Week 2: biology of cells Flashcards
what is euchromatin and heterochromatin?
- **euchromatin = ** lighter/paler areas where the DNA is not condensed (unravelled) –> indicats activity of cell as uncoiled DNA is what is transcripted.
- **heterochromatin = ** dark/almost black areas where DNA is tightly coiled –> Inactive areas wehre transcription is not occuring.
what are inclusions?
they are non-living components of cells
- secretory vesicles
- fats and lipid droplets
- glycogen
- stored waste products
what are the 3 proteins (fibres) which make up the cytoskeleton?
- microfilaments (smallest)
- intermediate filaments
- microtubules (largest)
what is a microfilament?
- concentrated underneath cell membrane
- determines cell shape/rigidity
- mechanical support via microvilli
- cell movement and locomotion
- phagocytosis
- cell division
- powered by ATP
what is an intermediate filament?
- provides general structural support, anchors, junctions in ALL cells
- types of intermediate filaments:
- keratin –> in epithelium
- vimetin –> in CT
- desmin –> in muscle - very strong, maintains tension/cell shape
- not involved in cell movement.
what is a microtubule?
- hollow tubular structures of variable length
- polymer, composed of tubulin (monomer)
- transport of organelles and vesicles within cell (e.g. mitotic spindle)
- form basis of specialised organelles (e.g. centrioles) and cellular structures (e.g. cilia)
what are the 5 main cell junctions
- tight junctions
- adherens junctions
- desmosomes
- hemidesmosomes
- gap junctions
lateral junctions = tight and adherens junctions, desmosomes, and gap junctins
basal specialisations/junctions = hemidesmosomes
decribe the 4 lateral junctions/specialisations
- tight junctions = seals intercellular spaces, belt-like distribution, prevents apical specialisations from moving to lateral surface joins areas of plasma membrane together, prevents passage between cells (watertight seal)
- adherense junctions = joins actin filaments of neighbouring cells together. dense protein plaque and initiate cell-cell contact
- desmosomes = ocalised spot-like welds. Proteins hold adjacent cells together, intercellular space not fully sealed. More abundant in deeper layers of epidermis
- gap junctions = cell-to-cell communication. Aligns protein pores, which allow for passage of small molecules. Connexons (protein)
describe the basal junction/specialisation
hemidesmosomes = half a desmosome, plaques attach to intermediate filaments in cytoplasm (keratin), anchors cell to basement membrane.
what are survival stratergies of bacteria which allow them to survive harsh environments?
- biofilms = protection and resistance to antibiotics
- slime capsules =
- granule inlusions
- endospores
Which type of microscope is commonly used for viewing live unstained cells including bacteria, parasites and cell cultures?
phase contrast microscope
Which type of microscope is commonly used for routine histology of biopsy tissues stained with dyes?
bright field light microscope
Which type of microscope is used for viewing ultrastructure of cellular detail of organelles?
transmission electron microscope
bWhich type of microscope forms images with light in the visible spectrum?
bright field light microscope
Which type of microscope forms images with UV or laser light that upon contact with specific chemical labels show excitation and luminescence?
flourescence microscope
