Oxygen-Carrying Protein in the Blood: Hemoglobin. Hemoglobin is the protein that transports oxygen (O 2) in human blood from the lungs to the tissues of the body. Proteins are formed by the linking of amino acids into polypeptide chains.n hemoglobin, each subunit contains a heme group, which is displayed using the ball-and-stick representation in Figure 2. Each heme group contains an iron atom that is able to bind to one oxygen (O 2) molecule.
Decomposer: is an organism, usually a bacterium or fungus, that breaks down the cells of dead plants and animals into simpler substances. A fungus, such as this mushroom, is a decomposer of dead plants.
Decay is an essential life process, which helps to digest food and recycle materials. Bacteria and fungi are the main groups of decomposer. They release enzymes to break down compounds, so that they can absorb the nutrients. We can preserve our food, for example by freezing or canning, to remove the conditions needed for decay to occur.