Cell Flashcards
Plasma membrane is made up of
Phospholipid bilayer - hydrophobic groups face inwards, polar groups externa
Transporters, receptros, invaginations and evaginations
What size are mitochondria
2 um
What occurs at the outer membrane of mitochondria?
Lipid syntehsis
Largen channel forming proteins
What happens in the intermembrane space?
Proteins responsible for transport of metabolites between cytosol and outer comparmtnetWha
t happens at the innermembrane of mitochondria? Structure?
FOlds / cristae
Electron traensport chain
ATP synthesis
TRanport proteins that allow metabolites in and out of matrix
What are the functions of mitochondria
ATP sytnehsis
ATP breakdown
Calcium store
Involved in apoptosis
What cells have no nucleus
Red blood cells
What is chrmoatin?
What is a nucleosome?
Long strands of DNA, RNA and associated nucleoproteins
Nucleosome = DNA assocaited with 8 histones
What is heterochromatin
Electron dense and distributed around the periphery of the nucleus in discrete masses within the nucleus - DNA assocaited with nucleoproeints but not actively undergoing RNA synthesis.
INACTIVE
What is euchromatin
Euchormatin - electron translucent - DNA is actively undergoing RNA synthesis
ACTIVE
BEads on string
Activated by acetylation
What is the endoplasmic retinculum
Bilatyered phospholipid membranes
What is the rough ER? Function?
Bilayered phospholipd membrane with ribosomes (RNA and protein)
Secretory, lysosomal and membrane protein assimilation on surface
More highly developed in secretory cells such as the lacrimal gland acinar cell
Synthesised proteins from ribosome enter ER and translationally folded for secretion via golgi apparatusW
What happens at the smooth ER
Site of synthesis for lipids, triglycerides, steroids
Highly developed in RPE and meibomian gland cells
What is the function of the golgi apparatus?
Falttened smooth membrane sacs and vesicles
Translational modifcation of secretory and membrane proteins by sequential glycosylation reactions
How many functional regions of golgi
5
Cis golgi network - connection with ER entry point
Cis golgi
Medial golgi
Trans golgi
Transgolgi network - exit point for vesicles
What are peroxisomes?
Contain enzuymes that funciton in oxidatie reactions which produce hydrogen peroxide and other organic peroxides e.g catalase
What are the structures of the cytoskeleton?
Microfilaments
Made of actin
Dynamic and contractile
7nm
Microtubules
Made of tubulis
Mobile, dynamix
24nm diameter
Intermediate filaments
Robust durable
10nm diameter
What are the three cell junctions
Tight (occluding junctions) zonula occludens
Anchoring junction
Communicating (gap) junctions
What are tight (occluding) junctions composed of
Occludin and claudin
What is the funciton of tight junctions
Seal neighbouring cells together so that water soluble molcules cannot pass between cells
Between epithelial
What are the funciton of anchoring junctions?
Maintaining tissue integrity
Link cellular cytoskeleton with that of neighbouring cell or the extracellular matrix
Consist of intracellular attachment protein
Transmembrane linked glucoprotein on anoterh cell
What do adherens junctions do?
Join actin cytoskeletons together
What do desmosomes do?
Anchoring sites for intermediate filaments in cell to cell adhesion and provide tensile strength
What are the cell adhesion proteins of the desmosomes?
Desmoglein and desmocollin
MEmbers ot he cadherin cell adhesion moelcule family
Bridge the space between adjacent epithelial cells by homophilic binding of extracellular domains to other desmosomal cadherins on adjcent cells
Calcium dependent
What are hemidsmosomes?
Attach to the extracellular matrix
Use integrin cell adhesion protins
Connect the basal aspect of cells to the basement membrane
What are gap junctions? Function?
Do not seal membranes together or restrict the passage of material between membranes
Allow inorganic ions carrying current and water soluble molecules to pass from one cell to another
Electrical and metabolic cell coupling
What is a gap junction composed of
2 connexons - hemi-channels
Cross intercellular space
Molecules of up to 1000Da can pass through a pore
What are cadherins?
Glycoproteins that form part of a desmosome and invovled in cell adhesion
Calcium dependent
What are integrins? Functions?
Receptors that mediate attachment between a cell and tissue surrounding it
Attachment of cell from ECM and signal transduction from ECM to cell
Invovled in immune response, cell migration and viral cell binding
Where are L-selectins?
Leukocytes
Where aer E electives
Activated endothelial celss
Where are P-selectins
Activated platelets and endothelial cells
What are selectins? Functions
Calcium dependent cell adhesion molecules
Heterophilic bidning to carbohydrate ligands
Leukocyte endothelial interactions
Local chemical mediators such as histamine, thrombin, cytokines, TNF-a
Results in trolling of cells across endothelial cells until integris are activated
