Acn dna notes

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DNA

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Acn dna notes

  1. 1. DNA (Deoxyribonucleic Acid)
  2. 2. A HISTORY OF DNA • Discovery of the DNA double helix A. Frederick Griffith – Discovers that a factor in diseased bacteria can transform harmless bacteria into deadly bacteria (1928) B. Rosalind Franklin - X-ray photo of DNA. (1952) C. Watson and Crick - described the DNA molecule from Franklin’s X-ray. (1953)
  3. 3. Watson & Crick proposed… •DNA had specific pairing between the nitrogen bases: ADENINE – THYMINE CYTOSINE - GUANINE •DNA was made of 2 long stands of nucleotides arranged in a specific way called the “Complementary Rule”
  4. 4. DNA Double Helix “Rungs of ladder” Nitrogenous Base (A,T,G or C) “Legs of ladder” Phosphate & Sugar Backbone
  5. 5. Genetic material of cells… • GENES – units of genetic material that CODES FOR A SPECIFIC TRAIT • Called NUCLEIC ACIDS • DNA is made up of repeating molecules called NUCLEOTIDES
  6. 6. DNA Nucleotide Phosphate Group O O=P-O O 5 CH2 O N C 1 C4 Sugar (deoxyribose) C3 C2 Nitrogenous base (A, G, C, or T)
  7. 7. DNA Double Helix 5 O 3 3 P 5 O O C G 1 P 5 3 2 4 4 2 3 P 1 T 5 A P 3 O O P 5 O 3 5 P
  8. 8. Nitrogenous Bases • PURINES 1. Adenine (A) 2. Guanine (G) A or G • PYRIMIDINES 3. Thymine (T) 4. Cytosine (C) T or C
  9. 9. Chargaff’s Rule • Adenine must pair with Thymine • Guanine must pair with Cytosine • Their amounts in a given DNA molecule will be about the same. same T A G C
  10. 10. BASE-PAIRINGS H-bonds G C T A
  11. 11. DNA is wrapped tightly around histones and coiled tightly to form chromosomes
  12. 12. Functions Genetic Diversity… • Different arrangements of NUCLEOTIDES in a nucleic acid (DNA) provides the key to DIVERSITY among living organisms.
  13. 13. The Code of Life… • The “code” of the chromosome is the SPECIFIC ORDER that bases occur. A T C G T A T G C G G…
  14. 14. DNA Replication • DNA must be copied • The DNA molecule produces 2 IDENTICAL new complementary strands following the rules of base pairing: A-T, G-C •Each strand of the original DNA serves as a template for the new strand
  15. 15. DNA Replication • Semi-conservative Model: 1. Watson and Crick showed: the two strands of the parental molecule separate, and each functions as a template for synthesis of a new complementary strand. . Parental DNA DNA Template New DNA
  16. 16. (1961) Watson & Crick proposed… • …DNA controlled cell function by serving as a template for PROTEIN structure. • 3 Nucleotides = a triplet or CODON (which code for a specific AMINO ACID) • AMINO ACIDS are the building blocks of proteins.
  17. 17. DNA Transcription • DNA can “unzip” itself and RNA nucleotides match up to the DNA strand. • Both DNA & RNA are formed from NUCLEOTIDES and are called NUCLEIC acids.
  18. 18. DNA Translation • The cell uses information from “messenger” RNA to produce proteins
  19. 19. AMAZING DNA FACTS… • DNA from a single human cell extends in a single thread for almost 2 meters long!!! • It contains information equal to some 600,000 printed pages of 500 words each!!! (a library of about 1,000 books)
  20. 20. RNA
  21. 21. Subdivisions • mRNA – messenger RNA • rRNA - ribosomal RNA • tRNA – transfer RNA
  22. 22. Thank you
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