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Chapter 3, Section 4 The DNA Connection

Chapter 3, Section 4 The DNA Connection. Monday, November 16, 2009 Pages 107 -- 112. Objectives. Explain the term “genetic code”. Describe the process by which a cell produces proteins. Describe the different types of mutations and how they affect organism. Vocabulary Words. Messenger RNA

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Chapter 3, Section 4 The DNA Connection

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  1. Chapter 3, Section 4The DNA Connection Monday, November 16, 2009 Pages 107 -- 112

  2. Objectives • Explain the term “genetic code”. • Describe the process by which a cell produces proteins. • Describe the different types of mutations and how they affect organism.

  3. Vocabulary Words • Messenger RNA • Transfer RNA • Mutation

  4. Review… • The main function of genes is to control the production of proteins in the organism’s cells. • Proteins help to determine the size, shape, and many other traits of an organism. • DNA is the major component of chromosomes.

  5. Review--cont’d… • A DNA molecule is made up of four different nitrogen bases (A, T, G, C). • Nitrogen bases for the rungs of the DNA ladder. • A single gene on a chromosome may contain anywhere from several hundred to a million or more bases.

  6. Genetic Code • The order of the nitrogen bases along a gene forms a genetic code that specifies what type of protein will be produced. • In the genetic code, a group of 3 bases code for the attachment of a specific amino acid. • The order of these bases determine the type of protein.

  7. Protein Synthesis • Protein synthesis the process in which protein is produced. • During protein synthesis, the cell uses information from a gene on a chromosome to produce a specific protein. • Protein synthesis occur on the ribosomes in the cytoplasm of the cell.

  8. The Role of RNA • RNA is the genetic messenger that carries the genetic code from the DNA inside the nucleus to the cytoplasm. • Physically, RNA looks like half a ladder.

  9. RNA vs. DNA • Looks like half a ladder. • Contains a different sugar molecule. • Nitrogen base is different. • RNA contains uracil instead of thymine.

  10. RNA • There are 2 types of RNA involved in protein synthesis. • Messenger RNA • Copies the code message from the DNA in the nucleus and carries the message into the cytoplasm. • Transfer RNA • Carries amino acids and adds them to the growing protein chain.

  11. Protein Synthesis Protein Amino Acid Protein DNA Ribosome Transfer RNA Nucleus Messenger RNA Messenger RNA

  12. Mutations • A mutation is any change that occurs in a gene or chromosome. • Mutations can cause a cell to produce an incorrect protein during protein synthesis. • Result: • The phenotype will be different than expected.

  13. Types of Mutations • Mutations occurring protein synthesis. • Substitution of a nitrogen base • DNA replication process • Incomplete separation during meiosis. • Mutations in a body cell.

  14. Effects of Mutations • A source of genetic variety. • Some changes are harmful to the organism. • It reduces the organism’s chances for survival and reproduction. • Example: Cancer. • Some changes are helpful. • Improves an organism’s chances for survival and reproduction. • Some changes are neither harmful nor helpful.

  15. Homework • Workbook 3.4 (due 11/18) • Vocabulary quiz 3.4 (11/18)

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