Chapter 12 DNA and RNA

1. Chapter 12DNA and RNA transformation, bacteriophage, nucleotide, base pairing, chromatin, histone, replication, DNA polymerase, gene, messenger RNA, ribosomal RNA, Transfer RNA, transcription, RNA polymerase, promoter, intron, exon, codon, translation, anticodon, mutation, point mutation, frameshift mutation, polyploidy, adenine, cytosine, deletion, guanine, nitrogen base, purine, pyrimidine, thymine, uracil

2. 12-1 DNA Frederick Griffith – 1928 – looking at how mice react to two related pneumonia bacteria • Experiment - Rough bacteria – mice live - Smooth bacteria – mice got pneumonia & die - Heat-killed smooth bacteria – mice live - Heat killed smooth + rough bacteria – mice got pneumonia & die

3. Heat-killed, disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Harmless bacteria (rough colonies) Control(no growth) Heat-killed, disease-causing bacteria (smooth colonies) Disease-causing bacteria (smooth colonies) Dies of pneumonia Dies of pneumonia Lives Lives Live, disease-causingbacteria (smooth colonies) Figure 12–2 Griffith’s Experiment

4. Results = heat killed smooth bacteria could pass on their trait to harmless strain… called transformation Oswald Avery – 1944 – repeated Griffith’s exp. and found thatDNA was the transforming factor

5. Alfred Hershey & Martha Chase – 1952 – worked with bacteria and virus to find out if protein or DNA held genes • Virus = DNA/RNA surrounded by a protein coat • Bacteriophage = a virus that infects bacteria • Experiment - Radioactive marker attached to protein part of bacteriophage… infects bacteria… marker was seen outside of bacteria - Radioactive marker to DNA…infection… marker was seen inside bacteria

6. Bacteriophage with phosphorus-32 in DNA Phage infectsbacterium Radioactivity inside bacterium Bacteriophage with sulfur-35 in protein coat Phage infectsbacterium No radioactivity inside bacterium Figure 12–4 Hershey-Chase Experiment • Results = genetic material of bacteriophage was DNA

7. Components and Structure of DNA Nucleotides = units (monomers) that make up DNA molecule • Made of 3 parts: - deoxyribose – a 5-carbon sugar - a phosphate group - a nitrogenous base

8. Purines Pyrimidines Adenine Guanine Cytosine Thymine Phosphate group Deoxyribose • 4 possible nitrogenous bases - purines: adenine or quinine - pyrimidines: cytosine or thymine

9. Nucleotide Hydrogen bonds Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Erwin Chargaff – studied amounts of nitrogenous bases in DNA • % guanine equal to % cytosine • % adenine equal to % thymine • also known as base pairing rule: A=T and C=G

10. Rosalind Franklin – 1952 – X-ray diffraction to get pattern from structure of DNA James Watson & Francis Crick – 1953 – published model and paper on DNA structure as a double helix • double helix is similar to a twisted ladder or spiral staircase - deoxyribose and phosphate make up sides/backbone - nitrogenous base makes up stairs/rungs

11. 12-2 – Chromosomes and DNA Replication Prokaryotes = generally circular strand of DNA in cytoplasm Eukaryotes = multiple molecules of DNA in nucleus Chromosome E.coli bacterium Bases on the chromosome

12. Nucleosome Chromosome DNA double helix Coils Supercoils Histones Chromosome structure • Chromatin = DNA that is tightly packed around proteins called histones - during cell division, chromatin form packed chromosomes

13. DNA Replication • Replication = process of copying DNA - occurs during S phase of Interphase - process: 1. DNA is separated into two strands by an enzyme 2. free nucleotides are added by DNA polymerase according to base pairing rule

14. Original strand DNA polymerase New strand Growth DNA polymerase Growth Replication fork Replication fork New strand Original strand DNA Replication Nitrogenous bases

15. DNA Replication

16. 12-3 RNA and Protein Synthesis RNA structure • Has ribose as a sugar instead of deoxyribose • Is generally single-stranded • Has uracil instead of thymine

17. Types of RNA • All types control protein synthesis in a cell • 3 main types - mRNA = messenger RNA – copies of instructions from DNA - rRNA = ribosomal RNA – part of ribosomes - tRNA = transfer RNA – transfers amino acids to ribosome

18. Messenger RNA Ribosomal RNA Transfer RNA Bringamino acids toribosome Combine with proteins tRNA mRNA Carry instructions rRNA DNA Ribosome Ribosomes RNA can be also called which functions to also called which functions to also called which functions to from to to make up

19. RNA Decoding Chart

20. Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) RNApolymerase DNA RNA Figure 12–14 Transcription • Transcription = process of copying part of nucleotide Sequence of DNA into a complementary strand of RNA • run by enzyme called RNA polymerase

21. Transcription

22. start codon A U G G G C U C C A U C G G C G C A U A A mRNA codon1 codon 2 codon 3 codon 4 codon 5 codon 6 codon 7 The Genetic Code • Proteins are chains of amino acids - 20 different amino acids - the order or sequence of amino acids determines properties of the protein - codon = 3 consecutive nucleotides that specify a single amino acid - one amino acid can have multiple codons

23. Translation • Translation = the decoding of an mRNA message into a polypeptide chain (protein) • Occurs on ribosomes

24. Translation

25. Process: - mRNA binds to ribosome - tRNA brings appropriate amino acid to ribosome – tRNA has anticodon that is complementary to codon on mRNA; begins with specific start codon - AUG - peptide bonds are made between amino acids - assembly line continues until a stop codon

26. Why bother? • Transcription and translation keep master plans (DNA) safe in the nucleus, while blueprints (RNA) are sent to the worksite (ribosomes) • Proteins are needed to act as enzymes that produces the color of your skin, the type of blood cell, the rate of growth

27. 12-4 Mutations • Mutation = a change in the genetic material • Point mutations = change in one or a few nucleotides • Frameshift mutations = adding or deleting a nucleotide… very disruptive

28. Deletion Duplication Chromosomal Mutations • Chromosomal mutations = change in the number or structure of chromosomes. - Deletion = loss of all or part of a chromosome - Duplication = produce extra copies of parts of chromosome

29. Deletion & Duplication

30. Inversion Translocation - Inversion = reverse direction of parts of chromosome - Translocation = part of one chromosome breaks and attaches to another - Polyploidy = an organism has an extra sets of chromosomes

31. Translocation & Inversion