1. 1. What are the 3 components of this DNA nucleotide? 2. What is the function of DNA in the cell?

2. Unit Overview – pages 250-251 Genetics DNA and Genes DNA: The Molecule of Heredity

3. Contributors to DNA Discovery Early 1950’s 1 st picture of DNA taken by Rosalind Franklin using an X-ray machine.

4. 1953 DNA structure discovered by James Watson & Francis Crick. “FATHERS OF DNA”

5. 1962 Watson, Crick and Franklin received Nobel Prize in Medicine.

7. Section 11.1 Summary – pages 281 - 287 Deoxyribose Nucleic Acid DNA determines an organism’s traits DNA ultimately determines the structure of proteins. –body is made up of proteins. –body’s functions depend on proteins called enzymes. What is DNA?

8. Section 11.1 Summary – pages 281 - 287 DNA is a polymer made of repeating subunits called nucleotides. Phosphate group Sugar (deoxyribose) Nitrogenous base The structure of nucleotides

9. Section 11.1 Summary – pages 281 - 287 The phosphate group is composed of one atom of phosphorus surrounded by four oxygen atoms. Deoxyribose is the simple sugar in DNA The structure of nucleotides Nucleotides have three parts: a simple sugar, a phosphate group, and a nitrogenous base.

10. The structure of nucleotides A nitrogenous base is a carbon ring structure that contains one or more atoms of nitrogen.

11. Section 11.1 Summary – pages 281 - 287 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

12. Section 11.1 Summary – pages 281 - 287 Thus, in DNA there are four possible nucleotides, each containing one of these four bases. The structure of nucleotides

13. Section 11.1 Summary – pages 281 - 287 Nucleotides join together to form long chains. Formed by covalent bonds The phosphate groups and deoxyribose molecules form the backbone of the chain. The nitrogenous bases stick out like the teeth of a zipper. (rungs of the ladder) The structure of nucleotides

14. Section 11.1 Summary – pages 281 - 287 In DNA, adenine always pairs with thymine, and guanine always pairs with cytosine. The structure of nucleotides

15. Section 11.1 Summary – pages 281 - 287 The structure of DNA Because DNA is composed of two strands twisted together, its shape is called double helix.

16. 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. The closer the relationship is between two organisms, the more similar their DNA nucleotide sequences will be.

17. Section 11.1 Summary – pages 281 - 287 Replication of DNA Before a cell can divide by mitosis or meiosis, it must first make a copy of its chromosomes. The DNA in the chromosomes is copied in a process called DNA replication. Without DNA replication, new cells would have only half the DNA of their parents.

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

19. Section 11.1 Summary – pages 281 - 287 DNA is copied during interphase prior to mitosis and meiosis. copies itself in order to be passed along on chromosomes during cell division. It is important that the new copies are exactly like the original molecules. Copying DNA

20. bELLRINGER page 288 1.What parts does RNA have that DNA does not have?

21. Section 11.2 Summary – page 2888- 295 WE learned earlier that proteins are polymers of amino acids. The sequence of nucleotides in each gene contains information for assembling the string of amino acids that make up a single protein. Genes and Proteins

22. Proteins make up the structure of an organism AND control all of the organism’s chemical reactions to keep it alive

23. Where does protein synthesis occur? *The DNA never leaves the nucleus. *RNA copies the DNA in the nucleus. *RNA carries the instructions from DNA out to the ribosome. *The protein is built on the ribosome in the cytoplasm. DNA in the nucleus is safe !! DNA in the cytoplasm can be destroyed

24. Section 11.2 Summary – pages 288 - 295 RNA is a nucleic acid. RNA is single stranded RNA The sugar in RNA is ribose

25. Section 11.2 Summary – pages 288 - 295 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 Hydrogen bonds Adenine RNA

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

27. Section 11.2 Summary – pages 288 - 295 3 types of RNA that help build proteins. Messenger RNA (mRNA) brings instructions from DNA in the nucleus to the cell’s factory floor, the cytoplasm. Ribosomal RNA (rRNA) binds to the mRNA and uses the instructions to assemble the amino acids in the correct order. Transfer RNA (tRNA) delivers amino acids to the ribosome to be assembled into a protein. RNA

28. Section 11.2 Summary – pages 288 - 295 “Making RNA? …. Let’s start with Transcription “Making RNA? …. Let’s start with Transcription Transcription is a process in which enzymes make an RNA copy of a portion of a DNA strand in the cell’s nucleus. Transcription results in the formation of one single-stranded RNA molecule. –DNA to mRNA

29. Section 11.2 Summary – pages 288 - 295 The nucleotide sequence transcribed from DNA to a strand of messenger RNA acts as a genetic message, the complete information for the building of a protein. The Genetic Code A code is needed to convert the language of mRNA into the language of proteins.

30. Section 11.2 Summary – pages 288 - 295 Sixty-four combinations are possible when a sequence of three bases is used. There are 64 different mRNA codons in the genetic code. The Genetic Code A codon is a group of three nitrogenous bases in mRNA that code for one amino acid.

31. 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)

32. Section 11.2 Summary – pages 288 - 295 Some codons do not code for amino acids; they provide instructions for making the protein. More than one codon can code for the same amino acid. However, for any one codon, there can be only one amino acid. The Genetic Code

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

34. Section 11.2 Summary – pages 288 - 295 Each tRNA molecule attaches to only one type of amino acid. An anticodon is a sequence of three bases found on tRNA. Amino acid Chain of RNA nucleotides Transfer RNA molecule Anticondon The role of transfer RNA

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

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

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

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

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

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

41. DNAi Triplet code Translation http://www.pbs.org/wgbh/nova/body/rnai.html

42. 11.3 Section Summary 6.3 – pages 296 - 301 Organisms have evolved many ways to protect their DNA from changes. Mutations In spite of these mechanisms, however, changes in the DNA occasionally do occur. A mutation is any change in a DNA sequence. Mutations can be caused by errors in replication, transcription, cell division, or by external agents.

43. 11.3 Section Summary 6.3 – pages 296 - 301 Mutations can occur in the reproductive cells. –becomes part of the genetic makeup of the offspring. If the body cell’s DNA is changed, this mutation would not be passed on to offspring –May be a problem for the individual Mutations

44. 11.3 Section Summary 6.3 – pages 296 - 301 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. Structure = Function The effects and types of mutations

45. 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

46. 11.3 Section Summary 6.3 – pages 296 - 301 Frameshift mutations This mutation would cause nearly every amino acid in the protein after the deletion to be changed. A frameshift mutation is a mutation in which a single base is added or deleted from DNA. A frameshift mutation shifts the reading of codons by one base.

47. 11.3 Section Summary 6.3 – pages 296 - 301 Frameshift mutations mRNA Protein Frameshift mutation Deletion of U

48. 11.3 Section Summary 6.3 – pages 296 - 301 Chromosomal mutations are structural changes in chromosomes. When a part of a chromosome is left out, a deletion occurs Chromosomal Alterations A B C D E F G H Deletion A B C E F G H

49. 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. 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

50. 11.3 Section Summary 6.3 – pages 296 - 301 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

51. 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. A B E F DCBX A W C H G G E H D F W XYZYZ Translocation Chromosomal Alterations

52. 11.3 Section Summary 6.3 – pages 296 - 301 A mutagen is any agent that can cause a change in DNA. 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. Causes of Mutations

53. 11.3 Section Summary 6.3 – pages 296 - 301 Causes of Mutations The breaking and reforming of a double- stranded DNA molecule can result in deletions. Chemical mutagens include dioxins, asbestos, benzene, and formaldehyde, substances that are commonly found in buildings and in the environment. Chemical mutagens usually cause substitution mutations.

54. 11.3 Section Summary 6.3 – pages 296 - 301 Repairing DNA Repair mechanisms that fix mutations in cells have evolved. Enzymes proofread the DNA and replace incorrect nucleotides with correct nucleotides. These repair mechanisms work extremely well, but they are not perfect. The greater the exposure to a mutagen such as UV light, the more likely is the chance that a mistake will not be corrected.