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BMS > Introduction to Cell Structure II > Flashcards

Introduction to Cell Structure II Flashcards

1
Q

Forms the interface between the cell and its environment and also functions as a permeability barrier

A

Plasma Membrane

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2
Q

Consists of a lipid bi-layer with embedded proteins

A

Plasma Membrane

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3
Q

Have very highly defined RERs and show many features characteristic of cells

A

Plasma cells

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4
Q

Amphipathic molecules with polar hydrophilic groups and aliphatic side chains that are hydrophobic

A

Lipids

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5
Q

The hydrophobic groups of the lipids are positioned to the interior of the

A

Bilayer

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6
Q

There are several classes of lipids and sterols in the plasma membrane, including

-often asymmetrically distributed

A

Phospholipids, glycolipids, and cholesterol

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7
Q

The fine structure of the plasma membrane is visible only with the

A

Electron microscope

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8
Q

The cell-cell boundaries seen at the light microscopic level consists of both plasma membranes of adjacent cells with the

A

Extracellular matrix between them

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9
Q

There are also proteins in the plasma membrane, many of which are

A

Glycosylated

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10
Q

What are the two classes of plasma membrane proteins?

A
  1. ) Integral membrane proteins

2. ) Peripheral membrane proteins

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11
Q

Traverse the entire width of the cell membrane and have three domains: Cytoplasmic, membrane spanning, and external

A

Integral membrane proteins

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12
Q

Attached to the cytoplasmic/extracellular regions of the lipid bilayer non-covalently

A

Peripheral membrane proteins

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13
Q

Cell membranes are fluid structures. Many, but not all proteins and lipids can move through the membrane in which way?

A

Laterally

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14
Q

Distribution of proteins in cell membranes can be studied by

A

Freeze-fracture electron microscopy

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15
Q

A frozen piece of membrane is split mechanically between the outer and inner lipid layers

A

Freeze-fracture EM

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16
Q

The outter face is called the

A

E (external face)

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17
Q

The inner leaflet is called the

A

P (protoplasmic or cytoplasmic) face

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18
Q

More integral membrane proteins are associated with the P-face because the P-face is stabilized by attachment to the

A

Cytoskeleton

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19
Q

Plasma membrane proteins can be stabilized by

-Best studied in RBCs

A

Cytoskeletal proteins

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20
Q

An inherited disorder characterized by defects in the membranes of erythrocytes. RBCs are more spherical, less deformable, and more susceptible to destruction by phagocytes in the spleen

A

Hereditary spherocytosis

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21
Q

Hereditary Spherocytosis is caused by a mutation in the cytoskeletal protein

A

Spectrin

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22
Q

Cytoskeletal proteins that associate with several membrane proteins to stabilize the biconcave shape of normal erythrocytes

A

Spectrins

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23
Q

The study of hereditary spherocytosis shows that interactions between the cell membrane and intracellular cytoskeletal proteins are needed to maintain normal

A

RBC morphology

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24
Q

Serve as linker/anchor proteins, transporters, receptors, and enzymes

A

Membrane proteins

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25
Q

The tall columnar cells making up the epithelium of the small intestine that functions in the absorption of nutrients

A

Enterocytes

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26
Q

Enterocytes have modifications to their surface to increase the surface area available for absorption. These modifications of the outer (apical or lumenal) surface are called the

A

Brush border (when viewed in LM) or Microvilli (EM)

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27
Q

Many cells exhibit microvilli at their surface, but few cells have them organized as a dense

A

Brush border

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28
Q

EM reveals that the brush border of enterocytes consists of envaginations of the apical cell membrane that are called

A

Microvilli

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29
Q

Extend as minute finger-like projections from the top (apical surface) of the cells and increase the absorptive surface

A

Microvilli

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30
Q

A “fuzzy coat” seen at the tips of the microvilli

A

Glycocalyx

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31
Q

An internal cytoskeleton of actin filaments supports the

A

Membrane Microvilli

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32
Q

Extends upward at the apical surface and encloses each microvilli

A

Plasma membrane

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33
Q

Within the core of each microvillus are filamentous structures composed primarily of the structural protein

A

Actin

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34
Q

These actin filaments are only visible by EM and extend downward to terminate in a filamentous complex at the top of the cells called the

A

Terminal Web (TW)

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35
Q

Each microvilli has a core of actin filaments and a glycocalyx at the

A

Surface

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36
Q

In intestinal epithelial cells, enzymes, especially those involved in the terminal stages of protein and carbohydrate digestion, are part of the

A

Glycocalyx

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37
Q

The glycocalyx consists of

A

Glycolipids, glycoproteins, and prteoglycans

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38
Q

In the core of each microvillus are actin, actin cross-linking proteins that stabilize the structure, and a motor protein that moves material along the actin filaments. What is the motor protein called?

A

Myosin

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39
Q

The terminal web at the base of each microvillus contains

A

Actin and intermediate filaments

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40
Q

Cells interact via several modifications of their lateral borders that together form a

A

Junctional Complex (JC)

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41
Q

Also contribute to junctional complexes that mediate interactions between epithelial cells

A

Membrane proteins

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42
Q

In LM, the locations of junctional complexes are identified by

A

Terminal bars (reddish dots at the tips of a cell junction)

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43
Q

Under EM, we see that cells maintain contact with each other by specializations of the lateral surface. These include

A
  1. ) Tight or occluding junctions (Zona occludens)
  2. ) Belt desmosomes (Zona adherens)
  3. ) Spot desmosomes (Macula adherens
  4. ) Communicating (gap) junctions
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44
Q

The zone of a junctional complex closes to the surface of the epithelial cells is called the

A

Tight (occluding) Junction (Zona Occludens)

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45
Q

For most cells (except RBCs) there are what two major cellular compartments?

A
  1. ) Nucleus

2. ) Cytoplasm

46
Q

The cytoplasm has which two main components?

A
  1. ) Cytosol

2. ) Organelles

47
Q

The cytoplasm outside of the organelles

-contains many enzymes and reactions of intermediate metabolism

A

Cytosol

48
Q

Free ribosomes/polysomes are located in the

A

Cytosol

49
Q

Temporary constituents without membranes including glycogen granules and lipid droplets, which are located in the cytosol

A

Inclusions

50
Q

The cytosol also contains a structure made up of actin, intermediate filaments, and microtubules, known as the

A

Cytoskeleton

51
Q

Localized in bundles of microfilaments that extend throughout the cell and are visualized through IHC

-also located in muscle cells and microvilli

A

Actin

52
Q

Small cylindrical structures that are widely distributed through the cell and are composed of the protein tubulin

-component of the cytoskeleton

A

Microtubules

53
Q

Microtubules not only extend through the cytoplasm, but also contribute to

A

Centrioles, Cilia, and Mitotic Spindles

54
Q

Complex membrane-bound structures within cells

-includes the ER, Golgi, mitochondria, lysosomes, and peroxisomes

A

Organelles

55
Q

An extensive cytoplasmic membrane system containing sites of protein and lipid synthesis and calcium storage

A

Endoplasmic reticulum

56
Q

Consists of an extensive array of membrane tubules and their enclosed cisterns or spaces

-Does not have ribosomes

A

Smooth ER

57
Q

Enzymes in the smooth ER function in

A
  1. ) Lipid and steroid synthesis
  2. ) Detoxification
  3. ) Drug metabolism
  4. ) Calcium ion storage
58
Q

A cell with an extensive SER and a lot of lipid droplets is likely making

A

Steroid hormones

59
Q

The outer nuclear membrane contains ribosomes and is continuous with the

A

Rough ER

60
Q

Basically a ribosome studded membrane-bounded space

A

Rough ER

61
Q

The rRNA of ribosomes contributes to the basophilic staining properties of

-Readily observed via LM

A

Secretory Cells (basophilia)

62
Q

The Rough ER is abundant in cells synthesizing

A

Secretory proteins (i.e. plasma cells)

63
Q

A few other proteins synthesized by the RER are not secreted by rather are retained in the cell, including

A

Lysosomal proteins and membrane proteins

64
Q

Function in the synthesis, packaging, and secretion of digestive enzymes, and have linear arrays of rough ER that function in secretory protein synthesis

A

Pancreatic Acinar cells

65
Q

Proteins synthesized in the rough ER are then transported to the

A

Golgi Complex

66
Q

Contains several individual subdivisions composed of flattened sacs of membrane

-made up of cis and trans faces

A

Golgi Apparatus

67
Q

Closest to the rough ER

A

cis-Golgi network (forming face)

68
Q

Furthest from the rough ER

A

trans-Golgi network (maturing face)

69
Q

What is between the cis- and trans- golgi networks?

A

cis-, medial, and trans-cisternae

70
Q

Used to transport material between the Golgi cisternae

A

Vesicles

71
Q

Bud from the trans Golgi network

A

Secretory Vesicles

72
Q

Proteins enter the Golgi at the

A

cis-face

73
Q

Associated with the cis-Golgi is a series of tubules (the cis-Golgi network), which transport vesicles carrying newly synthesized protein from the

A

Rough ER

74
Q

The trans-Golgi is the maturing face, directed toward the secretory granules and the apical or peripheral cytoplasm. The trans-Golgi is where proteins

A

Leave for sorting

75
Q

In some cells, proteins will accumulate in the Golgi and be sorted prior to secretion. This occurs in

A

Secretory Granules

76
Q

What are the two mechanisms by which release of granule contents from the cell (exocytosis) is regulated?

A

Constitutive secretion or Regulated secretion

77
Q

Proteins are packaged into secretory granules for export from the cell in the

A

trans-Golgi

78
Q

The continual secretion of proteins that are not stored

A

Constitutive secretion

79
Q

What are two examples of cells that perform constitutive secretion?

A

Plasma cells and fibroblasts

80
Q

Continually secrete immunoglobins for the entire two weeks of their lives

A

Plasma cells

81
Q

Continually secrete ECM components

A

Fibroblasts

82
Q

Few, if any, secretory granules accumulate in

A

Constitutive Secretion

83
Q

A large number of granules accumulate in many secretory cells that undergo

A

Regulated Secretion

84
Q

During a meal, the exocrine pancreas receives a signal from cholecystokinin (CCK) and the acinar cells secrete digestive enzymes into the duct system for transport to the duodenum. This is an example of

A

Regulated Secretion

85
Q

In addition to exocytosis (secretion), cells can also take in material in a process called

A

Endocytosis

86
Q

Receptors in the cell membrane (usually integral membrane proteins) can bind to signaling molecules or nutrients. The receptor-ligand complexes can then enter the cell via vesicle formation that is initiated when coat proteins associate with the

A

Cytoplasmic lipid layer

87
Q

The ligand-receptor complexes and the coat proteins then form a

-rapidly detaches from the surface to form a coated vesicle

A

Coated pit

88
Q

This process of endocytosis is termed

A

Receptor-mediated endocytosis

89
Q

The internalized vesicles then fuse with the

A

Early Endosomes

90
Q

Distinct organelles consisting of vesicles containing material that has entered the cell

A

Endosomes

91
Q

Receptors and ligands are separated, and the receptors are often recycled, in

A

Early endosomes

92
Q

Route nutrients such as cholesterol to the lysosome where nutrients can be made available to the cell

A

Late endosomes

93
Q

A cell that is undergoing regulatory cell secretion is characterized by well defined

A

Rough ER and Secretory Granules

94
Q

A cell that is undergoing constitutive cell secretion is characterized by well defined

A

Roguh ER but NO secretory Granules

95
Q

Mitochondria can move through the cytoplasm with the aid of

A

Cytoskeletal proteins

96
Q

On the cristae of the inner mitochondrial membrane are spherical protein particles which couple oxidation to phosphorylation and

A

ATP synthesis

97
Q

Mitochondria also participate actively in

A

Apoptosis

98
Q

The numbers of mitochondrial cristae vary in different cells depending on

A

Energy needs (more energy = more cristae)

99
Q

The liver is contains dark clumps in EM called

A

Glycogen granules

100
Q

Mitochondria in adrenal cells are different because their cristae are

A

Tubular

101
Q

Mitochondrial morphology can vary between

A

Cell types

102
Q

Mitochondrial DNA does encode a few peptides, however, most mitochondrial proteins are encoded by

-enter from the cytosol, not from the rough ER and Golgi pathway

A

Nuclear DNA

103
Q

Membrane bound packets of hydrolytic enzymes that become active at acidic pH and are the sites of intracellular digestion

A

Lysosomes

104
Q

An ATP-driven proton pump in the lysosomal membrane maintains the

A

pH

105
Q

Lysosomes process molecules that enter the cell from the

-Ex: cholesterol, antigens

A

External environment

106
Q

Also function in the removal of worn-out intracellular organelles (mitochondria, RER) as well as entire cells (erythrocytes and bacteria) following phagocytosis

A

Lysosomes

107
Q

Which dye will allow you to see lysosomes?

A

Trypan Blue

108
Q

Lysosomes that are in eosinophils can be detected in EM because they have a

A

Dark line down the center

109
Q

Membrane bound organelles involved in hydrogen peroxide metabolism and multiple other important metabolic processes

A

Peroxisomes

110
Q

Because of high enzyme concentrations, peroxisomes usually have a dense material in their matrix that forms a

A

Crystalline core

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