DNA Structure Flashcards
DNA (deoxyribonucleic acid)
a double-stranded nucleic acid molecule that governs the processes of heredity in the cells of all organisms. It is composed of nucleotides containing a phosphate group, nitrogenous base, and deoxyribose
Adenine (A)
a nitrogenous base of the purine group; complementary base pairs with thymine
Guanine (G)
a nitrogenous base of the purine group; complementary base pairs with cytosine
Cytosine (C)
a nitrogenous base of the pyrimidine group; complementary base pairs with guanine
Thymine (T)
nitrogenous base of the pyrimidine group; complementary base pairs with guanine
RNA (ribonucleic acid)
a short, single strand composed of nucleotides with a nitrogen base, ribose sugar, and phosphate group; nitrogen bases include adenine, guanine cytosine, and uracil; has a role in protein synthesis
Uracil (U)
a nitrogenous base found only in RNA, not DNA; replaces thymine when paired to adenine
Chargaff’s rule
in any sample of DNA, there is a constant relationship in which the amount of adenine is always approximately equal to the amount of thymine, and the amount of cytosine is always approximately equal to the amount of guanine
Watson and Crick
credited with co-discovery of the structure of DNA; received the Nobel Prize for their work
Double helix
spiral ladder shape of the DNA molecule, made up of two long strands of nucleotides bound together and twisted
Deoxyribose sugar
a ring-shaped sugar; has one less oxygen than ribose sugar
Phosphate
an inorganic phosphate group (PO43—)
Nitrogen base
an organic molecule containing nitrogen; two types present in DNA: double-ringed purines (A and G) and single-ringed pyrimidines (C and T)
Complementary base pairs
refers to the hydrogen-bonded, nitrogenous base pairs of A and T, and of C and G in the DNA double helix
Antiparallel
describes the property by which the 5’ to 3’ phosphate bridges run in opposite directions on each strand of nucleotides in a double-stranded DNA molecule
