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DNA Structure & Replication

DNA Structure & Replication. Sugar phosphate backbone. Deoxyribose sugar + Phosphate backbone; Make up what is known as the “backbone” of the DNA Molecule. One strand goes one Direction, the other strand Goes the other direction. Sugar phosphate backbone. Deoxyribose sugar +

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DNA Structure & Replication

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  1. DNA Structure & Replication

  2. Sugar phosphate backbone Deoxyribose sugar + Phosphate backbone; Make up what is known as the “backbone” of the DNA Molecule. One strand goes one Direction, the other strand Goes the other direction.

  3. Sugar phosphate backbone Deoxyribose sugar + Phosphate backbone; Make up what is known as the “backbone” of the DNA Molecule. One strand goes one Direction, the other strand Goes the other direction.

  4. Chargaff’s Rules • Dr. Erwin Chargaff discovered (around 1950) that the percentages of Adenine and Thymine; as well as Guanine and Cytosine, were consistent in DNA. • The observation that [A] = [T] and [C] = [G] are known as Chargaff’s Rules

  5. Watson and Crick • Francis Crick and James Watson were attempting to determine the structure of DNA. • Rosalind Franklin used X-Ray diffraction to get information about DNA structure. • Watson and Crick used Franklin’s x-ray evidence to determine that DNA was a Double-Helix molecular structure.

  6. Rosalind Franklin • Francis Crick and James Watson were attempting to determine the structure of DNA. • Rosalind Franklin used X-Ray diffraction to get information about DNA structure. • Watson and Crick used Franklin’s x-ray evidence to determine that DNA was a Double-Helix molecular structure.

  7. Double Helix

  8. Hydrogen Bonding • Slight difference in electric charge determines how molecules are attracted to each other. • DNA bases are attracted to each other via. Hydrogen bonding.

  9. DNA is able to make copies of itself. • This process is known as REPLICATION • Replica (n): an exact reproduction, a copy exact in all details •  Fun Fact:“Blade Runner” 1982 Science-Fiction movie where humans are made into replicas (replicants)

  10. Why replicate the DNA? • Remember Mitosis? Cell division? If one cell is going to become two, then one DNA molecule has to become two as well.

  11. Chromosome formation

  12. Key Words to remember • Histone – Protein around which DNA strands coil. • Nucleosome – A “bead-like” structure that is made of coils of DNA-wrapped histones • Chromatin – fiber made of tightly-wound nucleosomes. Chromatin fibers are what make up chromosomes. • Chromosome – An organized structure of DNA and protein found in cells. • Number of chromosomes in a cell is different in different organisms. (Humans have 23) • Prokaryote = bacteria (are a group of organisms whose cells lack a cell nucleus ) • Eukaryote = is an organism whose cells contain complex structures enclosed within membranes. (cells have a nucleus)

  13. If you knew beforehand what your baby would be, what would you do? • Is it right to terminate a pregnancy based on genetic information? • Is it wrong to change somebody’s genes? • Is it wrong to clone a human?

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