April 27, 2010 Ms. Simon Regents Biology Introduction to Genetics.
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Transcript of April 27, 2010 Ms. Simon Regents Biology Introduction to Genetics.
Do Now: 1) Identify some functions of proteinsMuscle, enzymes catalyze reactions, channels,
2) What does DNA stand for?Deoxyribose nucleic acid
3) Why is DNA important?Determines our traits“Hereditary material”
Meischer (1869)
• Treated pus (white blood cells) with pepsin enzyme breaks down proteins (protease)
• Isolated the nuclei, precipitate is formed (DNA)
• nitrogen and phosphorous found in nuclein= material of the nucleus
Characteristics of hereditary material (DNA)
• Found in the nucleus
• Controls heredity (inherited traits)
• Self-replicating
• Change should result in change in organism
Griffiths Experiments• Studies pneumonococcus, bacteria that
causes pneumonia
• Two strains of the bacteria:
1) R-strain
2) S-strain
R-strain bacteria: rough, nonpathogenic, non-capsulated
S-strain: carbohydrate capsule that avoids the immune system and is pathogenic
4. Injected a mixture of heated S strain and normal R strain
Results: Mice died
Blood shows live S strain
• Genetic material was released from the S strain and taken up by the R strain to produce S strain bacteria
• The R strain had transformed into S strain
Pneumoniae cell extracts contain protein, DNA, and RNA.
How did scientists show that the transforming material was DNA?
Avery, MacLeod and McCarthy
1) Mix dead S and
Live R bacteria
2) Add protease
3) Add RNA-ase
4) Add DNA-ase
Conclusion: DNA is the hereditary material!
http://www.youtube.com/watch?v=9hzUjx_oD8E
Techno
http://www.youtube.com/watch?v=xXbyJNRwjlg