BI236 : Cell and Molecular Biology
o AGolgi complex is composed of flat sacs known as cisternae. The sacs are
stacked in a bent, semicircular shape.
o Each stacked grouping has a membrane that separates its insides from the
cell's cytoplasm. Golgi membrane protein interactions are responsible for its
o Molecules synthesized in the ER exit via special transport vesicles which carry
their contents to the Golgi complex.
o The vesicles fuse with Golgi cisternae releasing their contents into the internal
portion of membrane.
o The molecules are modified as they are transported between cisternae layers
o Part of the cellular endomembrane system system
o Packages proteins inside the cell before they are sent to their destination
o Particulary important in the processing of proteins for secretion.
o Membranous sacs containing digestive enzymes found in animal cells
o Digest excess or worn-out organelles, food particles, and engulf viruses or
o Sacs of enzymes, typically hydrolytic and can digest cellular macromolecules.
o They are made by the ER and Golgi apparatus.
o They are active in recycling the cell's organic material and in the intracellular
digestion of macromolecules.
o The membrane around a lysosome allows the digestive enzymes to work at the 5
pH they require.
o Frequently nicknamed “suicide-bags” or “suicide-sacs” by cell biologists due to
o In humans, a variety of inherited conditions can affect lysosomes.
o These defects are called storage diseases and include Pompe's disease and Tay-
Sachs disease. People with these disorders are missing one or more of the
lysosomal hydrolytic enzymes. • Peroxisomes
o Also called microbodies -are organelles found in virtually all eukaryotic cells
Important in getting rid of toxic substances
o Amajor function of peroxisome is the breakdown of the very long chain fatty
acids through (Beta)-oxidation.
o In animal cells – the very long fatty acids are converted to medium chain fatty
acids, which are shuttled to mitochondria where they are broken down to carbon
dioxide and water.
o In yeast and plants cells, this process is exclusive for peroximes
o Membrane bound storage sacs
o Has no basic shape or size; its structure varies according to the needs of the cell.
o More common in plants than animals
o Mature plant cells have one large central vacuole
o Animal vacuoles are smaller than their plant vacuoles but also usually greater in
o There are animal cells that do not have any vacuoles
o A vacuole is surrounded by a membrane called the tonoplast or vacuolar
membrane, separating the vacuolar contents from the cell’s cytoplasm.
Mainly involved in regulating the movements of ions around the cell,
Isolating materials that might be harmful to the cell.
• Bacteria – Like organelles
o Release and store energy
Mitochondria (release energy) • Amembrane double) enclosed organelle found in most eukaryotic
• Have their own DNA
• Described as “cellular power plants” because they gene