Anatomy & Physiology I Unit Four

1. Anatomy & Physiology I Unit Four

2. DNA & RNA Structure The monomers are nucleotides Nitrogen base Functions: aaaaaaaaaaa • Heredity • Protein synthesis Phosphate group Pentose sugar

3. DNA & RNA Structure Examples: Single stranded with three forms – tRNA, rRNA, and mRNA Double stranded, double helix molecule • DNA • RNA

4. DNA & RNA Structure

5. DNA & RNA Functions

6. DNA & RNA Base Pairing

7. DNA & RNA Base Pairing DNA replication | | | | | | | | | | | | | | | | | | A T G C A T T G A A G C T G G T A G T A C G T A A C T T C G A C C A T C | | | | | | | | | | | | | | | | | | RNA transcription | | | | | | | | | | | | | | | | | | A U G C A U U G A A G C U G G U A G T A C G T A A C T T C G A C C A T C | | | | | | | | | | | | | | | | | |

8. DNA Replication

9. Protein Synthesis Protein synthesis goes on all the time in most cells This very important process is directed by the genetic code on DNA

10. Protein Synthesis Protein synthesis occurs in two processes: ~ transcription (production of RNA from DNA) ~ translation (production of proteins from RNA) Both processes are fueled by ATP

11. Protein Synthesis: Transcription

12. Protein Synthesis: Transcription RNA polymerase attaches to specific areas of the DNA (genes) and “unzips” the hydrogen bonds The RNA polymerase also begins the building of the RNA by adding RNA nucleotides in accordance with the DNA base sequence

13. Protein Synthesis: Transcription

14. Protein Synthesis: Transcription

15. Protein Synthesis: Transcription Once transcribed, mRNA and tRNA are sent out of the nucleus and to the ribosomes in the cytoplasm rRNA is transferred to the nucleolus to become a part of newly formed ribosomes

16. Protein Synthesis: Translation mRNA carries a series of codons that code for specific amino acids A codon is a sequence of three nucleotide bases on mRNA Since there are only four RNA bases and there are three in each codon, there are 64 condon possibilities

17. Protein Synthesis: Translation The genetic code is the use of these 64 codons coding for 20 amino acids Remember - the synthesis of a specific protein requires a specific sequence of amino acids

18. Protein Synthesis: Translation Therefore the sequence of codons on mRNA must be sequentially specific The genetic code is commaless and non-overlapping, meaning it is read in frames of three without gaps or overlaps

19. Protein Synthesis: Translation There is one initiation codon - AUG There are three stop codons - UAA, UAG & UGA

20. Protein Synthesis - Translation Translation is the process by which RNA produces proteins in ribosomes - mRNA carries the code from DNA - tRNA carries amino acids to the ribosome - rRNA is a component of the ribosome

21. Protein Synthesis: Translation By way of the genetic code, RNA “translates” from the language of nucleic acids to that of proteins

22. Protein Synthesis: Translation

23. Protein Synthesis: Translation

24. Protein Synthesis: Review

25. Protein Synthesis: Review

26. Interphase G1 – organelles double S – DNA replicates G2 – proteins produced

27. Mitosis Prophase Metaphase Anaphase Telophase

29. Cytokinesis

30. Significance of Cell Division Cell division (mitosis) is an efficient process that assures the correct number of chromosomes will be found in the new daughter cells

31. Significance of Cell Division Chromosome number is a critical characteristic in determining a species and the viability of an organism Correct chromosomes numbers are essential for successful fertilization events

32. Significance of Cell Division In animals, increasing or decreasing chromosome numbers has deleterious effects

33. Significance of Cell Division The functions of cell division are: ~ growth ~ repair ~ replacement Cellular homeostasis is the maintaining of a constant number of body cells

34. Significance of Cell Division Cellular homeostasis is maintained by a number of factors: + cell size + nutrient availability + DNA damage + growth factors + cell population density

35. Significance of Cell Division Surface to volume ratio determines the maximum size a cell can obtain The amount of nutrients available is a factor in the rate of growth Growth factors such as cyclins, Cdks and hormones influence the speed and amount of cell growth

36. Significance of Cell Division The density of cells also controls cell growth – loss of cells stimulates cell division, adequate numbers of cells inhibit the process

37. Cancer Cell division is orchestrated by proteins and hormones so that growth and division is controlled Cancer cells are normal body cells that are transformed. In this transformed state, they ignore the controls of cell division and multiply unchecked

38. Cancer Normally, the immune system destroys these cancer cells, but some may escape destruction and then form a tumor A tumor is a mass of cancer cells found within otherwise normal tissue

39. Cancer A tumor is said to be benign if the cancer cells remain within the tumor. These can usually be removed through surgery A malignant tumor contains cancer cells that are invasive, meaning they spread to other tissues. A person with a malignant tumor is said to have cancer

40. Cancer Remember - cell division is orchestrated by proteins and hormones so that growth and division is controlled Oncogenes are those that initiate cell division, but in an accelerated and exaggerated process

41. Cancer Tumor suppressor genes are those that prevent cell division and promote normal cell death If tumor suppressor genes are altered, inactivated or removed the result can be cancer

42. Cancer Cancer can occur through genetic abnormalities, activating oncogenes and/or inactivating tumor suppressor genes Environmental influences can also affect the activity and inactivity of these genes

43. Cancer Environmental influences include: ~ diet ~ exercise ~ sun exposure ~ smoking ~ altering of DNA