Telomere Found at each end of a linear chromosome. The enzyme telomerase periodically extends this simple sequence to avoid losing the end sequence after each replication. A gene is defined as a nucleotide sequence in a DNA molecule that acts as a fundamental unit for the production of a RNA molecule. A chromosome is formed from a single enormously long DNA molecule that contains a series of many genes. Histones Major DNA-binding protein of eucaryotes.
Histones associate with DNA to form nucleosomes .
RNA Synthesis and Processing RNA polymerase Catalyzes DNA transcription. Intron sequences are removed by a reaction catalyzed by a large ribonucleoprotein complex called a splicesome . RNA polymerase III synthesizes tRNAs and the small 5s rRNA of the ribosome. Nucleolus Nucleoli are distinct intranuclear organelles that are formed around tandemly arranged rRNA genes, brought together from several chromosomes.