10/15 Lecture video notes :( 1/10

understand dont memorize - if in lecture is in exam

cytoskelton and cell molityt, cell cel adhesion, cell cycl ergulation, and cancer these are the four topics

bodies have 210 cell types in humans, and approcilmaly 100 trilllion cells. each cell type. has its own pattern of trnacipriotn and has its own set of genes turned on and all the other genes turned off.  tracipriton at the level of organism we  must understand at least 210 differen ptatterns of tranciption there must be 210 diffferent sets of genes.  

what cells need to do to be part of tissues and organs, dif cellshave dif shapes, celss in nose eye and lung, they hav dif shapes. how do cells know what shape to adopt? we dont know. but there are molecules that give the cell its shape, and the seonc thing sis cells have to stick to eachother , cell adhesion. these cells in your nose form a barrier between inside and outside and keep things from moving into your body that u dont want in your body so the cells stick togeter very tightly . this is cell adhesion. ECM , 

Then ther eis the basal lamina which is a set of protein secreted by the cell that basically make up a solid structuere that cells can stick to and so part of the cell adhesion is to ithtly adher to the extracellular matrix. 

neurons rods cons reahc out and tough other neurons in a wirign arrangment to send electrical singal to eachother. that is a form of cell adhesion. cell adhesion is critical for building uour brain. withing a tissue cells are in a soical context, they are always talking to eacother. tissue hoemstasis we are all the same shape and size thopughout the life , we dont change all the time. there are also tisseues that are dying all the time so tissue hoemstssis is balacning cell death with cell birth so that any organ has roughly the same number of cells at any time.  

SKIN - dead cells are on the surface and we have to replace them , if we mess with a. knife and we cut into our skin, then uour skin then has to replace those mising cells and divide faster , we have to divide faster than before to repair. there has to have a xingaling mechanism that is tisssue hoemstsis. 

where do cells come from?

stem cells are cells that divide to give rise to all the other cells that make up the tissue, stem cells are realtively undifferentiated, when a stem cel divides it gives rise to two cells one of which itself a stem cell that renews the supplies of stem cell so we always have stem cells and the other cell can become spealized and undero differentation and no longer stem cell and beocme cell tat makes up the  tissue, it will be called terimally differentated cell (the worker bees of the tissue). these dont divide. 

it takes multiple steps to become a termianlly differnatied cell from a stem cell. symetric division is two cell products are the same.  and if they are differnet htey are assymetric. 

transient amplifying cells are the ones that area amplified

adult stem cells give rise to cell within a particualr tissue or organ, so blood stem cells give rise to terminally differnated blood cells not muscl ecells or neuron cells. 

often but not always stem cells are located in a partiuclar place in the  tissue, in the skin theya re located in the niche/crypt and they always stay there.  and then the differntation cells are moved in a particuarl pathway. cell movment . so cell division, differntation, and movment to properly build the skin.  adult stem cells are multipotentn.  

Embyronic stem cells are pluripotent. can give rise to any type of cell in the body. we take emrbyonci stem cells in differnt cultue and differnate them into any, we can maube biuild new organs one day. 

prorpotes of cells iwthin tissue, they have to adpot a defined shape, carry out and express a set of genes (differnatte) carry our spealized funciton, replace dad cells with ne ones, remian distainct from cells in enighboring tisses and adhere to eachother and communicate with eachother. 

in terms of communciations, there are four global reposnes, 1. for the cells to survive like EGF signal growth factor. . . 

there are cytoskins and mitogeines are singling moclules are all the same kind of singlaing molcules , cutokines are the ones for the immune system. growth factors are what they are. 

addition sinals can tell the cell to divide, fg can tell it to differtntation . singlin is going on all the  time. cells that dont recieve the porper singals die by a process of apotsis  in which the cell commits suicide. it is part of a pathway of events in which the cell killts itself. 

in emrbuonic developmetn of a frog paw, 

ancesstorys had web digest and they had to get rid of the webbed so the cells had to undergo apotsis  

i might or might not have stopped cuz i started getting tired af

at 30 mins

cells have one tyep and one shape have to stick to their neighboer weheter its the same type or dif type. In terms of communiations there are four global reponse to singals. the first one is to sruvive. EGF’s  are growth factors that can tell the cell to just survive, not differntate and not divide,. 

There are mitogens and cytokines that are the saemt hing as growth factors/ singling molcules. 

citokines are the singling moleucles in immune system. if we receive addtion singals that can tell the cell to divide, another set of singals can tell it to differntate. cells can die, cells that have the poper singals die from apotsis. it is part of a pathway of events . 

this occurs during normal developmoent. in early development of i think a mouse paw, they have webbed digits. early in evlotion organims that came before the mouse have webbed paw digist. there are developmental pathways that ollow evolutionary pathways, the mouse start building out webbed digist and get rid of the webbing. and so for that to happen the cells underhgo apotsis and die. so cells die  through apoptosis when they dont receive singals but there are also some singal durinb developemnt that tell speicifc cells to die.  so the mouse are getting singals that say kill off the webbed cells to make indepenent digits. same thing with tadpoles that are going to be frogs. the tail cells are going to die througha potsis and then it recyles its contentst to build a frog by resuing the part that  were in the tail . 

apoptosis can occur during normal developmetna nd cellular damage like dna damage. cells are smart and have mechanism to repaire damange to dna , which damange to dna happens all the time. dna can react with water in such a way that u loose a couple base pairs just reacting with water. the cell has to find the damage and fix it. if not fixed properly a mutation happens. cells puts in huge amoutn of effort to protect genetic matera, the dna. 

the cell cycle machinery is desinged to protect your dna dn trmait your dna o the daughter cells.  cells have a mecahnism that measures the amount of damanged dna, and if the damage is relatively low and there is enough machienry to fix the cell will fix the damange, if the cell measure damange to be high then the cell will commit sewerslide to avoid becoming cancerous. 

why do cells need signals just to surivie? this is because singal helps keep the parts in the right place. ex: skin cells are pushed into the muscle because u got vaccinated. a ball of skin do not get made in the myscle. because skin cells signal other skinc ells, if a skinc ell ends up in the muscle its not getting the righ singal so its not going to divide and not surivde. it allows us to keep cell types into respective tissues. 

if your surviiving ur not diviidng , if your dividing your not just surivivng. so singal tranduciton pathways that turn somet hign on and other thingd off.  if were turning on the genes to go down one development pathway were leaving off ther genes that go down a dif pathway. if your terminally differnating you adopt a dif pathway. 

stem cells undergo self renewl to generat a stem cel and then a partically differnaited cell, a transint amplifying cell, and then we have a serious of divisions and differnation steps until we end up with terminally differnated cells which are spezliased and dont divide. this is the linage of a cell

cancer -  what are the propties of cancer cell? rapidly dividing, and when theyre not suppose to . metastisis -skin cancer cells ending up in the brain, what is th primary way it travels? you got cells that divide when theyre not suppsoe to divide, and they gain mobility to crawl out of the blood vessels and into the tissues theyre not suppose to be in, this is called cell motlity.  cells know what tissue theyre in, but if u have carinoma it can form a tissue in your muslc ebecause the singling is screwed up. it learned to divide in a tissue where it should be commitin apotosis.  almsot all cancer cells are screwered up , liketheir dna . 

hallfmartk of cancers  is innparopriate growth, metasist and divide in new tissue to formasecondary tunmor.