Organelles

One of the primary differences between plant cells and animal cells is that plant cells must be able to undergo photosynthesis. Photosynthesis takes place in the chloroplasts, which contain the pigment chlorophyll. Chloroplasts are not found in animal cells, but are found in plant cells.

Both animal and plant cells contain Golgi bodies, smooth endoplasmic reticulum, and mitochondria.

Mitochondria are organelles that have an unusual double membrane. An out membrane surround the entire organelle, and a second, inner membrane contains numerous folds, called cristae. Cristae increase the surface area exposes to the matrix of mitochondria.

The mitochondria is the "powerhouse" of the cell and converts chemical energy (sugars) into ATP during cellular respiration.

Ribosomes are composed of a unique type of RNA, rRNA, and are located within the cytoplasm of the cell and on the surface of the rough endoplasmic reticulum. Here, proteins are assembled from amino acids piece by piece using instructions copied from DNA.

The ER has four major functions: Synthesis, storage, transport, and detoxification.

Synthesis - ER membrane contains enzymes that manufacture carbohydrates, steroids, and lipids.

Storage - ER holds synthesized molecules absorbed from the cytosol.

Transport - Substances travel from place to place within the cell inside the ER.

Detoxification - Cellular toxins are absorbed by ER and neutralized by enzymes in ER membrane.

The plasmalemma (plasma membrane) has a complex structure composed of phospholipids, proteins, glycolipids, and cholesterol. The phospholipids form two distinct layers that don't allow dissolved ions and water-soluble compounds to cross the plasmalemma. This makes the plasmalemma effective in isolating the cytoplasm from the surrounding fluid environment.

Mitochondia produce energy (ATP) required by the cell, if a cell has large amounts of mitochondria this implies the cell has a high energy requirement.

Nonmembranous organelles are always in contact with cytosol.

Membranous organelles are surrounded by membranes that isolate their contents from the cytosol.

Ribosomes are freely scattered in the cytoplasm and thus are nonmembranous organelles.

The mitochondria are organelles that are often referred to as the "power plant" of the cell. Mitochondria are responsible for extracting energy from food molecules and binding it in the high energy bonds of the ATP molecule.

The Golgi apparatus can be thought of as the "shipping center" of the cell. Here, proteins and other materials are packaged in vesicles which are transported to other sites in the cell or outside the cell membrane for "export".