Oragnelles II Flashcards
Peroxisome
- Membrane bound
- Generates hydrogen peroxide
- performs B-oxidation of long chain fatty acids
Peroxisomal Fission
- Different from prokaryote division
- gets larger and larger and splits into two daughter peroxisomes
Evidence for Porkaryote Origin of Mitochondria
- Contains its own small circular chromosome of DNA
- Originates by fission from pre existing mitochondria
- Double Membrane- host membrane and symbiotic prokaryote
- Closest relative is Rickettsia bacteria
Proton Pump
- facilitates the synthesis of ATP
- H+ ions cause the rotor to spin. Mechanical energy is converted to chemical energy in the form of synthesis of ATP.
- H+ ions are then pumped back into intermembrane space
Melanosomes
membrane bound cytoplasmic inclusions.
- contain melanin
- gives rise to pigmentation of the skin
Lipfuscin
Membrane bound cytoplasmic Inclusions
- Lipid containing residues of lysosomal digestion
- residual body (tertiary lysosome)
Glycogen
non membrane bound cytoplasmic inclusions
- stores of glucose
Lipid
non membrane bound cytoplasmic inclusions
- triglycerides in storage form
Microfilaments
- Actin Filaments- globular monomers that assemble in the presence of K and Mg into a double stranded filamentous actin
Actin
Functions
- Intracellular movement and muscle contraction by forming stress fibers
- Membrane structures like microvilli and stereocilia
- locomotion (filopodia)
Microtubules
- wider than actin
- Heterodimer of alpha and beta subunits.
Microtubule Fibers
- individual microtubules
- mitotic spindle of dividing cells
- axons of neurons
axoneme
- doublet of microtubules
- core of cilia and the sperm tail
centriole
- organization of microtubules into triplets.
- 2 centrioles constitute a centrosome.
basal Body
a centriole that nucleates the axoneme of cilia
Motile Cilia
Contain a central doublet of microtubules
Primary cilia
Lack a central doublet of microtubules.
- nonmotile
- used for sensory function
Keratin
Intermediate Filament
- attach to desomosmes to form a framework within the cytoplasm
- expression can be useful in grading tumor cells
- provides barrier to dehydration
Zonula occludens
tight junctions
- Form a band encircling the apical end of the cell
- prevent movement between the lumen and intercellular space
- facilitates polarity
- zip lock seal is formed
Zonula Adherens
Intermediate Junctions
- directly under tight junctions
- Anchors cells to one another
Cadherin proteins
mediate cell adhesion
- bind catenin to actin filaments
- this forms the terminal web that help anchor actin filaments originating from microvilli at the apical pole of epithelial cells
Macula Adherens
Desmosomes
- consists of transmembrane proteins, desmoglein and desmocollin that insert into a dense attachment plaque of anchoring proteins that then binds keratin
Gap Junctions
- pores between adjacent cells
- rapid communication between cells
- 6 connexin proteins froms a connexon
- 2 aligned connexons froms an open channel between cells
