Flashcards in 1. Epithelial cells Deck (53)
Where are ribosomes found and what do they do there?
Free in cytoplasm: synthesise cytoplasmic proteins
Attached to outer membrane of nuclear envelope and ER: make membrane proteins and proteins to be packaged in membranous organelles.
What is the function of nuclear pores?
control import and export of macromolecules into and out of nucleus
What is the relationship between nuclear envelope and endoplasmic reticulum?
There is physical continuity between nuclear envelope and ER
Describe the rough endoplasmic reticulum
Stacks of flattened membrane leaflets (cisternae), studded on outer face with ribosomes
What is the RER the site of?
protein synthesis and packaging in membrane-bound structures, e.g. secretory vesicles, lysosomes
What is the function of the smooth endoplasmic reticulum?
Enzymes involved are typically associated with the membranes.
Site of Ca2+ storage in cells (important in cell-signalling)
What is the Golgi apparatus and what does it do?
System of stacked, membrane bound, flattened sacs
Modifies, sorts and packages macromolecules for secretion/ delivery to other organelles
How is are the faces of the Golgi apparatus aligned?
Cis: to ER
Trans: to cell periphery
What are peroxisomes?
Single membrane bound organelles
Contain enzymes involved in lipid and oxygen metabolism, e.g. oxidases, catalases, peroxidases
What is the cytoskeleton?
A system of filaments formed by the polymerisation of protein monomers
What 3 types of filament constitute the cytoskeleton?
What are microtubules made of and what is the diameter of a microtubule?
Polymers of alpha and beta tubulin heterodimers
What are microtubules used for?
Movement of organelles through the cell
Involve motor proteins
Involved in spindle fibre formation
What are microtubules major components of?
Cilia and flagellae
Form 9 + 2 arrangement in the core
(9 doublets + 2 central singlets)
Describe the organisation of microtubules in cells.
Originate from a point within the cell called the microtubule organising centre (MTOC)
Describe structure of intermediate filaments
Group of polymers of filamentous proteins
Form rope-like filaments
Which component of the cytoskeleton distinguishes different cell types?
Intermediate Filaments are different for different cell types
What is the function of intermediate filaments?
Give mechanical strength to cells
What are desmosome cell-cell adhesions connected by?
Where else are intermediate filaments found other than in the cytoplasm?
Nuclear lamins are IF's found on the internal surface of the nuclear envelope
What are microfilaments made of and what is their diameter?
Polymers of Actin (filamentous actin, F-actin)
What do microfilaments associate with?
Adhesion belts in epithelia and endothelia
What are microfilaments involved in?
cell shape and movement
major component of contractile apparatus of muscle and involved in contraction of non muscle cells
What is the monomer of microfilaments?
G-actin (globular actin)
How is the cytoskeleton dynamic?
Various elements are subject to rapid re-modelling, stimulated by biochemical and bio-mechanical signals.
What are the 5 major groups of cell type?
Give 3 examples of connective tissue cells
Give 3 examples of contractile tissue cells
Give 3 examples of haematopoietic cells
Tissue-resident immune cells
Cells of the bone marrow from which they're derived