biology ok. So, the PAM sequence is a sequence of nucleotides called the protospacer adjacent motif (usually NNG, with N being any nucleotide). Viral DNA has many PAM sequences. When the protospacer is cut out of the viral DNA that has been injected into the bacteria, this is done a little after the PAM site by Cas1 and Cas2 (just other restriction endonucleases). The purpose of the PAM site is for the Cas9 cutting part of the CRISPR-Cas9 process. When the Cas9 enzymes identifies viral DNA and a PAM region on it, it opens up the DNA and sees whether or not the gRNA is complementary to the sequence of bases upstream from the PAM sequence but on the opposite strand. If the gRNA is complementary to the viral DNA section after the PAM sequence, it will cut the DNA on both strands just upstream from the PAM. However, if the gRNA does not match the viral sequence, Cas9 closes the viral DNA and continues to search for another PAM site (it can take multiple goes to find the right one since there are lots of PAM sites). So in summary, the PAM site is like a recognition tool or tag for Cas9 to search for and identify, allowing it to check the viral DNA with the gRNA before making a cut. Hope that makes sense!

      what is the difference between social implication and biological implication? and also do we need to include that in sympatric speciation gene flow doesnt occur

      for photosynthesis do you say the light dependent stage is the grana or thylakoid?

        Is it okay to write exam in pencil

          Hey guys, I got two questions:

          • From which ancestor did Aboriginals evolve from?
          • What is the MAIN difference between C3 plants and CAM/C4 plants (besides making 3 carbon vs 4 carbon compound)?

            Christ
            I don't do VCE, or biology, but I believe it is best you refrain from using pencil in your exam. If it doesn't scan through, the answers get marked nil. Best to stick to blue or black pen, but I believe you can use a 2B pencil for the multiple choice.

            p.s: as a rule of thumb, NEVER use frixion pens or an rub-out pen, our exams are stored in hot temperatures and your exam will be blank.

            -jinx_58

              spicynuggets

              Question 1/
              The key point that is need to be noted is that the modern human group that is hypothesised by the "Out of Africa Hypothesis which migrated out of Africa ~ 100,000 ya and reached Asia ~ 70,000 years ago before moving down through South-east Asia and into Australia 50,000 years ago. It can be concluded that Aboriginals were part of this group of Homo Sapiens.

              Question2/
              VCAA expects you know the adaptations C3/C4/CAM plants have and how it aids them to survive in their respective environments. It is not clear in how much depth they are looking for in this new study design, so here is my guide on what they could be expecting.

              C3 plants are the normal types of plants that are adapted to a variety of temperatures and levels of humidity.
              They convert CO2 into 3 carbon compound called PGA and then into glucose.

              C4 plants are adapted to much hotter environments. We know that Rubisco, enzyme responsible for the Calvin cycle, has increased affinity of O2 as substrate as temperatures increase, cause photorespiration and reducing photosynthetic efficiency. In order to combat this issue, the light dependant stage is separated from the light independent stage so that the O2 produce in light dependent stage does not come in contact with Rubisco. Therefore, the Calvin Cycle occurs in bundle sheath cells, deep in the leaf tissue, away from the stomata and the light dependent stage occur in the mesophyll cells. This means CO2 is converted into malic acid before being transported into the bundle sheath cells as bundle sheath cells don't have access to the stomata.

              CAM plants are adapted to dry climates and hence they are specialised to conserve H2O.
              To do this, they only open their stomata at night, in order to let in CO2. The CO2 is stored as malic acid in the cells large vacuole. When it is day time, the stored CO2 is release from malic acid and can be used to power photosynthesis without having to open their stomata during the day.
              This helps the CAM plants be much more efficient (up to 90%) in conserving water than C3 plants.

                is this question relevant to the study design or not any more. Also how in depth should we know about signaling molecules

                b. State two advantages of programmed cell death for a multicellular organism. ( 2 marks)

                  does anyone have any good diagrams about the key characteristics of primates, mammals, hominins, hominoids. thank you

                  Christ hey do we need to know the specific years when homo species evolved

                    clazah Rubisco aids in the carbon fixation of carbon dioxide to form glucose, specifically catalysing the formation of 3-PGA (3-carbon molecule) from RuBP (5-carbon molecule) and CO2, where 3-PGA is then converted into G3P (which is then used to form glucose) with the help of NADPH and ATP.

                      Describe how CRISPR-Cas9 works by using the terms listed below.
                      Target DNA, Cas 9, Spacer RNA, Guide RNA, Scaffold RNA, Cleavage