Chapter 11: Cell to Cell Interactions

signals interact via crosstalk

one pathway has the ability to either activate or inhibit another pathway within the cell

Plasmodesmata is a structure in which of the following types of cell?

plant cell

In animal cells, which of the following proteins is most abundant in the extracellular matrix?

collagen

A signal molecule is also known as a(n) _____. 1. protein 2. receptor 3. ligand 4. key 5. initiator

3. ligand

Predict what would happen if a mutant Ras protein was unable to exchange guanosine diphosphate (GDP) for guanosine triphosphate (GTP).

The proteins downstream from Ras would not become phosphorylated.

What causes turgor pressure in plant cells?

Osmosis of water into the plant cell as a result of the higher concentration of solutes inside the cell

what does integrins attach to in the cytoskeleton?

actin

In general, protein kinases act to __________.

add phosphate groups to other proteins

how to cells next to each other communicate in plants?

plasmodesmata

How are Ras proteins activated?

Ras proteins are activated when Ras is bound to guanosine triphosphate (GTP).

extracellular matrix in animals

SUPPORT collagen-most abundant. serves as a way to resist tension proteoglycans-ground substance. proteins and polysaccharides. why cartilage feels so cushiony

A protein kinase activating many other protein kinases is an example of _____. 1. amplification 2. sensitization 3. a cellular response 4. deactivation 5. mutualism

1. amplification

The primary role of _____ is to bind animal cells together. 1. desmosomes 2. the cytoskeleton 3. gap (communicating) junctions 4. tight junctions 5. plasmodesmata

1. desmosomes

Enzyme linked receptors

1. signal binds to RTK monomers, causing them to dimerize (shape change) 2. this dimerization activates the RTK and causes it to phosphorylate itself 3. this causes bridging proteins to be activated and bridge the gap between the RTKs and the RAS protein (off bc has DP) 4. once the gap is bridged, the RAS protein becomes activated (kicks off GDP for GTP) 5. Active RAS triggers a kinase by triggering its phosphorylation 6. this causes a phosphorylation cascade until a response is triggered within the cell

g protein coupled receptors (GPCRs)

1. signal binds to a integral protein. to the integral protein there is bound a G protein which is inactive as it has GDP 2. the binding of the signal causes a shape change which causes G protein to kick off GDP for GTP and now become active 3. active G protein splits in two and moves laterally through the membrane until it binds to the enzyme 4. once bound to the enzyme, it causes the enzyme to produce a second messenger 5. second messenger triggers a response in the cell

For a tissue or an organ to function as a unit, _____. 1. there must be cell-cell communication among the cells within a tissue or organ 2. the tissue or organ must perform similar functions 3. there must be a signal molecule recognized by all cells in the tissue or organ 4. the tissue or organ must be composed of all of the same type of cells

1. there must be cell-cell communication among the cells within a tissue or organ

Which of these cell junctions form a barrier to the passage of materials? 1. tight junctions 2. plasmodesmata 3. gap (communicating) junctions 4. keratin fibers 5. desmosomes (anchoring junctions)

1. tight junctions

Why does a hormone act only on specific cell types in an organism and not others? See Section 11.3 (Page) . View Available Hint(s) 1. Hormones only act on cells that are adjacent to the releasing cell. 2. A cell must have the appropriate receptor before it can bind to the hormone. 3. All cells will bind to the hormone and process it, but not all cells will produce a response. 4. Hormones are prevented from entering the bloodstream, and thus only act on the releasing cell itself.

2. A cell must have the appropriate receptor before it can bind to the hormone.

Which statement best describes what would happen if you treated cells in a developing frog embryo with a molecule that blocked a cadherin observed in muscle tissue? 1. Adhesion of muscle cells to cells of non-muscle tissues would be disrupted. 2. Adhesion of muscle cells to other muscle cells would be disrupted. 3. The formation of the middle lamella between adjacent muscle cells would be disrupted. 4. Connections between the cytoskeleton of muscle cells and the ECM would be disrupted.

2. Adhesion of muscle cells to other muscle cells would be disrupted.

Osteocytes are bone cells. Collagen fibers and calcium salts are found in abundance between and among the osteocytes. The collagen and calcium salts are _____. 1. components of the plasma membrane of osteocytes 2. part of the extracellular matrix 3. extensions of the endoplasmic reticulum 4. deposited by the circulatory system but not associated with the osteocytes

2. part of the extracellular matrix

_____ aid in the coordination of the activities of adjacent animal cells. 1. Desmosomes 2. Tight junctions 3. Gap (communicating) junctions 4. Keratin fibers 5. Plasmodesmata

3. Gap (communicating) junctions

How is phosphorylation important in a signal transduction cascade? See Section 11.3 (Page) . View Available Hint(s) 1. When the hormone itself becomes phosphorylated, it travels to all nearby cells and activates them to release more hormones of that same type. 2. A hormone will phosphorylate the entire cell, thus causing the cell to be marked for destruction. 3. Phosphorylation will change the activity of target proteins, which triggers another response in the cell. 4. Phosphorylation always shuts down a signal transduction cascade, thus leading to an end of the signal.

3. Phosphorylation will change the activity of target proteins, which triggers another response in the cell.

The most abundant protein found in the extracellular matrix of animal cells is _____. See Section 11.1 (Page) . View Available Hint(s) 1.hemoglobin 2. pectin 3. collagen 4. cellulose

3. collagen

Integrins are integral membrane proteins. They are often attached to _____. 1. glycogen molecules and other types of cellular inclusions 2. the outside of the plasma membrane 3. cytoskeletal proteins and proteins in the extracellular matrix 4. the membranes of intracellular organelles

3. cytoskeletal proteins and proteins in the extracellular matrix

A signal transduction pathway is initiated when a _____ binds to a receptor. 1. G protein 2. tyrosine kinase 3. signal molecule 4. calmodulin cyclic 5. AMP

3. signal molecule

What role does a transcription factor play in a signal transduction pathway? 1. By binding to a plasma membrane receptor it initiates a cascade. 2. It relays a signal from the cytoplasm to the plasma membrane. 3. It activates relay proteins. 4. By binding to DNA it triggers the transcription of a specific gene. 5. It is a plasma membrane protein that binds signal molecules.

4. By binding to DNA it triggers the transcription of a specific gene.

Which of the following statements most accurately describes the function of plasmodesmata in plant cells or gap junctions in animal cells? View Available Hint(s) 1. Gap junctions allow passage of only proteins between adjacent cells. 2. Gap junctions allow passage of proteins and small molecules between adjacent cells. 3. Plasmodesmata allow passage of only proteins between adjacent cells. 4. Plasmodesmata allow passage of proteins and small molecules between adjacent cells.

4. Plasmodesmata allow passage of proteins and small molecules between adjacent cells.

Which of these is the second of the three stages of cell signaling? 1. gene activation 2. reception 3. binding of a neurotransmitter to a plasma membrane receptor 4. transduction 5 cell response

4. transduction

Dihydrotestosterone is a lipid-based molecule that is important in the development of secondary sex characteristics. Which of the following scenarios best describes how dihydrotestosterone could act as a chemical signal? Dihydrotestosterone binds to the receptor, located in the cytosol, and the receptor goes through a conformational change. Dihydrotestosterone binds to receptor tyrosine kinases (RTKs). Dihydrotestosterone binds to a G-protein-coupled receptor. Dihydrotestosterone binds to the receptor calmodulin.

Dihydrotestosterone binds to the receptor, located in the cytosol, and the receptor goes through a conformational change.

Which of the following statements about the extracellular matrix (ECM) in organisms is true? The ECM is a fiber composite that provides strength. The ECM is always a cell wall. The ECM is found only in plants. The ECM consists only of proteins.

ECM is a fiber composite that provides strength

Which of the following is an example of signal deactivation? Guanosine diphosphate (GTP) bound to Ras becomes hydrolyzed to guanosine diphosphate (GDP). Cyclic adenosine monophosphate (cAMP) is produced from an enzyme activated by a G protein. A kinase catalyzes the phosphorylation of a downstream protein kinase. Calcium is released from the smooth endoplasmic reticulum.

Guanosine diphosphate (GTP) bound to Ras becomes hydrolyzed to guanosine diphosphate (GDP).

Adrenaline vs insulin

adrenaline is a GPCR insulin is a RTK

What is (are) the main advantage(s) of second messengers?

amplification and speed

Desmosomes are associated with which of the following? Anchoring junctions Gap junctions Auxin Tight junctions

anchoring junctions

Which of the following is a similarity between receptor tyrosine kinases (RTKs) and G-protein-coupled receptors? Both are plasma membrane receptors. Both are lipid-based molecules. Both produce a change in gene expression. Neither use second messengers.

both plasma membrance receptors

Signal receptors for lipid-soluble and hydrophilic (lipid insoluble) hormones are similar in which of the following ways?

both receptors change shape upon the signal binding

desmosomes

cadherins connect the cytoskeletons of adjacent animal cells to one another strongest interaction (responsible for the strength of the tissue)

Which of the following statements about cadherins is true? Cadherins mediate binding interactions between cells. Cadherins are found in plasmodesmata. Each organism produces only a single type of cadherin protein. Cadherins are the major component of bacterial biofilms.

cadherins mediate binding interactions between cells

Lipid insoluble hormones

cannot cross the plasma membrane 1. signal molecule binds to a receptor protein in the plasma membrane 2. this causes the amplification of the signal inside of the cytosol. transduction (outside signal transformed into inside signal) 3. inside signals can either cause a change in cytoplasmic activity 4. or it could lead to a change in gene expression (binds to a protein that binds to DNA)

Which of the following cell types are likely to contain tight junctions? Cells lining the stomach, which prevent nutrients from leaking out Bacterial cells that come in contact with one another Red blood cells that travel singly through the circulatory system Cells of water-transporting tissue in plant stems

cells lining the stomach

plant cells often have a secondary cell wall

correlates with cell functions. leaves have waxes while wood has lignin

Several different intercellular pathways interact and result in the modification of a cellular response that would be different if these pathways did not interact. Which word or words best describes this interaction of intercellular pathways? Crosstalk Quorum sensing Phosphorylation cascade Second messenger systems

cross talk

Which of the following is an example of an intracellular receptor? Cytosolic receptor proteins G-protein-coupled receptors Receptor tyrosine kinases (RTKs) Phosphatases

cytosolic receptor proteins

If two cells are connected by the cytoskeleton, which of the following structures would the cells have? Desmosomes Tight junctions Gap junctions Plasmodesmata

desmosomes

Which of the following connections between cells resemble rivets? Desmosomes Tight junctions Gap junctions Expansin

desmosomes

Which of the following statements about cell-cell attachments is true? Desmosomes link the cytoskeletons of adjacent cells. Tight junctions contain adhesion proteins called cadherins that bind only to other cadherins of the same type. The middle lamella consists mainly of gelatinous collagens that hold adjacent plant cells together. Tight junctions are static structures that seal adjacent plasma membranes.

desmosomes link the cytoskeletons of adjacent cells not the last one bc tight junctions are more loose than static

The cellular organization and extracellular environments of plants and animals are very different: membrane protein complexes that strengthen adhesion between cells, like rivets, to protect against pulling forces small channels that form across the plasma membranes of adjacent cells; especially important in intracellular communication membrane proteins that create a watertight seal between cells small channels between cells that are otherwise surrounded by walls; enable movement of water and solutes between cells a polysaccharide used to synthesize cell walls, which help plant cells maintain their shape long fibers of protein found in the extracellular matrix that provide structural support for cells

desmosomes. found in animal cells gap junctions. animal cells tight junctions. animal cells plasmodesmata. plant cells cellulose. plant cells collagen. animal cells

Plant species that do not produce lignin _________________.

do not produce lignin

Which of the following binds to receptors inside the cells? estrogen, calcium growth ions, insulin epidermal growth factor

estrogen (hormone) insulin- RTK

Integrins are transmembrane proteins that connect the __________ outside the animal cell to the __________ inside the animal cell.

extracellular matrix, cytoskeleton

two types of lipid insoluble pathways

g protein couple receptors how vision works fast requires a second messenger enzyme linked receptors (RTKs) ex: insulin slower phosphorylation cascade

Which of the following connections between cells resembles channels? Gap junction Desmosome Tight junction Dictyostelium

gap junctions

Which of the following is not found in a plant cell? Gap junctions Plasmodesma Pectins Microfibrils

gap junctions

Which of the following structures allow ions to pass between cells to coordinate cardiac muscle contractions? Gap junctions Plasmodesmata Cadherins Hormones

gap junctions

plasmodesmata

gaps in the cell wall through which organelles can be shared between adjacent cells

A similarity between plant and animal cells is that both __________________

have a ground substance composed primarily of gel-forming polysaccharides

What is the correct order for the three steps in signal transduction?

reception, transduction, response

gap junctions

meant for communication. channels that allow for the flow of small molecules between cells to coordinate cell function

Which of the following statements about signal receptors is true? Receptors change conformation upon signal binding. Each type of receptor is found in all cell types of an organism. Receptors cannot be blocked. The ability of a receptor to respond to a signal is unchanging.

receptors change conformation upon signal binding

Primary cell wall of plants are fiber composites

resist the turgor pressure from osmosis which help the plant stand erect

tight junctions

seal adjacent cells together meant to be waterproof epithelial cells

how do distance cells communicate?

send a signal that causes a change in a far away cell ex: neurotransmitters hormones a cell's sensitivity to a molecule depends on the receptors present has receptors-will respond to the molecule no receptor-ignores the molecule

how do adjacent plant cells connect?

middle lamella between the cell wall of adjacent plants that is made up of gelatinous pectins

Structure and function of extracellular layer

most cells possess a protective layer or cell wall that forms just beyond the membrane extracellular layers in eukaryotes have the same fundamental organization the cross-linked network of long filaments resist tension stiff ground substances resist compression

Which of the following statements about cell signaling is true? cell signaling is limited to eukaryotes only signal pathway with plasma membrane cause amplification in cell only cells in direct contact with one another can signal each other a signal receptor can bind to many different hormones

signal pathways with plasma membrane causes amplification in the cell

The drug tamoxifen binds to estrogen receptors in cancer cells but does not activate the receptor. This prevents estrogen from binding to the estrogen receptor. Which part of the signal transduction pathway is altered when a patient takes tamoxifen?

signal reception

Predict which type of receptor would contain a DNA-binding domain, allowing it to bind DNA and direct changes to gene expression when activated.

steroid hormone receptor

What if the RAS protein was always bound to GTP in the RTK pathway?

the pathway would never be shut off (always be active and phosphorylating kinases causing a phosphorylation cascade all the time)

Which of the following connections between cells resembles quilting? Tight junctions Desmosomes Gap junctions Phosphatases

tight junctions

Which of the following structures is created by "stitching" the membranes of cells together? Tight junctions Desmosomes Gap junctions Plasmodesma

tight junctions

Cell to cell adhesion in animals

tight junctions desmosomes gap junctions

Cell-cell interactions

unicellular organisms must contend with constant shifts in enviornmental changes multicellular organisms-cells must communicate with one another

Which of the following statements about G proteins is true? When activated, G proteins activate enzymes that catalyze the production of second messengers. G proteins are activated when they are bound to guanosine diphosphate (GDP). G proteins become phosphorylated after hormone binding. When activated, G proteins catalyze the phosphorylation of other proteins.

when activated, cause activation of enzyme that produces a second messenger

What is the correct order for the following structures in plants, if the first one listed is in contact with the cytoplasm?

plasma membrane, secondary cell wall and primary cell wall

Microfibrils and pectins are associated with which of the following? The primary cell wall The secondary cell wall The extracellular matrix Gap junctions

primary cell wall

signal deacivation

proteins that can cause for the degradation of the second messenger to turn off cell response or the enzyme phosphatases, which removes phosphates, can be activated to remove phosphates from proteins in the phosphorylation cascade, thus stopping the pathway that will activate a response in the cell

What is the function of the plasma membrane? The plasma membrane separates the cell's contents from the environment. The plasma membrane provides structural support. The plasma membrane forms a seal between cells. The plasma membrane binds to other proteins in the immune response.

The plasma membrane separates the cell's contents from the environment.

Second messengers are activated by which of the following signals? Lipid-insoluble hormones Lipid-soluble hormones Protein kinases Expansins

lipid insoluble hormones

Chemical messengers secreted from cells in a multicellular organism that travel throughout the body and act on distant cells are called __________. second messengers, hormones, G proteins, receptor tyrosine kinases

hormones

Lipid soluble hormones

hormones are lipid soluble because they are nonpolar and hydrophobic, just like the insides of the plasma membranes 1. brought to the cell membrane attached to a carrier protein 2. diffuse through the plasma membrane and into the cytosol 3. in the cytosol, they bind to a receptor protein and cause and shape change 4. that receptor protein then binds to the DNA causes a change in gene expression

What binds the extracellular matrix to the cytoskeleton?

integrins

Which of the following molecules or cell structures are most easily shared by adjacent plant or animal cells? DN, mitochondria, ions or proteins

ions

Integrin connect the cytoskeleton within the cell tot he extra cellular matrix outside of the cell

linking proteins. transverse/integral proteins anchor the dense ECM to the cytoskeleton integrins connect to laminin in the ECM and to micro filaments in the cytoskeleton