Chapter 11: cell-cell interactions

what is scurvy?

-Vitamin C deficiency, vitamin C is co-fact for enzyme that makes collagen, if you don't get enough you wont make enough collagen ( wont have cell protection) -Capillary bursting - b/c cell walls aren't strong enough to hold in contents -Break down of teeth -Joint issues

signal receptor

-cellular protein that binds to a particular signaling molecule and triggers a response by the cell -it changes its shape and activity after binding to signal molecule -receptors for lipid insoluble signals are transmembrane proteins in the plasma membrane -receptors for lipid soluble signals are often located in the cytosol ( steroid/hormones)

what fibers make up the ECM of plants?

-cellulose -pectins -they both provide structure and protection

cataracts

-clouding of lens in the eye -has to do with gap junctions- things aren't able to travel between cells and proteins build up and become clogged causing cloudiness -causes the building up of proteins on the eye

what fibers make up the animal ECM?

-collagen fibers-long proteins in a lattice pattern function is to protect the cell ( keeps it from getting squished) -proteoglycans- fill in the space like "cement", function as a protection measure to the cell the support cells (attached to the outside of the cell

what are extracellular material made of?

-cross linked network of long filaments ( that resist being pulled or pushed lengthwise) embedded in stiff surround material called ground substance ( gel forming mixture of polysaccharides that acts like a concrete)

gap junction

-directly connects the cytosol of adjacent animal cells, allowing passage of water, ions, and small molecules between cells

Cell interactions in the heart

-gap junction -very important that the heart contracts at once

what is the purpose of the secondary cell wall in plants?

-gives it extra strength -gives in between primary cell wall and plasma membrane -middle lamella- extra ECM that glues two cells together

cardiomyopathy

-has to do with desmosomes- which keep cells together and elastic -ARVP- muscle cell death because the cells aren't staying together. when they cells are replaced they are replaced with fatty cells -there is a genetic predisposition

inflammatory bowel disease

-has to do with tight junctions -stuff in bowel leaks out and causes inflammation causes by own immune system if tight junctions are faulty -very severe- churns disease and ulcerative colitis -irratible bowel syndrome is more common but less severe

what are desmosomes?

-inside of cell -connects inside of one cell to the inside of another -connects the cytoskeletons of cells -made of proteins -in skin and myocardium cells it keeps the cells elastic so the cells bounce back they are stretched

tight junction

-links plasma membrane of adjacent animal cells forming a barrier that restricts movement of substances in the space between the cells -water tight seal -two cells sewn together like a quilt -although held close together they have weak adhesions and can be easily broken

what is the primary cell wall composed of?

-microfibrils ( a bundle of cellulose strands that serve as the fibrous component in plant cell walls) -pectins ( gelatinous polysaccharide found in primary cell walls of plant cells. attracts and holds water, forming a gel that resist compression forces and helps keep the cell wall moist) -hydrophilic

Be familiar with the adenosine and epinephrine pathways.

-signaling cell -production of signaling molecule exocytosis of signaling molecule -signal molecule travels to target cell -binding to receptor on target cell -G protein activation -second messenger is released -response

processing lipid soluble signaling molecules

-steroid hormones such as estrogens and cortisol ( hydrophobic -most are carried through the bloodstream via hydrophilic proteins -when they reach their target cells they are released from carrier proteins and enter the cytosol -reaches hormone receptor complex in cytosol and then is transported to the nucleus where it triggers gene expression -causes cell to change the function or shape of the cell

how are connections between animal cells

-tight junctions -desmosomes -gap junctions

lignin

a complex polymer built from six carbon rings and found in the secondary cell walls of some plants; -stiff and strong( helps withstand forces of gravity and wind) -most abundant in woody plant parts

tissues

a group of cells that function as a unit, such as muscle tissue in and animal or xylem tissue in plants -the amount of ECM varies from tissue to tissue -skin cells have very little ECM while bone and cartilage have a lot of ECM

second messenger

a nonprotein signaling molecule produced or activated inside a cell in response to stimulation at the cell surface -commonly used to relay the message of a hormone or other extracellular signaling molecule

how do multicellular organisms do cell to cell signaling ?

allows distant cells to communicate through signaling molecules

laminins

an abundant protein in the extracellular matrix (ECM) of animals that binds to other ECM components and to interns helping to anchor cells -found in basal lamina

epithelia/epithelium

an animal tissue consisting of sheetlike layers of tightly packed cells that line and organ, a gland, a duct, or a body surface

differences between the animal ECM and plant/bacteria/archea/algae/fungi ECM

animal ECM contains much more protein relative to carbohydrate than does a cell wall -plant ECM is much less flexible because of this

integrins

any class of cell surface proteins that bind to proteins in the extracellular matrix, thus holding cells in place. Some interns also function in cell-cell adhesions -connects the ECM to the cytoskeleton -transmits signals that inform the cell it is in right place an anchored properly- cell death if linkage breaks

hormones

any of many different signaling molecules that circulate throughout the plant or animal body and can trigger characteristic responses in distant target cells at very low concentrations -include peptides, steroids, and gases

G proteins

any various proteins that are activated by binding to guanosine triphosphate and inactivated when GTP is hydrolyzed to GDP

cadherins

attach cells to other cells -involved in selective cell-cell adhesion -important for coordinating movements of cells and the establishment of tissues during embryological development

how does the flight or fight response work?

brain sends out signals to cells to focus on survival

desmosomes

cell to cell attachment structure in animals consisting of cadherins and other proteins anchored to intermediate filaments -serves to link the cytoskeletons of adjacent cells to form strong intercellular attachments throughout the tissue

how do plasmodesmata connect cells

connect cells via membrane line channels -c4 ships carbon from the mesophyll cells to bundle sheet cells

proteoglycan

consist of a core protein attached to many polysaccharides -gel forming ground substance

plasma membrane

consists of a phospholipid bilayer studded with membrane proteins that regulate the transport of substances -integral proteins- embedded in bilayer -peripheral proteins- attached to the surface

collagen

fibrous ,pliable, cable like glycoprotein that is a major component of ECM of animal cells

where does vitamin C occur?

in fruits and veggies -not an issue in the present because lots of foods are fortified

cross-talk

interactions among signaling pathways triggered by different signals that modify a cellular response -getting advice from multiple people before making a decision

caffeine and adenosine

o Body has a lot of adenosine when you haven't slept in awhile o But because caffeine is close to the same shape it can bind to a receptors and block them up so adenosine wont bind and you feel awake o Caffeine Tolerance ♣ Receptors can stop reacting with caffeine bc they lose affinity ♣ The body will make adenosine receptors o Caffeine is an antagonist- because it inhibits adenosine receptors

• What is the main signaling molecule for fight or flight response?

o Epinephrine made in signaling cells of the adrenal glands of the kidneys o Antagonist will slow down effects of epinephrine -like bp meds, panic disorder, beta blockers

how does cyclic AMP help with flight or fight?

o It will attach to enzyme, the enzyme will become active o Once activated it will active glycogen phosphorylate ( which breaks down glycogen) o Helps you run really fast when your scared

what does the middle lamella contain?

pectins - gelatinous polysaccharides that help glue together the walls of adjacent cells

plasmodesmata

physical connections between two plant cells, consisting of membrane lined gaps in the cell walls through which the cell's plasma membranes, cytoplasm, and smooth ER can connect directly

what are gap junctions?

pores between cells that allow signals between one cell to the next -plasmodesmata in plants

what does the extracellular matrix do in animal cells?

provides structural support -made up of collagen and proteoglycans

g protein coupling receptors

signal binding by a receptor directly trigger the activation of a G protein -leads to production of second messenger or initiation of phosphorylation cascade

processing lipid insoluble signaling molecules

signal that arrives on the surface cell must produce a intracellular signal

what is the ECM?

the extracellular matrix

primary cell wall

the outer most layer of a plant cell wall, made of cellulose fiber and gelatinous polysaccharides, that defines the shape of the cell and withstands the turgor pressure of the plasma membrane

turgor pressure

the outward pressure exerted by the fluid contents of a living plant cell against its cell wall

signal transduction

the process by which a stimulus ( hormone, neurotransmitter etc) outside a cell is converted to and intracellular signal required for cellular response

multicellularity

the sate of being composed of many cells that adhere to each other and do not express the same genes, resulting in cells with specialized functions

selective adhesion

the tendency of cells of one tissue type to specifically adhere to other cells of the same type

secondary cell wall

the thickened inner layer of a cell wall formed by certain plant cells as they mature and after they have stopped growing; contains lignin in water conduction cells. P -provides support and protection

what allows plants to stand up straight?

their cell wall is a part of their ECM

how are proteins of the ECM made?

they are synthesized in the rough ER, processed in the Golgi, and secreted from the cel via exocytosis -after secretion the proteins may assemble into larger structures ( groups of collagen form collagen fibrils these will eventually makeup large collagen fibers)

what are tight junctions?

water tight seal between cells -to prevent leakage

expansins

young plant cells secrete these proteins into their cell wall -it breaks down hydrogen bonds between components in the primary cell wall of plants allowing it to expand for cell growth