There are three types of genetic disorders: 1  Single-gene disorders, where a mutation affects one gene. Sickle cell anemia is an example. 2  Chromosomal disorders, where chromosomes (or parts of chromosomes) are missing or changed. Chromosomes are the structures that hold our genes. 3  Complex disorders, where there are mutations in two or more genes.
OSI model. The Open Systems Interconnection model (OSI model) is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system without regard to their underlying internal structure and technology. Its goal is the interoperability of diverse communication systems with standard protocols.
OSI Reference Model The Open Systems Interconnection (OSI) model was developed by the International Organization for Standardization (ISO), and formalized in 1984. It provided the first framework governing how information should be sent across a network. The OSI model consists of seven layers, each corresponding to a specific network function: 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data-link 1 Physical Note that the bottom layer is Layer 1. Various mnemonics make it easier to remember the order of the OSI modelâs layers: 7 Application All Away 6 Presentation People Pizza