Medical Cell Biology | Quizlet

what is approximate size of transmembrane proteins?

what is size of skin cells?

0.2 mm

what is an approximate size of cell organelles?

20 micrometers

what is basal side of the epithelial cell?

inside

what is apical side of the epithelial cell?

outside(facing the environment)

which desert do gap junctions remind?

donuts :also might be open or closed donuts

what do donuts remind?

gap junctions :also might be open or closed donuts

how is it ensured that epithelial monolayer stays a monolayer?what happens if the mechanism does not work?

contact inhibition

Tumors,possible cancer if division is not inhibited

20 nm is an approximate size of ...?

proteins

what are 4 types of well known cell-cell contacts?

Tight junctions

Adherens junctions

Desmosome(special form of adherent junctions)

Gap junctions

What are hemidesmosomes?

Hemi=half: Resemble desmosomes but they do not link adjacent cells but cells to extracellular matrix

why are tight junction are called so? for which function of epithelial membrane is it hepfull for?

because they are tight and there is not much space between cells, where they are connected by tight junctions.

This is very helpful for epithelial cells fence and barrier function

what is the function of adherent junctions?

to provide adhesison between epithelial cells

in which part of the epithelial cell are tight junctions found?

on the apical side (i.e. the side which faces the environment)

in which part of the epithelial cell are tight junctions found: apical or basal(basolateral)?

on the apical side (i.e. the side which faces the environment)

in which part of the epithelial cell are tight junctions found: apical or basolateral(basal)?

on the apical side (i.e. the side which faces the environment)

what is the function of tight junctions?

It creates a barrier that prevents the passage of water-soluble molecules from the environment to intercellular space ;

They also create battier between cell apical and basolateral side

they may be selectively permeable to certain substances.

what are methods to study tight junctions?

measurements of:

- electrical resistance = electron microscopy by using high electron markers which try to pass tight junctions, so we can measure changes in electron densities

- Fluorescence labeling

name tight junctions proteins?

JAMs = junction adhesion molecules

Ocludin = goes trough plasma membrane 4 times

Claudin = goes trough plasma membrane 4 times

how many times do ocluding and claudin(=tight junction proteins) go through plasma membrane?

= goes trough plasma membrane 4 times

What are linker proteins?what is their functions for tight junctions?

Zona occludes proteins (ZO 1,2,3)

they link tight junctions to cytoskeleton(actin)

what is function of Zona occludes proteins (ZO 1,2,3)?

they link tight junctions to cytoskeleton(actin)

what are 2 main function of tight junctions?

Fence function:to block passage of molecules between basolateral side and apical membrane

Barrier function as a while epithelial layer

(also can serve for signaling)

What is the function of occludins and claudins?part of what are they?

claudins on the one cell interact with occludins on ajaset cell and vise versa

they are being proteins of tight junctions, ensuring that they work and cell connect tightly. together with JAMs(junction adhesion molecules) they ensure that two membranes are so connected that they almost fuse together

what are the functions of adherent junctions?

- cell-cell adhesion

- cell strength

in which junctions are cadherins present?

adherent junctions

what are types of cadherins?

E-cadherin = epithellia

N-cadherin = neurones,heart,seceletal muscles,lens and fibroblasts

P-cadherin = placenta,epidermis,brest epithelia

VE-cadherin = endothelial cells

what happens if E-cadherin =a protein in adherent junctions in epithellia malfunctions?

death in blastocitic state

N-cadherin =a protein in adherent junctions in neurones,heart,seceletal muscles,lens and fibroblasts malfunctions?

embryo death from heart defects

P-cadherin =a protein in adherent junctions in placenta, epidermis, brest epithelia malfunctions?

abnormal mammaly gland development

VE-cadherin =a protein in adherent junctions in endothelial cells malfunctions?

abnormal vascular development

embryo death from heart defects is caused by malfunction of one cadherin.which one?

N-cadherin

how do cadherins(adherent junctions proteins) are influenced by Calcium?

only when calcium is present(on cytoplasmic site), they from a dimer and later a bind with adherent junction of neighboring cell in Ca concentration increases

how do cadherins(adherent junctions proteins) require Ca to work?

only when calcium is present(on cytoplasmic site), they from a dimer and later a bind with adherent junction of neighboring cell in Ca concentration increases

What are actin filaments? Part of which cell-cell junctions are they?

part of Adherens junctions

two stranded helical polymers of actin. Flexible, with 5-9 nm in diameter and are organized in bundles, two dimensional networks and three dimensional gels. They are concentrated in cortex, just beneath the plasma membrane

What are actin filaments? Part of which cell-cell junctions are they? What is their diameter? How are they organized and where concentrated?

part of Adherens junctions

two stranded helical polymers of actin. Flexible, with 5-9 nm in diameter are flexible and are organized in bundles, two dimensional networks and three dimensional gels. They are concentrated in cortex, just beneath the plasma membrane

What are microtubules? Part of which cell-cell junctions are they?

part of adherent junctions

long, hollow cylinders made of tubulin protein. have diameter 25 nm and are much more rigid than actin filaments. They are long and strait and usually have one end attached to MTOC(microtubule organized center, called a centrosome

What are microtubules? Part of which cell-cell junctions are they? What is their diameter? How are they organized and where concentrated?

part of adherent junctions

long, hollow cylinders made of tubulin protein. have diameter 25 nm and are much more rigid than actin filaments. They are long and strait and usually have one end attached to MTOC(microtubule organized center, called a centrosome

What is a centrosome?

microtubule organizing center (MTOC)

what is MTOC?

microtubule organizing center (MTOC) also called centrosome

what kind of cell-cell junctions provide strength of cells?

adherent junctions

which 2 structures make up adherent junctions?

actin filaments and microtubules

What are desmosomes?

A type of junction in which cells are fastened together in strong sheets

have very high electron density

though them intermediate filaments connect two cells very closely like a sheet

What are intermediate filaments?

middle in diameter = 10nm = bigger than actin filaments and smaller than microtubules

are ropelike fibers. Different types do different things: one stretches throughout cytoplasm, giving cell mechanical strength another makes up nuclear lamina

in epithelium they connect not only neighboring cells but calls beyond them into a one strong network.

Entrance and exit points are called desmosomes

What are intermediate filaments? part of which cell -cell junction are they?

middle in diameter = 10nm = bigger than actin filaments and smaller than microtubules

are ropelike fibers. Different types do different things: one stretches throughout cytoplasm, giving cell mechanical strength another makes up nuclear lamina

in epithelium they connect not only neighboring cells but calls beyond them into a one strong network.

Entrance and exit points are called desmosomes

which kind of filaments are connecting not only neighboring epithelial cells but also those beyond, creating a generally mechanically strong epithelium

intermediate filaments

middle in diameter = 10nm = bigger than actin filaments and smaller than microtubules

are ropelike fibers. Different types do different things: one stretches throughout cytoplasm, giving cell mechanical strength another makes up nuclear lamina

in epithelium they connect not only neighboring cells but stretch beyond them into a one strong network.

Entrance and exit points are called desmosomes

what is desmosome function?

Cell-cell adhesion between cells!

Ancher cytoskeleton

Strength in tissue

see intemediate filaments

how do desmosomes attach to neigbouring cells desmosomes(besides intermediate filaments?

desmocolins(Ca dependent)

desmogleins

why are the proteins of the desmosomes more visible compared to the adherence junctions

desmosomes have higher concentration of proteins, making essentially a button while adherent junctions can be compared to a zipper

to what can adherent junctions be compeared?

zipper

what plays role of a zipper in cell-cell epithelial junctions?

adherent junctions

why are the proteins of the desmosomes can be compeared to?and why are they highly visible under electron microscopy?

desmosomes have a very higher concentration of proteins, and can be compeared to a button(пуговица) connecting two cells

What are gap junctions?

Small tunnels that connect cells, facilitating the movement of small molecules and ions between the cells.

made of connexins, forming a connexon

what do gap junctions do??

connect cytoplasm of neighboring cells

are ZO proteins are present in only tight junctions?

no,also in Gap junctions but in lower concentrations

what is the general structure of gap junction?

made of connexins, forming a connexon

Gap junctions themselves are small tunnels that connect cells, facilitating the movement of small molecules and ions between the cells. There are many those channels(напоминают пучки)

are Zona Ocludense proteins are present in only tight junctions?

no,also in Gap junctions but in lower concentrations

what do gap junctions remind of?(open/closed conformations)

donuts :also might be open or closed donuts

transport of what molecules requires Gap junctions between epithelial cells?

Ions

Nutrients

Amino acids

Peptides

Signaling molecules: IP3, ATP, AMP, cAMP, cGMP, Ca2+, glucose, glutathione

what is the function of Gap junctions?

to connect cytoplasm of neighboring cells

Diffusion of small molecules between cells

Ions

Nutrients

Amino acids

Peptides

Signaling molecules: IP3, ATP, AMP, cAMP, cGMP, Ca2+, glucose, glutathione

Essential in development and tissue function:

Electrical synchronization

Energy metabolism

Antigen presentation

Wound healing

Growth control

which tissue normal development and function aspects require functioning Gap junctions?

Essential in development and tissue function:

Electrical synchronization

Energy metabolism

Antigen presentation

Wound healing

Growth control

what is connexon consists of?

6 connexins

can neurons communicate

which connections in Gap junctions lead to eye problems(cataracts)?

connection 46 and 50

which connections in Gap junctions lead to deafness, oral erosions and hyperkeratosis?

connection 26

wo thich problems gap junction connection number connection 46 and 50 lead to?

eye problems(cataracts)

wo thich problems gap junction connection number 26 lead to?

deafness, oral erosions and hyperkeratosis

Summary of junctions

tight junctions = seals neigbouring cells together in an epithelial sheet to prevent leakage of molecules between them(fense)

adherens junctions = (a zipper, ensuring cell- cell adherence) joins an actin bundle in one cell to a similar bundle in a neighboring cell

desmosome =( buttons, provide tissue strength) joins the intermediate filaments in once cell to those in a neighbor

gap junctions = cell-cell channels that allow the passage of small water soluble ions and molecules

hemidesmosome = anchors intermediate filaments in a cell to basal lamina

describe the function of tight junctions

tight junctions = seals neigbouring cells together in an epithelial sheet to prevent leakage of molecules between them(fense)

describe the function of adherense junctions

adherens junctions = (a zipper, ensuring cell- cell adherence) joins an actin bundle in one cell to a similar bundle in a neighboring cell

describe the function of desmosomes

desmosome =( buttons, provide tissue strength) joins the intermediate filaments in once cell to those in a neighbor

describe the function of gap junctions

gap junctions = cell-cell channels that allow the passage of small water soluble ions and molecules

describe the function of hemidesmosome s

hemidesmosome = anchors intermediate filaments in a cell to basal lamina

how are gap junctions closed?

the grop of AA forms sort of a ball that closes the pore of gap junction channel

also it kinda looks how anus muscles work too(those 6 proteins)

so it is ball and chain mechanism essentially that also twists itself to close

what is necessary to make a gap junction?

6 connexins form 1 haf channel(connexon) in one cell

however another cell has to do the same those two have to connect into extracellular space to form a channel

many channels form gap junction

what is the structure of a gap junction?

6 connexins form 1 haf channel(connexon) in one cell

however another cell has to do the same those two have to connect into extracellular space to form a channel

many channels form gap junction

GPCR/RTK:

G Protein coupled receptor/receptortyrosine kinase

react to outside ligands

how can adherent junctions be used for signalling?

(Delta-Notch signalling) cadherins can be cleaved using regulated membrane proteolisis, and that part can go into nucleus and alter gene transcription

part of which junction can be used for signaling?

(Delta-Notch signalling) cadherins can be cleaved using regulated membrane proteolisis, and that part can go into nucleus and alter gene transcription

how can c adherins from adherense junctions be used for signalling?

(Delta-Notch signalling) cadherins can be cleaved using regulated membrane proteolisis, and that part can go into nucleus and alter gene transcription

how do cell-cell contacts regulate proliferation?

contact inhibition

contact inhibition

Less ZONAB: Less proliferation

More ZO-1: less proliferation

what is the mechanism behind cell-cell contacts regulate proliferation?

contact inhibition

Less ZONAB: Less proliferation

More ZO-1: less proliferation

how does ZONAB influences cell proliferation?how about ZO-1?

Less ZONAB: Less proliferation

More ZO-1: less proliferation

how does ZO-1 influences cell proliferation?how about ZONAB?

Less ZONAB: Less proliferation

More ZO-1: less proliferation

how does ZO-1 influences cell proliferation?

Less ZONAB: Less proliferation

More ZO-1: less proliferation

how does ZONAB influences cell proliferation?

Less ZONAB: Less proliferation

More ZO-1: less proliferation

ignaling from plasma membrane into the nucleus:Cell-cell junctions act as a magnet for transcription (co) factors

Loss of cell-cell junctions results in loss of the 'magnet' and translocation

with possible loss of contact inhibition

what are consequences for cell signalling in case of a loss of cell-cell junctions?

Loss of cell-cell junctions results in loss of the 'magnet' and translocation

with possible loss of contact inhibition

What is the Wnt pathway?

The Wnt signaling pathways are a group of signal transduction pathways which begin with proteins that pass signals into a cell through cell surface receptors.

what is desmosome composition?

what is delta-notch signalling?

The Notch pathway regulates cell proliferation, cell fate, differentiation, and cell death in all metazoans. Notch itself is a cell-surface receptor that transduces short-range signals by interacting with transmembrane ligands such as Delta (termed Delta-like in humans on neighboring cells. Ligand binding leads to cleavage and release of the Notch intracellular domain (NICD), which then travels to the nucleus to regulate transcriptional complexes containing the DNA-binding protein

how does delta-notch signalling work in cell-cell junctions(a display of contact inhibition)?

The Notch pathway regulates cell proliferation, cell fate, differentiation, and cell death in all metazoans. Notch itself is a cell-surface receptor that transduces short-range signals by interacting with transmembrane ligands such as Delta (termed Delta-like in humans on neighboring cells. Ligand binding leads to cleavage and release of the Notch intracellular domain (NICD), which then travels to the nucleus to regulate transcriptional complexes containing the DNA-binding protein

delta notch signaling and cell-cell junctions with contact inhibition

The Notch pathway regulates cell proliferation, cell fate, differentiation, and cell death in all metazoans. Notch itself is a cell-surface receptor that transduces short-range signals by interacting with transmembrane ligands such as Delta (termed Delta-like in humans on neighboring cells. Ligand binding leads to cleavage and release of the Notch intracellular domain (NICD), which then travels to the nucleus to regulate transcriptional complexes containing the DNA-binding protein

in cases of contact inhibition this signaling prevents cells to grow too much

what is the role of cadherin in cell-cell junctions and signaling?

Cadherin-catenin complexes are critical for the assembly of cell-cell adhesion structures known as adherens junctions. In addition to the mechanical linkage of neighboring cells to each other, these cell-cell adhesion protein complexes have recently emerged as important sensors and transmitters of the extracellular cues inside the cell body and into the nucleus. In the past few years, multiple studies have identified a connection between the cadherin-catenin protein complexes and major intracellular signaling pathways.

Cadherin-mediated intracellular signaling has a pivotal role in contact inhibition of cell proliferation

what is the role of in signaling and cell-cell contacts?

Cadherin-catenin complexes are critical for the assembly of cell-cell adhesion structures known as adherens junctions. In addition to the mechanical linkage of neighboring cells to each other, these cell-cell adhesion protein complexes have recently emerged as important sensors and transmitters of the extracellular cues inside the cell body and into the nucleus. In the past few years, multiple studies have identified a connection between the cadherin-catenin protein complexes and major intracellular signaling pathways.

Cadherin-mediated intracellular signaling has a pivotal role in contact inhibition of cell proliferation

Magnetic bar inhibition

ZO-1/ ZONAB

Less ZONAB: Less proliferation

More ZO-1: less proliferation

what is magnetic bar contact inhibition?

Less ZONAB: Less proliferation

More ZO-1: less proliferation

what are 4 main tissue types?give 3 examples of each

Epithelial cells

- lining of gastrointestinal tract organs

- other hollow organs

- skin surfaceetc

Nerve cells

- brain

- spinal cord

- nerves

Muscle cells

- cardiac muscle

- skeletal muscle

- smooth muscle

Connective tissue cells

- fat and other soft padding tissue - bone

- tendon

what are 4 main tissue types?what are examples?

Epithelial cells

- lining of gastrointestinal tract organs

- other hollow organs

- skin surfaceetc

Nerve cells

- brain

- spinal cord

- nerves

Muscle cells

- cardiac muscle

- skeletal muscle

- smooth muscle

Connective tissue cells

- fat and other soft padding tissue - bone

- tendon

what are examples of 4 main tissue types?

Epithelial cells

- lining of gastrointestinal tract organs

- other hollow organs

- skin surfaceetc

Nerve cells

- brain

- spinal cord

- nerves

Muscle cells

- cardiac muscle

- skeletal muscle

- smooth muscle

Connective tissue cells

- fat and other soft padding tissue - bone

- tendon