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Biology 202: > Chapter 11 > Flashcards

Chapter 11 Flashcards

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1
Q

What is the ECM?

A

Collection of proteins and polysaccharides that cells secrete into their local environment, that then create the substrates exterior to cell so other cells can interact.

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2
Q

All tissue’s have what two components?

A
  • A cellular component

- An ECM component

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3
Q

T/F an ECM’s make up is cellular dependent?

A
  • True
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4
Q

Describe the analogy of ECM to cement roadway?

plant oriented

A

road: they primarily lay the ground with steel rods at various levels running perpendicular of one anther
- Then they pour the concrete over top (made of various mixtures and such).
- The two elements hold very different functions much like a fiber composite.
-Ex: the steel rods = the fibers prevent/protect against twisting and pulling forces.
concrete = the ground substance, serves to resist compression via water in it.
—————————————————————–
- Most ECM’s have a highly similar structure.
- I.E. : the plant cell wall is a fiber composite tied extra cellular matrix.
- The cellulose makes hydrogen bonds with other fibers to make strong polysaccharides acting like the rods in road work.
Cell wall = fiber component
//////////////////////////////////////
The ground component = pectin ( polysaccharide) that is hydroscopic - binds a lot of water, and causes them to swell up making them uncompressible.
- Much like the concrete.

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5
Q

Many organ systems contain what two different tissue types?

A
  • Epithelial tissue: Lots of tightly packed cells
  • that form adhesions to one anther and
  • located on top of a very dense ECM.
  • Connective tissue:
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6
Q

What is the purpose of epithelial cells?

A
  • They serve as a barrier

- They secrete a type of protein that is used to develop a layer of cells known as the basal lamina ( basement membrane)

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7
Q

What is located beneath the epithelial layer?

A

Connective tissue:

  • much more voluminous layer
  • contains less densely packed cells/organelles
  • much higher ratio of ECM to cells
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8
Q

Which is denser connective tissue or epithelial tissue?

A

Epithelial tissue

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9
Q

T/F the types of proteins and polysaccharides found within the ECM of a connective tissue vs. epithelial cells of the same organism are different?

A
  • True.
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10
Q

T/F differing types of cell densities and ECM’s allows epithelial and connective tissues to handle mechanical stress in different ways?

A

True, the differences in their properties allows them to better handle mechanical stress in different ways

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11
Q

How do epithelial tissues handle mechanical stress?

A

It is resisted strongly through the large cell to cell contacts between adjacent cells.

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12
Q

How do a connective tissues handle differing mechanical stress?

A

-primarily, the ECM that provides resistance to mechanical stresses.

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13
Q

What are commonalties between the connective and epithelial tissues ECM?

A
  • usually the fiber component of their respective ECM’s is full of collagen.
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14
Q

What is a collagen fibril?

A
  • collagen proteins will line up next to one anther to make long, think, collagen fibers
  • a collagen fibril is very elastic, strong and flexible
  • thus why animal tissue is more bendy > plants.
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15
Q

T/F the collagen fibers in the connective tissue of both plants and animals is layered on top of one anther for maximal strength?

A

F, they are oriented adjacent to one anther at tons of differing angles for max strength.

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16
Q

What is the difference in the fiber components of the ECM s of plants and animals?

A 
Plant = cellulose
Animal = collagen
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17
Q

What is the ground substance component of the ECM’s?

A
  • A category of proteins known as proteoglycans.
  • Short protein with long poly saccharide chains branching off of it.
  • Hydroscopic.
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18
Q

What are the components of the monomers of the polysaccharide chains of proteoglycans.?

A
  • charged, with lots of functional polar groups attached to them, thus
  • Making them very hydroscopic ( can make lots of hydrogen bonds, or bond with lots of water molecules)
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19
Q

What are the other proteins in the ECM , besides , collagen provide a better adhesive substrate for cells?

A
  • They are referred to as (laminin).
  • They interact with proteins in the plasma membrane
  • Helps provide an adhesive substrate for cells in the ECM to grab on to.
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20
Q

T/F collagen is a great substrate for cells to bind to?

A

False

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21
Q

What is the prime adhesive substrate for cells in the ECM of connective tissue to bind to? (type of laminin)

A

Fibronectin,

  • binds to collagen
  • provides a “foothold” for other cells to bind to
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22
Q

How do cells interact with these substrates like laminin and fibronectin ?

  • What is the key in what is occurring in this process?
A
  • Through integral membrane proteins called integrins.
  • on the extracellular side of the cell they bind to the ECM, which is what secures them to fibronectin or laminin.
  • on the inside part of the cell they bind to the cytoskeleton ( actin or intermediate filaments)
  • Integrin is connecting the ECM (laminin or fibronectin) on the outside of the cell to the strong cytoskeletal structures inside the cell.
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23
Q

For plant cells adjacent of each where must they be located to interact with one anther?

A
  • There cell walls must grow together.
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24
Q

What is the region in-between two plant cells that are interacting with one anther?

A
  • Middle lamella, basically where the two cells walls have grown together.
  • proteoglycan acts like glue to keep them stuck to one anther.
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25
Q

What are the variety of structures seen in the middle lamella known as and what is their function?

A
  • plasmodesmata, places where their is a passage between the two cell walls, through the lamella.
  • allowing the two differing cells to have direct exchange of cytoplasmic materials.
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26
Q

What is the size of plasmodesmata and why is it important?

A
  • They are fairly large and allow water to flow back and forth.
  • even large macro molecules and even organelle protrusions to span form one cell to the next.
27
Q

What does plasmodesmata do for the structural integrity of the plant?

A
  • It allows for the cells to be highly integrated:
  • Structurally ( they are stuck together very tightly by these middle lamella)
  • Functionally ( they are doing so much sharing that they kind of act like a unit.)
28
Q

What is the shared cytoplasm between plant cells with plasmodesma?

A

symplast

29
Q

What are the shared cell walls of plants cells referred to as?

A

apoplast

30
Q

t/f we don’t see the same cell degree and strength of cell-cell junctions in connective tissue that we see in epithelial tissues?

A

True, remember they are less densely packs.

31
Q

What are the three primary types of cell junctions in animal cells (epithelial)?

A

Gap junctions- act as channels for cytoplasmic material between adjacent cells
- forms when two membrane channels line up with one anther, thus creating a long and thin continuous channel that spans both of the lipid bi-layers
- usually forms in clusters
- weak at mechanical stress points
—————————————————–
Tight junctions- help seal cells and prevent material from sneaking from one adjacent cell to the next.
- form from very small integral membrane proteins in the membrane of two adjacent cells.
- essentially stiches the two together.
- critical in the barrier function of the tissue.
- plugs to space between two adjacent cells about 2/3 of the way to the top.
- weak at mechanical stress points
———————————————
Desmosomes- provide the real adhesive strength of adjacent cells to one anther ( connected to the cytoskeleton cells)
- Strong at mechanical stress points.

32
Q

What is the animal cell version of plasmodesmata?

A

Gap junctions,

  • Structurally very different
  • allows for the movement of cytosol between cells and any really small molecules that is dissolved in the cytosol.
  • not built for large macromolecules like the plasmodesma can move.
33
Q

What is the purpose of the cadherin molecules?

A
  • They serve to provide strong cell-cell adhesion in epithelial tissues.
  • family of proteins
  • integral membrane proteins, that serve to bind to the inside ( cytoplasmic side) to the cytoskeleton (intermediate filaments) and on the outside to cadherins on adjacent cells.
  • Very strong, thus providing good support in the duration of mechanical stress.
34
Q

What is the desmosomes?

A
  • linked to intermediate filaments in the cytoskeleton inside the cell.
  • mediating very strong adhesions to one anther.
  • binds to cadherins in a desmosome of an adjacent cell.
35
Q

What is the purpose of the intermediate filaments in regard to cell- cell adhesions?

A
  • They tie all the desmosomes of one cell together to make into a singular functionally adhesive unit.
36
Q

t/f intermediate filaments go from one cell to the next?

A

false

37
Q

What is the scientific name for the basement membrane?

A

basal lamina

38
Q

where are integrin proteins found?

A

basal lamina

39
Q

What is a hemi-desmosome?

A

cluster of integrins connected to the basal lamina linked to the intermediate cytoskeleton on the inside.

40
Q

what is the chemical signal that allows cells to communicate over a distance?

A

hormones

41
Q

t/f hormones are a wide variety of molecule types?

A

T, amino acids, proteins, lipids, ect

42
Q

What has to happen in order for a chemical signal to work?

A
  1. ) A cell has to release a chemical signal out into an environment.
  2. ) A cell has to respond via binding to the cell signal
  3. ) the bind cell must be the correct shape in order to bind to signal.
  4. ) following binding, the cell that binded to the hormone will change in shape a cause a signaling pathway.
43
Q

What are the steps of a signaling pathway?

A
  1. ) signal reception
  2. ) signal processing and amplification
  3. ) signal response
  4. ) signal deactivation
44
Q

Describe signal reception?

A
  • them chemical nature of the hormone, in other words, different hormones activate different receptors,
  • The primary concern is whether or not the hormone is able to get across the cell membrane directly and into the interior of the cell.
45
Q

Which hormones can get across the cell membrane directly and into the interior of the cell?

A
  • hormones that are lipid soluble and hydrophobic
  • primarily derivatives of lipids like: steroids’
  • They bind to intercellular protein receptors.
  • meaning it can make it through the membrane and bind to a receptor inside the cell
  • large and polar/ charged proteins, would not on their own be able to get into the cell, so their receptors are on the cell surface (integral membrane protein):
  • amino acid derivatives, peptides and polypeptides
46
Q

ex: what are some hydrophobic hormones mentioned in lecture, name some and their commonalties?
2. ) where are their intracellular receptors located?

A
  • cortisol, testosterones, estrogen, dioxin
  • derived from cholesterol, meaning they are mostly small and nonpolar
  • ## thus they can get through the bi layer on their own.cytosol and the nucleus
47
Q

what does the binding to the hormone usually trigger in the case of lipid soluble or hydrophobic steroids’?

A
  • causes the receptor + plus hormone to go to the nucleus.
  • receptor = intracellular receptor proteins.
  • Does this via:
  • hormone entering the bilayer and binding to its receptor (intracellular receptor), thus changing its shape.
  • exposes its NLS
  • then is directed to the nucleus
  • directly binds to DNA and directly regulates which genes are turned on and off (which genes are transcribed via messenger rna.)
48
Q

How does amplification occur in terms of steroid hormone receptor mean?

A
  • single hormone receptor binding event can trigger a really large and robust response in a cell.
49
Q

Which types of hormones can amplification occur in?

2.) describe what is happening?

A
  • hydrophobic/lipid soluble hormones.
    2.) when the hormone goes through the process of binding with its receptor, changing in shape, thus exposing its NLS and finds it way to the nucleus, then allowing for messenger rna to transcribe certain genes….
  • the rna is then sent to the cytosol and used as a template to make the protein, based off the transcript,
    BUT HOLD UP WAIT A MINUTE…..
    ———————————————————-
    *** a single messenger RNA can make more than one protein,
    meaning: one hormone can have significant effect on the protein composition of cell..
50
Q

What do cell surface receptors bind with?

  1. )What are these receptors?
  2. ) what happens once blank binds to the receptor?
A
  • hormones that are large and charged, or hydrophilic.
    2. ) integral membrane proteins.
    3. ) The hydrophilic hormone binds to the extracellular face of the receptor, causing a change in shape to the receptor.
  • Then that propagates it to open to the intracellular side.
  • Then causes signal transduction to occur.
51
Q

What is signal transduction in hormones that are hydrophilic/charged enter via a integral membrane protein?
2.) - T/F Amplification allows for strong a robust?

A

from extracellular signal to intracellular signal/ Signal is amplified ( in most cases).

i. e.
- Activated protein A enters and activates four molecules of protein b before it gets shut down.
- Activated protein B then activates more than one molecule of protein C before getting cut off.
- ————————————————————————-
- in just a few steps we have a bunch of molecules of protein C from a single protein A
- ————————————————————————-
- True.

52
Q

What are the three primary categories of cell-surface receptors?
- what types of molecules use these?
WHEN THE ENZYME LINED RECEPTOR HAS A HORMONE BOND TO IT IS CALLED….?

A
  • hydrophilic steroids’:
    1.) ion channel coupled receptors:
    binding of hormone to the receptor, causes the channel to open and allows for ions to cross the membrane.
  • ## important for phis and Nero bio2.) G-protein coupled receptors:
  • the effect or the hormone binding to the receptor causes the cytoplasmic domain of that receptor to activate a G-protein within the cell.
  • a G-protein is like a molecular switch ( binds to GTP: on and GDP=off)
    -When the G-protein is on they bind to an activated enzyme that will make a new chemical within the cell.
    —————————————————————————-
    3.) Enzyme linked receptors:
  • receptors themselves have enzymatic activity:
  • receptor has the ability to catalyze certain reactions, but will only do so when bound to the hormone.
    WHEN THE ENZYME LINED RECEPTOR HAS A HORMONE BOND TO IT IS CALLED….? active catalytic domain
  • The active catalytic domain is caused by two molecules that dimerize.
  • This causes their receptors to modify and activate the next step in the pathway.
53
Q

Describe the process of a G-protein linked receptor?

A
  • G protein is inactive, (bound to GDP)
    2.) - signal arrives and binds it to a receptor, thus changing the shape of the cytoplasmic domain of the receptor, where the G-protein binds to the receptor.
    4.) - This causes the release of GDP, then picks up a GTP- making it active.
    ————————————————————————
    ( when GTP hydrolysis it self back to GDP it is no longer active.)
    —————————————————————————-
    4.) Then, binds to an enzyme- at which point the enzyme produces new chemicals within the cell (second messengers).
54
Q

What is G-protein-coupled receptor pathway?

- Talk about the Epinephrine example:

A

Ex: epinephrine pathway; Epinephrine, or a derivate of an amino acid binds to the receptor in the membrane (G coupled protein receptor).

  1. ) Adrenaline binds to the receptor (G-Protein Coupled Receptor) making it active.
    - and in turn makes it so the receptor no longer associates with a G-protein. G sub s
    - GDP is released and GTP is picked up which activates the enzyme adenylyl cyclase.
  2. ) Adenylyl cyclase, then takes atp and turns it to cyclic amp ( second messenger)
  3. ) which regulates anther phosphorylase kinase and adds a phosphate to it.
    - all working towards glycogen break down.
55
Q

What is a kinase?

A
  • An enzyme that will add a phosphate to something else.
56
Q

What are receptor tyrosine kinases?

A
  • a subcategory of enzyme linked receptors:
  • contains a kinase receptor that phosphorylases a tyrosine amino acid on its target.
    1. ) - The hormone binds to the receptor, causing: two molecules of receptor to dimerize.
    2. ) then the two molecules of receptor phosphorylate one anther. (Cross Phosphorylation)
    3. ) The P groups located on the bottom of the enzyme, within the cell, are tyrosine and they serve as docking sites for other signaling molecules to bind to.
    4. ) Then a G-protein ( Ras) binds to a tyrosine, causing it to lose its GDP and pick up an GTP (active)
    5. ) typically the activated G-protein (Ras) causes a kinase cascade
57
Q

Why aren’t preceptor tyrosine kinases the same as G-protein coupled receptor?

A
  • Ras or the G-protein is bound to the docking tyrosine, as opposed to the enzyme itself.
58
Q

T/F, different pathways can intersect?

why is either answer that is potentially correct important?

A

True, Crosstalk
2.) it is important for cells because it is how they integrate inside the different extracellular events at their surface.

59
Q

T/F single cells change their activity when they reach a certain density?

A
  • True, via quorum-threshold, # of individuals are present and quorum sensing
  • a way for certain cells to tell when they have reached a certain density.
  • they have lots of receptors that allow them to sense what is near and around
60
Q

What is a biofilm?

A
  • A type of extracellular matrix known for being composed of carbohydrates and allowing for many bacterial cells to be added and locked into place at high density location.
  • Related to implants.
61
Q

T/F do we see quorum sensing in eukaryotes?

A

yes, especially in a slime mold

62
Q

What type of tissue is hydroscopic?

A

Pectin/ peptidoglycan.

- any of the ground substance tissues.

63
Q

What provides the bulk of resistance to mechanical stress in epithelial tissue?

A
  • the connection between :
    strong and stable intermediate filaments tie together all the points of the desmosome and hemidesmosome.
    -
64
Q

What is a second messenger?

A
  • A chemical that is produced inside the cell that is in response to an extracellular signal at the cell surface.

Biology 202: (39 decks)

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