(4) The attachment of the pyrimidine base to the ribose phosphate ring is catalyzed by orotate phosphoribosyl transferase (OPRT) and PRPP provides the ribose-5-phosphate moeity. Hydrolysis of the PP i that is split off of the PRPP makes this reaction irreversible.
Red Squirrels shed their coats twice a year, switching between a thinner coat in summer and a darker, thicker winter coat. 6. Males may live in an area of up to 17 hectares of woodland... thatâs about the same size as 34 football pitches! 7.
1 If your horse is soaked to the skin, shivering or his ears are cold, heâs chilled and stressed; he needs a dry shelter and perhaps a blanket.  Long winter coats can hide early signs of weight loss, skin problems or lice, so check your horse daily, including his skin, eyes, feet and overall well-being.