Cell Bio Quiz 2

Front 1

Plasma membrane

Back 1

made of a phospholipid bilayer and defines the cell and separates interior from exterior

Front 2

Membranes aren't rigid because...

Back 2

of abundant noncovalent interactions that hold lipids and proteins together

Front 3

What drives formation/stability of lipid bilayer structures?

Back 3

~Hydrophobic interactions

~van der Waals interactions

~Ionic and H bonding

Front 4

Exoplasmic Face

Back 4

the side of a biomembrane that faces internally

Front 5

Cytosolic Face

Back 5

the side of a biomembrane that faces externally towards the cytosol

Front 6

What are the 3 classes of membrane lipids?

Back 6

~phosphoglycerides

~sphingolipids

~cholesterol

Front 7

Unsaturated hydrophobic tails are...

Back 7

cis double bonds that increase the fluidity and decrease stability of the membrane

Front 8

Flippases

Back 8

ATP-powered transport proteins that move phospholipids from leaflet to another

Front 9

Lipid rafts

Back 9

formed by cholesterol and sphingolipids clustering with specific proteins

Front 10

Integral Membrane Protein

Back 10

proteins that are embedded into the membrane and typically contain one or more membrane-spanning alpha helices comprised of 20-25 hydrophobic a.a.'s

Front 11

How are integral membrane proteins attached to the membrane?

Back 11

Through hydrophobic and van der Waals interactions between hydrophobic side chains and fatty acyl chains in the bilayer

Front 12

Lipid-Anchored Membrane Proteins

Back 12

lipid hydrocarbon chains that are embedded in the bilayer but the protein itself isn't in the bilayer

Front 13

How are lipid-anchored membrane proteins attached to the membrane?

Back 13

they are anchored by covalently attached lipids

Front 14

Peripheral Membrane Proteins

Back 14

proteins bound to the membrane indirectly by interactions with integral or lipid-anchored proteins or directly by interactions with lipid head groups

Front 15

How to remove intermembrane proteins...

Back 15

detergent (transmembrane) or high-salt solution (peripheral & transmembrane)

Front 16

FABP

Back 16

fatty acid binding proteins that fatty acids bind to in order to be transported; belongs to a small group of small cytosolic proteins

Front 17

Phosphoglyceride Synthesis

Back 17

synthesis occurs on the cytosolic leaflet and can then be moved to the exoplasmic leaflet via transport by flippase

Front 18

Sphingosine Synthesis

Back 18

Synthesis of sphingosine and ceramide occur in the ER with the completion of the sphingolipid occurring in the golgi

Front 19

Cholesterol Synthesis

Back 19

Cholesterol synthesis is done by enzymes in the cytosol and in the ER

Front 20

Diffusion

Back 20

Movement from a higher concentration to a lower concentration; thermodynamically spontaneous

Front 21

Active Transport

Back 21

Movement from a lower concentration to a higher concentration; requires energy

Front 22

ATP-Powered Pumps

Back 22

require ATP hydrolysis and move molecules (ions, hydrophilics, or lipids) against an electric/chemical gradient

Front 23

Ion Channels

Back 23

facilitated diffusion that involves moving molecules (ions, water, or hydrophilics) down a gradient; can be gated or non-gated

Front 24

Uniporter

Back 24

facilitated diffusion that moves a single type of molecule or a single group of closely related molecules (glucose or a.a.'s) following a gradient

Front 25

Cotransporter

Back 25

transport of one molecule against its conc. gradient, driven by movement of one or more ions down an electrochemical gradient

Front 26

Symporter

Back 26

a cotransporter that involves the movement of two different types of molecules in the same direction

Front 27

Antiporter

Back 27

a cotransporter that involves the movement of two different types of molecules in different directions

Front 28

Molecules transported by simple diffusion:

Back 28

O2,CO2, steroid hormones, many drugs

Front 29

Molecules transported by facilitated transport:

Back 29

Glucose, amino acids (uniporter), ions and water (channels)

Front 30

Molecules transported by active transport:

Back 30

Ions, small hydrophilics, lipids (ATP-powered pumps)

Front 31

Molecules transported by cotransport:

Back 31

Glucose and amino acids (symporters), ions and sucrose (antiporters)

Front 32

P-class Pumps

Back 32

catalyzed by ATPase, this pump is located in the plasma membrane of higher eukaryotes (Na+/K+ pump) and in the sarcoplasmic reticulum membrane in muscle cells (Ca2+ pump)

Front 33

V-Class Proton Pump

Back 33

catalyzed by ATPase, this pump is located in endosomal and lysosomal membranes in animal cells

Front 34

F-Class Proton Pump

Back 34

catalyzed by ATP synthase, this pump is located in the inner mitochondrial membrane

Front 35

ATP-Binding Cassette

Back 35

catalyzed by ATPase, this pump is located in mammalian plasma membranes

Front 36

MDR1

Back 36

an ABC protein identified from tumor cells that showed resistance to several drugs with unrelated chemical structures

Front 37

CFTR

Back 37

A Cl- channel expressed in the interior plasma membranes of epithelial cells in the lung, sweat glands, and pancreas

Front 38

Membrane Potential

Back 38

the difference in voltage between the interior and exterior of a cell

Front 39

Osmosis

Back 39

a process whereby water moves across a semipermeable membrane from a sol'n of low solute conc. to one of high solute conc.

Front 40

Osmotic Pressure

Back 40

the hydrostatic pressure required to stop the net flow of water across a membrane separating sol'n of different compositions

Front 41

Aquaporin Proteins

Back 41

expressed on plasma membrane; mainly transports water in either direction depending on the osmotic gradient

Front 42

Transepithelial Transport

Back 42

Transport of molecules across layers of epithelial cells covering the internal surface of organs such as the intestine

Front 43

N-Linked Oligosaccharides

Back 43

linked through amide nitrogen of asparagine

Front 44

O-Linked Oligosaccharides

Back 44

linked through -OH in Serine/Threonine; A, B, O blood-group antigen

Front 45

How many fatty acyl tails are there on phosphoglycerides?

Back 45

2

Front 46

How many fatty acyl tails are there on sphingomyelin?

Back 46

1

Front 47

How many fatty acyl tails are there on cholesterol?

Back 47

none

Front 48

Example of a lipid in a glycolipid anchor:

Back 48

GPI

Front 49

Example of a lipid in an acyl anchor:

Back 49

myristate

Front 50

Example of a lipid in a prenyl anchor:

Back 50

farnesyl

Front 51

What side of the plasma membrane does the glycolipid anchor protein face?

Back 51

exoplasmic side

Front 52

What side of the plasma membrane does the acyl anchor protein face?

Back 52

cytosolic side

Front 53

What side of the plasma membrane does the prenyl anchor face?

Back 53

cytosolic side

Front 54

Where does the last step of phophoglyceride synthesis occur?

Back 54

ER

Front 55

Where does the last step of sphingolipid synthesis occur?

Back 55

Golgi

Front 56

Where does the last step of cholesterol synthesis occur?

Back 56

ER

Front 57

Which side of the ER membrane is topologically equivalent to the exterior of the plasma membrane?

Back 57

Luminal

Front 58

Do ions move against a concentration gradient with a Na+/K+ pump?

Back 58

Yes

Front 59

Do ions move against a concentration gradient with a non-gated K+ channel?

Back 59

No

Front 60

What type of transport maintains the K+ concentration gradient across the membrane?

Back 60

Na+/K+ pump

Front 61

What type of transport protein determine the membrane potential of a cell at the resting phase?

Back 61

Non-gated K+ channel

Front 62

Does a aquaporin protein transport molecules down a concentration gradient?

Back 62

yes

Front 63

Does a GLUT1 proteintransport molecules down a concentration gradient?

Back 63

yes

Front 64

Which terminus of Type I membrane proteins is facing the exoplasmic space?

Back 64

N-terminus

Front 65

Which terminus of Type II membrane proteins is facing the exoplasmic space?

Back 65

C-terminus

Front 66

How does the mature form of Type I membrane protein stay attached to the membrane?

Back 66

via stop-transfer anchor sequence

Front 67

How does the mature form of Type II membrane protein stay attached to the membrane?

Back 67

via signal-anchor sequence

Front 68

How does the mature form of GPI-linked membrane protein stay attached to the membrane?

Back 68

via the GPI anchor covalently linked to the protein

Front 69

Where does glycosylation occur?

Back 69

ER and Golgi

Front 70

Where does formation of disulfide bonds occur?

Back 70

ER

Front 71

Where does folding occur?

Back 71

ER

Front 72

Which two enzymes are involved in formation of disulfide bonds?

Back 72

Protein disulfide isomerase

Ero1

Front 73

Which two enzymes are involved in folding?

Back 73

Bip

Calnexin

Calreticulin

Front 74

What type of glycosylation involves several branches of oligosaccharides?

Back 74

N-linked

Front 75

Give two examples of cargos that would be transported by Ran-dependent nuclear import:

Back 75

histones, RNA polymerase, DNA polymerase, transcription factors

Front 76

Give two examples of cargos that would be transported by Ran-dependant nuclear export:

Back 76

ribosomal subunits, tRNA

Front 77

What signal sequence is present on Ran-dependent nuclear import cargos?

Back 77

NLS (nuclear-localization signal)

Front 78

What signal sequence is present on Ran-dependent nuclear export cargos?

Back 78

NES (nuclear-export signal)

Front 79

What protein binds to the signal sequence on Ran-dependent import?

Back 79

importin

Front 80

What protein binds to the signal sequence on Ran-dependent export?

Back 80

exportin

Front 81

What status of Ran would induce release of cargos from cargo complexes in Ran-dependent import?

Back 81

GTP-bound

Front 82

What status of Ran would induce release of cargos from cargo complexes in Ran-dependent export?

Back 82

GDP-bound