The Structure of DNA

DNA: The Genetic Material

• Mendel (1800’s) showed that traits are passed from parents to offspring

DNA: The Genetic Material

• The instructions for inherited traits are called genes– 1950’s – scientists

determined that genes were made of DNA

• DNA: primary material that causes recognizable, inheritable characteristics in related groups of organisms

Discovering DNA’s Structure

• Rosalind Franklin used x-ray diffraction to determine the structure of DNA– Images suggested DNA resembled a tightly coiled

helix composed of two chains of nucleotides

Discovering DNA’s Structure

• Watson and Crick constructed a 3D model of DNA– Used information from

experiments conducted by other scientists

– Determined the structure of DNA was a double helix made of two strands of nucleotides

– Won Nobel Prize in 1962

The Shape of DNA

• A DNA molecule looks like a spiral staircase and is composed of two parallel strands of linked subunits called nucleotides

The Shape of DNA

• A nucleotide has 3 parts: phosphate group, sugar (deoxyribose), and a base

• The phosphate and sugar link together to form the back bone

• The bases pair together to connect the two strands

DNA Assignments

• DNA – The Double Helix practice sheet

• Build a 3D DNA Model

• Build a DNA Molecule Online Activity: http://learn.genetics.utah.edu/content/begin/dna/builddna/

(see my webpage for link)