Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Foundations 1 > Histo: Cytoplasm, Membranous Organelles, Plasma Membrane > Flashcards

Histo: Cytoplasm, Membranous Organelles, Plasma Membrane Flashcards

1
Q

Definition of cells

A

Basic structural, functional, and integral units of all multicellular organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

(T/F) Some cells become specialized in certain functions.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

2 major components of cells

A

Cytoplasm and nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The cytoplasm contains…

A

Organelles and cytoplasmic matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

The cytoplasmic matrix consists of…

A

Variety of solutes (including inorganic ions - Na+, K+, Ca2+), organic molecules (intermediate metabolites, carbohydrates, lipids, proteins, RNA), inclusions (crystals, pigment granules, lipids, glycogen, other stored waste products)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

(T/F) Concentration of solutes within cytoplasmic matrix does not influence rate of metabolic activity within the cytoplasm.

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

The largest organelle in the cell with a distinct boundary is…

A

Nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Nucleus contains…

A

Genome, enzymes necessary for DNA replication and RNA transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

2 types of organelles

A

Membranous and nonmembranous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The spaces enclosed by organelle membranes constitute the…

A

Intracellular microcompartments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The membranous organelles include…

A

Plasma (cell) membrane), rough-surfaced endoplasmic reticulum (rER), smooth-surfaced endoplasmic reticulum (sER), Golgi apparatus, endosomes, lysosomes, transport vesicles, mitochondria, peroxisomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

The nonmembranous organelles include…

A

Microtubules (cytoskeleton in general), filaments, centrioles, ribosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the plasma membrane?

A

A lipid-bilayered structure that actively participates in many physiologic and biochemical activities essential to cell function and survival.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The plasma membrane consists of…

A

Amphiphatic phospholipid bilayer, cholesterol, protein molecules (integral and peripheral)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

(T/F) Lipids are distributed symmetrically between inner and outer leaflets of the lipid bilayer.

A

False - Lipids are distributed asymmetrically.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

In most plasma membranes, protein molecules constitute approximately what portion of the total membrane mass?

A

Half

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Peripheral membrane proteins are associated with the membrane by…

A

Strong ionic interactions, mainly with integral proteins on the extracellular and intracellular surfaces.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Glycoproteins are formed when…

A

Carbohydrates attach to proteins, especially on extracellular membrane surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Glycolipids are formed when…

A

Lipids attach to proteins, especially on extracellular membrane surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the glycocalyx?

A

The “cell coat” formed by glycolipids and glycoproteins at the surface of a cell. It helps establish extracellular microenvironments and has specific functions in metabolism, cell recognition, and cell association.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are lipid rafts?

A

Microdomains of the plasma membrane that control movement and distribution of proteins within the lipid bilayer. Acts as “signaling platforms.” Less fluidity/diffusion than surrounding membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What do lipid rafts consist of?

A

High concentrations of cholesterol and glycosphingolipids. Integral and peripheral membrane proteins involved in cell signaling, enzymes, receptors, etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Integral membrane proteins can be visualized with what technique?

A

Freeze fracture - membranes cleaved along hydrophobic plane to expose E-face (backed by ECM) and P-face (backed by cytoplasm). Normally more integral proteins on P-face.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Integral membrane functions have important functions in…

A

Cell metabolism, regulation, and integration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

6 functional categories of membrane proteins

A

Pumps, channels, enzymes, structural proteins, receptors, linkers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

(T/F) A membrane protein can be both a receptor and a structural protein.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

The fluidity of the membrane is a function of…

A

Types of phospholipids in membrane and variations in local concentrations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Lateral migrations of proteins in the membrane is limited by physical connections between membrane proteins and intracellular/extracellular structures such as…

A

Proteins associated with cytoskeletal elements, portions of proteins that extend into adjacent cytoplasm, cytoplasmic domains of membrane proteins, peripheral proteins associated with ECM, integral proteins that extend from cell surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Transmembrane linkers are…

A

Proteins localized/restricted to specialized regions of the plasma membrane, link intracellular/extracellular filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Cell injury often manifests as…

A

Morphologic changes in the cell’s plasma membrane, which results in formation of plasma-membrane blebs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Plasma-membrane blebs are…

A

Protrusions of plasma membrane caused by detachments of plasma membrane from underlying actin filaments of the cell cytoskeleton

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Simple diffusion allows what substances to pass through the plasma membrane?

A

Fat-soluble, small, uncharged molecules down their concentration gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

2 classes of membrane transport proteins

A

Carrier proteins and channel proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Carrier proteins transfer what substances?

A

Specific small, water-soluble molecules by a conformational change of the protein. May be active or passive transport.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

(T/F) Glucose carrier proteins do not require energy.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Channel proteins transfer what substances?

A

Specific small, water-soluble molecules through hydrophilic channels/a pore domain.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Channel protein transport can be regulated by…

A

Membrane potentials (voltage-gated ion channels in neurons), neurotransmitters (ligand-gated ion channels such as acetylcholine receptors in muscle cells), mechanical stress (mechanically gated ion channels in internal ear)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Endocytosis is…

A

Process of vesicular transport in which fluid and macromolecules enter the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Exocytosis is…

A

Process of vesicular transport in which fluid and macromolecules leave the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Clathrin is…

A

Best known protein that interacts with the plasma membrane in vesicle formation - endocytosis can be dependent on or independent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

3 mechanisms of endocytosis

A

Pinocytosis, phagocytosis, receptor-mediated endocytosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Pinocytosis is…

A

Nonspecific ingestion of fluid and small protein molecules via small vesicles; constitutive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Constitutive means…

A

Involves continuous dynamic formation of small vesicles at the cell surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Dynamin is…

A

GTPase, a mechanoenzyme that helps with pinching off a pinocytotic vesicle scission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Characteristics of pinocytotic vesicles…

A

Visible with TEM, smooth surface, numerous in endothelium of blood vessels and smooth muscle cells, clathrin-independent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Phagocytosis is…

A

Nonselective ingestion of large particles such as cell debris, bacteria, nonbiologic materials such as carbon, inorganic dusts, asbestos fibers, etc.; involves pseudopodia engulfing particles in large vesicles called phagosomes; clathrin-independent, actin-dependent.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Phagocytosis is performed mainly by specialized group of cells belonging to the…

A

MPS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

(T/F) Phagocytosis is generally a receptor-mediated process.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Phagocytosis is triggered by recognition of…

A

PAMPs that are commonly expressed on pathogen surfaces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Receptor-mediated endocytosis involves…

A

Cargo receptors accumulating in well-defined regions of cell membrane, forming coated pits. These receptors bind specific molecules. Clathrin mlcls, interacting with adaptin, form basketlike cage around formed “coated vesicle,” which moves to early endosomes and other parts of the cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Process of exocytosis

A

1) Molecules produced by the cell for export are delivered from site of formation to Golgi apparatus.
2) Sorting and packaging the secretory product into transport vesicles.
3) Fuses with plasma membrane, contents released.

52
Q

2 pathways of exocytosis

A

Constitutive pathway and regulated secretory pathway

53
Q

What is the constitutive pathway of exocytosis?

A

Substances are continuously and immediately delivered in transport vesicles to the plasma membrane - ex. immunoglobulins by plasma cells, procollagen by fibroblasts

54
Q

What is the regulated secretory pathway of exocytosis?

A

Secretory proteins are concentrated and stored in secretory vesicles until regulatory event activated, then secretion occurs - ex. chief cells of gastric mucosa, acinar cells of pancreas. Signaling stimulus causes influx of Ca2+ into cytoplasm, which stimulates secretory vesicles to fuse with plasma membrane and release contents.

55
Q

The precise targeting of vesicles to appropriate cellular compartments is initially controlled by…

A

Docking proteins - RAB-GTPase interacting with tethering proteins located on the target membrane

56
Q

Specificity of targeting of vesicles to appropriate cellular compartment is ensured by…

A

Interactions between soluble SNARE proteins

57
Q

t-SNARE interacts with v-SNARE to form…

A

cis-SNARE complex

58
Q

SNARE complexes are dismantled wit help of…

A

NSF/alpha-SNAP protein complex

59
Q

Early endosomes are…

A

Membrane-enclosed compartments restricted to portion of cytoplasm near cell membrane where vesicles originating from the cell membrane fuse

60
Q

Early endosomes develop into…

A

Late endosomes and then lysosomes

61
Q

2 models of the origin/formation of endosomal compartments in cell

A

Stable compartment model (they are stable cellular organelles), maturation models (early endosomes formed from endocytotic vesicles, developed into late ensomes, then lysosomes)

62
Q

Hydrolases are…

A

Lysosomal enzymes

63
Q

The precursor of a hydrolase is…

A

A prohydrolase - heavily glycosylated protein with signal patch that is modified by enzymes that attach M-6-P to the surface.

64
Q

M-6-P acts as…

A

A target for proteins possessing M-6-P receptor (on early/late endosomes, lysosomes, Golgi aparatus). Acidic environment of late endosome causes release of prohydrolases destined for transport to endosomes.

65
Q

Early and late endosomes differ in their…

A

Cellular localization, morphology, state of acidification and function.

66
Q

What is the name of vesicles that transport substances between early and late endosomes?

A

MVBs

67
Q

Late endosomes are also called…

A

Prelysosomes

68
Q

The major function of early endosomes is…

A

To sort and recycle proteins internalized by endocytotic pathways.

69
Q

What constitutes the basis of the sorting mechanism in early endosomes?

A

Localized changes in pH (causes dissociation of ligands from receptors), mechanical sorting of molecules by size (through different sized tubules)

70
Q

What are the pathways for processing internalized ligand-receptor complexes in the cell?

A

1) Receptor is recycled and ligand is degraded.
2) Both receptor and ligand are recycled.
3) Both receptor and ligand are degraded.
4) Both receptor and ligand are transported through the cell.

71
Q

What is transcytosis?

A

Transport of substances through a cell.

72
Q

Examples where ligand is degraded and receptor is recycled?

A

Low-density lipoprotein (LDL)-receptor complex, insulin-glucose transporter (GLUT) receptor complex, peptide hormones and receptors

73
Q

Examples where both receptor and ligand are recycled?

A

Low pH of endosome dissociates iron from iron-carrier protein transferrin, but transferrin remains with receptor. Also major histocompatibility complex (MHC) I and II mlcls.

74
Q

Examples where both receptor and ligand are degraded?

A

Epidermal growth factor and its receptor

75
Q

Example where both receptor and ligand are transported through the cell?

A

Secretion of immunoglobulins (secretory IgA) into saliva and human milk.

76
Q

Function of rER?

A

Binds ribosomes for translation; chemical modifications of proteins; membrane lipid synthesis

77
Q

Function of sER?

A

Lipid and steroid metabolism

78
Q

Function of Golgi apparatus?

A

Chemical modification of proteins, sorting/packaging of molecules for secretion/transport

79
Q

Function of mitochondria?

A

Aerobic energy supply

80
Q

Function of peroxisomes?

A

Production and degradation of H2O2 and degradation/oxidation of fatty acids

81
Q

Function of microtubules?

A

Form elements of cytoskeleton, provide dynamic instability (ability to elongate and shorten)

82
Q

Function of filaments?

A

Form elements of cytoskeleton, actin filaments (flexible), intermediate filaments (ropelike fibers) provide tensile strength to withstand tension and confer resistance to shearing forces

83
Q

Function of centrioles?

A

Short, paired cylindrical structures in center of MTOC/centrosome and whose derivatives give rise to basal bodies of cilia

84
Q

Function of ribosomes?

A

Protein synthesis and synthesis of rRNA and ribosomal proteins

85
Q

What do membranes do for the cell?

A

Divide it into compartments with unique functions, leading to chemical specificity. Also insure integrity of the cells (keep outside out and inside in).

86
Q

(T/F) In cells, you can have membranes inside of membranes.

A

True

87
Q

The space between 2 cells is called…

A

The intercellular space

88
Q

What was the first experimental evidence demonstrating membrane fluidity?

A

1 human and 1 mouse cell, each with unique colored antibody, were fused together. After heat added and time, the resulting heterokaryon showed an intermixing of colors, demonstrating that molecules could diffuse within the membrane.

89
Q

Endocytosis would not occur efficiently in the absence of…

A

Membrane fluidity - it allows receptors to diffuse in plasma membrane until they are stopped by binding to the adaptin molecules in the clathrin coated pits.

90
Q

High blood cholesterol is a major risk factor for…

A

Cardiovascular disease (in the US)

91
Q

What are the domains of an LDL receptor?

A

LDL binding domain (N terminus, upper tip), ligand dissociation domain, transmembrane domain, coated pit binding (C terminus)

92
Q

How do receptors “know” to enter the cell via the coated pit?

A
  1. The receptors are transmembrane proteins
  2. They have a consensus sequence at the end of the cytoplasmic domain (ex. Tyr-X-Arg-Phe) that recognizes the coated pit
  3. This sequence binds to adaptin molecules in the clathrin coat
  4. This binding stops and concentrates the receptors
93
Q

Membrane phospholipids are amphiphatic, which means…

A

They have both hydrophilic and hydrophobic portions

94
Q

What are the normal components of a phospholipid?

A

Hydrophilic head (choline-phosphate-glycerol) and hydrophobic tail (2 fatty acids, one with a cis-double bond). Phosphate has - charge.

95
Q

What are the major types of phospholipids?

A
  1. Phosphatidyl-ethanolamine (PE)
  2. Phosphatidyl-serine (PS)
  3. Phosphatidyl-choline (PC)
  4. Sphingomyelin (SM)
96
Q

What is phosphatidylinositol?

A

Minor type of phospholipid with overall (-) charge, primarily on inner (cytosolic) leaflet.

Involved in cell signaling - lipid kinases phosphorylate various portions, resulting in recruitment of signaling molecules to the cell membrane.

97
Q

What are characteristics of PE?

A

+ charge on end (neutral overall), primarily on inner (cytosolic) leaflet, randomly distributed

98
Q

What are characteristics of PS?

A

+ and - charges on end (- overall), primarily on inner (cytosolic) leaflet, randomly distributed

99
Q

What are characteristics of PC?

A

+ charge on end (neutral overall), primarily on outer (extracellular) leaflet, randomly distributed

100
Q

What are characteristics of SM?

A

+ charge on end (neutral overall), primarily on outer (extracellular) leaflet, tend to cluster in the membrane (along with cholesterol) to form lipid rafts

101
Q

What are the types of movement/diffusion phospholipid molecules can undergo?

A

Lateral diffusion (rapid), flexion (swaying side to side), rotation (rapid), flip-flop (rarely occurs, may require enzymes)

102
Q

What enzymes allow phospholipids to “flip-flop”?

A

Flippase and scramblase

103
Q

What is the general structure and placement of cholesterol in the plasma membrane?

A

Rigid steroid ring - between polar head and hydrophobic tail of phospholipids.

104
Q

Glycolipids consist of about what percent of the membrane phospholipids?

A

5%

105
Q

What are the different functions of membrane proteins?

A

Transporters, anchors (between extracellular and intracellular proteins), receptors, enzymes

106
Q

Proteins account for about what percent of the plasma membrane’s mass?

A

50%

107
Q

What are the different structural types of membrane proteins?

A

Transmembrane, membrane-associated (integral, not necessarily transmembrane), lipid-linked, protein attached (peripheral, attached to transmembrane protein)

108
Q

Integral proteins can be removed from the membrane only with…

A

Detergent extraction of the membrane

109
Q

How are peripheral proteins connected to the membrane?

A

Only through non-covalent interactions with other proteins

110
Q

Peripheral proteins can be removed from the membrane by…

A

Extremes of ionic strength or pH

111
Q

What are characteristics of transmembrane proteins?

A

Integral, amphiphatic, may be single-pass or multi-pass. Hydrophobic regions are often made of alpha-helical structures.

112
Q

(T/F) Alpha-helical membrane proteins are always transmembrane.

A

False, not necessarily.

113
Q

What are characteristics of lipid-linked proteins?

A

Integral, hydrophilic protein covalently connected to phospholipid modification on membrane. Can be direct or through carbohydrate linkers.

114
Q

(T/F) Membrane proteins are asymmetrical.

A

True

115
Q

(T/F) Membrane proteins can function in large complexes.

A

True

116
Q

What is the purpose of connections between membrane proteins and the cytoskeleton?

A

Reduce membrane protein diffusion/movement, aid in intracellular communication, reinforce the integrity of the plasma membrane.

117
Q

What is the glycocalyx?

A

Carbohydrate coating on cell surface that protects cells in harsh conditions (ex. stomach) or can be involved in cell signaling and recognition.

118
Q

What are membrane domains?

A

Specific regions of the membrane where membrane proteins can be sequestered into. Lateral diffusion is restricted.

119
Q

Formation of membrane domains can be mediated by:

A

Cytoskeletal components, extracellular matrix, cell surface proteins (ex. attachment to membrane proteins of other cells), diffusion barriers (ex. tight junctions that “fence” proteins in)

120
Q

Of the drugs currently in use, what percent of them target some aspect of the plasma membrane?

A

Over 50%

121
Q

What is the major cell type in blood?

A

Red blood cells

122
Q

What are the features of a mature red blood cell?

A

Lacks internal organelles or a nucleus, major function is to transport O2 and CO2 between lungs and tissues, biconcave shape (increasing surface area for gas exchange), flexible/deformable and strong because of the “membrane skeleton”

123
Q

Why must RBCs be deformable?

A

Because they are subject to shear forces as they move around in the circulatory system. Also need to pass through tight spaces in blood capillaries.

124
Q

What is the major protein in the RBC membrane skeleton?

A

Spectrin

125
Q

How is the RBC membrane skeleton attached to the plasma membrane?

A

Mediated by protein ankyrin and protein 4.1

Foundations 1 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions