The Endomembrane System
The endomembrane system (endo = within) is a group of membranes and organelles in eukaryotic cells that work together to modify, package, and transport lipids and proteins. It includes the nuclear envelope,…
Flagella and Cilia
Flagella (singular = flagellum) are long, hair-like structures that extend from the plasma membrane and are used to move an entire cell, (for example, sperm, Euglena). When present, the cell has…
The Cytoplasm
The cytoplasm comprises the contents of a cell between the plasma membrane and the nuclear envelope (a structure to be discussed shortly). It is made up of organelles suspended in…
The Plasma Membrane
Like prokaryotes, eukaryotic cells have a plasma membrane (Figure 3.9) made up of a phospholipid bilayer with embedded proteins that separates the internal contents of the cell from its surrounding environment. A…
Eukaryotic Cells
At this point, it should be clear that eukaryotic cells have a more complex structure than do prokaryotic cells. Organelles allow for various functions to occur in the cell at…
Comparing Prokaryotic and Eukaryotic Cells
Cells fall into one of two broad categories: prokaryotic and eukaryotic. The predominantly single-celled organisms of the domains Bacteria and Archaea are classified as prokaryotes (pro– = before; –karyon– =…
Microscopy
Cells vary in size. With few exceptions, individual cells are too small to be seen with the naked eye, so scientists use microscopes to study them. A microscope is an instrument that…
Introduction to Cell Structure and Function
Figure 3.1 (a) Nasal sinus cells (viewed with a light microscope), (b) onion cells (viewed with a light microscope), and (c) Vibrio tasmaniensis bacterial cells (viewed using a scanning electron…
DNA Double-Helical Structure
DNA has a double-helical structure. It is composed of two strands, or polymers, of nucleotides. The strands are formed with bonds between phosphate and sugar groups of adjacent nucleotides. The…
Nucleic Acids
Nucleic acids are key macromolecules in the continuity of life. They carry the genetic blueprint of a cell and carry instructions for the functioning of the cell. The two main types…
