Part 1 - DNA Structure
Unit 3.2 - Structure and Function of DNA
DNA
- DNA = Deoxyribonucleic Acid
- DNA is the molecule that carries genetic information and passes it from one generation to the next.
- During DNA replication, DNA is copied so that every cell in an organism contains all its DNA.
DNA
Nucleotides
- DNA is made of monomers, or building blocks, called NUCLEOTIDES.
- Each nucleotide is made of 3 parts:
- Nitrogenous Base, Sugar, Phosphate Group
Nucleotides
Nitrogenous Bases
- There are four different kinds of bases separated into 2 groups:
Nitrogenous Bases
Chargaff's Rule
- When you look at ANY organism, the amount of adenine bases always nearly equals the amount of thymine.
- Same for guanine and cytosine.
- in other words, A bonds with T and G bonds with C
Chargaff's Rule
DNA Structure
- Using a technique called X-ray diffraction, a scientist named Rosalind Franklin discovered that DNA was not a single strand of nucleotides, but two strands twisted around each other in a DOUBLE HELIX.
- Using the clues about DNA structure from Rosalind Franklin’s research, Watson and Crick made a 3D model of DNA in 1953, showing its double-helix shape.
DNA Structure
Two Forms of DNA
1. CHROMATIN: DNA and proteins are densely packed in the nucleus
2. CHROMOSOMES: separated into 23 pairs of chromosomes, 46 total
Two Forms
Additional Resources
Science in Pajamas
Other Videos
Additional Resources
Science in Pajamas
History of DNA
DNA Structure
Other Videos
Amoeba Sisters - DNA, Chromosomes, Genes, and Traits: An Intro to Heredity
Don't Memorise - Structure of the Double Helix
Stately Clearly - What is DNA and How Does it Work?
TED-Ed - Rosalind Franklin: DNA's Unsung Hero
Other Videos
AS - DNA, Chromosomes, Genes, and Traits: An Intro to Heredity
AS - DNA, Chromosomes, Genes, and Traits
DM - Structure of the Double Helix
SC - What is DNA and How Does it Work?
SC - What is DNA?
TE - Rosalind Franklin: DNA's Unsung Hero
TE - Rosalind Franklin