primosome is repetitive dna at the end of a eukaryotic chromosome.
repetitive dna at the end of a eukaryotic chromosome?
primosome
eukaryotes initiate dna replication at multiple points in the chromosome, so replication forks meet and terminate at many points in the chromosome. because eukaryotes have linear chromosomes, dna replication is unable to reach the very end of the chromosomes. due to this problem, dna is lost in each replication cycle from the end of the chromosome. telomeres are regions of repetitive dna close to the ends and help prevent loss of genes due to this shortening. shortening of the telomeres is a normal process in somatic cells. this shortens the telomeres of the daughter dna chromosome. as a result, cells can only divide a certain number of times before the dna loss prevents further division. (this is known as the hayflick limit.) within the germ cell line, which passes dna to the next generation, telomerase extends the repetitive sequences of the telomere region to prevent degradation. telomerase can become mistakenly active in somatic cells, sometimes leading to cancer formation. increased telomerase activity is one of the hallmarks of cancer.
dna replication
simple eukaryotes such as "c. elegans" and fruit fly, have more non-repetitive dna than repetitive dna, while the genomes of more complex eukaryotes tend to be composed largely of repetitive dna. in some plants and amphibians, the proportion of repetitive dna is more than 80%. similarly, only 2% of the human genome codes for proteins. 





















































section::::eukaryotic genomes.:noncoding sequences.





















































noncoding sequences include introns, sequences for non-coding rnas, regulatory regions, and repetitive dna. noncoding sequences make up 98% of the human genome. there are two categories of repetitive dna in the genome: tandem repeats and interspersed repeats.





















































section::::eukaryotic genomes.:noncoding sequences.:tandem repeats.
genome