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Title: DNA Structure and Replication
Description: These notes briefly discuss the mechanisms by which DNA replicates itself, as well as the basic structure of DNA. These notes were taken for an introductory college biology course.
Description: These notes briefly discuss the mechanisms by which DNA replicates itself, as well as the basic structure of DNA. These notes were taken for an introductory college biology course.
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DNA Structure and Replication
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DNA is the basis of genetics, and a macromolecule (nucleic acid)
All living things have DNA --> but viruses do not have DNA, just RNA
Made up of nucleotides (monomers)
o Phosphate group
o Sugar (deoxyribose)
o Nitrogenous bases --> A, T, C, G
DNA is a double stranded molecule, thus it is very stable
o Thought of as a ladder --> double helix
▪ Phosphates and sugars form a backbone rail
▪ Complementary bases form the rungs
• Complementary base pairing
• A always pairs with T
• G always pairs with G
Hydrogen bonds hold the DNA strands together
o Individually weak, but collectively very strong
Discovery of DNA
o James Watson and Francis Crick in 1953 discovered the double helix
▪ Used the work of Rosalind Franklin and Maurice Wilkins
DNA, Chromosomes, and Genomes
o In eukaryotic cells, DNA in nucleus; in prokaryotic cells, DNA in cytoplasm
o DNA packaged in chromosomes
▪ DNA wrapped tightly around proteins
▪ Individuals of the same species usually have an equal number of chromosomes
o A genome is an organism's complete set of DNA
▪ Not all genomes are equal in size
DNA Replication (Semi-Conservative)
o Begins with one molecule of DNA
o Split the hydrogen bonds in order to separate (unzip) the two strands
o Add complementary bases
o In the end, you get two DNA molecules identical to the original
o The old strand is the template
o Use of enzymes to break the H bonds and add nucleotides
Mutations
o DNA polymerase proofreads the new strands as it adds new nucleotides
o Caused by errors in DNA replication, UV radiation, chemicals, etc
Title: DNA Structure and Replication
Description: These notes briefly discuss the mechanisms by which DNA replicates itself, as well as the basic structure of DNA. These notes were taken for an introductory college biology course.
Description: These notes briefly discuss the mechanisms by which DNA replicates itself, as well as the basic structure of DNA. These notes were taken for an introductory college biology course.