Chloroplast and mitochondria are two organelles that have very similar characteristics and are present in plants and eukaryotic cells, respectively. Among the characteristics that both share are that both contain tRNA genes (which play a pivotal role in the inner organelle functions), both encode proteins that participate in electron transport pathways (since both organelles perform electron transport pathway for cellular respiration) and neither have all the genes necessary for function of the organelle are present (they need genomic DNA for this purpose). On the other hand, only mitochondrial genomes vary greatly in size from organism to organism, since chloroplast genome is very consistent, having 120 to 130 genes in total.
Transverse tubules (T tubules) are extensions of the sarcolemma that penetrate into the interior of the muscle transmitting electrical signals to the sarcoplasmic reticulum.
