DNA Structure
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Lectures
PPT: DNA Replication Summary
Also see: http://www.sparknotes.com/biology/molecular/dnareplicationandrepair/section1.rhtml Practice Questions hereVideos/ Tutorials
Assignments/ResourcesInteractive Activities:
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- DNA is a polymer (large molecule) composed of small monomer subunits called nucleotides
Nucleic Acids are polymers of nucleotides
- Nucleotides are made up of a five-carbon sugar, a nitrogenous base, and an ion of phosphoric acid (PO43-)
- There are 2 basic types of nucleotides: DNA Nucleotide with a deoxyribose sugar, and the RNA Nucleotide with a ribose sugar, hence their names.
- Nitrogenous bases come in two forms: the purines (2 rings) and the pyrimidines (1 ring)
DNA NUCLEOTIDE: The Building Block of DNA
Who has DNA, and where?
- DNA is found in all living things:
b) floating free in the cytoplasm of Prokaryotic cells (Bacteria and Archaea)
- DNA could also be found inside mitochondria (mitochondrial DNA) and chloroplasts; after all, according to the Theory of Endosymbiosis, these organelles used to be free independent prokaryotic organisms that ended up living inside larger cells.
- The building block of DNA is the DNA nucleotide. (see below)
- The basic components of DNA are universal in all organisms. This means that the DNA of a bacterium and in you are both made up of the basic building blocks. The similarity in the genetic codes of organisms are due to common ancestry. The differences are based in the way (sequence) in which those building blocks are arranged.
Prokaryotic DNA
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Eukaryotic DNA
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Mitochondrial DNA
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DNA, Gene, and Chromosomes: How is DNA organized in Eukaryotic cells?
1. Read the section title “What Are Genes?”: Understanding Gene Testing
2. Describe the relationship between DNA, chromosomes, and genes. |
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DNA Replication
DNA replication is the process by which DNA makes a copy of itself during the S Phase of the cell cycle, before cell division. By doing so, a cell can divide and two cells will be produced each having identical DNA.