DNA and Gene Control

1. DNA and Gene Control Chapters 10 & 11

2. DNA verse RNA�.Review DNA and RNA are nucleic acids DNA � genetic information RNA � used to build proteins Built by nucleotides Can be single stranded or double stranded Bases Bonds

4. DNA Replication Complete set of genetic instructions must pass from one generation to the next Begins at specific sites on a double helix Proceeds in both directions

5. Overview:

6. Flow of Genetic Information from DNA to RNA to Protein Information contained in DNA is stored in blocks called genes genes code for proteins proteins determine what a cell will be like DNA stores information in nucleus instructions are copied from the DNA into messages comprised of RNA these messages are sent out into the cell direct the assembly of proteins

7. Flow of Genetic Information from DNA to RNA to Protein The path of information is often referred to as the central dogma DNA ? RNA ? protein Gene expression : Transcription messenger RNA (mRNA) made from a gene within the DNA Translation Using the mRNA to direct the production of a protein

9. Transcription Occurs in the nucleus

10. Transcription The cell uses three kinds of RNA messenger RNA (mRNA) ribosomal RNA (rRNA) transfer RNA (tRNA)

11. Transcription RNA polymerase Produces the mRNA copy of DNA during transcription Binds to one strand of the DNA at a site called the promoter �start transcribing� signal nucleotide sequence moves down the DNA molecule assembles a complementary copy of RNA Transcription ends when RNA polymerase reaches a certain nucleotide sequence signals it stop

12. Transcription Steps First phase of transcription is initiation: RNA polymerase attaches to the promoter RNA synthesis begins Second phase of transcription is elongation: RNA grows longer Third phase of transcription is termination: RNA polymerase reaches a sequence of DNA bases called a terminator Eukaryotic cell then processes the RNA after transcription

15. Translation Occurs in the cytoplasm

17. Translation Conversion from the nucleic acid language to the protein language messenger RNA (mRNA) produced by transcription is decoded by the ribosome to produce a specific amino acid chain, or polypeptide, that will later fold into an active protein mRNA Is the first ingredient for translation tRNA Acts as a molecular interpreter Carries amino acids Matches amino acids with codons in mRNA using anticodons

18. Translation To correctly read a gene, a cell must translate the information encoded in the DNA into the language of proteins translation follows rules set out by the genetic code mRNA is �read� in three-nucleotide units called codons each codon corresponds to a particular amino acid

19. The genetic code (RNA codons)

20. 3 Phases� Translation is divided into three phases: Initiation Elongation Termination

21. Initiation The first phase brings together: The mRNA The first amino acid with its attached tRNA The two subunits of the ribosome

22. Elongation Step 1, codon recognition The anticodon of an incoming tRNA pairs with the mRNA codon Step 2, peptide bond formation The ribosome catalyzes bond formation between amino acids Step 3, translocation A tRNA leaves the P site of the ribosome The ribosome moves down the mRNA

23. Termination Elongation continues until the ribosome reaches a stop codon ribosome then falls apart newly made protein is released into the cell

25. Genes gone bad� Mutation Any change in the nucleotide sequence of DNA Can result in changes in the amino acids in proteins Often harmful, but are they always?? Mutations may result from Errors in DNA replication Physical or chemical agents called mutagens

26. Gene Control

27. Human Cells�. All share the same genome What makes them different????

28. How are Genes Regulated?? In cellular differentiation: Certain genes turned on and off Cells become specialized in structure and function

29. How are Genes Regulated?? In gene expression: A gene is turned on and transcribed into RNA Information flows from genes to proteins, genotype to phenotype

30. Bacteria Control sequences Stretches of DNA that coordinate gene expression An operon Cluster of genes with related functions, including the control sequences A promoter Control sequence Site where the transcription enzyme initiates transcription An operator DNA sequence between the promoter and the enzyme genes Acts as an on and off switch for the genes

33. Eukaryotic Cells Eukaryotic cells More sophisticated

34. Initiation of Transcription Eukaryotic control mechanisms Involve regulatory proteins Regulate transcription

35. RNA processing The eukaryotic cell: Localizes transcription in the nucleus Processes RNA in the nucleus; includes: Addition of a cap and tail to the RNA Removal of introns Splicing together of the remaining exons

37. Translation regulation Regulated by many different proteins Post-translational control mechanisms Occur after translation Often involve cutting polypeptides into smaller, active final products Selective breakdown of proteins is another control mechanism operating after translation

38. VIRUSES AND OTHER NONCELLULAR INFECTIOUS AGENTS

39. VIRUSES Viruses exhibit some, but not all, characteristics of living organisms Possess genetic material in the form of nucleic acids Are not cellular Cannot reproduce on their own Bacteriophages viruses that attack bacteria. Student Misconceptions and Concerns 1. Students and many parents with young children expect a treatment of antibiotics for many respiratory infections, even though such infections may result from a virus. Students will benefit by a thorough explanation of the inappropriate use of antibiotics for viral infections and the risks of overuse of antibiotics leading to increased numbers of antibiotic-resistant bacteria. 2. The success of modern medicine has perhaps led to an overconfidence in our ability to treat disease. Students often do not understand that there are few successful treatments for viral infections. Instead, the best defense against viruses is prevention by reducing the chances of contacting the virus and the use of vaccines. Teaching Tips 1. Students (and instructors) might enjoy thinking of a prophage as a smudge mark on the master copy of a class handout. The smudge is replicated every time the original is copied! 2. Viruses can spread throughout a plant by moving through plasmodesmata (not specifically discussed in this chapter). This is like smoke spreading throughout a building by moving through air ducts. 3. There is an interesting relationship between the speed at which a virus kills or debilitates a host and the extent to which it spreads from one organism to another. This is something to consider for a class discussion. Compare two viral infections. Infection A multiplies within the host, is spread by the host to other people through casual contact, but does not cause its lethal symptoms until 5�10 years after infection. Virus B kills the host within 1�2 days of infection, is easily transmitted, and causes severe symptoms within hours of contact. Which virus is likely to spread the fastest through the human population on Earth? Which might be considered the most dangerous to humans? 4. Students often do not understand the disproportionate distribution of HIV infections and AIDS in our world. Consider an Internet assignment, asking students to identify the regions of the world most affected by HIV-AIDS. The Centers for Disease Control and Prevention has extensive information about AIDS at www.cdc.gov/hiv/.Student Misconceptions and Concerns 1. Students and many parents with young children expect a treatment of antibiotics for many respiratory infections, even though such infections may result from a virus. Students will benefit by a thorough explanation of the inappropriate use of antibiotics for viral infections and the risks of overuse of antibiotics leading to increased numbers of antibiotic-resistant bacteria. 2. The success of modern medicine has perhaps led to an overconfidence in our ability to treat disease. Students often do not understand that there are few successful treatments for viral infections. Instead, the best defense against viruses is prevention by reducing the chances of contacting the virus and the use of vaccines. Teaching Tips 1. Students (and instructors) might enjoy thinking of a prophage as a smudge mark on the master copy of a class handout. The smudge is replicated every time the original is copied! 2. Viruses can spread throughout a plant by moving through plasmodesmata (not specifically discussed in this chapter). This is like smoke spreading throughout a building by moving through air ducts. 3. There is an interesting relationship between the speed at which a virus kills or debilitates a host and the extent to which it spreads from one organism to another. This is something to consider for a class discussion. Compare two viral infections. Infection A multiplies within the host, is spread by the host to other people through casual contact, but does not cause its lethal symptoms until 5�10 years after infection. Virus B kills the host within 1�2 days of infection, is easily transmitted, and causes severe symptoms within hours of contact. Which virus is likely to spread the fastest through the human population on Earth? Which might be considered the most dangerous to humans? 4. Students often do not understand the disproportionate distribution of HIV infections and AIDS in our world. Consider an Internet assignment, asking students to identify the regions of the world most affected by HIV-AIDS. The Centers for Disease Control and Prevention has extensive information about AIDS at www.cdc.gov/hiv/.

40. Animal Viruses Viruses that infect animals are: Common causes of disease May have RNA or DNA genomes Some animal viruses steal a bit of host cell membrane as a protective envelope Student Misconceptions and Concerns 1. Students and many parents with young children expect a treatment of antibiotics for many respiratory infections, even though such infections may result from a virus. Students will benefit by a thorough explanation of the inappropriate use of antibiotics for viral infections and the risks of overuse of antibiotics leading to increased numbers of antibiotic-resistant bacteria. 2. The success of modern medicine has perhaps led to an overconfidence in our ability to treat disease. Students often do not understand that there are few successful treatments for viral infections. Instead, the best defense against viruses is prevention by reducing the chances of contacting the virus and the use of vaccines. Teaching Tips 1. Students (and instructors) might enjoy thinking of a prophage as a smudge mark on the master copy of a class handout. The smudge is replicated every time the original is copied! 2. Viruses can spread throughout a plant by moving through plasmodesmata (not specifically discussed in this chapter). This is like smoke spreading throughout a building by moving through air ducts. 3. There is an interesting relationship between the speed at which a virus kills or debilitates a host and the extent to which it spreads from one organism to another. This is something to consider for a class discussion. Compare two viral infections. Infection A multiplies within the host, is spread by the host to other people through casual contact, but does not cause its lethal symptoms until 5�10 years after infection. Virus B kills the host within 1�2 days of infection, is easily transmitted, and causes severe symptoms within hours of contact. Which virus is likely to spread the fastest through the human population on Earth? Which might be considered the most dangerous to humans? 4. Students often do not understand the disproportionate distribution of HIV infections and AIDS in our world. Consider an Internet assignment, asking students to identify the regions of the world most affected by HIV-AIDS. The Centers for Disease Control and Prevention has extensive information about AIDS at www.cdc.gov/hiv/.Student Misconceptions and Concerns 1. Students and many parents with young children expect a treatment of antibiotics for many respiratory infections, even though such infections may result from a virus. Students will benefit by a thorough explanation of the inappropriate use of antibiotics for viral infections and the risks of overuse of antibiotics leading to increased numbers of antibiotic-resistant bacteria. 2. The success of modern medicine has perhaps led to an overconfidence in our ability to treat disease. Students often do not understand that there are few successful treatments for viral infections. Instead, the best defense against viruses is prevention by reducing the chances of contacting the virus and the use of vaccines. Teaching Tips 1. Students (and instructors) might enjoy thinking of a prophage as a smudge mark on the master copy of a class handout. The smudge is replicated every time the original is copied! 2. Viruses can spread throughout a plant by moving through plasmodesmata (not specifically discussed in this chapter). This is like smoke spreading throughout a building by moving through air ducts. 3. There is an interesting relationship between the speed at which a virus kills or debilitates a host and the extent to which it spreads from one organism to another. This is something to consider for a class discussion. Compare two viral infections. Infection A multiplies within the host, is spread by the host to other people through casual contact, but does not cause its lethal symptoms until 5�10 years after infection. Virus B kills the host within 1�2 days of infection, is easily transmitted, and causes severe symptoms within hours of contact. Which virus is likely to spread the fastest through the human population on Earth? Which might be considered the most dangerous to humans? 4. Students often do not understand the disproportionate distribution of HIV infections and AIDS in our world. Consider an Internet assignment, asking students to identify the regions of the world most affected by HIV-AIDS. The Centers for Disease Control and Prevention has extensive information about AIDS at www.cdc.gov/hiv/.

41. HIV, the AIDS Virus HIV is a retrovirus RNA virus that reproduces by means of a DNA molecule Retroviruses use the enzyme reverse transcriptase to synthesize DNA on an RNA template HIV steals a bit of host cell membrane as a protective envelope Student Misconceptions and Concerns 1. Students and many parents with young children expect a treatment of antibiotics for many respiratory infections, even though such infections may result from a virus. Students will benefit by a thorough explanation of the inappropriate use of antibiotics for viral infections and the risks of overuse of antibiotics leading to increased numbers of antibiotic-resistant bacteria. 2. The success of modern medicine has perhaps led to an overconfidence in our ability to treat disease. Students often do not understand that there are few successful treatments for viral infections. Instead, the best defense against viruses is prevention by reducing the chances of contacting the virus and the use of vaccines. Teaching Tips 1. Students (and instructors) might enjoy thinking of a prophage as a smudge mark on the master copy of a class handout. The smudge is replicated every time the original is copied! 2. Viruses can spread throughout a plant by moving through plasmodesmata (not specifically discussed in this chapter). This is like smoke spreading throughout a building by moving through air ducts. 3. There is an interesting relationship between the speed at which a virus kills or debilitates a host and the extent to which it spreads from one organism to another. This is something to consider for a class discussion. Compare two viral infections. Infection A multiplies within the host, is spread by the host to other people through casual contact, but does not cause its lethal symptoms until 5�10 years after infection. Virus B kills the host within 1�2 days of infection, is easily transmitted, and causes severe symptoms within hours of contact. Which virus is likely to spread the fastest through the human population on Earth? Which might be considered the most dangerous to humans? 4. Students often do not understand the disproportionate distribution of HIV infections and AIDS in our world. Consider an Internet assignment, asking students to identify the regions of the world most affected by HIV-AIDS. The Centers for Disease Control and Prevention has extensive information about AIDS at www.cdc.gov/hiv/.Student Misconceptions and Concerns 1. Students and many parents with young children expect a treatment of antibiotics for many respiratory infections, even though such infections may result from a virus. Students will benefit by a thorough explanation of the inappropriate use of antibiotics for viral infections and the risks of overuse of antibiotics leading to increased numbers of antibiotic-resistant bacteria. 2. The success of modern medicine has perhaps led to an overconfidence in our ability to treat disease. Students often do not understand that there are few successful treatments for viral infections. Instead, the best defense against viruses is prevention by reducing the chances of contacting the virus and the use of vaccines. Teaching Tips 1. Students (and instructors) might enjoy thinking of a prophage as a smudge mark on the master copy of a class handout. The smudge is replicated every time the original is copied! 2. Viruses can spread throughout a plant by moving through plasmodesmata (not specifically discussed in this chapter). This is like smoke spreading throughout a building by moving through air ducts. 3. There is an interesting relationship between the speed at which a virus kills or debilitates a host and the extent to which it spreads from one organism to another. This is something to consider for a class discussion. Compare two viral infections. Infection A multiplies within the host, is spread by the host to other people through casual contact, but does not cause its lethal symptoms until 5�10 years after infection. Virus B kills the host within 1�2 days of infection, is easily transmitted, and causes severe symptoms within hours of contact. Which virus is likely to spread the fastest through the human population on Earth? Which might be considered the most dangerous to humans? 4. Students often do not understand the disproportionate distribution of HIV infections and AIDS in our world. Consider an Internet assignment, asking students to identify the regions of the world most affected by HIV-AIDS. The Centers for Disease Control and Prevention has extensive information about AIDS at www.cdc.gov/hiv/.

42. AIDS AIDS (acquired immune deficiency syndrome) is: Caused by HIV infection Treated with drugs that interfere with the reproduction of the virus

43. Figure 10.32a The behavior of HIV nucleic acid in an infected cell.Figure 10.32a The behavior of HIV nucleic acid in an infected cell.

44. Prions are responsible for neurodegenerative diseases including: Mad cow disease Scrapie in sheep and goats Chronic wasting disease in deer and elk Creutzfeldt-Jakob disease in humans Student Misconceptions and Concerns 1. Students and many parents with young children expect a treatment of antibiotics for many respiratory infections, even though such infections may result from a virus. Students will benefit by a thorough explanation of the inappropriate use of antibiotics for viral infections and the risks of overuse of antibiotics leading to increased numbers of antibiotic-resistant bacteria. 2. The success of modern medicine has perhaps led to an overconfidence in our ability to treat disease. Students often do not understand that there are few successful treatments for viral infections. Instead, the best defense against viruses is prevention by reducing the chances of contacting the virus and the use of vaccines. Teaching Tips 1. Students (and instructors) might enjoy thinking of a prophage as a smudge mark on the master copy of a class handout. The smudge is replicated every time the original is copied! 2. Viruses can spread throughout a plant by moving through plasmodesmata (not specifically discussed in this chapter). This is like smoke spreading throughout a building by moving through air ducts. 3. There is an interesting relationship between the speed at which a virus kills or debilitates a host and the extent to which it spreads from one organism to another. This is something to consider for a class discussion. Compare two viral infections. Infection A multiplies within the host, is spread by the host to other people through casual contact, but does not cause its lethal symptoms until 5�10 years after infection. Virus B kills the host within 1�2 days of infection, is easily transmitted, and causes severe symptoms within hours of contact. Which virus is likely to spread the fastest through the human population on Earth? Which might be considered the most dangerous to humans? 4. Students often do not understand the disproportionate distribution of HIV infections and AIDS in our world. Consider an Internet assignment, asking students to identify the regions of the world most affected by HIV-AIDS. The Centers for Disease Control and Prevention has extensive information about AIDS at www.cdc.gov/hiv/.Student Misconceptions and Concerns 1. Students and many parents with young children expect a treatment of antibiotics for many respiratory infections, even though such infections may result from a virus. Students will benefit by a thorough explanation of the inappropriate use of antibiotics for viral infections and the risks of overuse of antibiotics leading to increased numbers of antibiotic-resistant bacteria. 2. The success of modern medicine has perhaps led to an overconfidence in our ability to treat disease. Students often do not understand that there are few successful treatments for viral infections. Instead, the best defense against viruses is prevention by reducing the chances of contacting the virus and the use of vaccines. Teaching Tips 1. Students (and instructors) might enjoy thinking of a prophage as a smudge mark on the master copy of a class handout. The smudge is replicated every time the original is copied! 2. Viruses can spread throughout a plant by moving through plasmodesmata (not specifically discussed in this chapter). This is like smoke spreading throughout a building by moving through air ducts. 3. There is an interesting relationship between the speed at which a virus kills or debilitates a host and the extent to which it spreads from one organism to another. This is something to consider for a class discussion. Compare two viral infections. Infection A multiplies within the host, is spread by the host to other people through casual contact, but does not cause its lethal symptoms until 5�10 years after infection. Virus B kills the host within 1�2 days of infection, is easily transmitted, and causes severe symptoms within hours of contact. Which virus is likely to spread the fastest through the human population on Earth? Which might be considered the most dangerous to humans? 4. Students often do not understand the disproportionate distribution of HIV infections and AIDS in our world. Consider an Internet assignment, asking students to identify the regions of the world most affected by HIV-AIDS. The Centers for Disease Control and Prevention has extensive information about AIDS at www.cdc.gov/hiv/.