2.1.3: Nucleotides & ATP Flashcards
DNA is a polymer of
nucleotides
The main components of a nucleotide are:
- Phosphate group
- Pentose monosaccharide –> deoxyribose for DNA, ribose for RNA
- Nitrogenous base
Nucleotides join together by ____________ reactions
condensation
Adenine base pairs with
thymine
Thymine base pairs with
adenine
Cytosine base pairs with
guanine
Guanine base pairs with
cytosine
Molecules in the DNA double helix are:
- Complementary
- Antiparallel
- Run in 3’ to 5’, and 5’ to 3’
Structure of DNA
- Double helix of polynucleotide strands
* Hydrogen bonds between complementary bases
What are the two types of nitrogenous bases?
- Purines
* Pyrimidines
Purine
• Larger nitrogenous base
• Double ring
e.g. adenine, guanine
Pyrimidine
• Smaller nitrogenous base
• Single ring
e.g. cytosine, thymine
When cytosine pairs with guanine, they are held together by how many hydrogen bonds?
3
When adenine pairs with thymine they are held together by how many hydrogen bonds?
2
How DNA differs from RNA
- DNA double-stranded; RNA single-stranded
- RNA contains uracil; DNA contains thymine
- Pentose sugar: in DNA = deoxyribose, in RNA = ribose
RNA
Ribonucleic acid
• Molecules involved in transfer and copying of genetic information from DNA.
• Polynucleotides consist of ribose sugar + U, C, A or G.