1. Chapter 8 and 9 Notes: Genetics Background: Hershey and Chase Experiment animation animation –Proved DNA as genetic material Rosalind Franklin –X-ray Diffraction pattern (Double Helix) Watson and Crick –Structure of DNA DVD-animationanimation Erwin Chargoff –Chargoff’s Ratios DVD-animationanimation

2. Avery

3. Hershey/ Chase

4. Chapter 12- DNA & RNA Components & Structure of DNA How does DNA: -carry information from one generation to next? -use information to determine heritable characteristics of organisms? -be easily copied (replicated)? All things genes known to do…

5. Chapter 12- DNA & RNA DNA is long molecule made up of units called nucleotides Units have three main parts: -5-carbon sugar (deoxyribose) -phosphate group -nitrogenous base

6. Chapter 12- DNA & RNA Consists of three parts: Nitrogenous Base 5-Carbon Sugar Phosphate

7. Chapter 12- DNA & RNA 4 kinds of nitrogenous bases: -adenine (A) -guanine (G) Together called purines (two rings) -cytosine (C) -thymine (T) Together called pyrimidines (one ring)

9. Chapter 12- DNA & RNA Sugar-phosphate groups in each nucleotide form backbone of molecule Bases stick out sideways from the chain Nucleotides can be joined in any order Any sequences of bases is possible

11. Chapter 12- DNA & RNA Chargaff’s Rules Shows relationship between nucleotides %G = %C in any sample of DNA %A = %T in any sample of DNA So… Adenine bonds only with Thymine Cytosine only bonds with Guanine Holds true for all organisms

12. Chapter 12- DNA & RNA X-ray Evidence Rosalind Franklin used technique called X-ray diffraction Shows clues to DNA structure X-shape in pattern shows it is a helix Other clues showed it had two strands & bases were in the middle

13. Chapter 12- DNA & RNA The Double Helix Watson & Crick With Franklin’s X-ray diffraction, were able to show structure as a double helix Looks like a twisted ladder: Sugar-phosphate backbone Bases in middle according to Chargaff’s base-pairing rules (A with T; C with G) Hydrogen bonds hold strands together

15. Chapter 12- DNA & RNA Chromosomes & DNA Replication DNA & Chromosomes Prokaryotic cells: DNA found in cytoplasm Single, circular DNA molecule (chromosome) Eukaryotic cells: located in nucleus Many chromosomes Number varies from species to species

17. Chapter 12- DNA & RNA Chromosome Structure DNA in eukaryote cells packed even tighter Nucleus of human cells contains over 1m of DNA Eukaryotic chromosomes contain both protein & DNA Forms chromatin

18. Chapter 12- DNA & RNA Composed of DNA tightly wound around proteins called histones Form beadlike structures called nucleosomes Nucleosomes pack together tightly to form thick fiber (chromatin) Normally in this form, but during mitosis (& meiosis), fibers coil to form chromosomes

20. Chapter 12- DNA & RNA DNA Replication Watson & Crick: with structure discovered, realized method of replication Each strand of DNA has all information needed to reconstruct other half through base-pairing EX.-A-G-G-C-T-A-C-G-T-T-A-T-G T-C-C-G-A-T-G-C-A-A-T-A-C

21. Strands are said to be complementary Rules of base-pairing allow for reconstruction of new strand In prokaryotes, replication begins at single point Proceeds in both directions until chromosome is copied

23. Chapter 12- DNA & RNA In eukaryotes, replication occurs in hundreds of places Proceeds in both directions until completed Sites where separation of strand & replication occurs called replication forks

25. Chapter 12- DNA & RNA Duplicating DNA Process ensures each cell resulting from division will have complete set of DNA During replication: -DNA molecule separates into two strands -two new complementary strands produced according to base-pairing rules Each old strand serves as a template for new one

26. Chapter 12- DNA & RNA Strands of double helix separate to form two replication forks Base-pairing rules are followed Result is two DNA molecules identical to one another and the original molecule Each new molecule made from one old strand and one new strand Called semi-conservative replication animation animation

27. Chapter 12- DNA & RNA How Replication Occurs Carried out by a series of enzymes Enzymes “unzip” double helix (break hydrogen bonds; unwind molecule) Each strand serves as a template Involves many regulatory molecules and enzymes

28. Chapter 12- DNA & RNA Principle enzyme: DNA polymerase Also “proofreads” as it works Maximizes odds that new copy is a perfect copy of original strand replicationreplication-DVD

30. Chapter 12- DNA & RNA RNA & Protein Synthesis Double helix structure explains how DNA is copied, but not how genes work Genes are coded instructions that control the production of proteins within the cell First step in process: Copy part of nucleotide sequence from DNA into RNA (ribonucleic acid)

31. Chapter 12- DNA & RNA Structure of RNA Like DNA, RNA consists of a long chain of nucleotides 3 main differences btw RNA & DNA: -sugar is ribose (not deoxyribose) -single-stranded (not double-stranded) -contains uracil (instead of thymine)

32. Chapter 12- DNA & RNA Basically a disposable copy of a segment of DNA RNA - working copy of a single gene Ability to copy DNA into RNA allows for multiple copies of a gene to be working at any time

33. Types of RNA Assembly of amino acids into proteins controlled by RNA Three main types of RNA: - messenger RNA (mRNA) - ribosomal RNA (rRNA) - transfer RNA (tRNA)

35. Chapter 12- DNA & RNA Most genes contain instructions for assembling amino acids into proteins mRNA carry copies of instructions from DNA to the rest of the cell Proteins are assembled on ribosomes (made of several kinds of proteins & rRNA) 3 rd type of RNA transfers each amino acid to the ribosome as it is needed (tRNA)

36. Chapter 12- DNA & RNA Transcription Messenger RNA (mRNA)- temp. copy of a gene that encodes a protein Process of making a mRNA copy called transcription Requires an enzyme called RNA polymerase Attaches to DNA, separates strands, & makes an RNA copy of DNA sequence

37. Chapter 12- DNA & RNA RNA polymerase only binds to DNA sequences called promoters Signals where RNA polymerase should start Similar sequences tell where to stop animation

38. Chapter 12- DNA & RNA The Genetic Code Proteins made by joining amino acids into long chains (polypeptides) Each polypeptide contains combination of any or all 20 different amino acids Properties of proteins determined by sequence of amino acids in structure

39. Chapter 12- DNA & RNA “Language” of mRNA instructions called the genetic code A, G, C, U serve as the four letters of the code alphabet; 20 amino acids to code 1 letter = 4 amino acids; 16 not covered 2 letters = 16 a.a.’s; 4 not covered 3 letters = 64 a.a.’s; 44 more than needed Each 3 letter “word” is called a codon

40. Chapter 12- DNA & RNA UCGCACGGUACU Read 3 bases at a time: UCG – CAC – GGU – ACU Codons represent different amino acids: Serine – Histidine – Glycine - Threonine

41. Some amino acids are coded for by more than one codon One codon, AUG, codes for methionine OR acts as the “start” or initiation codon Also three “stop” codons Stop and start codons act as punctuation in process of translation (protein synthesis)

44. Chapter 12- DNA & RNA Translation Decoding of an mRNA message into polypeptide (protein) is called translation Takes place on ribosomes Cell uses information from mRNA to produce proteins

45. Chapter 12- DNA & RNA Begins when a mRNA attaches to a ribosome in the cytoplasm (at start codon) As each codon moves through the ribosome, tRNA molecules bring the correct amino acid Ribosome attaches new amino acid to growing polypeptide chain

46. Each tRNA carries only one kind of amino acid Each tRNA molecule has three unpaired bases called an anticodon Anticodon on tRNA binds to complementary codon found on mRNA Ribosome adds each amino acid to chain as the correct tRNA binds to next codon on mRNA Process continues until a stop codon is reached animation

48. Chapter 12- DNA & RNA DNA:GCCTTATCGATCGAA mRNA:CGGAAUAGCUAGCUU Codons: CGG – AAU – AGC – UAG – CUU tRNA Codons: GCC – UUA – UCG – AUC – GAA Amino Acids: Alanine – Leucine – Serine – Isoleucine – Glutamic Acid

49. Chapter 12- DNA & RNA Roles of RNA & DNA Master building plan has all the information needed to construct the project Disposable, inexpensive copies of plan brought to job site to use Cell uses vital DNA “master plan” to prepare RNA copies of plan DNA remains safely in nucleus RNA travels to cytoplasm to ribosomes

50. Chapter 12- DNA & RNA Genes & Proteins What do proteins have to do with color of a flower, shape of a leaf, human blood type, or sex of a newborn? Many proteins are enzymes: catalyze chemical reactions Gene may code for enzyme that produces pigment: controls flower color

51. Chapter 12- DNA & RNA Another gene may produce an enzyme that produces blood cell surface protein: Determines your blood type Other genes for certain proteins regulate rate and pattern of growth: Controls size and shape Proteins are microscopic tools/machines Each designed to build or operate a component of a living cell