Nucleic acid Flashcards
Definition of DNA
Genetic instructions for the development and function of living things
Structure of nucleosides, nucleotides, and nucleic acid
Nucleosides: sugar and base
Nucleotides: sugar, base and phosphate
Nucleic acid: many nucleotides
How can bases be classed?
Purines: Adenine and Guanine
Pyrimidines: Cytosine, Thymine and Uracil
Purine vs Pyrimidine nucleoside
Purine: N-glycosidic bond between carbon in sugar and nitrogen 9 in base
Pyrimidine: N-glycosidic bond between carbon in sugar and nitrogen 1 in base
What are the base pairs in DNA?
Adenine and Thymine (A-T/T-A) and Guanine and Cytosine (G-C/C-G)
How are bases joined?
Via nitrogen bonds (A-T has 2 and G-C has 3)
What is the sugar in DNA?
Deoxyribose
What is the sugar in RNA?
Ribose
Chargaff’s first rule
The amount of Guanine should be equal to Cytosine and the amount of Thymine should be equal to Adenine
Why do bases always bond with opposite hydrogens (5-3)?
Because sugar phosphate backbones run in opposite directions
Different types of DNA
- Single stranded DNA (ssDNA): circular shape found in some viruses
- Double stranded loop DNA (dsDNA): found in viruses, bacteria, mitochondria, chloroplasts
- Double stranded linear DNA (dsDNA): found in most eukaryotic cells
What is chromatin?
Double-stranded helical structure of DNA
What is a histone?
Basic protein
What is a chromatosome?
Histone and a nucleosome
What is a chromatid?
1 half of a chromosome
