Physio Chapter 2 Functional Organization Of The Cell

Front 1

Cytoplasm

Back 1

is an extraordinarily complex solution, the constituents of which include myriad proteins, nucleic acids, nucleotides, and sugars that the cell synthesizes or accumulates at great metabolic cost

Front 2

Plasma membrane

Back 2

provides the requisite barrier;
forms the cell's outer skin

Front 3

Plasma Membrane

Back 3

is impermeable to large molecules such as proteins and nucleic acids, thus ensuring their retention within the cytosol

Front 4

Plasma Membrane

Back 4

is selectively permeable to small molecules such as ions and metabolites

Front 5

Active transport

Back 5

uphill movement of substances

Front 6

Phospholipids

Back 6

the cell membrane is composed primarily of ______

Front 7

Lipid and Protein

Back 7

Two principal constituents of Plasma Membrane

Front 8

Phospholipids

Back 8

Most of the lipid associated with erythrocyte plasma membranes belongs to the molecular family of ________

Front 9

Glycerol backbone

Back 9

In general, phospholipids share a ________ backbone

Front 10

Head Group

Back 10

Determines the name as well as the many properties of the individual phospholipids

Front 11

Phosphatidylethanolamnines

Back 11

Glycerol-based phospholipids that bear an ethanolamine molecule in the head group position

Front 12

Fatty acids

Back 12

are nonpolar molecules

Front 13

Fatty acids' long carbon chain

Back 13

lack the charged groups that would facilitate interactions with water, which is polar

Front 14

Fatty acids

Back 14

dissolve poorly in water but readily in organic solvents

Front 15

Fatty acids

Back 15

are hydrophobic

Front 16

Head groups (of most phospholipids)

Back 16

are charged or polar

Front 17

Head groups

Back 17

interact well with water and consequently are very water soluble

Front 18

Head groups

Back 18

are hydrophilic

Front 19

Ampipathic

Back 19

Because phospholipids combine hydrophilic heads with hydrophobic tails, their interaction with water is referred to as_______

Front 20

Monolayer

Back 20

When added to water at fairly low concentrations, phospholipids form a ________ on the water's surface at the air-water interface

Front 21

Micelles

Back 21

at higher concentrations, phospholipids assemble into __________

Front 22

Micelles

Back 22

the hydrophilic head groups form the surfaces of these small spheres, whereas the hydrophobic tails point toward their centers

Front 23

Bilayers

Back 23

at still higher concentrations, phospholipids spontaneously form ______

Front 24

Bilayers

Back 24

In these structures, the phospholipid molecules arrange themselves into two parallel sheets or leaflets that face each other tail to tail

Front 25

length of the fatty acid side chains

Back 25

the width of the bilayer is determined by the length of the fatty acid side chains

Front 26

head groups

Back 26

its nature determines how densely packed adjacent phospholipid molecules are in each leaflet of the membrane

Front 27

Detergents

Back 27

can dissolve phospholipid membranes because like the phospholipids themselves, they are ampipathic

Front 28

Detergents

Back 28

they possess very hydrophilic head groups and hydrophobic tails and are water soluble at much higher concentrations than are the phospholipids

Front 29

Sol state

Back 29

at high temperatures, the thermal energy of any given lipid molecule is greater than the interaction energy that would tend to hold adjacent lipid molecules together

Front 30

Sol state

Back 30

lateral diffusion can proceed rapidly

Front 31

Gel state

Back 31

at lower temperatures, interaction energies exceed the thermal energies of most individual molecules

Front 32

gel state

Back 32

phospholipids diffuse slowly because they lack the energy to free themselves from the embraces of their neighbors

Front 33

Transition temperature

Back 33

the temperature at which the bilayer membrane converts from the gel to the sol phase

Front 34

High transition temperature

Back 34

Phospholipids with LONG, SATURATED fatty acid chains can extensively interact with one another. Consequently, a fair amount of thermal energy is required to overcome these interactions and permit diffusion. These phospholipids have a __________

Front 35

shorter fatty acid chains;
unsaturated

Back 35

lowers transition temperature

Front 36

Glycerol-based lipids

Back 36

the most common membrane lipids

Front 37

Phosphatidylethanolamines;
Phosphatidylinositols;
Phosphatidylserines;
Phosphatidylcholines

Back 37

examples of Glycerol-based phospholipids

Front 38

Sphingolipids

Back 38

the second major class of membrane lipids

Front 39

Sphingomyelins;
Glycosphingolipids;
Gangliosides

Back 39

Sphingolipid Subgroups

Front 40

Cholesterol molecule

Back 40

its rigid steroid ring binds to and partially immobilizes fatty acid side chains

Front 41

Cholesterol decreases fluidity

Back 41

cholesterol at modest concentrations

Front 42

Cholesterol increases fluidity; lowers gel-sol transition temperature

Back 42

cholesterol at high concentrations

Front 43

Regions with "gel-like" properties

Back 43

formed when phospholipids with long-chain, saturated fatty acids will adhere to one another relatively tightly

Front 44

Sol-like regions

Back 44

Phospholipids with short-chain, unsaturated fatty acids form these regions

Front 45

Phosphilipid Bilayer Membranes

Back 45

are impermeable to charged molecules

Front 46

Gorter and Grendel

Back 46

measured the surface area of the lipids they extracted from erythrocyte plasma membranes

Front 47

Langmuir trough

Back 47

a device in which lipids are allowed to line up at an air-water interface and are then packed together into a continuous monolayer by a sliding bar that decreases the surface available to them.

Front 48

Phosphatidylethanolamine and Phosphatidylserine

Back 48

Phospholipids in the cytoplasm-facing leaflet

Front 49

Phosphatidylcholine

Back 49

Phospholipids in the outward-facing leaflet

Front 50

Peripherally associated membrane proteins

Back 50

are neither embedded within the membrane nor attached to it by covalent bonds; instead, they adhere tightly to the cytoplasmic or extracellular surfaces of the plasma membrane

Front 51

Peripherally associated membrane proteins

Back 51

can be removed from the membrane by mild treatments that disrupt ionic bonds (very high salt concentrations) or hydrogen bonds (very low salt concentrations)

Front 52

very high salt concentrations

Back 52

disrupt ionic bonds

Front 53

very low salt concentration

Back 53

disrupt hydrogen bonds

Front 54

Integral Membrane Proteins

Back 54

are intimately associated with the lipid bilayer

Front 55

Integral Membrane proteins

Back 55

cannot be eluted from the membrane by high or low salt washes

Front 56

Detergents

Back 56

To dislodge integral membrane proteins, the membrane itself must be dissolved by adding _______

Front 57

Transmembrane Proteins

Back 57

Proteins that actually span the lipid bilayer once or several times

Front 58

Hydrophobic alpha helices

Back 58

The membrane spanning portions of transmembrane proteins are usually _______

Front 59

AVLIP PTM
Alanine (Ala)
Valine (Val)
Leucine (Leu)
Isoleucine (Ileu)
Proline (Pro)
Phenylalanine (Phe)
Tryptophan (Trp)
Methionine (Met)

Back 59

8 Nonpolar/ Aromatic/ Uncharged Aliphatic groups of amino acids

Front 60

membrane-spanning segments

Back 60

the short stretch of amino acids that passes through the membrane once

Front 61

these hydrophobic sequences (proteins) tend to interact tightly with one another rather than with water.

These large protein aggregates are generally insoluble and precipitate out of the solution

Back 61

If we separate the membrane-spanning segments from the amphipathic phospholipids that surround them....

Front 62

the amphipathic detergent molecules can substitute for the phospholipids

Back 62

If we disrupt phospholipid membrane by adding detergent...

Front 63

transmembrane proteins

Back 63

can have a single membrane-spanning segment or several

Front 64

Membrane topology

Back 64

The pattern with which the transmembrane protein weaves across the lipid bilayer

Front 65

Alpha Helices, with 3.6 amino acids per turn

Back 65

the amino acid sequences of membrane spanning segments tend to form ______

Front 66

the polar atoms of the peptide backbone are maximally hydrogen bonded to one another - from one turn of the helix to the next - so they do not require the solvent to contribute hydrogen bond partners

Back 66

ensures the solubility of the membrane spanning sequence in the hydrophobic environment of the membrane

Front 67

Beta barrel

Back 67

arrangement of the membrane spanning portions of porin

Front 68

Multimeric proteins

Back 68

many membrane proteins form tight, noncovalent associations with other membrane proteins in the plane of the bilayer

Front 69

Protein diffusion in the plane of the membrane is much slower than that of lipids

Back 69

Because transmembrane proteins are large molecules...

Front 70

Receptors
Adhesion Molecules
Transmembrane Movt of Water Sol Subs
Enzymes
Intracellular Signaling

Back 70

Functions of Integral Membrane Proteins

Front 71

Adhesion Molecules

Back 71

Cells can exploit Integral Membrane Proteins that form physical contacts with the surrounding extracellular matrix or with their cellular neighbors.

Front 72

Integrins

Back 72

Example of matrix receptor or cell matrix adhesion molecules

Front 73

Cell matrix adhesion molecules

Back 73

comprise a large family of transmembrane proteins that link cells to components of the extracellular matrix at adhesion plaques

Front 74

Cell-cell adhesion molecules

Back 74

attach cells to each other

Front 75

Cadherins

Back 75

Ca2+ dependent cell adhesion molecule

Front 76

N-CAMs

Back 76

Ca2+ independent neural cell adhesion molecules

Front 77

Cadherins

Back 77

are glycoproteins
with one membrane spanning segment
and a large extracellular domain that binds calcium

Front 78

N-CAMs

Back 78

generally, are members of the immunoglobulin superfamily

Front 79

Loss of cell-cell and cell-matrix adhesion

Back 79

hallmark of metastatic tumor cells

Front 80

Pores and Channels

Back 80

serve as conduits that allow water, specific ions, or even very large proteins to flow passively through the bilayer

Front 81

Carriers

Back 81

can either facilitate the transport of a specific molecule across the membrane or couple the transport of a molecule to that of other solutes

Front 82

Pumps

Back 82

use the energy that is released through the hydrolysis of ATP to drive the transport of substances into or out of cells against energy gradients

Front 83

ION PUMPS are actually ENZYMES

Back 83

ION PUMPS are actually ENZYMES

Front 84

Spectrin

Back 84

two closely related isoforms (alpha & beta) form dimers, and two of these dimers assemble head to head with one another to form heterotetramers

Front 85

band 4.1

Back 85

a globular protein;
binds to the tail region of spectrin

Front 86

actin fibrils

Back 86

band 4.1 binds to....

Front 87

ankyrin

Back 87

binds to spectrin as well as to the cytoplasmic domain of band 3

Front 88

band 3

Back 88

the integral membrane protein responsible for transporting Cl and HCO3 ions across the membrane

Front 89

Subcortical Cytoskeleton

Back 89

provides the erythrocyte plasma membrane with strength and resilience

Front 90

Nucleus

Back 90

largest organelle

Front 91

Nucleus

Back 91

houses the cell's complement of genetic information

Front 92

Nucleus

Back 92

can range in diameter from 2 to 20 um

Front 93

endoplasmic reticulum

Back 93

a web of tubules or saccules surrounding the nucleus

Front 94

endoplasmic reticulum

Back 94

can either exist in two form, rough or smooth

Front 95

Rough ER

Back 95

surface is studded with ribosomes

Front 96

Ribosomes

Back 96

major site of protein synthesis

Front 97

Ribosomes

Back 97

can also exist free in the cytosol

Front 98

smooth ER

Back 98

participates in lipid synthesis

Front 99

endoplasmic reticulum

Back 99

also serves as a major reservoir for calcium ions

Front 100

Golgi Complex

Back 100

resembles a stack of pancakes

Front 101

Golgi complex

Back 101

processing station that participates in protein maturation and targets newly synthesized proteins to their appropriate subcellular destinations

Front 102

Mitochondrion

Back 102

a balloon within a balloon

Front 103

Cristae

Back 103

dramatic folds in the surface of the inner mitochondrial membrane

Front 104

Mitochondria

Back 104

0.2 um in diameter (at the limit of resolution of the light microscope)

Front 105

Lysosome

Back 105

the cell's digestive organelle

Front 106

exosomes

Back 106

smaller round vesicles within the lysosome

Front 107

Nucleus

Back 107

stores, replicates, and reads the cell's genetic information

Front 108

`Nucleus

Back 108

surrounded by a double membrane

Front 109

Outer Membrane (nucleus)

Back 109

studded with ribosomes and is continuous with the membranes of the rough ER

Front 110

Inner membrane (nucleus)

Back 110

smooth and faces the intranuclear space or nucleuoplasm

Front 111

Nuclear Pores

Back 111

penetrate the nuclear envelope and provide a pathway between the cytoplasm and the nuclear interior

Front 112

Nuclear Localization Sequence

Back 112

Cytoplasmic proteins destined for the nuclear interior must be endowed with this to gain entry

Front 113

100 nm

Back 113

outer diameter of the entire nuclear pore

Front 114

Nuclear Pore Complex

Back 114

provides for the nuclear pore's specificity;
an intricate matrix of protein that is distributed in a highly organized octagonal array

Front 115

Chromatin

Back 115

A complex between DNA and numeroud DNA binding proteins

Front 116

Nucleosomes

Back 116

tightly folded DNA-protein assemblies

Front 117

Nucleoli

Back 117

where the transcription of ribosomal RNA and the assembly of ribosomal subunits appear to occur

Front 118

Nuclear Lamina

Back 118

a fibrillar protein skeleton apposing the interior surface of the inner nuclear membrane

Front 119

Nuclear Lamina

Back 119

This meshwork, composed of proteins known as lamins, is presumably involved in providing structural support to the nuclear envelope

Front 120

Lysosome

Back 120

The cell's trash incinerator

Front 121

Lysosome

Back 121

filled with a broad assortment of degradative enzymes that can break down most forms of cellular debris

Front 122

Proton pumps

Back 122

embedded within the lysosome's limiting membrane ensures that this space is an extremely acidic environment which aids in protein hydrolysis

Front 123

Endocytic vesicle

Back 123

material that has been internalized from the cell exterior by endocytosis is surrounded by the membrane of an __________.

Front 124

Autophagy

Back 124

intracellular structures that are destined for degradation, are engulfed by the lysosome in this process

Front 125

Mitochondrion

Back 125

site of oxidative energy production

Front 126

Chemiosmotic model

Back 126

the inner membrane of the mitochondrion uses the energy in these gradients to generate ATP from ADP and Pi

Front 127

Mitochondrion

Back 127

maintains and replicates its own genome

Front 128

Mitochondrion

Back 128

also serves as reservoir for intracellular calcium

Front 129

Mitochondrion

Back 129

plays a central role in the process called apoptosis

Front 130

Cytoplasm

Back 130

is not amorphous but is organized by the cytoskeleton

Front 131

Thin Filaments

Back 131

5-8 nm;
actin

Front 132

Thick Filaments

Back 132

10 nm;
myosin

Front 133

Intermediate Filaments

Back 133

8-10;
tetramer of 2 coiled dimers

Front 134

Microtubules

Back 134

25 nm;
heterodimers of alpha and beta tubulin

Front 135

Vimentin

Back 135

intermediate filament found in cells that are derived from the mesenchyme

Front 136

Glial fibrillary acidic protein

Back 136

intermediate filament expressed exclusively in glial cells

Front 137

Neurofilament proteins

Back 137

intermediate filaments present in neuronal process

Front 138

Keratins

Back 138

intermediate filaments present in epithelial cells

Front 139

nuclear lamins

Back 139

intermediate filaments forming the structural scaffolding of the nuclear envelope

Front 140

Microtubules

Back 140

provide structural support and provide the basis for several types of subcellular motility

Front 141

Plus end (mIcrotubule)

Back 141

tubulin heterodimers can be added to the growing polymer at three times the rate that this process occurs at the opposite end

Front 142

Dynamic instability

Back 142

microtubules can undergo rapid rounds of growth and shrinkage

Front 143

Centrosome

Back 143

Microtubule-organizing center

Front 144

Axoneme

Back 144

structure at the center of the cilium;
composed of 9+2 microtubules

Front 145

Cilia

Back 145

oar like beating motions

Front 146

Flagellum

Back 146

serpentine motions

Front 147

Radial Spokes

Back 147

connect the outer tubules to the central pair

Front 148

Dynein
Nexin

Back 148

outer tubules attach to their neighbors by these linkages

Front 149

Kinesin

Back 149

minus to plus (body to axon)

Front 150

anterograde fast axonal transport

Back 150

minus to plus

Front 151

Dynein

Back 151

Plus to minus direction (retrograde)

Front 152

Gunter Blobel

Back 152

Nobel Prize for his work on SIGNAL SEQUENCES

Front 153

Cotranslational Translocation

Back 153

Proteins are inserted in the rough ER at the same time that they are translated