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BIOCHEMISTRY > MEMBRANES AND TRANSPORT > Flashcards

MEMBRANES AND TRANSPORT Flashcards

1
Q

The membrane is not_________ or _______ but highly _______ and dynamic structures

A

The membrane is not rigid or impermeable but highly mobile and dynamic structures

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2
Q

Proton pumps are examples of—

A

Examples of primary transporters

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3
Q

Role of integral transmembrane proteins

A

Transporting molecules to maintain concentration gradients of Na, K and Ca. The fuel for this is ATP.

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4
Q

type of transport that allow small, non polar molecules (O2, CO2, N2) , and uncharged polar molecules (urea, ethanol, small organic compounds) to move through the membrane without aid of proteins.

A

simple diffusion

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5
Q

How we transport water?

A

Small molecules can be transported by simple diffusion but channel proteins take care of this mostly.

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6
Q

nephrogenic diabetes insipidus

A

disease characterized by excessive urination but without hyperglycemia characteristic of diabetes mellitus. This is caused by mutation in aquaporin 2

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7
Q

What are transporters?

A

Also known as translocases, permeases, or carrier proteins. Transport large molecules through the membrane. They are specific. commonly drug targets

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8
Q

Two mechanisms of transporters?

A

Facilitated diffusion or active transport

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9
Q

facilitated diffusion

A

type of transport mediated by protein which allows transport of large molecule from high to lower []. It involves protein, and specificity.

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10
Q

WHAT IS active transport?

A

type of transported mediated by proteins that requires energy to transport large molecules from low [] to high []

type: uniport or cotransport, opposite directions.

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11
Q

primary active transporter

A

active transport that uses ATP It has transport protein, energy coupling, specifity and saturability via PUMPS

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12
Q

secondary active transporter

A

active transport that use electrochemical gradient (membrane potential) of one molecule to move another molecule without hydrolyzing ATP.

It has transport protein, energy coupling, specifity and saturability.

types of secondary transport: antiporters or symporters

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13
Q

uniport (monoport)

A

transmembranal transportation unidirectional

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14
Q

Symport system

A

transmembranal transportation involving two cotransported substrates.

Ex. glucose symporter SGLT1

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15
Q

antiport

A

transmembranal transportation involving substrates moving in opposite directions

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16
Q

Examples of facilitated diffusion channel

A

H20, Na, K, Ca, cl, GLU 1-5

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17
Q

ABC transporters are examples of —

A

primary active transporters unless its coupled

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18
Q

What is the difference between a transporter and a channel?

A

Transporter undergo conformational changes and channels are just a “tubo” where they can go through.

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19
Q

What are ionophores?

A

molecules that facillitate the tranport of ions across the membrane and allow net movement of ion only down their electrochemical gradient by increasing the permeability of specific ions.

This is how antibiotics works.

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20
Q

Types of ionophores

A

mobile carrier and channel formers

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21
Q

Explain the diagram

A

The rate of transport of substrate is plotted against the concentration of substrate in the extracellular medium. Incommon with enzyme catalysis, transporter-catalyzed uptake has a maximum transport rate, Tmax (saturable). Kt is the concentration at which the rate of substrate uptake is half-maximal. For simple diffusion, the transport rate is slower and directly proportional to substrate concentration.

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22
Q

Is the maximun transporter rate and its achieved when its saturated. Its not a characteristic of simple diffusion.

A

t max

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23
Q

What is Kt?

A

half maximal transport rate and is the dissociation constant of the susbtrate transporter complex.

24
Q

Transmembrane proteins similar in size, having all 500 aa and 12 transmembrane helices

A

GLU transporters

25
Q

Type of GLU transporter in red blood cells and it operates in needs of the red cell

A

GLU 1

26
Q

GLU 2

A

Transporter in pancreatic beta cells that responds to intake of food and the increase of glucose concetration. They increase glucose uptake into beta cells, which stimulates insulin secretion.

27
Q

Muscles and adipose tissue have this type of transporter. Insulin stimulates translocation of this transporter from intracellular vesicles to the plasma membrane, accelerating postprandial (after lunch) glucose uptake

A

GLU 4

28
Q

What is voltage or ligant gatting?

A

conformational changes made into the channel or pore that allows molecules to pass through like ions, metabolites, proteins. Its not that specific and its more based on size.

29
Q

What mediates channels and pores (facilitatted difussion) ?

A

chaperones and escort proteins

30
Q

How sugars and Amino acids are transported into cells?

A

Commonly by GLU transporters or secondary active transport systems

31
Q

Types of primary active transports or types of pumps

A
  1. coupling factor ATPases (F-ATPases)
  2. V-type (vacuolar) H-ATPase
  3. P-ATPase
  4. ATP binding cassete (ABC) transporters
32
Q

how F-ATPase works?

A 
Coupling-factor ATPases (F-ATPases) in mitochondrial, chloroplast, and bacterial membranes hydrolyze ATP and transport
hydrogen ions (H+).

MITOCHONDRIAL pump works by synthesizing ATP from ADP and phosphate as proton move down the electrochemical gradiente generated across mithocondrial memebrane during oxidative metabolism.

33
Q

What is V-type (vacuolar) H-ATPase?

A

enzyme in lysosomes, endosomes, secretory granules which acidifies this organelles in the membranes and are important for lysosomal activity.

34
Q

V-ATPase also acidifies extracellular environment of ———

A

osteoclasts (for reasbsoption) in bone and renal epithelial cells

35
Q

mutations on V-ATPase in renal tubes can cause _____ and in osteoclast plasma membrane _________.

A

mutations on V-ATPase in renal tubes can cause renal tubular acidosis and in osteoclast plasma membrane high bone density.

36
Q

P-ATPase

A

primary active transport pump that forms phosphorylated intermediates that drive on translocation

“P” phosphorilation

Ex. Ca ATP ase

37
Q

How P-ATPases work?

A

have a active side in aspartate residue that is phosphorilated by ATP for transport processes

38
Q

P type Na/K ATPase in __________ and Ca-ATPase in _________ mantain ________

A

P type Na/K ATPase in various tissues and Ca-ATPase in muscle sarcoplasmic reticulum mantain ion gradients

39
Q

X linked Menkes disease

A

lethal disorder that have defective copper-transporting P-ATPase, expressed in all tissues except the liver in this disease.

Copper enter the intestinal cells but cant be transported resulting in copper defficency

40
Q

What is Wilso’s disease?

A

encodes a copper transporting P-ATPase. Failure to excrete copper from the liver to bile resulting in toxic accumulation in the liver, kidney, brain and cornea.

Treatment? penicillamine and triethylamine, oral zinc to decrease absorption of diatery copper

41
Q

what are ATP-binding cassette transporters?

A

ABC binding cassette, referring to an ATP binding motif in transporter.

42
Q

What are TAP transporters?

A

A class of ABC transporters

“Transporters Antigen Presentation”

are required to iniate immune responses against foreign proteins; mediate transport of peptides from cytosol into endoplasmic reticulum.

43
Q

What is cystic fribrosis?

A

most commonly potentially lethal autosomal recessive disease of caucasians. Its manifested by exocrine pancreatic insuffency, high [] of cl in sweat, male infertility, and airway disease (increased viscosity )

This is causes by mutations in the gene CFTR wich contains ABC motif and encode Cl channels. ATP binding to CFTR is needed for channel to open.

44
Q

what is a electrochemical gradient?

A

combination of the concentration gradient (chemical potential) and the voltage gradient across the membrane

45
Q

what is SGLT1?

A

symple transporter that pumps glucose into the cell and passes out of the cell by facilitated diffusion meduated by GLUT 2 uniporter.

the gradient its mantained by Na/K ATPase

46
Q

What causes a defect of SGTL1?

A

glucose/galactose malabsorption

47
Q

What are Voltage dependant Ca channels in muscles? VCCs

A

channels found in tubules T which change conformation in response to membrane depolarization, and they directly activate Ca release channel into the sarcoplasmic reticulum membrane and that way hydrolisis of ATP in myosin starts muscle contraction

48
Q

How glucose is transported from intestine to blood?

A

It needs facilitated diffusion and active transport.

49
Q

________ in gastric parietal cells mantains the _____ of the stomach

A

P-ATPase in gastric parietal cells mantains the low PH of the stomach.

50
Q

bomba hydrogeno/potasio ATPase mantiene ________ en el estomago

A

ph de 1

51
Q

How the gastric proton pumps ( H/K ATPase) get activated?

A

Stimuli such as histamine and gastrin induce fusion of vesicles (where this pumps are) with plasma membrane.

52
Q

the gastric proton pumps ( H/K ATPase) is a __________ transporter pumping _______________ coupled with hydrolysis of ATP

A

the gastric proton pumps ( H/K ATPase) is a antiport transporter pumping 2 cytoplasmic protons and 2 extracellular potassium ions coupled with hydrolysis of ATP

53
Q

The Cl channel is considered a ——-

A

ABC transporter

54
Q

Examples of P-ATPase

A

Na/K P-ATPase

H/K P ATPase

Ca P-ATPase

Cu- P ATPase

55
Q

Explica como funciona Ca-ATPase

A
56
Q
A
57
Q

GLUT Types

A

I- BBB- blood, babies (fetus) and blood brain barrier

II- Kids Lips - kidney, liver, pancreas

are

III- Pink- placenta, neurons, kidney

IV- mother fucker- muscle, fat (insulin dependent)

BIOCHEMISTRY (2 decks)

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