Advanced Molecular Cell Biology L1-
14 Final Exam 2025-2026 All Questions
Answered Correct.
Understand the conceptual basis of cell communication - Answer - cellular or organ level
- speed, duration and mechanism vary
Understand what a signal can be - Answer - Contact-dependent/short-range (e.g. neuronal
synapsing)
- Paracrine signaling (local mediators)
- Endocrine signaling (long-distance, e.g. adrenaline)
Understand how cells can respond to signaling - Answer - receptors
- intracellular protein de/activation
- cells can react in different ways depending on the strength of the signal they receive (not just
on/off)
- morphogen gradient: different responses occur at particular thresholds
Understand how a signal is regulated and why this is important - Answer Destroying a
protein when it is used would be wasteful and time-consuming, therefore post-translational
modifications (such as phosphorylation to activate) makes a protein available when needed.
K+ channels - structure and gating mechanism - Answer - 4 subunits surrounding a pore
- TM helices structures form a p-loop (pore)
- highly selective to K+
- On cytoplasmic side, the TMDs are more tightly packed, forming a gate
Voltage-gated ion channels structure - Answer - Gated (controlled by changes in electrical
membrane potential)
- 4 subunits
- 6-24 helices
- P-loop (pore)
,Voltage- gated ion channel functions - Answer - Na+ and K+ create APs in excitable cells
- Ca2+ transported into cytoplasm where 2nd messenger elicits a cellular response
Transient receptor potential (TRP) channels - Answer - Gated
- 4 subunits
- 6 helices across lipid bilayer
- P-loop (pore)
- Anchored
- Don't detect voltage, but rather different chemical stimuli (such as temperature)
- Plugging mechanism
Identify features and function of ligand-gated ion channels - Answer - Gated (controlled by
chemical transmitters)
- 4 Subunits
- 6 helices
- P-loop
- Anchored
- No voltage sensors or plugging mechanism
- Function examples; olfaction (cAMP) and muscle (calmodulin)
- ligand must bind to 3/4 subunits to elicit a response
Ligand-gated ion channel regulatory unit function - Answer If calcium binds to calmodulin, it
provides negative feedback response (channel closes)
Simple channels - Answer - 2 subunits
- 2 helices
- not gated
- p-loop
- not anchored
- no voltage sensor
- no plugging mechanism
- function: secretion/ absorption of fluids
, - 5 subunits
- each subunit has 4 TMDs
- large external-facing domain
- specificity for the pore
- subunits can move to make more space to allow for different ions to flow through
Glutamate receptors - Answer - trimeric
- main NT in brain is glutamate
- 4 subunits
- different isoforms due to different genes, RNA splicing, etc (e.g. flip and flop are two different
splicing isoforms of subunits with different functions)
- AMPA, NMDA and Kainate receptors are all types of glutamate receptors
P2X receptors - Answer - ATP-gated ion channels
- trimeric
- 3 subunits with 2 TM helices
- large EC domain
- 3 ATP molecules needed for opening
- widely expressed
- 7 subtypes of subunits which can be combined to respond to different stimuli
Ion channels and drug targeting - Answer - dysfunction of receptors in different cell types
lead to physiological diseases
- you can use small molecule drugs which are complementary to receptors to inhibit or activate
receptors to produce a desired response
Describe characteristic structural features of GPCRs - Answer - 7 TMDs (7 helices)
- TMD 3 lines binding pocket
- N terminus is EC, C terminus in IC
- Most diverse form of receptor due to amino acid sequence in the ligand-binding site
- Respond to a wide range of stimuli (lipids, protons, proteins, photons, etc)
14 Final Exam 2025-2026 All Questions
Answered Correct.
Understand the conceptual basis of cell communication - Answer - cellular or organ level
- speed, duration and mechanism vary
Understand what a signal can be - Answer - Contact-dependent/short-range (e.g. neuronal
synapsing)
- Paracrine signaling (local mediators)
- Endocrine signaling (long-distance, e.g. adrenaline)
Understand how cells can respond to signaling - Answer - receptors
- intracellular protein de/activation
- cells can react in different ways depending on the strength of the signal they receive (not just
on/off)
- morphogen gradient: different responses occur at particular thresholds
Understand how a signal is regulated and why this is important - Answer Destroying a
protein when it is used would be wasteful and time-consuming, therefore post-translational
modifications (such as phosphorylation to activate) makes a protein available when needed.
K+ channels - structure and gating mechanism - Answer - 4 subunits surrounding a pore
- TM helices structures form a p-loop (pore)
- highly selective to K+
- On cytoplasmic side, the TMDs are more tightly packed, forming a gate
Voltage-gated ion channels structure - Answer - Gated (controlled by changes in electrical
membrane potential)
- 4 subunits
- 6-24 helices
- P-loop (pore)
,Voltage- gated ion channel functions - Answer - Na+ and K+ create APs in excitable cells
- Ca2+ transported into cytoplasm where 2nd messenger elicits a cellular response
Transient receptor potential (TRP) channels - Answer - Gated
- 4 subunits
- 6 helices across lipid bilayer
- P-loop (pore)
- Anchored
- Don't detect voltage, but rather different chemical stimuli (such as temperature)
- Plugging mechanism
Identify features and function of ligand-gated ion channels - Answer - Gated (controlled by
chemical transmitters)
- 4 Subunits
- 6 helices
- P-loop
- Anchored
- No voltage sensors or plugging mechanism
- Function examples; olfaction (cAMP) and muscle (calmodulin)
- ligand must bind to 3/4 subunits to elicit a response
Ligand-gated ion channel regulatory unit function - Answer If calcium binds to calmodulin, it
provides negative feedback response (channel closes)
Simple channels - Answer - 2 subunits
- 2 helices
- not gated
- p-loop
- not anchored
- no voltage sensor
- no plugging mechanism
- function: secretion/ absorption of fluids
, - 5 subunits
- each subunit has 4 TMDs
- large external-facing domain
- specificity for the pore
- subunits can move to make more space to allow for different ions to flow through
Glutamate receptors - Answer - trimeric
- main NT in brain is glutamate
- 4 subunits
- different isoforms due to different genes, RNA splicing, etc (e.g. flip and flop are two different
splicing isoforms of subunits with different functions)
- AMPA, NMDA and Kainate receptors are all types of glutamate receptors
P2X receptors - Answer - ATP-gated ion channels
- trimeric
- 3 subunits with 2 TM helices
- large EC domain
- 3 ATP molecules needed for opening
- widely expressed
- 7 subtypes of subunits which can be combined to respond to different stimuli
Ion channels and drug targeting - Answer - dysfunction of receptors in different cell types
lead to physiological diseases
- you can use small molecule drugs which are complementary to receptors to inhibit or activate
receptors to produce a desired response
Describe characteristic structural features of GPCRs - Answer - 7 TMDs (7 helices)
- TMD 3 lines binding pocket
- N terminus is EC, C terminus in IC
- Most diverse form of receptor due to amino acid sequence in the ligand-binding site
- Respond to a wide range of stimuli (lipids, protons, proteins, photons, etc)
