Answer:
a) the pyrimidine ring is assembled before being bonded to the ribose phosphate, whereas the purine ring is bonded to the ribose phosphate as it is formed
Explanation:
There are two ways for the synthesis of purines and pyrimidines:
- de novo synthesis-from basic simple units
- "recycling" synthesis-reuse of metabolites
Purines are synthesized directly on ribose sugar, in segments.
Pyrimidines are attached to the ribose after the synthesis of the base.
Answer: A) an abnormally large number of collagen fibers and relatively few blood vessels at the repair site
Explanation:
The scar tissues are the thick fibrous tissues typically the collagen fiber that have the role of replacement of healthy tissues after the injury has taken place to initiate the recovery process.
The scars are produced as a biological process at the site of wound repair on the skin. The scar develops on the superficial surface of the skin due to external injury. It is a natural healing process.
There are few blood vessels that can be found at the site of repair along with the collagen fibers.
Aluminium, an adjuvant.
MF59 (squalene oil), an adjuvant.
Thiomersal, also called Thimerosal.
Chemical (mutagens)
usually either mimic the structure of nucleotides and are inserted in DNA or either cause
chemical changes (such as alkylation) in nucleotides hence causing mismatching during replication.
Radiation, on the other hand, (due to its high energy) causes double-strand breaks in DNA causing an
increased likelihood of mutations during the repair of the DNA by cell
mechanisms.
