1. Structure and Function of DNA

2. 1 2 3 4 5 6 7 8 9 10

3. RNA, what’s different from DNA? The RNA sugar has 2 OH groups vs 1 in DNA (Instead of thymine (T) in DNA) (Ribose vs deoxyribose) RNA has the base uracil (U)

4. 1 2 34 Complementary = DNA: A-T, C-G; RNA: A-U, C-G Names of structures? 5

5. What are the structures? And, which is which?

6. Complementary = DNA: A-T, C-G; RNA: A-U, C-G Name of structure? What type of bond is this?

7. Learning check 1.Along one strand of a DNA double helix is the nucleotide sequence GGCATAGGT. Want is the sequence for the other DNA strand? ___ ___ ___ ___ ___ ___ ___ ___ ___ 2.A molecule of DNA contains 2 polymer strands called _________ made by bonding many monomers called ____________ together. Each monomer contains 3 parts: __________, _________ and _________. 3.DNA and RNA are polymers of _______ monomers. 4.What type of bond joins the bases of complementary DNA strands?

8. What is the flow of Genetic Information? From DNA To RNA To Protein 1 2 In 2 stages

9. DNA is transcribed The result is mRNA mRNA is then translated The result is a sequence of amino acids in a polypeptide

10. But, what is the correspondence… Between nucleotides of an RNA What are the 4 types of nucleotides? DNA: ATCG RNA: AUCG And the amino acids of a polypeptide

11. How do we get to protein? There are 20 amino acids in protein How do the 4 nucleotides specify 20 amino acids? Each designated by a single letter

12. Amino acids are identified by triplets of bases which What are the triplets of bases called? Cod ons Specify all the amino acids

13. The genetic code is The relationship between nucleotide sequence And amino acid sequence One DNA codon (3 nt) => one RNA codon (3 nt) => one amino acid

14. How is this read?

15. 1.How many nucleotides are necessary to code for a polypeptide that is 100 amino acids long? 2.An organism’s genetic information is stored within the sequence of ___________. 3.The genetic information is transcribed into a sequence of ____________. 4.(the answer to #3) are then translated into a sequence of ______________. 5.The nucleotide sequence of a DNA codon is GTA. The mRNA complementary sequence codon is _____. 6.The above codon codes for the _________ amino acid. Learning check

16. Did you know that the genetic code is shared by all organisms? Mixing genes from various species Tobacco plant The code is the same in different species After genes have been transferred, They can be transcribed and translated (one species to another) What does this allow for? expressing firefly gene All 20 amino acids are common to all living systems

17. Overview: What is the flow of genetic information? DNA  RNA  Protein In eukaryotic cells where does transcription occur? Where is mRNA synthesized? The nucleus Where does translation occur? The cytoplasm

18. What happens to protein as it is made? It coils It folds It forms a 3-D shape And, several polypeptide chains bind together How do genes control structures and activities of cells? Via transcription & translation processes What are each of these shapes called?

19. Learning check 1.Information in a gene is a specific linear sequence of ____________ in DNA. 2.The gene serves as a template in ____________. 3.The gene produces a ___________ strand of mRNA. 4.mRNA specifies a linear sequence of ___________.

20. The Genetic Basis of Cancer In recent years, scientists have learned more about the genetics of cancer What have they identified? That cells escape from control mechanisms This causes changes in some of the cells genes Or changes in the way certain genes are expressed

21. Cancer causing genes First discovered in a chicken virus What is a (chicken) virus? Molecules of DNA or RNA Surrounded by protein How do they work? Become a permanent resident in host cells And, insert their nucleic acid into DNA Of host chromosomes

22. What happens when they insert into a host cell? They make the host cell cancerous Is there something unique about the virus nucleic acids? They contain a gene that causes cancer Called an oncogene (tumor gene)

23. In many cases we all have some of these genes… They are called ‘proto-oncogenes’ They are normal genes that can become oncogenes They are found in many animals They code for growth factors They are proteins that stimulate cell division What do these growth factors do?? Or, are others that affect the cell cycle

24. What happens when these proteins malfunction? Uncontrolled cell growth - cancer What causes the proto-oncogene to malfunction? A mutation must occur Several types of mutations can occur A mutation within a gene An error in DNA replication = many gene copies The normal location of the gene is changed

25. Proto-oncogene Gene mutation Multiple gene copies Gene location moved oncogene Normal growth stimulating protein, but in excess! Hyperactive! Growth stimulating protein New promoter In all cases, normal gene expression is changed => cell division

26. Which cancer is one of the best understood? Colon cancer What is the progression of colon cancer? Begins as an unusually frequent division of normal-looking cells in the colon lining Several (4 or more) mutations are needed Activation of cellular oncogene And inactivation of 2 tumor-suppressor genes These mutations result in altered signal transduction pathways Then see full-fledged cancer cells

27. Typical colon cancer progression - mutations Normal cell Count the mutations… What do the mutations lead to? Increased cell division And, structure of cell grossly altered Malignant cell

28. What are the cellular changes? DNA changes? Increased cell division Growth of benign tumor Growth of malignant tumor Oncogene activated Tumor- suppressor gene inactivated 2 nd Tumor- suppressor gene inactivated Typical colon cancer progression – oncogene & TSG

29. What are cancer causing agents called? Carcinogens 1 What is the carcinogen for these cancers? UV radiation Tobacco 2

30. Microscopic changes that happen when a person smokes Normal lung tissue Ciliated columnar epithelia H = cilia sweep mucus J = goblet cell produces mucus L = basal layer of cells Abnormal lung tissue Columnar cells becoming crowded out Displaced by basal cells Fewer cilia, reduced capability Chemicals in tobacco toxic to cilia, paralyzing Smokers cough

31. Exam 3 Next Tuesday, 11/20/07 The exam covers: Chapter 8, Mitosis & Meiosis Chapter 10 Structure / Function of DNA Some cancer: Pages 128-129 & 211-215