Cells and Organelles Flashcards
What processes are nuclear lamins involved in?
nuclear structural support, chromatin organisation, anchoring nuclear pore complexes
what is the major microtubule organising centre called and where is it located
the centrosome, near the nucleus
what structures are responsible for the movement of vesicles and organelles around the cell
microtubules
___ move cargo to the periphery, ___ move cargo to the cell body
kinesics, dyneins
cilia and flagella are both composed of microtubules and ___ arranged into a structure called an ___
dynein, axoneme
what is kartageners syndrome
Defective cilia and
flagella associated with a condition called Kartageners syndrome, which are
the result of mutations in the dynein motor proteins.
Individuals with Kartageners syndrome will suffer recurrent respiratory infections, and
males will suffer from infertility.
what is a cell junction
These are transmembrane protein complexes that interact with similar proteins
on adjacent cells, linking not only the cell to each
other but linking to each other’s cytoskeletons as
well.
what are the 3 different types of cell junctions
anchoring, occluding
which are also called tight junctions, and communicating or Gap
Junction,
what do anchoring junctions do
Anchoring junctions provide
mechanical stability to groups of epithelial cells so that they
can function cooperatively.
what junctions does the actin cytoskeleton interact with
adherens junction (joins cells together) and focal adhesions (connects cells to the underlying extracellular matrix
what junctions does the intermediate filament network interact with
desmosomes (connects cells to each other) and hemidesmosomes (connects to the extracellular matrix)
what is the name of the condition where defects in cell junctions are apparent and what are the effects of this
Defects
In junctions are apparent in individuals with epidermolysis bulosa simplex
In this condition, defects in the Hemidesmosome complex
disrupts the dermo-epidermal layer, resulting in severe blistering.
what are 2 functions of tight junctions
Tight junctions are a specialised cell cell contact that have two
functions.
The junctions create a seal preventing diffusion of molecules between
adjacent cells, thereby creating a barrier function for epithelial cells.
They also create a barrier within epithelial cell membranes, which
prevents mixing of membrane proteins, creating two distinct membranes.
The apical and basolateral membranes.
what are gap junctions, what are they composed of
intercellular channels that connect the cytoplasm of adjacent
cells.
They permit the passage of inorganic irons and other small
molecules. Gap junctions are composed of connexins, which are a large
family of different proteins.
during what stage of development are gap junctions found in large numbers
embryogenesis
what types of muscle are gap junctions important in and why
cardiac and smooth, involved in contraction
what can defective gap junctions result in
Gap junctions are composed of connexins, which are a large
family of different proteins.
Mutations in different connexins that result in defective gap junctions results
in a range of clinical manifestations.
Mutations in connexin-26 for example, results in deafness and
Vohwinkel syndrome, which is a disorder of the skin, resulting
in thick honeycomb-like callouses and a build up
of abnormal fibrous tissue on the hands and feet
give examples of cell junctions and their roles in skin
The importance of junctions can be shown using skin as
an example.
Adherens junctions act to hold epithelial cells together.
Desmosomes provide strength for the epidermal keratinocytes.
, tight junctions provide a seal in the stratum granulosum
and hemidesmosomes are responsible for the integrity
of the dermo-epidermal Junction. And, of course, gap junctions
allow for the passage of small molecules in between cells.
give an example where a cells’ shape is adapted to its function
Plasma cells, for example, are immune cells whose sole function
is to produce immunoglobulin.
which are antibodies as you might predict, and as you
can see in this electron micrograph, the Plasma cell has
an extensive rough endoplasmic reticulum consistent with its function.
what is responsible for the extensive Ca storage in muscle cells
Muscle cells contain an elaborate and specialised ER called a
sarcoplasmic reticulum to fulfil this function.
A molecule that has a polar and non-polar end
A lipid made up of a phosphate polar head group and two fatty acids chains (one usually saturated, the other unsaturated)
Microfilament-based membrane protrusions that help cells move
Very small spikes of microfilament-based protrusions of the plasma membrane involved in cell motility
A molecule that has a polar and non-polar end
= amphipathic
A lipid made up of a phosphate polar head group and two fatty acids chains (one usually saturated, the other unsaturated)
= phospholipid
Microfilament-based membrane protrusions that help cells move
= lamellipodia
Very small spikes of microfilament-based protrusions of the plasma membrane involved in cell motility
= filopodia
what is a glycocalyx
a layer of carbohydrate that covers cells. Many functions including cell recognition. Cells lining the gut have a thick glycocalyx where digestive enzymes reside
what are lipid rafts
lipid rafts: cholesterol-rich domains that compartmentalise function by concentrating molecules, eg act as ‘signalling platforms’ by concentrating signalling receptors
what is the gate and fence function of tight junctions
The ‘gate’ regulates paracellular permeability, that is, things moving inbetween cells
The ‘fence’ function prevents membrane components on the apical surface from mixing with membrane components in the basolateral membrane. This results in cell polarity. All epithelial cells have cell polarity which means that they have functionally different sides to them.
