From Gene to Protein

1. From Gene to Protein

2. DNA, genes, chromosomes How does a chemical control so much?

3. Intro to DNA Video • http://www.youtube.com/watch?v=bVk0twJYL6Y&feature=youtube_gdata_player

4. Review of ch 16 • Vocabulary: • 1. DNA /double helix, • 2. Nucleosome

5. Griffith’s experiment 1928: transformation • Showed that “something” changed the non virulent bacteria into virulent!

6. Frederick Griffith--Discovery of the Transforming Principle (Video Clip)

7. Avery 1944 • To show that it was DNA and not protein that transformed the bacteria…

8. Hershey and Chase 1952 • Convinced people that DNA not protein contained the genetic material. Radioactive Sulfur found in protein only and radioactive phosphorus, found in DNA only was inserted into bacteria using viruses that infect bacteria called bacteriophages that had been labeled with the radioactive elements. Radioactivity showed the protein remained outside the bacteria and could not cause the transformations!

9. Franklin 1952 • Rosalind Franklind and Wilkins X ray diffraction pictures helped determind the shape of DNA

10. Erwin Chargaff1950 • He found that when he analyze DNA, the amount of Adenine always equaled the amount of Thymine and the amount of Guanine equaled the amount of cytosine.

11. Watson and Crick 1953 • Determined the basic structure of DNA. Antiparallel sides of deoxyribose sugar and phosphate with nitrogen bases paired A-T and C-G, (with the help of Chargaffs research)

12. How does DNA replicate? • 1. Before replication can occur, the length of the DNA double helix about to be copied must be unwound. DNA helicase

13. 2. the two strands must be separated, much like the two sides of a zipper, by breaking the weak hydrogen bonds that link the paired bases.  • 3. Once the DNA strands have been unwound, they must be held apart to expose the bases so that new nucleotide partners can hydrogen-bond to them.

14. 4. The enzyme DNA polymerase III then moves along the exposed DNA strand, joining newly arrived nucleotides into a new DNA strand that is complementary to the template

15. Animation of replication • http://www.nobel.se/medicine/educational/dna/a/replication/replication_ani.html

16. DNA replication Video • http://www.youtube.com/watch?v=zdDkiRw1PdU&feature=youtube_gdata_player

17. Vocabulary: 1. mRNA 2. rRNA 3. tRNA 4. Transcription 5. RNA polymerase 6. Intron 7. Exon 8. Codon 9. Translation

18. DNA • Deoxyribo • Nucleic • Acid

20. Answers 1. Proteins are chains of linked amino acids that have been folded into compact shapes. Some proteins play important roles as enzymes. Other proteins are structural components of cells and tissues. 2. Ribosomes are structures built of proteins and RNA that serve as assembly sites for protein synthesis.

21. 3. DNA is an extremely long, linear molecule containing many genes; genes are relatively short segments of DNA that code for protein or RNA. 4. DNA is made of two strands of complementary nucleotides and contains the four bases adenine, thymine, cytosine, and guanine. DNA contains the sugar deoxyribose and serves to store the complete set of an organism’s genetic material. 5. In DNA, adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C).

22. General Vocabulary 1. gene 2. chromosome 3. chromosomal mutation 4. codon 5. double helix 6. frameshift mutation 7. messenger RNA mRNA 8. monosomy 9. mutation 10. nitrogen base 11. nondisjunction 12. point mutation 13. replication 14. ribosomal RNA rRNA 15. transcription 16. transfer RNA tRNA 17. translation 18. trisomy 19. anticodon 20. protein

23. The instructions for building a protein are found in a gene and are “rewritten”to a molecule of RNA during transcription. The RNA is then “deciphered” during translation

24. Making a protein • DNA is found in the nucleus. • The proteins are made on a ribosome from amino acids found in the cytoplasm. • The instructions must get from the nucleus to the ribosome…

25. Start and stop codes on the DNA define where one gene starts and ends. • The DNA has to be un wound and un zipped for this process to work, just like in DNA synthesis. • Some sections of DNA will be used more often then others.

26. 1. What is gene expression?

27. Gene expression is the process by which information encoded in DNA directs the synthesis of proteins or, in some cases, RNAs that are not translated into proteins and instead function as RNAs enzyme like RNA’s • This expression happens in two stages: transcription and translation

28. 2. What situation did A. Garrod suggest caused inborn errors in metabolism?

29. A person’s inability to make a particular enzyme.

30. 3. Describe one example Garrod used to illustrate his hypothesis.

31. Garrod gave as one example the hereditary condition called alkaptonuria. In this disorder, the urine is black because it contains the chemical alkapton, which darkens upon exposure to air. • Garrod reasoned that most people have an enzyme that metabolizes alkapton, whereas people with alkaptonuria have inherited an inability to make that enzyme.

32. 4. State the hypothesis formulated by George Beadle while studying eye color mutations in • Drosophila.

33. The hypothesis stated that in Drosophila, each of the various mutations affecting eye color blocks pigment synthesis at a specific step by preventing production of the enzyme that catalyzes that step. • He showed that the genes control the production of enzymes and that the enzymes are related to traits! Often these occur in a series of steps and if one is missing the entire process can be altered!

34. 5. What strategy did Beadle and Tatum adopt to test this hypothesis?

35. Beadle and Tatum bombarded the bread mold Neurospora with X-rays, and then looked among the survivors for mutants that differ in their nutritional needs from the wild-type bread mold.

36. 6. Which organism did Beadle and Tatum use in their research?

37. Neurospora. • MOLD!

38. How did this organism’s nutritional requirements facilitate this research?

39. Wild-type Neurospora has modest food requirements. It can grow in the laboratory on a simple solution of inorganic salts, glucose, and the vitamin biotin, and incorporated into agar, a support medium. From this minimal medium, the mold cells use their metabolic pathways to produce all other molecules they need. • Beadle and Tatum identified mutants that could not survive on minimal medium, apparently because they were unable to synthesize certain essential molecules

40. 7. How were Neurospora spores treated to increase the mutation rate?

41. Neurospora spores were treated with X-rays to increase the mutation rate.

42. Wild can grow on any thing • Mutant: can’t grow • Gene A • Gene B • Gene C

43. 9. Cite two significant findings that resulted from the research of Beadle and Tatum.

44. 1. that metabolic defects are linked to defective genes, • 2. support for the one gene–one enzyme hypothesis

45. 10. What revision of detail (but not of basic principle) did this hypothesis undergo as more information was gained? Write this restatement and then box or highlight it. This is an important concept! • .

46. Because not all proteins are enzymes, and because each protein consists of two or more different polypeptide chains, each specified by its own gene, the hypothesis was revised. • Beadle and Tatum’s idea was restated as the one gene–one polypeptide hypothesis

47. Best current gene definition! • a DNA sequence that is expressed to form a functional product: either RNA or polypeptide

48. DNA and RNA • Sugars ribose and deoxy ribose are different!

49. RNA has the nitrogenous base uracil rather than thymine.

50. An RNA molecule usually consists of a single strand rather than DNA’s double strand