Structure of DNA Flashcards
What are the 4 criteria that make DNA the hereditary material?
Information: contains the instructions to make an organism
Replication: able to be copied
Transmission: must be able to be passed from parent to offspring
Variation: can be changed to account for phenotypic variation
What are the 5 nitrogenous bases? Which ones are purines and which ones are pyrimidines?
Adenine, guanine, cytosine, thymine, and uracil. Adenine and guanine are purines, cytosine, thymine, and uracil are pyrimidines.
What are the 3 components of a nucleotide?
Phosphate backbone, pentose sugar, nitrogenous base
What is Chargaff’s rule?
Amount of A = T, amount of C = G
What bond linked nucleotides together
Phosphodiester bonds
How does complementary base pairing occur?
Hydrogen bonding. A and T pair with 2 hydrogen bonds, G and C pair with 3 hydrogen bonds
What is the structure of DNA?
Double helix
What is the directionality of the strands in relation to each other?
They run antiparallel, one runs 5’ to 3’ and the other runs 3’ to 5’
How are bases, nucleosides, and nucleotides named?
Base: just the name of the base, adenine, thymine, guanine, cytosine, or uracil
Nucleoside: base + sugar. Named as adenosine, guanosine, thymidine, cytidine, or uridine. Add a deoxy in front if the sugar is deoxyribose
Nucleotide: base + sugar + phosphates. adenosine monophosphate, guanosine diphosphate, deoxyuridine triphosphate, etc
What provides the energy to link nucleotides together?
Cleaving off two of the phosphates in a triphosphate nucleotide
Where on the sugar ring is the next nucleotide attached?
The 3’ hydroxyl wil attach to the 5’ phosphate
Why is a purine always paired with a pyrimidine?
Keeps the diameter of DNA constant at 2nm wide
How many nucleotides are in each turn of the double helix? How long is a turn?
10.5 nucleotides, 3.4 nm
What is the difference between the major groove and the minor groove?
The major groove is more accessible and is where proteins will bind
