DNA Structure - Part 1
Learning Objectives Describe the overall structure of the DNA molecule
Chromosomes and DNA Chromosomes are made up of DNA and protein. A gene is a sequence of DNA found in chromosomes.
DeoxyriboNucleic Acid All life on earth uses DNA to carry its genetic code or blueprint.
DNA DNA is often called the blueprint of life DNA contains the instructions for making proteins
Watson and Crick’s Model With the help of Rosalind Franklin’s X-ray diffraction image, Watson and Crick discovered the structure of DNA
DNA Double Helix Structure YouTube Video DNA Double Helix Structure
The Shape of the DNA Molecule DNA is a very long polymer The basic shape is like a twisted ladder called a double helix The DNA double helix has two strands twisted together
Structure of DNA The DNA backbone is made of alternating phosphates and deoxyribose sugar The rungs are nitrogenase bases Bases = Deoxyribose Sugar = Phosphate
One Strand of DNA DNA is made of monomers called nucleotides
Nucleotide Phosphate Nitrogenous Base Deoxyribose Sugar One deoxyribose sugar, one phosphate and one nitrogenous base make a nucleotide.
YouTube Video DNA Structure
DNA Structure Amoeba Sisters YouTube Video DNA Structure Amoeba Sisters
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DNA Structure - Part 2
Learning Objectives Explain how bonds are formed between nitrogenous bases
Nucleotide Phosphate Nitrogenous Base Deoxyribose Sugar One deoxyribose sugar, one phosphate and one nitrogenous base make a nucleotide.
Nitrogenous Bases DNA has two different types of nitrogenous bases - pyrimidines and purines.
Purines and Pyrimidines Cytosine (C) Thymine (T) Purines: Adenine (A) Guanine (G)
Chargaff’s Rule = = # of # of Chargaff’s Rule - In DNA, the amount of G is equal to C and the amount of A is equal to T
Base Pairing Adenine is paired to Thymine and Guanine is paired to Cytosine
Two Strands of DNA DNA has two strands of DNA that fit together like a zipper The teeth of the zipper are the nitrogenous bases How do the two strands stick together?
Hydrogen Bonds Guanine Cytosine Adenine Thymine The nitrogenous bases are attracted to each other because of hydrogen bonds.
Why Study DNA? Medical benefits such as cures for diseases Better food crops Central importance to all life on earth
What is DNA and How Does it Work? YouTube Video What is DNA and How Does it Work?
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DNA Facts Each cell has about 2 meters of DNA The average human has 75 trillion cells The average human has enough DNA to go from the earth to the sun more than 400 times. The earth is 150 billion meters from the sun
Summary of DNA Structure Nucleotide: deoxyribose sugar, phosphate and nitrogenous base Adenine - Thymine Guanine - Cytosine A - T G - C Hydrogen bonds hold DNA strands together Nucleotides joined together make up a strand of DNA.