LIGAND GATED CHANNELS Flashcards

1
Q

WHAT IS THE FUNCTION OF SIGNALLING SYSTEMS

A
RECOGNISE A STIMULUS
TRANSFER A STIMULUS INTO A CELL
AMPLIFY CYTOPLASMIC SIGNAL
MODULATE EFFECTOR SYSTEMS
ADAPT THROUGH FEEDBACK
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

IN MULTI CELLULAR ORGANISMS …………………….. EXPRESSION OF CERTAIN RECEPTORS AND THEIR MOLECULES INVOLVED IN SIGNAL …………………….. ALLOWS CELLS TO RESPOND…………………………. TO PARTICULAR STIMULI

A

SELECTIVE
TRANSDUCTION
SPECIFIC

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

WHAT IS THE ROLE OF RECEPTORS

A

TO DETECT CHEMICAL AND PHYSICAL STIMULI

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

PHYSICAL INTERACTION BETWEEN STIMULUS AND …………….. PROVIDES………………. TO CHANGE THE STRUCTURE OF THE RECEPTOR IN SUCH A WAY THAT MAY INITIATE ……………………..

A

RECEPTOR
ENERGY
SIGNALLING

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

WHAT KIND OF RECEPTOR ARE INVOLVED

A

MOST ARE EMBEDDED IN THE PLASMA MEMBRANE
SOME CAN BE IC RECEPTORS
SOME ARE TRANSMEMBRANE RECEPTORS

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

HOW MANY RECEPTOR FAMILIES ARE IN THE MAMMALIAN GENOME

A

25

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

HOW MANY GENES CODE FOR ION CHANNELS

A

400

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

WHAT TYPES OF GATED ION CHANNELS ARE THERE

A

LIGAND

VOLTAGE

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

ION SELECTIVITY OF A PORE IS DEFINED BY WHAT FACTORS

A

THE SIZE OF THE ‘FILTER’

THE AMINO ACID LINING THE PORE

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

EVOLUTIONARILY SIMPLE ORGANISMS HAD SIMPLE CHANNELS. OVER ………………….. OF A GENE CODING FOR 2TM DOMAIN CHANNELS GAVE RISE TO A FAMILY OF 2 - …………… TM DOMAINS.
POSITIVE CHARGES IN THE AMINO ACIDS IN TM……. GAVE RISE TO …………………… SENSITIVITY.

A

DUPLICATION
24
4
VOLTAGE

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

DESCRIBE THE STRUCTURE OF A Kir CHANNEL

A
  1. 2 TM DOMAINS
  2. NH2 AND COOH TERMNII CYTOPLASM FACING
  3. EXTRACELLULAR LOOP THAT FOLDS BACK TO FOR THE PORE LINING ION SELECTIVITY FILTER
  4. 4 OF THESE UNITS COME TOGETHER TO FORM A TETRAMER
  5. THIS IS THE BASIC STRUCTURE OF MOST ION CHANNELS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

IF THE BASIC STRUCTURE OF KIR CHANNEL FUNCTIONS AS NEEDS, WHY ARE THERE OTHER CHANNELS WITH MORE TM DOMAINS

A

MOST CHANNELS ARE BUILD AROUND THE BASIC STRUCTURE, THE EXTRA DOMAINS IN MORE COMPLEX CHANNELS ARE THE REGULATORY ELEMENTS THAT CONTROL THE OPENING OF CHANNELS AS WELL AS OTHER MORE COMPLEX FEATURES OF VOLTAGE SENSORS ETC

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

DO ALL CHANNELS EVOLVE FROM THE PRIMORDIAL BACTERIAL K CHANNEL

A

NO, SOME ARE THOUGHT TO HAVE EVOLVED SEPARATELY

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

WHAT IS AN EXAMPLE OF A CHANNEL THAT HAS EVOLVED SEPARATELY FROM THE PRIMORDIAL BACTERIAL K CHANNEL

A

NICOTINIC ACH CHANNELS

GABA CHANNELS

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

WHAT ARE THE STRUCTURE OF NICOTINIC ACH CHANNELS AND GABA CHANNELS THAT MAKE THEM DIFFERENT FROM THE EVOLUTIONARY PRIMORDIAL BACTERIAL K CHANNEL

A

THEY ARE PENTAMERIC

THEY HAVE NO P LOOP

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

SUBUNITS COME TOGETHER TO FORM A …………..

A

PORE

17
Q

WHAT IS THE FUNCTION OF A P LOOP

A

P LOOPS COME TOGETHER TO CREATE A HIGHLY SELECTIVE FILTER/GATE

18
Q

EXPLAIN THE PROCESS OF A K+ ION MOVING THROUGH A PORE

A

TO BE SMALL ENOUGH TO FIT INTO THE PORE, K+ MUST LOSE ITS WATER
ITS BINDING GENERATES ENERGY TO OPEN THE CHANNEL
K+ LINE UP TO FIT IN THE PORE CREATING REPULSION WHICH CAUSES FLOW CONDUCTION
THE PORE MUST BE OPEN AT BOTH ENDS

19
Q

HOW MANY TM DOMAINS DO VOLTAGE GATED K+ CHANNELS HAVE

A

6

20
Q

WHAT IS THE STRUCTURE OF A VOLTAGE GATED K+ CHANNEL SUCH AS KV1

A
  1. 6 TM DOMAINS
  2. 4 SUBUNITS
  3. TM4 IS POSITIVELY CHARGED AND DETECTS POTENTIAL
  4. ADDITION OF ALPHA AND BETA SUBUNITS FOR REGULATION
  5. HAS AN INACTIVATION PEPTIDE
21
Q

LIGAND GATED ION CHANNELS HAVE A …………….. PORE AND ARE …………….. SELECTIVE

A

LARGER

LESS

22
Q

WHAT IS THE STRUCTURE OF A LIGAND GATED ION CHANNEL EG CYCLIC NUCLEOTIDE GATED CHANNELS

A
  1. 6TM DOMAINS
  2. EACH SUBUNIT ALSO HAS A CYCLIC NUCLEOTIDE BINDING BINDING DOMAIN
  3. FOUR SUBUNITS MUST COME TOGETHER TO CREATE THE ION CHANNEL
  4. THEREFORE THERE ARE 4 NUCLEOTIDE BINDING SITES PER CHANNEL
  5. AT LEAST 3 MUST BE FILLED FOR THE CHANNEL TO OPEN
23
Q

IN ION CHANNEL STRUCTURE THE PORE IS USUALLY BETWEEN

A

S5 AND S6 TMS

24
Q

WHAT DOES CYCLIC NUCLEOTIDE GATED CHANNELS BINDING DOMAIN DETECTS WHAT

A

CAMP

GGMP

25
Q

WHAT IS THE STRUCTURE OF THE P2X RECEPTOR

A
  1. 2TM DOMAINS
  2. TRIMERIC
  3. GATED BY ATP
  4. BINDING OF 3 MOLECULES OF ATP CAUSES A CONFORMATIONAL CHANGE TO OPEN THE CHANNEL
26
Q

WHAT IS THE STRUCTURE OF THE IONOTROPIC GLUTAMATE RECEPTOR

A
  1. 4TM DOMAINS
  2. TETRAMERIC (MADE UP OF A DIMER OF DIMERS)
  3. EXTENDED EC N TERMINUS WITH A GLUTAMATE BINDING SITE
  4. HAS A CLAM SHELL CLEFT (WHEN GLUTAMATE BINDS, THE CLEFT CLOSES AND THE PORE OPENS)
27
Q

WHAT IS AN EXAMPLE OF AN IONOTROPIC GLUTAMATE TYPE LIGAND GATED ION CHANNEL

A

NMDA RECEPTOR

28
Q

WHAT IS THE STRUCTURE OF A CYS LOOP LIGAND GATED ION CHANNEL

A
  1. 4TM
  2. NO P LOOP
  3. PENTAMERIC ASSEMBLY
  4. AMINO ACIDS LINE THE PORE AND CAN CHANGE SELECTIVITY FROM +VE TO -VE
  5. TO OPEN THE PROTEINS TWIST
  6. MUST HAVE TWO ALPHA SUBUNITS WHERE THE LIGAND BINDING SITE IS.
29
Q

WHAT IS AN EXAMPLE OF A CYS LOOP LIGAND GATED CHANNEL

A

NICOTINIC ACHR

GABA A

30
Q

WHAT IS DIFFERENT ABOUT THE CYS LOOP TYPE CHANNELS COMPARED TO OTHER ION CHANNELS

A

THEY ARE NOT EVOLVED FROM THE THE PRIMORDIAL BACTERIAL K CHANNEL