Biology 1a03 theme 1 module 1 and 2. Eukaryotic cells: has nucleus that contain most of the genetic material (chromosomes, estimated 10 trillion cells in an adult human, appeared about 2 billion years ago, same genetic heritage but differ in function (muscle cells, skin cells, neurons) Prokaryotic cells: do not contain nucleus, 10 times eukaryotic cells (100 trillion, 2-3 percent of our body mass, provide essential functions throughout our physiological systems, most are not harmful. Streptococcus salivarius a population of microbiotic organisms, microorganisms, or microbes within our body. Staphylococcus haemolyticus: resides on our skin, harmless if it stays there, pathogenic if it get inside the body. Infection commonly leads to activation of the immune system. Bacteroides thetaiotaomicron: predominant intestinal bacteria, makes enzymes that are useful in the breakdown of plant materials that we ingest (oat fiber) Cell a membrane bound structure containing macromolecules.