A netlike array of protein filaments that maintains the shape of the nucleus.
Capsid
The protein coat of a virus that encloses the nucleic acid.
Limit of resolution
The minimum distance between which two objects can be discriminated.
Electron configuration
The distribution of electrons in an atom's electron shells.
Testcross
Breeding of an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype.
Telomere
The protective structure at each end of a eukaryotic chromosome. Specifically, the tandemly repetitive DNA at the end of the chromosome's DNA molecule. See also repetitive DNA.
Secondary structure
The localized, repetitive coiling or folding of the polypeptide backbone of a protein due to hydrogen bond formation between peptide linkages.
Sexual reproduction
A type of reproduction in which the offspring have unique combinations of genes inherited from the gametes of the two parents.
Carrier
An individual who is heterozygous with one potentially harmful recessive allele
Operator
In prokaryotic DNA, a sequence of nucleotides near the start of an operon to which an active repressor can attach. The binding of the repressor prevents RNA polymerase from attaching to the promoter and transcribing the genes of the operon.