A (adenine): In genetics, A stands for adenine, one member of the A-T (adenine-thymine) base pair in DNA. The other base pair in DNA is G-C (guanine-cytosine).
Each base pair forms a “rung of the DNA ladder.” A DNA nucleotide is made of a molecule of sugar, a molecule of phosphoric acid, and a molecule called a base. The bases are the “letters” that spell out the genetic code. In DNA, the code letters are A, T, G, and C, which stand for the chemicals adenine, thymine, guanine, and cytosine, respectively. In DNA base pairing, adenine always pairs with thymine, and guanine always pairs with cytosine.
Adenine is also one of the bases in RNA. There it always pairs with uracil (U). The base pairs in RNA are therefore A-U and G-C.
- Abortive polio
Abortive polio: Abortive polio is a minor illness. It accounts for 80-90% of clinically apparent cases of polio infection, chiefly in young children. It does not involve the CNS. The usual symptoms are slight fever, malaise, headache, sore throat and vomiting which hit 3-5 days after exposure to the polio virus. Full recovery occurs in […]
- Abortion, recurrent
Abortion, recurrent: The occurrence of 3 or more miscarriages (which are medically termed “spontaneous abortions”) with no intervening pregnancies. Recurrent abortion (or, as it is sometimes called, habitual abortion) is a form of infertility. It may be due to chromosome abnormalities.
Abraham-man: Also abram-man. One of a class of beggars who once wandered over England after the dissolution of the religious houses in the 16th century, pretending lunacy for the sake of obtaining alms. To sham Abraham (or sham Abram) now means to feign sickness, to fake illness.
Abortive: Tending to cut short the course of a disease, as in abortive polio (polio cut short).
Abrin: A phytotoxin (plant poison) found in the seeds of a plant called the rosary pea or jequirity pea. These seeds are red with a black spot covering one end. Abrin is similar to ricin, a toxin that is also found in the seeds of a plant (the castor bean plant), although abrin is much […]