The Y chromosome is metacentric and the X chromosome is variable, ranging from nearly metacentric to acrocentric in five specimens studied.
12.
A Robertsonian translocation results when the long arms of two acrocentric chromosomes fuse at the centromere and the two short arms are lost.
13.
In some cases, a metacentric chromosome is formed by balanced translocation : the fusion of two acrocentric chromosomes to form one metacentric chromosome.
14.
The karyotype of the ring-tailed lemur has 56 chromosomes, of which four are acrocentric ( the short arm is hardly observable ).
15.
In an acrocentric chromosome the p arm contains genetic material including repeated sequences such as nucleolar organizing regions, and can be translocated without significant harm, as in a balanced Robertsonian translocation.
16.
The extant, it is apparent that the evolutionary sequence is a reduction of two acrocentric chromosomes in the great apes to one metacentric chromosome in humans ( see Karyotype # Aneuploidy ).
17.
Mouflon and domestic sheep have 54 chromosomes, with three pairs ( 1 + 3, 2 + 8, 5 + 11 ) of ancestral acrocentric chromosomes joined to form bi-armed chromosomes.
18.
Common Robertsonian translocations are confined to the acrocentric chromosomes 13, 14, 15, 21 and 22, because the short arms of these chromosomes encode for rRNA which is present in multiple copies.
19.
In contrast, a sample from south of the Gulf had 2n = 54, FN = 60, including 23 pairs of acrocentrics and four pairs of metacentrics ( with two equally long arms ).
20.
Before the discovery of " Dichroplus silveiraguidoi " in Uruguay in 1956, " Dactylotum bicolor " had the lowest known number of chromosomes among grasshopper species, with seventeen acrocentric chromosomes.
