Cell Ultrastructure Flashcards
Plasma Membrane
- phospholipids are amphipathic
- the bilayer for as a relatively impermeable barrier to most water-soluble molecules
- protein molecules dissolved in the lipid bilayer mediated most of the other functions of the membrane
- glycocalyx - oliosaccharides and polysaccharide side chains on the outside of the plasma membrane
Functions of the plasma membrane
- selective permeability
- transport of materials along cell surface
- endocytosis and exocytosis
- intercellular adhesion and recognition
- signal transduction
Endoplasmic Reticulum (is continuous and encloses a single lumen)
sER - no ribosomes - found in liver, mammary gland, ovary, testis and adrenal gland rER - ribosomes synthesise proteins
The Golgi Apparatus
cis face - receives vesicles from rough ER
trans face - exports vesicles (signal mediated diversions for lysosomes or regulated secretion - not for constitutive secretion)
The Golgi Apparatus functions to modify, sort, concentrate and package proteins synthesised on the rER
Lysosomes
- are generated by the Golgi apparatus
- contain many hydrolytic enzymes to break down anything in the cell that is defunked
- fuse with ,aerial requiring digestion
Peroxisomes
- detoxify (oxidise) a number of molecules including alcohol, phenols, forming acid and formaldehyde
- abundant in the liver and kidney
Mitochondrion
female lineage - always inherited from mother
Matrix - 100s of enzymes - mitochondrial DNA genome (has bacterial like replication - endosymbiosis theory) Inner Membrane (cristae) - enzymes for oxidative phosphorylation (ATP synthesis) - impermeable to small ions e.g. H+ Outer Membrane - permeable by all molecules
Actin Filaments
Microfilaments
- 5-9nm in diameter
Intermediate filaments
- 10nm in diameter
- tough supporting mesh work in cytoplasm
- cancer source can be traced by looking at filament type in cancer cell
Microtubules
- 25nm in diameter
- hollow cylinders made of protein tubulin
- found where structures move (nerve fibres, mitotic spindle, cilia and flagella)
- 9+2 arrangement in cilium or flagellum
The limit of resolution
proportional to wavelength
The minimum distance at which two objects can be distinguished (seen as distinct)
Theoretical limit of resolution
- light microscope is 0.2um
- electron microscope is 0.002nm