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1 Introduction

Figure 1.1: Cell Structure and Components.

in DNA gets translated into ribonucleic acid (RNA) and then proteins by ribosomes, and

the proteins are distributed to their specific locations in the cell via the endoplasmic

reticulum (ER) and the Golgi complex. Some proteins are structural, creating the dif-

ferent structures in the cell and human body. Most of the proteins are enzymes, i. e.

they catalyze reactions and thus either construct needed compounds in the cell or break

them down to generate energy (anabolism or catabolism, respectively). Some catalysts

are also part of signal transduction pathways and thus part of cell communication.

The place where energy is generated is in the mitochondria. Lysosomes, vacuoles,

and peroxisomes either ingest fuel or break down toxic compounds. The cytoskeleton is

made from structural protein fibers and holds the shape of the cell and act as “roads”

for organelle and other transport throughout the cell. The cell membrane is the barrier

that allows for homeostasis. It contains a lot of proteins which are mostly channels that

allow for very specific and regulated transport in and out of the cell. Other transport

across the membranes operates via vesicles that are endocytosed or exocytosed. Other

transmembrane proteins are designed to transfer signals. Some proteins on the outside

of the cell membrane act as a “marker”, or recognition element, for the cell, and some

cause the cell to adhere to other cells or the extracellular matrix (ECM). ECM consists of

fibers (collagen, elastin) and an amorphous matrix (proteoglycans, cell-binding adhesive