nucleotide
Repeating unit of DNA or RNA made up of a sugar, a phosphate, and a base.
Chargaff's rules
Rules developed by Erwin Chargaff and his colleagues concerning the ratios of bases in DNA. A =T and G = C
transforming principle
Substance responsible for transformation. DNA is the transforming principle.
isotopes
Different forms of an element that have the same number of protons and electrons but differ in the number of neutrons in the nucleus.
X-ray diffraction
Method for analyzing the 3D shape and structure of chemical substances. Crystals of a substance are bombarded with X-rays, which hit the crystals, bounce off, and produce a diffraction pattern on a detector. The pattern of the spots produced on the detect
purine
double ring structure: guanine & adenine
pyrimidine
Single ring structure: Cytosine, Thymine, and Uracil
phosphate group
A phosphorus atom attached to four oxygen atoms; one of the three components of a nucleotide.
deoxyribonucleotide
Basic building block of DNA -- deoxyribose + phosphate + nitrogenous base.
ribonucleotide
Nucleotide containing ribose; present in RNA.
polynucleotide strand
Series of nucleotides linked together by phosphodiester bonds.
5? end
a phosphate is attached to this end
3? end
an OH group is attached to this end
antiparallel
Refers to a characteristic of the DNA double helix in which the two polynucleotide strands run in opposite directions.
complementary DNA strands
The relation between the two nucleotide strands of DNA in which each purine on one strand pairs with a specific pyrimidine on the opposite strand (A pairs with T, and G pairs with C).
transcription
DNA -> RNA
translation
messenger RNA > protein
replication
DNA > DNA
reverse transcription:
Going from RNA to DNA
RNA replication
Process in some viruses by which RNA is synthesized from an RNA template.
hairpin
Secondary structure formed when sequences of nucleotides on the same strand are complementary and pair with each other.
DNA methylation
Modification of DNA by the addition of methyl groups to certain positions on the bases.
5?-methylcytosine
Modified nucleotide, consisting of cytosine to which a methyl group has been added; predominate form of methylation in eukaryotic DNA.