Presentation is loading. Please wait.

Presentation is loading. Please wait.

Mendel’s Experiments  Gregor Mendel was an Austrian monk who conducted experiments on pea plants  Mendel’s experiments answered many questions, but led.

Similar presentations


Presentation on theme: "Mendel’s Experiments  Gregor Mendel was an Austrian monk who conducted experiments on pea plants  Mendel’s experiments answered many questions, but led."— Presentation transcript:

1 Mendel’s Experiments  Gregor Mendel was an Austrian monk who conducted experiments on pea plants  Mendel’s experiments answered many questions, but led to even more!  What are genes made of!  We will study Gregor Mendel in the next unit!

2 Griffith’s Experiment – 1928  Examined Streptococcus pneumoniae strains and mice  S strain of bacteria cause pneumonia  R strain of bacteria does NOT cause pneumonia  S strain of bacteria can be killed and rendered harmless by heating  R bacteria mixed with heat-killed S bacteria can still cause infection  Griffith's Experiment Video Clip Griffith's Experiment Video Clip

3 Griffith’s Experiment – 1928  Conclusion – Some type of material can move from the heat–killed S bacteria to the R bacteria to cause disease, and that this must be the genetic material—TRANSFORMATION  Transformation – change in the genotype (genetic makeup of an organism) caused when cells take up foreign genetic material  The cause of transformation was not known at the time

4 Griffith’s Experiment – 1928  The DNA of the heat–killed bacteria was not altered and became incorporated into the DNA of the live bacteria.

5 Avery’s Experiment – 1944  Material responsible for transformation is not affected by protein–destroying enzymes  The activity is stopped by a DNA–destroying enzyme!  Proved DNA is the material responsible for transformation.

6 Hersey and Chase’s Experiment – 1952  Worked with bacteriophages (viruses), which are made of only DNA and protein  Alternated between using radioactive DNA or radioactive protein  Sulfur isotope ( 35 S) – only found in protein coat  Phosphorous isotope ( 32 P) – only found in DNA  Looked to see if bacteria became radioactive when radioactive DNA or when radioactive protein was inserted by the virus  Hershey Chase Video Clip Hershey Chase Video Clip

7 Hersey and Chase’s Experiment – 1952  The bacteria only became radioactive when radioactive DNA was used  Conclusion – DNA is what is inserted into the bacteria, not the protein!

8 Hersey and Chase’s Experiment – 1952  They all prove that DNA, not proteins, are what is being passed on and is the heredity material!


Download ppt "Mendel’s Experiments  Gregor Mendel was an Austrian monk who conducted experiments on pea plants  Mendel’s experiments answered many questions, but led."

Similar presentations


Ads by Google