BIO 202: Chapter 11 - Cell Interactions (Unit 3)

cadherins

proteins that attach cytoskeletons of adjacent cells together to provide strong cell-cell adhesion

in plant cells, a polysaccharide that is used to synthesize cell walls, which protects cells and helps maintain their shape

cellulose

ECM of animal tissues: what composes the fibers and ground substance?

- fibers are protein, usually collagen - ground substance is a type of proteoglycan, a gelatinous polysaccharide

What do integrins attach to?

- inside of cytoskeleton - outside of ECM

What do cadherins attach to?

- inside of cytoskeleton - outside of other cadherins

3 stages of cell signaling

1. Reception 2. Transduction 3. Cell Response

How does the absence of a signal transduction cascade in the processing of steroid hormones affect the cellular response that is possible?

As with a signal transduction pathway, gene expression may be altered. Other types of responses, such as muscle contraction or the rapid mobilization of glucose, are not possible.

How do connective tissues resist mechanical stress?

ECM directly bears mechanical stresses of tension and compression

integrins

In animal cells, a membrane protein with two subunits that binds to ECM on the outside of cell and cytoskeleton on inside of the cell to interconnect the two (amphipathic)

Epinephrine acts as a signal molecule that attaches to _____ proteins.

G-protein-linked receptor

apoplast

In plants, the continuum of cell walls plus the extracellular spaces. Provides strength

symplast

In plants, the continuum of cytoplasm connected by plasmodesmata between cells. Coordinates behavior via exchange of materials

How does the absence of a signal transduction cascade in the processing of steroid hormones affect signal amplification?

No amplification can occur because the number of signaling molecules dictates the size of the response. Submit

epithelial tissue structure

One or more layers of densely arranged epithelial cells with very little extracellular matrix (basal lamina)

How does the absence of a signal transduction cascade in the processing of steroid hormones affect signal regulation?

Only one step is available for regulation, which includes either blocking the receptor or making it more responsive to the signaling molecule.

Predict what would happen if a mutant Ras protein was unable to exchange GDP for GTP.

The proteins downstream from Ras would not become phosphorylated

extracellular matrix (ECM)

a collection of extracellular molecules secreted by cells that provides structural and biochemical support to the surrounding cells.

desmosomes

a type of cell-cell junction in epithelial cells that are clusters of cadherins linked to intermediate filaments inside of the cell

tight junctions (animal cells)

a type of cell-cell junction in epithelial cells that bring the membranes of adjacent epithelial cells close enough together to form a seal between the cells critical in helping epithelial cells to serve a barrier function

gap junctions (animal cell's version of plasmodesmata)

a type of cell-cell junction in epithelial cells that provide small and non-permanent cytoplasmic channels between adjacent animal cells

Hemidesmosomes

anchor cells to the basal lamina

fibronectin and laminin

cell adhesion proteins in ground substance of animal cell tissues

The _______ microfibrils in plants and ______ fibrils in animals functionally resemble the _______________ in reinforced concrete. The _________ in plants and ________ in animals functionally resemble the _________

cellulose; collagen; steel rods; pectins; proteoglycans; concrete ground substance

in animal cells, long fibers of protein found inn the ECM that provides structural support for cells

collagen

in animal cells, membrane protein complexes that strengthen the adhesion between adjacent cells, like rivets, to protect against pulling forces

desmosomes

The primary role of _____ is to bind animal cells together.

desmosomes (anchoring junctions)

How do plant cells share materials?

direct cytoplasmic connections between cells allow cells int he same tissue to share materials plasmodesmata create gaps that connect the cell membranes that allow exchange of materials

In animal cells, small channels that form across the plasma membrane of adjacent cells; especially important in intercellular communication

gap junctions

_____ aid in the coordination of the activities of adjacent animal cells.

gap junctions

The cleavage of glycogen by glycogen phosphorylase releases _____.

glucose-1-phosphate

epithelial tissue cell to ECM ratio

high cell to ECM ratio

Where are protein components of the extracellular matrix synthesized?

in the rough ER

A signal molecule is also known as a(n) _____.

ligand

connective tissue cell to ECM ratio

low cell to ECM ratio

fiber composite structure

materials that are good at resisting twisting and pulling mechanical forces (tension) as well as compressive forces

How do epithelial tissues resist mechanical stress?

mechanical stresses are transmitted from cell to cell by cytoskeletal filaments anchored to cell-matrix and cell-cell adhesion sites

A bacterium lacking the receptor for responding to quorum-sensing signals would be unable to ________.

mount a coordinated response with other microbes

ground substance

part of the ECM structure that resists compression

fibers

part of the ECM structure that resists tension (twisting/pulling force)

How are plant cells combined with one another?

plant cell walls are "glued" together by the middle lamella, formed by the gelatinous pectins from adjacent cell walls growing together results in very strong interaction between cells and makes plants very rigid

in plant cells, small channels between cells that are otherwise surrounded by walls; enable movement of water and solutes between cells

plasmodesmata

Which cell junctions allow for communications between cells?

plasmodesmata and gap junctions

Plant extracellular filaments consist of _________

polysaccharides (cellulose)

Animal cell extracellular filaments consist of __________

proteins (collagen)

Extracellular filaments in both animal and plant cells:

resist pulling forces, are able to slide past each other, are crisscrossed

connective tissue structure

sparse cells in a very voluminous extracellular matrix (low cell to ECM ratio)

structure of collagen

strong material, very flexible

A fiber composite consists of cross-linked filaments that withstand ________ and a ground substance that withstands __________

tension, compression

cellulose

the fibers of a plant's ECM (provides tension resistance)

pectin

the ground substance in a plant's ECM (provides compression resistance)

In animal cells, membrane proteins that create a watertight seal between cells

tight junctions

What cell junction forms a barrier to the passage of materials?

tight junctions

What kinds of molecules pass through gap junctions in animal cells tissue?

water, ions, monomers