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2- 32 and 33- Some beta barrels form large channels (20 oct)…
2- 32 and 33- Some beta barrels form large channels (20 oct)
1- beta barrels usually acting as channels because the lumen size are usually larger
2- phospholipid= 5 nm
adding protein and glycosilation on top of the protein it may go up to 10 nm
glycosalation= sugar rings attached to the proteins
in electromicrograph you'll see very hairy dark surface twards the outside these are suger rings densly coated on top of THE PROTEINS
some cells have that hairy layer because we use suger ring as an ID recognising tool
immune cell in blood vesels wants to recognise certain type of cell when they need them
information that you want in one area a lot of cleanup cells
they need to be recognised by glycocalyx
coming out of the blood vessle find that local information and clean up
if you isolate some endothelial cells from blood vessels
condition them in a right situation you'll see a glycocalyx will grow
failing to recreate those environment you wont be able to see these gycocalyx from the endothelial cell
3- Membrane protein purification using detergents
lipisome merge into cell membrane so they could probably be usefull as drug deliver system
another thing that can disrupt the phospholipid bylayer is the bleach
cheapest way to kill cells
as soon as you add bleach into the media the cell membrane raptures
reason: bleach has hydrophilic head and hydrophobic tail which is a molecule we call ampypathic
detergent is amphypathic as well you can have smaller units mixed with detergent and a little phospholipid
detergent will wrap around phospholipids
usefull tools to isolate glyco prteins to study the function of a single type of protein
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another way to wrap around phospholipids with some proteins = nanodisc :star:
this is high density lipoprotein you find in the blood vessel
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4- bacteriorhodopsin
one of the famous alpha halix base transmembrane protein which has 7 alpha halices
atomic phospho microscopy images : imaging in nano scale
conformational change in structure within that 7 alph helices will transport the proton
there is one famous transmembrane protein which can pump proton based on the absobance of the light with conformational change of the structure
5-proteins/lipids to specific domains
how proteins work together have some function
left is the example of bacterial rodupsin type
they work as a patch to be more efficient
the second one is a cluster of glyco protein in transmembrane location will be act with some type of molecule
3rd one intracellulary when they have to cluster when they act with some molec. intra cellulary
D) example of cell cell adhision molecule , could be a dasmeson or caterin :!?:
good junction between 2 cells have these green proteins twards the nabouring cells rather than somewhere else.
localization or special arrangement of these proteins will definitely dictate the function of the protein
bottom pic is extreme case of the cell in case of arrangements which is an epithelial cell
green protein exposed to the area for example to absorb the nutrients into the cell
makes sense to have green protein twards that layer rather than somewhere else
tight junctions to have it more polarized
no leakage going through that cell layer so only cell with those proton receptors can act as an absorbing channel
some junction protein from cell to basal lamina (specific extra cellular matrix you find it in the apethelial layer)
red blood cells cell membrane extreme example
float around in blood vessels
but skin cells stick to each other or the extracellular matrix
have to endure the stress from the blood vessels
endure mechanical stresses whenever they go to the smaller channels so they developed extra mechanical enduring structure
they have networkish protein arrangment within the cell membrane so they can support the mechanical property of the cell membrane
Membrane bending proteins deform bilayers
when we only have phospholipidsit it will be linear hollow sphere
look at small area it looks flat we dont realise the curviture of the surface becaouse it is too small
proteins can help make curve by inserting a large portion into onesite
or you can have binding protein which is large it will push it down
or some phospholipid which has larger polar head becaouse you have larger pole which bound to a protein will help to create a curviture
if you have a structure which look like s shape you can put these proteins specially to help that curviture
function of membrane proteins
as transporter
as an anchor
or receptors
enzymes
6- summary of the lecture
120 nm nuclear pore of nuclear envelop
7- the cytoskeleton
read polarisation and cell migration of the end of ch 16
goole: Stem cells are undifferentiated biological cells that can differentiate into specialized cells and can divide to produce more stem cells
culture the stem cells from fat from one obese patient
only the stiffness of hydrogel
first one 1 K pascal= stiffness of brane
second 10 K pascal mimics skeletal muscle
3rd 40 k pascal mimics bone
cells within a week change their morphology into native brane cells or skeletal muscle cells
even though you start from exactly the same origin based on the environment cell has to be flexible and adaptable to the environment and they have to change the structure
how dynamics cells are
neutrophil chasing after a bacteria= chemotaxis :star:
bacteria will release some chemical that the lucacite can sense those chemical gradient and chase after them and eat up other wise we gonna be sick
slightly different biochemical gradient
2nd photo: top: 10% serum from cow: better environment for cells to live >>> open the gates and cells will move up
3rd pic; cells are every where about 24 huors later cells are on these lanes
the only difference is that it is a flat surface and channels are different stiffness , we have 1 vs 10 k pascal . cells can sense stifness differently and migrate slowly twards stiffer end
mechanobiology
reason: they will change shape and they will rearrange the cytoskeleton --- the cell has to be sense the stiff or the soft differently so they can rearrange something different . the whole thing culled mechano transduction :star: cell has some sensor that will touch the ground feel how stiff those material are , generate some forces... on softer ones they can not pull against hard so they generate smaller force but on the hard surface they can pull strong agains they can generate larger force
based on those forces they do things differently
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8- 3 major protein filaments that form the cytoskeleton
Actin filament
will decide the shape of the cell
we need actin filament to be adaptable to whole cell locomotion
they will move around and actin filament has to maintain the shape
they are required when they grow into 2 doughter cells when they pinch into 2 we need a lot of actin filament
9- Actin filament
electromicrograph : diameter of actin filament about 8nm the thinest of the 3
in the cell they look like straight lines
usually coming from nucleusish twards the periphery
not necessarily star shape
microvilli :star: one of the structures we find actin filament alot
cells are connected to the ground>>> the point thet they make that connection to the extra cellular matrix which is the green and actin filament usually end with focal adhesions complex which is stained in green
last photo is actin filament found in the skeletal muscle which generated the contractial forces whenever your muscle has to contract
building block is actin monomer
actin monomer has ATP binding site
ATP is important to polimerise the actin filament
actin has 1 subunit
microtubule
decide the position of the organels within the cell
they will bond to the organells
act as a train track so they can transport some intra cellular vesicles
forming mitotic spindle during cell division
10- microtubule
has hollow shape : hollow lumen within the microtubule
diameter is 25nm which is the bigest one of 3 cytoskeleton
we have actual centre of microtubial called centrosome
microtubules always grow out of centrosome
sometime they retrac back from the centrosome
microtubials found in ceilia
cilia acts as sensory as well
small microorganisms use cilia or flagela as swiming organ
so ther create a lot of forces
look at the celium or microtubule you see triplets form a big structure like a centrosome
microtubule has alfa and beta sub units
intermediate filament
main job is giving a mechanical strength
most famous one is found within a nucleus because nucleus has to be very stable
11- intermediate filaments
different in structure : rope like structure
it will develop ropes and bind together and form a tube like shape
10 nm diameter
mesh type network from intermediate filament
no iv is the nuclear lamina to protect or give mechanical strength to the nucleus : you see a lot of network meshtype structure which is intermediate filament
9- Dynamic reorganization of cytoskeleton
1st photo on the left is during cell division
actin in red
microtubule in green
as soon as they decide to grow and divide they spread out
because they have to spend energy slightly differently
microtubule has a lot of desrtucture
so they can pull away those DNA to make it even
later they have to pinch so actin filament have to come in wrap around these narrow channel
later they can depart having individual cells
then they go back to the normal morphology
they will do it again and again
in intestinal epithelial cell
dynamic situation
intermediate filaments connected through the desmosome
give a whole layer of mechanical strength
we have microtubules running vertically
get some nutrients
from site on top going down to basal lamina where the blood vessel will run
better to have train track which we can transport those nutrients
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we have a microvili = actinfilaments
intermediate filaments connected through the desmosome
give a whole layer of mechanical strength
we have microtubules running vertically