Edexcel GCSE Biology | 1) DNA
•
3 recomendaciones•2,405 vistas
From the Edexcel GCSE additional science specification for biology. Talks about
Recomendados
Más contenido relacionado
La actualidad más candente
La actualidad más candente (20)
Destacado
Destacado (20)
Similar a Edexcel GCSE Biology | 1) DNA
Similar a Edexcel GCSE Biology | 1) DNA (20)
Más de Mr. Science
Más de Mr. Science (7)
Edexcel GCSE Biology | 1) DNA
- 1. DNAIt’s structure and practical Edexcell GCSE gcsepresentations
- 2. *BASICS* ! DNA is fundamental for all life - it contains genes (short sections of DNA), which code for making different proteins, the building blocks of life. ! DNA is what you find, tightly coiled up, inside all 46 chromosomes in every nucleus in every single human diploid body cell. ! It consists of two strands coiled together with a double helix structure and just 4 base pairs: ! ! A (adenine) <—> T (thymine) ! C (cytosine) <—> G (guanine)
- 3. *FRANKLIN & WILKINS* ! Franklin and Wilkins were the brains behind DNA and it’s structure: ! They emitted X-Rays at the crystallised DNA and recorded the patterns of the reflected rays onto a screen. ! From this they discovered the DNA’s helical structure ! *WATSON & CRICK* ! Watson and Crick used information of the double helix ! and that the amount of A + G was equal to the amount of C + T to make a model of DNA with the paired bases.
- 4. *PRACTICAL EXPERIMENT* ! This practical shows DNA as a stringy white substance, which proves that there is DNA in cells of living organisms.
- 5. *STEP 1* ! Chop a big juicy fresh onion into tiny pieces. ! Put it into a beaker.
- 6. *STEP 2* ! Add salt and detergent to the onions and stir. ! ! ! ! ! ! ! ! ! ! ! The detergent will help to break down the cell membranes; ! The salt helps to make the DNA stick together.
- 7. *STEP 3* ! Put the beaker into a water bath. ! ! ! ! ! ! ! ! ! ! ! Set the water to 60 celsius for 15 minutes and then remove the solution.
- 8. *STEP 4* ! Cool the solution with ice. ! ! ! ! ! ! ! ! ! ! ! This stops the DNA from breaking down.
- 9. *STEP 5* ! Blend the mixture. ! ! ! ! ! ! ! ! ! ! ! To open the cell walls and reelase the DNA.
- 10. *STEP 6* ! Cool the solution with ice. ! ! ! ! ! ! ! ! ! ! ! This stops the DNA from breaking down.
- 11. *STEP 6* ! Filter the mixture. ! ! ! ! ! ! ! ! ! ! ! Removing any big parts of cell and stop froth.
- 12. *STEP 6* ! Add ice cold alcohol to the solution. ! ! ! ! ! ! ! ! ! ! ! Do this slowly, and you should see the DNA separating from the cells as a white stringy substance, which can be removed with a glass rod.
- 13. DNA