights what you know about DNA. Write your paragraph in your science journal. Chapter 6

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How DNA Works Objectives Explain the relationship between DNA, genes, and proteins. Outline the basic steps in making a protein. Describe three types of mutations, and provide an example of a gene mutation. Describe two examples of uses of genetic knowledge. Chapter 6

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How DNA Works Unraveling DNA Every cell has 2m of DNA All organisms have DNA and it is unique in each organism, but it functions the same way. The order of bases on one side is the code that carries the information. A gene consists of a string of nucleotides that give the cell information about how to make a specific trait. Chapter 6

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How DNA Works Chapter 6

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How DNA Works Genes and Proteins Chapter 6 DNA helps make proteins Genes code for protein synthesis. Proteins are made of chains of amino acids Proteins help determine traits. RNA, or ribonucleic acid. Helps DNA make proteins 2 Types mRNA = messenger RNA tRNA = transfer RNA

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How DNA Works Genes and Proteins, continued Chapter 6 The Making of a Protein 1.copy one side of the segment of DNA containing a gene. This copy is called messenger RNA (mRNA). 2.mRNA carries the “message” to the Ribosome. 1.A ribosome is an organelle that uses mRNA, transfer RNA (tRNA), and amino acids to make proteins. 3.tRNA delivers amino acids to the Ribosomes. 4.Amino acids are linked together to form proteins.

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How DNA Works Chapter 6

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How DNA Works Chapter 6

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How DNA Works Changes in Genes Mutations Changes in the number, type, or order of bases on a piece of DNA are known as mutations. Chapter 6

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How DNA Works Changes in Genes, continued Three possible changes in DNA: 1.an improved trait, 2. no change, 3.a harmful trait. Mutagen = Any physical or chemical agent that can cause a mutation in DNA. If the changes happens in sex cells the change can be passed on. Chapter 6

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How DNA Works Carcinogens and Mutagens Chapter 6 Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How DNA Works An Example of Substitution A mutation, such as a substitution, can be harmful because it may cause a gene to produce the wrong protein. A simple change in an amino acid can cause a disease such as sickle cell anemia, as shown on the next slide. Chapter 6

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How DNA Works Chapter 6

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How DNA Works Uses of Genetic Knowledge Genetic Engineering Scientists can manipulate individual genes within organisms. Genetic Identification DNA fingerprinting identifies the unique patterns in an individual’s DNA. Chapter 6