Organelles Self-study Flashcards
Phospholipids
- Found in cell membranes - Glycerol molecule with two fatty acid chains and one phosphate containing side group attached - forms the lipid bilayer - Amphipathic – having both hydrophilic (head) and hydrophobic (tail) domain in the same molecule
Neutral lipids
- Found in cell membranes - Primarily cholesterol and cholesterol esters - Important for control of membrane fluidity
Glycolipids
- Found in cell membranes - Glycerol chain with two fatty acid chains and one carbohydrate group attached - Most important as antigens or membrane recognition molecules
Where are phospholipids synthesized?
on the endoplasmic reticulum membrane
Integral membrane proteins
- Proteins embedded in the lipid bilayer - They may span entire bilayer in one-pass or multi-passes - May be embedded in just the outer or inner portion - Some are glycoproteins with an attached carbohydrate chain on the outer cell surface.
Peripheral membrane proteins
Protein closely associated with the inner surface of the membrane by interaction with membrane lipids, integral membrane proteins or both
Zonula Occludens
- tight junctions - closely associated areas of two cells whose membranes join together forming a virtually impermeable barrier to fluid
Zonula Adherens
protein complexes that occur at cell–cell junctions in epithelial and endothelial tissues, usually more basal than tight junctions
Desmosomes
- also macula adherens - they are localized spot-like adhesions randomly arranged on the lateral sides of plasma membranes - anchors cells to adjacent cells to maintain tissue integrity
Gap junctions
- Bridges the space or gap between cells - allows molecules, ions, electrical impulses to pass through regulated gates between calls - They are arranged in arrays to form channels
The nucleus is lined by …., called the …
The nucleus is lined by fibrous meshwork, called the nuclear lamina.
Nuclear Pore Complex formed by specific proteins that …
Nuclear Pore Complex formed by specific proteins that regulate movement of material (RNAs, proteins and ribosome subunits) in and out of nucleus.
In the Nuclear Pore Complex, proteins are carried in via binding to a carrier protein called …
In the Nuclear Pore Complex, proteins are carried in via binding to a carrier protein called importin.
Chromatin is organized as …
euchromatin and heterochromatin
Heterochromatin
- condensed chromatin (tightly packed DNA) - transcription inactive - located peripherally in the nucleus
Euchromatin
- extended chromatin - transcriptionally active - makes up 92% of chromatin
Functions of the nucleus
- transmission of genetic material from generation to generation 2. transcription of RNA 3. Formation of ribosomes
Structure of Golgi Apparatus
- stack of membrane bound disc shaped cisternae - cis face - entry face. Closely associated with RER - Trans face - exit face. Closely associated with trans network
Trans golgi network
interconnected membrane bound vesicles directing material to various locations in the cell after leaving the Golgi Apparatus
Structure of mitochondria
tubular or sausage shaped structures with a double membrane
The outer membrane of mitochondria is
highly permeable
The inner membrane of mitochondria is …. forming ….
highly folded, cristae
Myosins are …
- family of ATP-dependent motor proteins - known for their role in muscle contraction
Extracellular Matrix (ECM)
-a collection of extracellular molecules secreted by cells that provides structural and biochemical support to the surrounding cells - consists of ground substance and fibers
Ground substance (ECM)
amorphous and couscous intercellular mixture of proteoglycans, structural glycoproteins, and tissue fluid
Glycosaminoglycans (GAGs)
- found in ground substance of ECM - long, unbranched molecules composed of disaccharides, with an amino group (sulphated) and glucohyaluronic acid - the negative charge attracts cations, which attract water (hydrophilic) to help resist compression forces
Proteoglycans (in ground substance)
- a very large molecule which consists of GAGs bound covalently to a protein core, which is in turn, attached via a link protein to hyaluronic acid - Proteoglycans provide a gel state in the ECM and also provide some of its barrier functions - location: basement membranes, eye, skin, blood vessels, and cartilage
Structural glycoproteins (found in ground substance) are molecules that bind … They are involved in cell …
Structural glycoproteins (found in ground substance) are molecules that bind cells to the ECM. They are involved in cell adhesion and migration.
fibronectin
- glycoprotein - derived from fibroblasts - binding sites on cell surface, in basement membrane, along collagen fibers, chemotactic
laminin
- glycoprotein - derived from epithelial cells - found in the basal lamina - binds type IV collagen
chondronectin
- glycoprotein - derived from chondrocytes - found in cartilage - binds to type II collagen
osteonectin
- glycoprotein - found in bone - associated with type I collagen
Tissue fluid in ground substance
- similar to and derived from the blood plasma - bound to the negatively charged GAGs - transports nutrients and wastes by hydrostatic and osmotic pressure 
reticular fibers
- type III collagen - thinner fibrils - located in smooth muscle, nerve
Epithelial tissue may be derived from all three embryonic germ layers (…..). However, most epithelia are derived from the … and ….
Epithelial tissue may be derived from all three embryonic germ layers (ectoderm, endoderm and mesoderm). However, most epithelia are derived from the ectoderm and endoderm.
The epithelium is attached to ….
the basal lamina
The basal lamina is produced by
epithelial cells
Epithelial cells are …., they receive … via blood vessels in the underlying ….
Epithelial cells are avascular, they receive nutrients, O2 via blood vessels in the underlying connective tissue.
Stratified epithelium are classified according to the morphology of the …
apical cell layer
Glycocalyx
In the cell membrane, the carbohydrate-rich region of glycolipids is referred to as the glycocalyx
