DNA Structure

Unit 5: DNA - The Molecule of Life

Page 3: Part 1 - What is DNA?

• DNA is located in the nucleus of cells.

Page 4: Characteristics of DNA

• DNA Composition: Contains deoxyribose (a 5-carbon sugar).

• Nucleic Acid: DNA is a nucleic acid, made up of nucleotides.

• Full Name: Stands for deoxyribonucleic acid, indicating its composition.

  • First fact: DNA contains a sugar;

  • Second fact: It is composed of nucleotide sequences.

Page 5: Part 2 - Structure of DNA

• Shape: DNA is shaped like a double helix.

  • Double: Composed of 2 strands of nucleotides.

  • Helix: Twisted structure resembling a ladder or staircase.

Page 6: Visualizing DNA

• When straightened, DNA resembles a ladder.

Page 7: Nucleotides

• DNA is made of nucleotides composed of:

  • Phosphate

  • Sugar

  • Nitrogen Bases (the building blocks of genetic code).

Page 8: The Nitrogen Bases

• Four different nitrogen bases in DNA:

  • Adenine (A)

  • Guanine (G)

  • Cytosine (C)

  • Thymine (T)

• Importance: These bases contribute to genetic diversity.

Page 10: DNA Structure Details

• Backbone of DNA:

  • Comprised of sugar and phosphate.

  • Backbones are referred to as the "5' side" and "3' side," indicating the orientation of the phosphate and sugar linkage.

  • The two strands are arranged in an antiparallel manner.

Page 11: Sugar-Phosphate Backbone

• Sides of the DNA ladder consist of:

  • Sugar: Deoxyribose molecules

  • Phosphates: Connecting the sugars.

  • Nitrogen Bases: Form the rungs (steps) of the ladder structure.

Page 12: Base-Pairing Rules

• Base-pairing specifics:

  • Adenine (A) pairs with Thymine (T) via 2 hydrogen bonds.

  • Cytosine (C) pairs with Guanine (G) via 3 hydrogen bonds.

• Importance of hydrogen bonds in holding base pairs together.