Cell Wall & Membrane

• The cell membrane, or plasma membrane, is a layered structure that surrounds the cell and provides a barrier between the environment outside the cell and that inside the cell. The membrane does allow materials to pass through, but its biochemical makeup functions as a selective barrier. The cell wall is a more porous, rigid structure outside the membrane. There are passageways, called plasmodesmata, connecting cell to cell through the wall and membrane.
  
  

Nucleus

• The nucleus in a microalgal cell is, in effect, the command center. A key constituent of the cell's nucleus is DNA. Deoxyribonucleic acid -- the full name for the acronym DNA -- is the genetic material of the cell. It contains the biological source code that orchestrates many complex cell functions. The nucleus is surrounded by a membrane called the nuclear envelope.
  
  

Chloroplasts

• Algae, like so-called higher plants, are remarkable in their ability to manufacture their own food through the process of photosynthesis. The algal cell organelle that makes this possible is the chloroplast. The chloroplast has an intricate internal structure. At the core of it is the chlorophyll molecule. Through a complex series of biochemical reactions, chlorophyll uses carbon dioxide from the atmosphere and light energy to manufacture the sugar glucose.
  
  

Endoplasmic Reticulum

• The endoplasmic reticulum, or ER, of the cell is an intricate internal membrane structure. A crumpled plastic bag with all of its folds and wrinkles -- and the small space of the inside of the bag all compressed -- is a fair analogy of the ER. This organelle's function is manufacturing and transporting vital biochemical substances, like proteins, within the cell. Ribosomes are small organelles attached to some of the ER and are active in protein synthesis.
  
  

Golgi Apparatus

• Oftentimes, good analogies for living systems can be found in the workings of the industrial age. The cell's Golgi apparatus exemplifies this. As the University of Florida's Molecular Expressions website points out, the Golgi apparatus is like the shipping department of the cell. The Golgi apparatus repackages and effectively ships proteins and other materials manufactured in the ER out to other parts of the cell.
  
  

Mitochondria

• If the Golgi apparatus is comparable to the shipping department, the mitochondria are analogous to a power generating plant. It is in the microalgae cells' mitochondria that the process of respiration, using oxygen, generates the compound adenosine triphosphate, or ATP. ATP is the metabolic currency of the cell, providing the chemical energy necessary to carry out vital cellular processes.
  
  

Vacuole

• The vacuole is a bladder-like organelle that can take up a considerable volume of space inside the cell. Its functions include waste disposal and, since it is often such a large presence within the cell, it exerts pressure and helps the cell maintain its structure and shape.
  
  

Other Organelles

• The peroxisome is the most prominent member of a group of organelles called microbodies. It converts toxic hydrogen peroxide, a compound that would otherwise build up in the cell, into water. Other organelles are microfilaments and microtubules. Microfilaments provide structural integrity to the cell and function in cell contraction and other cell movements. Like microfilaments, microtubules provide a structural framework and aid in cell division.