Organelles are structures within a cell that have specific functions; membrane-bound organelles are organelles protected by a single or double plasma membrane. Mitochondria, lysosomes, the endoplasmic reticulum and the Golgi apparatus are examples of membrane-bound organelles.Continue Reading
Membrane-bound organelles are one of the defining characteristics of eukaryotic cells. Prokaryotic cells such as bacteria do not possess these organelles. Certain species of bacteria possess primitive protein pockets that fulfill some organelle functions but are not defined structures protected by a membrane.
Mitochondria are unique organelles that contain their own DNA. They produce the cell's energy through respiration. Because of this, they are also known as the powerhouse of the cell. Mitochondria are covered by two membranes: a smooth outer membrane and a folded inner membrane. Mitochondrial DNA is passed down through the mother and is a useful tool in genetic tests.
The endoplasmic reticulum produces lipids and proteins. The rough outer membrane of the endoplasmic reticulum is covered with ribosomes and is responsible for protein synthesis; the smooth endoplasmic reticulum lacks ribosomes and synthesizes lipids. Ribosomes and the Golgi apparatus assist the rough endoplasmic reticulum in protein synthesis. Lysosomes are the digestive system of the cell. They use enzymes to digest food, waste, toxins and dead cellular material.Learn more about Cells
The primary reason that scientists and students stain onion cells is to make it easier to discern the various structures and organelles. In practice, most cells are treated with stains or dyes to give them higher contrast and improve the researcher’s ability to visualize the key features. Several different stains and dyes are in common use, including eosin, iodine and safranin.Full Answer >
Vacuoles are the large, sac-like organelles that are used for storage and other functions within the cell. They are similar to, but distinct from, the vesicles, which are tiny sacs that help transport chemicals within the cell.Full Answer >
One purpose that membrane-bound organelles serve is to allow the isolation and concentration of enzymes and reactants within a small space. This enables chemical reactions in a cell to occur faster and with greater efficiency. Membrane-bound organelles can also confine harmful proteins and molecules from the rest of the cell.Full Answer >
Human epithelial cells, which are animal cells, and elodea cells, which are plant cells, share many structures because both are eukaryotic cells, or cells with a membrane-bound nucleus. Common structures in animal and plant cells include the nucleus, cytoplasm, endoplasmic reticulum, ribosomes, mitochondria, Golgi apparatus, microtubules/microfilaments and in some organisms flagella.Full Answer >