electron microscopy

• plasma membranes are composed of a phospholipid bilayer with cholesterol and glycoproteins and lipids. It appears trilaminer
• the nucleus is the largest organelle in the cytoplasm
• heterochromatin are electron-dense accumulations within the nucleus, it represents packaged DNA not actively involved in transcription
• euchromatin are electron-lucent regions in the nucleus, often found in the middle. it represents decondensed unzipped DNA
• the nuclear membrane is a double membrane found around the nucleus. in it are nuclear pores
• rER are elongated, regularry arranged membranes with electron dense ribosomes on the surface. the space between the membranes is the cisternae
• sER are membranes irregularly arranged in the cytoplasm. it products lipids, detoxifies, and stores Ca2+ in the cells. It is often found in conjunction with lipid droplets
• golgi complex are involved in post-translational modification of proteins and packaging of them into secretory vesicles. often found in conjunction with rER
• as water in secretory vesicles are absorbed, the material becomes more concentrated. the more electron dense vesicles are the more mature ones
• lipid droplets are encased within a layer of phospholipids. they often occur in cells with alot of sER