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.
Two Membranes. The mitochondria and nucleus are pouches whose walls are made of two membranes. A mitochondrion has an outer membrane and an inner membrane. A nucleus also has an outer membrane and an inner membrane. The two membranes of a mitochondrion serve different purposes. The inner membrane is where energy molecules are made. For the nucleus, its outer membrane is connected to the endoplasmic reticulum, another membranous organelle.