An alkene is a hydrocarbon containing double bonds. An alkyne is a hydrocarbon containing triple bonds. Ethene, C 2 H 4, is an example of an unsaturated hydrocarbon with a double bond.ethyne (acetylene), C 2 H 2 is an example of an unsaturated hydrocarbon with a triple bond.thene, C 2 H 4, is an example of an unsaturated hydrocarbon with a double bond. ethyne (acetylene), C 2 H 2 is an example of an unsaturated hydrocarbon with a triple bond.
Mitochondria and chloroplasts are also surrounded by membranes, but they have unusual membrane structures â specifically, each of these organelles has two surrounding membranes instead of just one. The outer membrane of mitochondria and chloroplasts has pores that allow small molecules to pass easily.
Individual organelles are usually separately enclosed within their own lipid bilayers. The name organelle comes from the idea that these structures are to cells what an organ is to the body (hence the name organelle, the suffix-elle being a diminutive).evertheless, the use of organelle to refer to non-membrane bound structures such as ribosomes is common. This has led some texts to delineate between membrane-bound and non-membrane bound organelles.