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General Biology 1 > Chapter 8 Cell-Cell Interactions > Flashcards

Chapter 8 Cell-Cell Interactions Flashcards

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1
Q

Primary Cell Wall

A

The outermost layer of a plant cell wall, made of cellulose fibers and gelatinous polysaccharides, that defines the shape of the cell and withstands the turgor pressure of the plasma membrane.

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2
Q

Pectin

A

A gelatinous polysaccharide found in the primary cell wall of plant cells. Attracts and holds water, forming a gel that helps keep the cell wall moist.

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3
Q

Turgor Pressure

A

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

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4
Q

Secondary Cell Wall

A

The inner layer of a plant cell wall formed by certain cells as they mature. Provides support or protection.

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5
Q

Lignin

A

A substance found in the secondary cell walls of some plants that is exceptionally stiff and strong. Most abundant in woody plant parts.

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6
Q

Extracellular Mix (EMC)

A

A complex meshwork of proteins (e.g., collagen, fibronectin) and polysaccharides secreted by animal cells and in which they are embedded.

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7
Q

What is the Extracellular Mix (EMC) most important function?

A

Structural support

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8
Q

The fibrous component of animal Extracellular Mix (EMC) is dominated by _______________.

A

A cable like protein called collagen

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9
Q

Collagen

A

A fibrous, pliable, cable-like glycoprotein that is a major component of the extracellular matrix of animal cells. Various subtypes differ in their tissue distribution.

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10
Q

Integrins

A

Any of a class of cell-surface proteins that bind to fibronectins and other proteins in the extracellular matrix, thus holding cells in place.

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11
Q

Fibronectins

A

An abundant protein in the extracellular matrix that binds to other ECM components and to integrins in plasma membranes; helps anchor cells in place. Numerous subtypes are found in different tissues.

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12
Q

Why is the direct linkage between the cytoskeleton and EMC important?

A

In addition to keeping individual cells in place, it helps adjacent cells adhere to each other via their common connection to the EMC.

If it breaks down, cancer can develop.

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13
Q

Metastasis

A

The spread of cancerous cells from their site of origin to distant sites in the body where they may establish additional tumors.

*Happens when EMC-cytoskeleton linkage break down and cells grow uncontrollably forming a tumor, can break away and form tumors throughout the body

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14
Q

What is the state of being composed of many cells that adhere to each other and do not all express the same genes with the result that some cells have specialized functions.

A

Multicellularity

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15
Q

______________ organisms are made up of cells that adhere to each other and have distinctive structures and functions.

A

Multicellularity

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16
Q

A group of similar cells that function as a unit, such as muscle tissue or epithelial tissue.

A

Tissue

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17
Q

What is the middle lamella?

A

It connects adjacent plant cells and is made of gelatinous polysaccharides called pectins.

*It serves as glue.

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18
Q

Epithelium

A

An animal tissue consisting of sheet-like layers of tightly packed cells that lines an organ, a duct, or a body surface. Also called epithelial tissue.

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19
Q

Tight junction

A

A type of cell-cell attachment structure that links the plasma membranes of adjacent animal cells, forming a barrier that restricts movement of substances in the space between the cells. Most abundant in epithelia (e.g., the intestinal lining). Compare with desmosome and gap junction.

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20
Q

_____________ is a cell-cell attachment imposed of specialized proteins in the plasma membranes of adjacent animal cells.

A

tight joint

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21
Q

Why is tight joint important ?

A

It forms a tight barrier between organs and prevents ions from leaking in our out. Important for organs like the stomach and the intestines.

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22
Q

Desmosome

A

A type of cell-cell attachment structure, consisting of cadherin proteins, that binds the cytoskeletons of adjacent animal cells together. Found where cells are strongly attached to each other. Compare with gap junction and tight junction.

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23
Q

Selective adhesion

A

The tendency of cells of one tissue type to adhere to other cells of the same type.

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24
Q

Antibody

A

An immunoglobulin protein, produced by B cells, that can bind to a specific part of an antigen, tagging it for attack by the immune system. All antibody molecules have a similar Y-shaped structure and, in their monomer form, consist of two identical light chains and two identical heavy chains.

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25
Q

Cadherins

A

Any of a class of cell-surface proteins involved in cell adhesion and important for coordinating movements of cells during embryological development.

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26
Q

Synaptic signaling involves

A)	endocrine signals

B)	paracrine signals

C)	autocrine signals

    D)	neurotransmitters
A

D) neurotransmitters

In synaptic signaling, a neurotransmitter is passed from one cell to another.

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27
Q

________________ provide the physical basis for selective adhesion in may cells and are a critical component of the desmosomes that join mature cells.

A

Cadherins

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28
Q

In plants, gaps in cell walls create direct connections between the cytoplasm of adjacent cells. At these connections, named _____________ the plasma membrane and they cytoplasm of the two cells are continuous.

A

plasmodesmata

*smooth ER runs through theses holes.

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29
Q

What are communication portals in plant cells?

A

plasmodesmata

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30
Q

What is the key feature of gap junctions ?

A

to specialize proteins that create channels between animal cells

*small molecules such as amino acids, sugars, and nucleotides move between the channels.

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31
Q

____________ are usually small molecules and are typically present in minute concentrations.

A

Hormones

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32
Q

In cell-cell signaling, most ____________________ signals diffuse across the plasma membrane and enter the cytoplasm of their target cell.

A

lipid-soluble

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33
Q

Large or _______________ cell-cell signals re lipid-soluble and do not cross the plasma membrane.

A

hydrophilic

*To affect a target cell, they have to be recognized at the cell surface.

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34
Q

How do cells receive and respond to signals from distant cells?

A

signal reception
signal processing
signal response
signal deactivation

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35
Q

In signal reception, the presence of an appropriate receptor dictates what?

A

which cells will respond to a particular hormone.

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36
Q

In signal reception, what are two critical points?

A

Receptors are dynamic: the sensitivy of a cell to a particular hormone may change over time.

receptors can be blocked: that’s why beta blockers are prescribed

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37
Q

A protein that changes it shape and activity after binding to a signaling molecule.

A

signal receptor

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38
Q

In signal reception, receptors that respond to lipid-soluble signals are locate where?

A

inside the cell, because the signals readily diffuse through the plasma membrane.

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39
Q

In signal reception, the majority of signals are located where?

A

in the plasma membrane.

*they can bind to signals that cannot or do no cross the plasma membrane

40
Q

When lipid-soluble signals enter a cell, how is the information processed?

A

directly, w/o any intermediate steps

41
Q

Lipid-soluble signals are processed directly, what are the steps?

A

1) arrival of signal: steroid hormone diffuses across plasma membrane into cells
2) signal reception: Hormone binds to receptor, including conformational change
3) Direct signal response: Hormone-receptor complex binds to DNA, including change in gene expression

42
Q

Explain some cell-cell signals that enter the cell and bind to receptors in the cytoplasm.

A

Because they are lipids, steroid hormones can diffuse across the plasma membrane and bind to signal receptors inside the cell. The hormone-receptor complex is transported to the nucleus and binds to genes, changing their activity.

43
Q

When a signal binds at the cell surface it triggers ___________, the conversion of the signal from one form to another.

A

signal transduction

*A long and often complex series of events ensues, collectively called a signal transduction pathway.

44
Q

In a cell, signal transduction converts an extracellular signal to an _____________.

A

intracellular signal

45
Q

Lipid-insoluble signals require transduction. What is the process?

A

1) signal reception

46
Q

Hormones

A

Any of numerous different signaling molecules that circulate throughout the body in blood or other body fluids and can trigger characteristic responses in distant target cells at very low concentrations.

47
Q

Signal Receptor

A

Any cellular protein that binds to a particular signaling molecule (e.g., a hormone or neurotransmitter) and triggers a response by the cell. Receptors for water-soluble signals are transmembrane proteins in the plasma membrane; those for many lipid-soluble signals (e.g., steroid hormones) are located inside the cell.

48
Q

Signal transduction

A

The process by which a stimulus (e.g., a hormone, a neurotransmitter, or sensory information) outside a cell is amplified and converted into a response by the cell. Usually involves a specific sequence of molecular events, or signal transduction pathway.

49
Q

In a cell, signal transduction converts an extracellular signal to an _____________.

A

intracellular signal

50
Q

Lipid-insoluble signals require transduction. What is the process?

A

1) Signal reception (1st it’s a intercellular signal)
2) Signal transduction from intercellular signal to intracellular signal
3) Signal amplification (in most cases)
4) Signal response. (For example, specific genes ore proteins are activated or deactivated)

51
Q

____________ are present in minuscule concentrations but trigger large responses from cells. Why?

A

Hormones; via signal amplification

52
Q

How does signal amplification work?

A

When a hormone arrives a the cell surface, the message it transmit may be amplified as it changes form. (like a radio speaker)

53
Q

In cells, signal transduction begins ____________; amplification occurs inside.

A

at the plasma membrane

54
Q

What are two types of signal transduction and amplification systems?

A

(1) G proteins

(2) enzyme-linked receptors

55
Q

______________ initiate the productionof a n intracellular or “second” messenger

A

G proteins

56
Q

_________________ receptors trigger the activation of series of proteins inside the cell, through the addition of phosphate groups.

A

Enzyme-linked

57
Q

Many signal receptors span the plasma membrane and are closely associated wit the peripheral membrane proteins inside the cell called _______________.

A

G proteins

58
Q

What happens when G proteins are activated by a signal receptor?

A

they trigger the key steps in signal transduction: the production of a messenger inside the cell. They link the receipt of an extracellular signal to the production of an intracellular signal.

59
Q

How did G protein get its name?

A

they bind to guanosine triphosphate (GTP) and guanosine diphosphate (GDP).

*GTP is a nucleoside triphosphate that is similar in structure to adenosine triphosphate (ATP).

**nucleoside triphosphate have high potential energy b/c their three phosphate groups have four negative charges close together. The cluster of charges result in electrons repulsing each other and moving father from nearby nuclei.

60
Q

What happens when GTP binds to a protein?

A

the addition of the negative charges alter the proteins shape.

  • Changes in shape produce changes in activity
  • G proteins are turned on or activated when they bind GTP; they are turned off or inactivated when a phosphate group drops away to form GDP.
61
Q

a nonprotein signaling molecule that elicits a response to the first messenger (the signal that arrived at the cell surface)

A

second messenger

62
Q

The arrival of a single hormone molecule can stimulate the production of many _______________ molecules, the signal transduction even amplifies the original signal.

A

second messenger

63
Q

______________ are enzymes that activate or inactivate other proteins by adding a phosphate group to them.

A

protein kinases

64
Q

Name two important notes about second messengers

A

1) They aren’t restricted to a single role or single cell type~the same second messenger can initiate dramatically different events in different cell types
2) It is common for more than one second messenger to be involved in triggering a cell’s response to the same extracellular signal.

65
Q

Name two important notes about second messengers

A

1) They aren’t restricted to a single role or single cell type~the same second messenger can initiate dramatically different events in different cell types
2) It is common for more than one second messenger to be involved in triggering a cell’s response to the same extracellular signal.

66
Q

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.

A

Second messenger

67
Q

Protein Kinases

A

An enzyme that catalyzes the addition of a phosphate group to another protein, typically activating or inactivating the substrate protein.

68
Q

receptor tyrosine kinases (RTKs)

A

Any of a class of cell-surface signal receptors that undergo phosphorylation after binding a signaling molecule. The activated, phosphorylated receptor then triggers a signal-transduction pathway inside the cell.

69
Q

Instead of activating a nearby G protein, enzyme-linked receptors transduce the signal from a hormone by directly catalyzing a reaction inside the cell. This is called?

A

receptor tyrosine kinases (RTKs)

70
Q

______________________ trigger a phosphorylation cascade.

A

enzyme linked receptors

71
Q

G proteins trigger _________________ and some ____________ result in the production of second messengers.

A

phosphorylation cascades; phosphorylation cascades

72
Q

the signal transduction event has two results, what are they?

A

1) It converts an easily transmitted extracellular message into an intracellular message
2) in many cases it amplifies the original message many times over.

73
Q

In signal response, second messengers or cascade or proteins phosphorylation events may:

A

1) change which genes are being expressed in the target cell
2) or activate or deactivate a particular target protein that already exists in the cell; an enzyme, a membrane channel, or a protein that activates certain genes.

74
Q

Phosphorylation Cascade

A

A series of enzyme-catalyzed phosphorylation reactions commonly used in signal transduction pathways to amplify and convey a signal inward from the plasma membrane.

75
Q

What is cross-talk

A

Interactions among signaling pathways that modify a cellular response.

76
Q

What is quorum sensing?

A

Cell-cell signaling in bacteria, in which cells of the same species communicate via chemical signals. It is often observed that cell activity changes dramatically when the population reaches a threshold size, or quorum.

77
Q

In bacteria, cell-cell communication is called ______________.

A

quorum sensign

78
Q

_____________ are hard, polysaccharide-rich substances that encases the cells and attach them to a surface

A

biofilm

79
Q

______________, which bind cells together, are found predominantly in epithelial tissues, such as the lining of the intestines. _________________ form a barrier that prevents fluids from moving between the intestinal space and the space between cells.

A

tight junctions; tight junctionsDesmosomes

80
Q

________________, or anchoring junctions, appear as thickened patches in the cell membrane region between two cells. ________________ contain specialized proteins, such as keratin (the same protein found in fingernails and hair), that increase the rigidity of tissues. ___________________— such as those found in epithelium, smooth muscle, and many other animal tissues— are button like junctions that bind cells together and also function as anchors for fibers in the ____________________.

A

Desmosomes; Desmosomes; Desmosomes; cycoskeleton

81
Q

In _______________, or communicating junctions, two cells are separated by a small gap, which is bridged by specialized channels that allow the passage of water and small molecules. ________________ help coordinate the activities of adjacent cells. For example, a hormone that stimulates one cell will often activate adjacent cells as well by the passage of intracellular signals through ________________.

A

gap junctions; gap junctions; gap junctions

82
Q

Which of these cell junctions form a barrier to the passage of materials?

desmosomes (anchoring junctions)
plasmodesmata
keratin fibers
gap (communicating) junctions
tight junctions
A

Tight junctions form a barrier that prevents fluids from moving between cells.

83
Q

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

	tight junctions
	gap (communicating) junctions
	the cytoskeleton
	plasmodesmata
	desmosomes
A

The primary role of desmosomes (anchoring junctions) is to bind cells together

84
Q

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

	Tight junctions
	Keratin fibers
	Desmosomes
	Plasmodesmata
	Gap (communicating) junctions
A

Gap junctions allow for the passage of material between cells, thus facilitating communication between these cells.

85
Q

An open channel in the cell wall of a plant through which strands of cytosol connect from an adjacent cell.

A

plasmodesma

86
Q

Like gap junctions in animal cells, ______________ allow the free exchange of small molecules and help coordinate the activities of neighboring cells.

A

plamodesmata

87
Q

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

A

desmosomes found in animal cells

88
Q

Small channels that from across the plasma membranes of adjacent cells; especially important in intercellular communication

A

gap junctions; animal

89
Q

Membrane proteins that create a watertight seal between cells

A

tight junctions; animals

90
Q

Small channels between cells that are otherwise surrounded by walls; enabled movement of water and solutes between cells

A

plasmodesmata; plant

91
Q

Polysaccharides that is used to synthesize cell walls, which protect cells and help maintain their shape

A

cellulose; plant

92
Q

Long fibers of protein found in extracellular matrix that provide structural support for cells

A

collagen; animal

93
Q

For the receiving cell, there are three stages in the signaling process:

A

reception, transduction, and cell response.

94
Q

A signal transduction pathway is initiated when a _____ binds to a receptor.

	G protein
	tyrosine kinase
	cyclic AMP
	signal molecule
	calmodulin
A

The binding of a signal molecule to a receptor initiates a signal transduction pathway.

95
Q

Which of these is the second of the three stages of cell signaling?

	gene activation
	reception
	binding of a neurotransmitter to a plasma membrane receptor
	transduction
	cell response
A

Transduction is the second of the three stages of cell signaling.

96
Q

Which of these is the second of the three stages of cell signaling?

	gene activation
	reception
	binding of a neurotransmitter to a plasma membrane receptor
	transduction
	cell response
A

Transduction is the second of the three stages of cell signaling.

General Biology 1 (7 decks)

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