Test 3

• Photophosphorylation

  The process where the flow of electrons across the thylakoid membrane supplies energy which is used for the phosphorylation of ADP to form ATP
• Photophosphorylation is driven by light energy from the sun
• Types of photophosphorylation

  • Non-cyclic photophosphorylation
  • Cyclic photophosphorylation
• Non-cyclic photophosphorylation

  1. Electron flow is in a zig-zag/linear (non-cyclic) pattern, as the electrons move from photosystem II to photosystem I

  2. Unidirectional, as electrons move from photosystem II to photosystem I

  3. Produces ATP (from 4 H+) and NADPH (from 2 electrons)
• Cyclic photophosphorylation

  1. Electron flow is in a cyclic pattern, as the electrons move from photosystem I to cytochrome BF and then back to photosystem I

  2. Occurs when there is no NADP available for the light reactions

  3. Produces only ATP
• Calvin cycle

  The series of reactions in the stroma of the chloroplast that use the products of the light reactions (ATP and NADPH) to "fix" CO2 and produce glucose
• Calvin used Chlorella (single-celled green algae) to study the dark reactions of photosynthesis
• Calvin's experiment

  1. Injected 14CO2 (radioactive carbon dioxide) into a culture of Chlorella in bright light

  2. Killed the Chlorella in boiling alcohol and analyzed the samples using 2D chromatography

  3. Used radioautography to identify the radioactive compounds involved in the dark reactions
• Calvin assumed that radioactive CO2 would participate in the dark reactions the same as ordinary CO2
• PGA was identified as the first intermediate product of the dark reactions since it was the most abundant radioactive compound after 30 seconds
• The Calvin cycle

  1. Carbon fixation (unstable 6C compound RuBP reacts with CO2 to form 2 3C PGA)

  2. Reduction (PGA is reduced to G3P using ATP and NADPH from light reactions)

  3. Regeneration (G3P is used to regenerate RuBP)
• The Calvin cycle requires 18 ATP and 12 NADPH to produce glucose and other organic compounds
• Gregor Mendel


  Austrian monk who presented the results of his research on patterns of inheritance in garden peas to the Natural Science Society in Brunn, Austria
• Frederich Miescher


  Swiss biochemist who isolated a substance from the nuclei within white blood cells, which he called "nuclein". Nuclein was made of an acidic portion (which he called "nucleic acid") and an alkaline portion (which was later shown to be protein)
• Phoebus Levene


  Studied nucleic acids in more detail and isolated two types of nucleic acids that could be distinguished by their different sugars - one containing the five-carbon sugar ribose (ribonucleic acid or RNA) and the other containing the five-carbon sugar deoxyribose
• Joachim Hammerling


  Danish biologist who determined the importance of the cell nucleus in the passing of inherited information from parents to offspring, concluding that the nucleus likely contained hereditary information
• Frederick Griffith


  British bacteriologist who reported an interesting phenomenon in pneumonia bacteria, Streptococcus pneumoniae, which he called "transformation"
• Griffith's transformation experiment


  1. Tested Streptococcus pneumoniae, type S (deadly) and type R (alive)

  2. Expected heated S to be alive, but it was dead

  3. Expected heated R to be dead, but it was alive

  4. Concluded that a "transforming principle" was passed from the dead S strain to the live R strain
• Avery, MacLeod and McCarty


  Scientists who discovered that Griffith's "transforming principle" was actually DNA
• Hershey and Chase experiment


  1. Used a virus (bacteriophage T2) that infects bacteria

  2. Showed that DNA, not protein, was the hereditary material of the virus
• Erwin Chargaff


  Determined that there were chemical differences between the DNA of different species, and found that the total amount of purines always equaled the total amount of pyrimidines, and the amount of adenine always equaled the amount of thymine while the amount of guanine always equaled the amount of cytosine - these findings became known as Chargaff's Rules
• Rosalind Franklin


  Succeeded in preparing an X-ray diffraction photograph of DNA that indicated it was helical in structure
• James Watson and Francis Crick

  Used Chargaff's rules and Franklin's X-ray diffraction photograph to determine the double-helix structure of DNA
• Gel electrophoresis


  A laboratory technique used to separate large molecules like proteins and nucleic acids based on their differing sizes, charges or structures by using an electric current to carry them through a gel
• Gregor Mendel


  Austrian monk who presented the results of his research on patterns of inheritance in garden peas to the Natural Science Society in Brunn, Austria
• Frederich Miescher


  Swiss biochemist who isolated a substance from the nuclei within white blood cells, which he called "nuclein". Nuclein was made of an acidic portion (which he called "nucleic acid") and an alkaline portion (which was later shown to be protein)
• Phoebus Levene


  Studied nucleic acids in more detail and isolated two types of nucleic acids that could be distinguished by their different sugars - one containing the five-carbon sugar ribose (ribonucleic acid or RNA) and the other containing the five-carbon sugar deoxyribose
• Joachim Hammerling


  Danish biologist who determined the importance of the cell nucleus in the passing of inherited information from parents to offspring, concluding that the nucleus likely contained hereditary information
• Frederick Griffith


  British bacteriologist who reported an interesting phenomenon in pneumonia bacteria, Streptococcus pneumoniae, which he called "transformation"
• Griffith's transformation experiment


  1. Tested Streptococcus pneumoniae, type S (deadly) and type R (alive)

  2. Expected heated S to be alive, but it was dead

  3. Expected heated R to be dead, but it was alive

  4. Concluded that a "transforming principle" was passed from the dead S strain to the live R strain
• Avery, MacLeod and McCarty


  Scientists who discovered that Griffith's "transforming principle" was actually DNA
• Hershey and Chase experiment


  1. Used a virus (bacteriophage T2) that infects bacteria

  2. Showed that DNA, not protein, was the hereditary material of the virus
• Erwin Chargaff


  Determined that there were chemical differences between the DNA of different species, and found that the total amount of purines always equaled the total amount of pyrimidines, and the amount of adenine always equaled the amount of thymine while the amount of guanine always equaled the amount of cytosine - these findings became known as Chargaff's Rules
• Rosalind Franklin


  Succeeded in preparing an X-ray diffraction photograph of DNA that indicated it was helical in structure
• James Watson and Francis Crick


  Used Chargaff's rules and Franklin's X-ray diffraction photograph to determine the double-helix structure of DNA
• Gel electrophoresis


  A laboratory technique used to separate large molecules like proteins and nucleic acids based on their differing sizes, charges or structures by using an electric current to carry them through a gel
• 3. Why was DNA placed in a warm water bath?
• 4. Why was a concentrated salt solution added to the tube?
• 5. What is the purpose of placing the tube in a centrifuge? to separate DNA from debris
• 6. Where are the proteins and other cellular debris? Are they important to the experiment? bottom of test tube , they are not important