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Understanding DNA: Structure, Function, and Importance

DNA, or deoxyribonucleic acid, is crucial for life, containing the genetic blueprint of organisms. Found in the nucleus of eukaryotic cells and in the cytoplasm of protists, DNA performs two main functions: it stores genetic information and contains instructions for building essential biological molecules, such as new cells. Structurally, DNA is characterized by its double helix shape, composed of a phosphate group, five-carbon sugar, and four nitrogenous bases: adenine, guanine, cytosine, and thymine. The sequence of these bases determines the genetic code, following base pairing rules that ensure stability and fidelity during genetic replication.

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Understanding DNA: Structure, Function, and Importance

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Presentation Transcript

  1. ?

  2. DNA!

  3. What is this DNA you speak of? • DNA stands for deoxyribonucleic acid - Found in nucleus of eukaryotic cells - Found in cytoplasm of protists

  4. Why should I care about DNA? • Two main functions 1.) Stores the genetic information of an organism.

  5. Why should I care about DNA? • Two main functions 2.) Contains instructions for how to construct important biological molecules. Example: Building new cells

  6. What is the structure of DNA? • Twisted ladder-like shape called a double helix Three main components 1.) Phosphate group 2.) 5 carbon sugar 3.) Nitrogenous base

  7. What is the structure of DNA? Three main components 1.) Phosphate group 2.) Five carbon sugar 3.) Nitrogenous base – Four types - Adenine - Guanine - Cytosine - Thymine DNA ‘backbone’ “Purines” “Pyrimidines”

  8. Nitrogenous Bases 1.) Purines - Adenine - Guanine 2.) Pyrimidines - Cytosine - Thymine The sequence of the nitrogenous bases in DNA determines the genetic code!

  9. Nitrogenous Bases • Base Pairing - Purines ALWAYS bond with pyrimidines! Chargaff’s Rules: - Adenine ALWAYS bonds with thymine A---T - Cytosine ALWAYS bonds with guanine C---G The amount of A = amount of T The amount of C = amount of G

  10. What is the structure of DNA?

  11. What is the structure of DNA? • A single strand of DNA has a 5’ and 3’ end. 3’ end: Terminates with an exposed –OH group on deoxyribose sugar 5’ end: Terminates with an exposed phosphate group

  12. What is the structure of DNA? • Antiparallel strands - Single strands of DNA run opposite to one another in the double-helix.

  13. What is the structure of DNA? • Antiparallel strands - Sequence of nucleotides is typically written in the 5’ to 3’ direction. 5’-ACTG-3’ Which is NOT the same as: 5’-GTCA-3’

  14. Can you build your own DNA model?

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