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Biochemistry 2 > Lipid membrane and solute transport > Flashcards

Lipid membrane and solute transport Flashcards

1
Q

Why the membrane is called mosaic?

A

Because it consists of different kinds of molecules

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2
Q

The integral proteins are called like that because

A

They are embedded in the membrane. They can pass through the lipid bilayer or only on one side

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3
Q

Example of integral proteins

A

Receptors ( GPCRs)

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4
Q

Why do detergents are needed to detach the integral proteins form the membrane?

A

Because they are strongly associated with it

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5
Q

What does amphitropic protein mean

A

Having an affinity for both lipid and aqueous environments. Thus, if needed they can detach from the membrane and play its role in the aqueous environment

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6
Q

What do you need to make amphitropic proteins detach from the membrane?

A

Some kind of enzyme ( phospholipase C) or postranslational modification (phosphorylation)

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7
Q

What is GPI?

A

Glycosylphosphatidyllinositol

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8
Q

An example of GPI linked protein

A

Phosphatases

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9
Q

Different organelles within the cell have different ____

A

Cell wall components ( the ratio of components)

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10
Q

Inner and outer cell membrane ___ each other

A

Differ from each other

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11
Q

What molecules are involved in cell signaling in the cell membrane

A

phosphatidyllinositol

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12
Q

Most of phosphatidyllinositol is inside/outside of the cell

A

inside

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13
Q

Phosphatidylserine is usually maintained

A

Inside of the cell

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14
Q

When Phosphatidylserine flips to the outer membrane, then

A

It signals for apoptosis or blood clot

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15
Q

Acyl groups in the bilayer affect

A

Flexibility

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16
Q

There are two states of the bilayer

A

Ordered state(Lo) and disordered state(Ld). It is a range of temperatures rather than points

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17
Q

The transition from Lo->Ld of side chains is a result of

A

Heat that produces thermal motion in side chains. The more temperature it is exposed to, the more disordered the side chains will be.

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18
Q

What increases order in the bilayer

A

Saturation of FA
Uniform length of FA
Sterol content can decrease or increase order

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19
Q

How do cells regulate the membrane

A

FA content ( increase Saturated FA at higher temperatures)

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20
Q

Ordered state is more ___, and disordered is more ___

A

Rigid

Flexible

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21
Q

uncatalyzed lipid movement ( what direction)

A

Lateral diffusion

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22
Q

three catalyzed transbilayer translocation

A

flippase (from outer to inside)
Floppase ( form inside to outside)
Scramblase ( moves lipids in either direction, toward equilibrium)

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23
Q

what enzymes perform flippase and floppase

A

Flippase- P-type ATPase
Floppase- ABC transporter
With the use of ATP

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24
Q

What holds protein in the bilayer

A

Cytoskeleton

Lipid rafts

25
Sphingolipids give __ to the bilayer
Order, thus more rigid. | Sphingolipids give order to an area, not flexible within the region, but as a whole free to move
26
Lipid rafts contain specific___
Double or triply acylated proteins
27
6 things for two membranes to fuse
- triggering signal - recognize each other - close apposition - local disruption of bilayer - hemifusion - fusion proteins
28
All neurotransmitters are stored in ___
Vesicles
29
Four types of proteins that are involves in fusion at synapse
T-SNARE V-SNARE Q-SNARE(SNAP-25) NSF (N-ethylmaleimide-sensitive fusion factor)
30
What does T-SNARE do
They are assembled on the target membrane. At this pont of time the cell should know at what part of the exon( because it is huge) it will secret the neurotransmitters. This is done by them
31
What does V-SNARE do
It recognizes the vesicle that should be emptied out. It is assembled on the vesicle site
32
What do Q-SNARE do
They help T-SNARE and V-SNARE to come together | They are induced by Ca
33
The stages in fusion of the vesicle with neurotransmitter
1) The vesicle has V-SNARE and the plasma membrane has T-SNARE. SNAP-25 helps this two to come together 2) V and T bind to each other and start to zip, thus they are brought closer to each other 3) When the vesicles are brought close enough to each other, hemifusion occurs between outer leaflets 4) Hemifusion-> full fusion. Now the vesicle can open up, because it is part of the membrane
34
What does NSF do
They disassemble the proteins that were bound to each other, the SNARE complex
35
Three glucose transporters that are studied a lot
Glut 1 Glut 2 Glut 4
36
Glut 1,2 and 4 belong to what kind of transporters
Passive, do not need energy, down the concentration gradient
37
Glut 4 is regulated by what mechanism
RTK and PIP3 and PKB
38
How GLUT 4 is regulated
Amount of transporter presented in the cell membrane by RTK thus regulating how much glucose is available for glucose transport. The more transporters are available, the more glucose goes from outside to inside. If no RTK signal, transporters are stored in the cell in vesicles
39
What is diabetes mellitus ( biochemically)
Lack of signal transduction of RTK, thus less transporters come form the inside to the outside-> less glucose uptake
40
Respiration is what kind of transport
Facilitated passive transport
41
Explain what happen in erythrocyte when it comes to respiring tissue
CO2 diffuses through the membrane inside the erythrocyte. CO2+H2O->HCO3-+H+ HCO3- is thrown outside the membrane and CL- is taken in by a cotransporter(antiporter)
42
What is the enzyme for conversion of CO2 to HCO3-
carbonic anhydrase
43
What happens in lungs
The same reaction as in erythrocyte but in reverse. | Cl- is given off, HCO3- is taken, converted to CO2 and given to lungs
44
Two types of active transporters
Primary active transport | Secondary active transport
45
Explain the difference between primary active transport and secondary active transport
Primary- with the use of ATP, the molecule is transported across the concentration gradient Secondary- an artificial gradient of one molecule is created by pumping it across the gradient, to allow another protein to use this gradient to transport another molecule symporter)
46
An active transport: symport example and antiport example
Symport: Na+ glucose, Na+ AA in intestinal epithelium Antiport:Na+K+ATPase,Na+H= pumps in kidney
47
What type of ATPases in used in mitochondria
F type
48
Explain ABC transporters
When ATP is boiund to the cassette, the transporter is opened outward, when ADP- inward, when the molecule comes there is a change in conformation, because of ATP\ADP
49
RBCs comparing to the stem cell does not have
Nucleus and mitochondria
50
As RBCs do not have mitochondria what does it mean for them
They cannot produce energy and they rely only on glycolysis
51
Tissue repair requires____
Energy and biosynthesis precursors
52
Neurons depend more on ___
Glucose
53
Cardiac myocytes (muscles int he heart) depend more on ___
FAs
54
Where can the regulation be inserted in the cell
1. Extracellular signals 2. Transcription regulation (a-TF phosphorylation/dephosphorylation,b-TF interactions) 3. mRNA stability (degradation) - miRNA) 4. mRNA translation 5. Protein half-life (stability) 6. Enzyme localization 7. Changes of levels of substrate( the more substrate- the more active the enzyme) 8. Enzyme binding "allosteric effectors" 9. Covalent modification 10. Interaction with regulatory protein
55
The longer mRNA is maintained within the cell- the longer it is going to be ___
Translated, the more protein produced
56
What are cyclins
Proteins involved in cell cycle- cell division, their half-life is very short
57
Mitochondrial enzymes are only functional
In mitochondria
58
Pathways in opposite directions are not favored ___. For example
At the same time | Glycolysis and Gluconeogenesis

Biochemistry 2 (17 decks)

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