2. Chapter Intro-page 280 What You’ll Learn You will relate the structure of DNA to its function. You will explain the role of DNA in protein production. You will distinguish among different types of mutations. 1 of 42

3. Section 11.1 Summary – pages 281 - 287 The genetic information that is held in the molecules of DNA ultimately determines an organism’s traits. The genetic information that is held in the molecules of DNA ultimately determines an organism’s traits. DNA achieves its control by determining the structure of proteins. DNA achieves its control by determining the structure of proteins. What is DNA?

4. Section 11.1 Summary – pages 281 - 287 DNA is a polymer made of repeating subunits called nucleotides. DNA is a polymer made of repeating subunits called nucleotides. Nucleotides have three parts: a simple sugar, a phosphate group, and a nitrogenous base. Nucleotides have three parts: a simple sugar, a phosphate group, and a nitrogenous base. Phosphate group Sugar (deoxyribose) Nitrogenous base The structure of nucleotides

5. Section 11.1 Summary – pages 281 - 287 The simple sugar in DNA, called deoxyribose (dee ahk sih RI bos), gives DNA its name— deoxyribonucleic acid. The simple sugar in DNA, called deoxyribose (dee ahk sih RI bos), gives DNA its name— deoxyribonucleic acid. The structure of nucleotides

6. Section 11.1 Summary – pages 281 - 287 A nitrogenous base is a carbon ring structure that contains one or more atoms of nitrogen. A nitrogenous base is a carbon ring structure that contains one or more atoms of nitrogen. In DNA, there are four possible nitrogenous bases: adenine (A), guanine (G), cytosine (C), and thymine (T). In DNA, there are four possible nitrogenous bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Adenine (A) Guanine (G)Thymine (T) Cytosine (C) The structure of nucleotides

7. Section 11.1 Summary – pages 281 - 287 In 1953, Watson and Crick proposed that DNA is made of two chains of nucleotides held together by nitrogenous bases. In 1953, Watson and Crick proposed that DNA is made of two chains of nucleotides held together by nitrogenous bases. The structure of DNA Watson and Crick also proposed that DNA is shaped like a long zipper that is twisted into a coil like a spring. Watson and Crick also proposed that DNA is shaped like a long zipper that is twisted into a coil like a spring. Because DNA is composed of two strands twisted together, its shape is called double helix. Because DNA is composed of two strands twisted together, its shape is called double helix.

8. Section 11.1 Summary – pages 281 - 287 The importance of nucleotide sequences Chromosome The sequence of nucleotides forms the unique genetic information of an organism.

9. Section 11.1 Summary – pages 281 - 287 Replication of DNA The DNA in the chromosomes is copied in a process called DNA replication. The DNA in the chromosomes is copied in a process called DNA replication.

10. Section 11.1 Summary – pages 281 - 287 Replication of DNA DNA Replication

11. Section 11.1 Summary – pages 281 - 287 Copying DNA Original DNA Original DNA Strand Free Nucleotides New DNA molecule New DNA Strand New DNA molecule

12. Section 11.2 Summary – pages 288 - 295 RNA like DNA, is a nucleic acid. RNA structure differs from DNA structure in three ways. RNA like DNA, is a nucleic acid. RNA structure differs from DNA structure in three ways. First, RNA is single stranded—it looks like one-half of a zipper—whereas DNA is double stranded. First, RNA is single stranded—it looks like one-half of a zipper—whereas DNA is double stranded. RNA

13. Section 11.2 Summary – pages 288 - 295 The sugar in RNA is ribose; DNA’s sugar is deoxyribose. The sugar in RNA is ribose; DNA’s sugar is deoxyribose. Ribose RNA

14. Section 11.2 Summary – pages 288 - 295 Both DNA and RNA contain four nitrogenous bases, but rather than thymine, RNA contains a similar base called uracil (U). Both DNA and RNA contain four nitrogenous bases, but rather than thymine, RNA contains a similar base called uracil (U). Uracil forms a base pair with adenine in RNA, just as thymine does in DNA. Uracil forms a base pair with adenine in RNA, just as thymine does in DNA. Uracil Hydrogen bonds Adenine RNA

15. Section 11.2 Summary – pages 288 - 295 DNA provides workers with the instructions for making the proteins, and workers build the proteins. DNA provides workers with the instructions for making the proteins, and workers build the proteins. The workers for protein synthesis are RNA molecules. The workers for protein synthesis are RNA molecules. RNA

16. Section 11.2 Summary – pages 288 - 295 There are three types of RNA that help build proteins. There are three types of RNA that help build proteins. Messenger RNA (mRNA), brings instructions from DNA in the nucleus to the cell’s ribosome. Messenger RNA (mRNA), brings instructions from DNA in the nucleus to the cell’s ribosome. RNA The ribosome, made of ribosomal RNA (rRNA), binds to the mRNA and uses the instructions to assemble the amino acids in the correct order.

17. Section 11.2 Summary – pages 288 - 295 Transfer RNA (tRNA) is the supplier. Transfer RNA delivers amino acids to the ribosome to be assembled into a protein. Transfer RNA (tRNA) is the supplier. Transfer RNA delivers amino acids to the ribosome to be assembled into a protein.

18. Section 11.2 Summary – pages 288 - 295 Transcription In the nucleus, enzymes make an RNA copy of a portion of a DNA strand in a process called transcription. In the nucleus, enzymes make an RNA copy of a portion of a DNA strand in a process called transcription.

19. Section 11.2 Summary – pages 288 - 295 RNA strand DNA strand RNA strand Transcription A B C

20. Section 11.2 Summary – pages 288 - 295 RNA Processing Regions that contain information are called exons because they are expressed. Regions that contain information are called exons because they are expressed. When mRNA is transcribed from DNA, both introns and exons are copied. When mRNA is transcribed from DNA, both introns and exons are copied. The introns must be removed from the mRNA before it can function to make a protein. The introns must be removed from the mRNA before it can function to make a protein.

21. Section 11.2 Summary – pages 288 - 295 Enzymes in the nucleus cut out the intron segments and paste the mRNA back together. Enzymes in the nucleus cut out the intron segments and paste the mRNA back together. The mRNA then leaves the nucleus and travels to the ribosome. The mRNA then leaves the nucleus and travels to the ribosome. RNA Processing

22. Biochemists discovered that a group of three nitrogenous bases in mRNA code for one amino acid. Each group is known as a codon. Biochemists discovered that a group of three nitrogenous bases in mRNA code for one amino acid. Each group is known as a codon. The Genetic Code

23. Section 11.2 Summary – pages 288 - 295 Sixty-four combinations are possible when a sequence of three bases is used; thus, 64 different mRNA codons are in the genetic code. Sixty-four combinations are possible when a sequence of three bases is used; thus, 64 different mRNA codons are in the genetic code. The Genetic Code

24. Section 11.2 Summary – pages 288 - 295 The Genetic Code The Messenger RNA Genetic Code First Letter Second Letter U U C A G Third Letter U C A G U C A G U C A G U C A G C A G Phenylalanine (UUU) Phenylalanine (UUC) Leucine (UUA) Leucine (UUG) Leucine (CUU) Leucine (CUC) Leucine (CUA) Leucine (CUG) Isoleucine (AUU) Isoleucine (AUC) Isoleucine (AUA) Methionine; Start (AUG) Valine (GUU) Valine (GUC) Valine (GUA) Valine (GUG) Serine (UCU) Serine (UCC) Serine (UCA) Serine (UCG) Proline (CCU) Proline (CCC) Proline (CCA) Proline (CCG) Threonine (ACU) Threonine (ACC) Threonine (ACA) Threonine (ACG) Alanine (GCU) Alanine (GCC) Alanine (GCA) Alanine (GCG) Tyrosine (UAU) Tyrosine (UAC) Stop (UAA) Stop (UAG) Histadine (CAU) Histadine (CAC) Glutamine (CAA) Glutamine (CAG) Asparagine (AAU) Asparagine (AAC) Lysine (AAA) Lysine (AAG) Aspartate (GAU) Aspartate (GAC) Glutamate (GAA) Glutamate (GAG) Cysteine (UGU) Cysteine (UGC) Stop (UGA) Tryptophan (UGG) Arginine (CGU) Arginine (CGC) Arginine (CGA) Arginine (CGG) Serine (AGU) Serine (AGC) Arginine (AGA) Arginine (AGG) Glycine (GGU) Glycine (GGC) Glycine (GGA) Glycine (GGG)

25. Section 11.2 Summary – pages 288 - 295 Translation: From mRNA to Protein The process of converting the information in a sequence of nitrogenous bases in mRNA into a sequence of amino acids in protein is known as translation. The process of converting the information in a sequence of nitrogenous bases in mRNA into a sequence of amino acids in protein is known as translation. Translation takes place at the ribosomes in the cytoplasm. Translation takes place at the ribosomes in the cytoplasm.

26. Section 11.2 Summary – pages 288 - 295 For proteins to be built, the 20 different amino acids dissolved in the cytoplasm must be brought to the ribosomes. For proteins to be built, the 20 different amino acids dissolved in the cytoplasm must be brought to the ribosomes. This is the role of transfer RNA. This is the role of transfer RNA. The role of transfer RNA

27. Section 11.2 Summary – pages 288 - 295 Each tRNA molecule attaches to only one type of amino acid. Each tRNA molecule attaches to only one type of amino acid. Amino acid Chain of RNA nucleotides Transfer RNA molecule Anticondon The role of transfer RNA

28. Section 11.2 Summary – pages 288 - 295 The role of transfer RNA Ribosome mRNA codon

29. Section 11.2 Summary – pages 288 - 295 The first codon on mRNA is AUG, which codes for the amino acid methionine. The first codon on mRNA is AUG, which codes for the amino acid methionine. AUG signals the start of protein synthesis. AUG signals the start of protein synthesis. When this signal is given, the ribosome slides along the mRNA to the next codon. When this signal is given, the ribosome slides along the mRNA to the next codon. The role of transfer RNA

30. Section 11.2 Summary – pages 288 - 295 tRNA anticodon Methionine The role of transfer RNA

31. Section 11.2 Summary – pages 288 - 295 A new tRNA molecule carrying an amino acid pairs with the second mRNA codon. A new tRNA molecule carrying an amino acid pairs with the second mRNA codon. Alanine The role of transfer RNA

32. Section 11.2 Summary – pages 288- 295 The amino acids are joined when a peptide bond is formed between them. The amino acids are joined when a peptide bond is formed between them. Alanine Methionine Peptide bond The role of transfer RNA

33. Section 11.2 Summary – pages 288 - 295 A chain of amino acids is formed until the stop codon is reached on the mRNA strand. A chain of amino acids is formed until the stop codon is reached on the mRNA strand. Stop codon The role of transfer RNA

34. 11.3 Section Summary 6.3 – pages 296 - 301 Mutations Any change in DNA sequence is called a mutation. Any change in DNA sequence is called a mutation. Mutations can be caused by errors in replication, transcription, cell division, or by external agents. Mutations can be caused by errors in replication, transcription, cell division, or by external agents.

35. 11.3 Section Summary 6.3 – pages 296 - 301 A point mutation is a change in a single base pair in DNA. A point mutation is a change in a single base pair in DNA. A change in a single nitrogenous base can change the entire structure of a protein because a change in a single amino acid can affect the shape of the protein. A change in a single nitrogenous base can change the entire structure of a protein because a change in a single amino acid can affect the shape of the protein. The effects of point mutations

36. 11.3 Section Summary 6.3 – pages 296 - 301 The effects of point mutations Normal Point mutation mRNA Protein Stop mRNA Protein Replace G with A

37. 11.3 Section Summary 6.3 – pages 296 - 301 Frameshift mutations A mutation in which a single base is added or deleted from DNA is called a frameshift mutation because it shifts the reading of codons by one base. A mutation in which a single base is added or deleted from DNA is called a frameshift mutation because it shifts the reading of codons by one base. Structural changes in chromosomes are called chromosomal mutations.

38. 11.3 Section Summary 6.3 – pages 296 - 301 Any agent that can cause a change in DNA is called a mutagen. Any agent that can cause a change in DNA is called a mutagen. Mutagens include radiation, chemicals, and even high temperatures. Mutagens include radiation, chemicals, and even high temperatures. Forms of radiation, such as X rays, cosmic rays, ultraviolet light, and nuclear radiation, are dangerous mutagens because the energy they contain can damage or break apart DNA. Forms of radiation, such as X rays, cosmic rays, ultraviolet light, and nuclear radiation, are dangerous mutagens because the energy they contain can damage or break apart DNA. Causes of Mutations

39. 11.3 Section Summary 6.3 – pages 296 - 301 When a part of a chromosome is left out, a deletion occurs. When a part of a chromosome is left out, a deletion occurs. Deletion A B C D E F G H A B C E F G H Chromosomal Alterations

40. 11.3 Section Summary 6.3 – pages 296 - 301 When part of a chromatid breaks off and attaches to its sister chromatid, an insertion occurs. When part of a chromatid breaks off and attaches to its sister chromatid, an insertion occurs. The result is a duplication of genes on the same chromosome. The result is a duplication of genes on the same chromosome. Insertion A B C D E F G H A B C B C D E F G H Chromosomal Alterations

41. 11.3 Section Summary 6.3 – pages 296 - 301 When part of a chromosome breaks off and reattaches backwards, an inversion occurs. When part of a chromosome breaks off and reattaches backwards, an inversion occurs. Inversion A B C D E F G H A D C B E F G H Chromosomal Alterations

42. 11.3 Section Summary 6.3 – pages 296 - 301 When part of one chromosome breaks off and is added to a different chromosome, a translocation occurs. When part of one chromosome breaks off and is added to a different chromosome, a translocation occurs. A B E F DCBX A W C H G G E H D F W XYZYZ Translocation Chromosomal Alterations