(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.
In addition to increased fat stores, raccoons grow a thicker coat of fur to help insulate them in the winter. The fur traps body heat close to the skin and helps keep them warm both in their dens and outside. The animals in colder climates will grow thicker coats in proportion to the severity of the winter.