For other uses, see Transition. Definition of transitions and transversions. In genetics, a transition is a point mutation that changes a purine nucleotide to another purine (A â G) or a pyrimidine nucleotide to another pyrimidine (C â T).Approximately two out of three single nucleotide polymorphisms (SNPs) are transitions.Transitions can be caused by oxidative deamination and tautomerization.or other uses, see Transition. Definition of transitions and transversions. In genetics, a transition is a point mutation that changes a purine nucleotide to another purine (A â G) or a pyrimidine nucleotide to another pyrimidine (C â T).
fringe benefit - an incidental benefit awarded for certain types of employment (especially if it is regarded as a right); a limousine is one of the fringe benefits of the job. perk, perquisite. benefit - financial assistance in time of need.
Tax-free employee fringe benefits include: 1  health insurance (up to certain dollar amounts) 2  accident insurance. 3  Health Savings Accounts.  dependent care 1  assistance. educational assistance.  group term life insurance coverageâlimits apply based on the policy value.