Are some cell membrane proteins receptors?
Some proteins in the plasma membrane function as receptors for special communicating substances in our body such as hormones and neurotransmitters. Typically, receptors will interact with only one specific molecule and ignore all other substances. In a way, then, these proteins can also be viewed as being involved in transport processes; however what’s being transported isn’t ions or molecules but information.
What is DNA?
DNA (deoxyribonucleic acid) is found in almost all the cells of our body. Within those cells DNA is mostly housed in the nucleus, while a much smaller amount of DNA can be found in mitochondria. DNA contains the instructions (blueprints) for putting specific amino acids together to make proteins. You see, the human body contains thousands of different proteins, all of which our cells have to build using amino acids as the building blocks. Without the DNA’s instructions, our cells would not know how to perform such a task.
DNA is long and strand like and organized into large structures called chromosomes. Normally we have twenty-three pairs of chromosomes in our nuclei. If we were to take a chromosome and find the end points of the DNA, we could theoretically straighten it out like thread from a spool. If we did so we would find thousands of small stretches called genes on the DNA. We have thousands of genes, which contain the actual instructions for building specific proteins.
To oversimplify one of the most amazing events in nature, when a cell wants to make a specific protein, it makes a copy of its DNA gene in the form of RNA (ribonucleic acid). You see, DNA and RNA is virtually the same thing. However, one of the most important differences is that the RNA can leave the nucleus and travel to where proteins are made in cells, the ribosomes. At this point both the blueprint instructions (RNA) and the amino acids are available and it’s the job of the ribosomes to link (bond) amino acids together in the correct sequence.
What does “tissue” mean, and do our different body tissues work as a team?
Humans are truly a complex array of organs and other tissues designed to support the basic functions and vitality of our body. We are able to process inhaled air and ingested food and regulate body content. We selectively take what we need from the external environment and eliminate what we do not need. We think, move about, and reproduce. Many of these operations occur without us even being aware.
One other term we should be familiar with is tissue. Quite simply, tissue is comprised of similar or cooperating cells performing similar or cooperative tasks. These cells may be grouped together to form fascinating tissues such as bone, skin, muscle, nerves, and blood.
