Master Receptor Signaling: Enhance Your Cell Biology Knowledge

Question 1

Which of the following is NOT a characteristic of G protein-coupled receptors (GPCRs)?

Accepted Answer

Activation of ion channels

Answer

Ligand binding to the extracellular domain

Answer

Seven transmembrane alpha helices

Question 2

What is the primary mechanism of signal transduction for tyrosine kinase receptors?

Accepted Answer

Phosphorylation of tyrosine residues on the receptor itself.

Answer

Activation of G proteins.

Answer

Guanine nucleotide exchange on small GTPases.

Answer

Intracellular calcium release.

Question 3

Chronic exposure to certain hormones can result in the downregulation of their cognate receptors. What is the primary mechanism for this downregulation?

Accepted Answer

Internalization and degradation of the receptor

Answer

Inhibition of receptor synthesis

Answer

De-phosphorylation of receptor tyrosine residues

Answer

Altered coupling to G proteins

Question 4

Which molecule is NOT a second messenger in signal transduction pathways?

Accepted Answer

Guanosine triphosphate (GTP)

Answer

Cyclic AMP (cAMP)

Answer

Diacylglycerol (DAG)

Answer

Inositol trisphosphate (IP3)

Question 5

Which of the following is not a type of protein kinase?

Accepted Answer

Guanylate cyclase

Answer

Receptor tyrosine kinase

Answer

Mitogen-activated protein kinase

Answer

Serine/threonine kinase

Question 6

How do protein phosphatases regulate signal transduction pathways?

Accepted Answer

They reverse the effects of protein kinases on target proteins.

Answer

They activate protein kinases to initiate signal transduction.

Answer

They have no role in signal transduction pathways.

Answer

They increase the number of active protein kinases.

Question 7

The primary mechanism of RTK activation involves:

Accepted Answer

Binding of ligands to their extracellular domain.

Answer

Interaction with G proteins.

Answer

GTP hydrolysis.

Answer

Phosphorylation of their intracellular domain.

Question 8

A common downstream effector activated by RTK signaling is:

Accepted Answer

Phosphatidylinositol 3-kinase (PI3K)

Answer

Phospholipase C (PLC)

Answer

Protein kinase A (PKA)

Answer

Guanylyl cyclase

Question 9

Arrestins, in GPCR signaling, primarily serve to:

Accepted Answer

Bind to active GPCRs, leading to their desensitization.

Answer

Activate downstream effectors.

Answer

Split apart upon GTP hydrolysis.

Answer

Recruit G proteins to the membrane.

Question 10

An example of a G protein-mediated second messenger is:

Accepted Answer

Cyclic AMP (cAMP)

Answer

Diacylglycerol (DAG)

Answer

Inositol trisphosphate (IP3)

Answer

Calcium ions (Ca2+)

Question 11

Tyrosine kinase receptors primarily phosphorylate downstream targets by:

Accepted Answer

Directly phosphorylating target proteins.

Answer

Activating downstream kinases.

Answer

Binding to and activating G proteins.

Answer

Splitting apart upon GTP hydrolysis.

Question 12

Which characteristic is a defining feature of tyrosine kinase receptors?

Accepted Answer

Contain an intracellular tyrosine kinase domain

Answer

Bind to growth factors or cytokines

Answer

Activate the MAP kinase pathway

Answer

Function exclusively as monomers

Question 13

Which of the following tyrosine kinase receptors is known for its role in cell growth and proliferation?

Accepted Answer

EGFR

Answer

PDGFR

Answer

VEGFR

Answer

NGFR

Question 14

Which of the following is a type of receptor that responds to changes in the plasma membrane voltage?

Accepted Answer

Voltage-gated ion channel

Answer

Ligand-gated ion channel

Answer

G protein-coupled receptor

Answer

Tyrosine kinase receptor

Question 15

Which of the following is NOT a type of membrane-bound cell surface receptor?

Accepted Answer

Nuclear hormone receptor

Answer

G protein-coupled receptor

Answer

Tyrosine kinase receptor

Answer

Ligand-gated ion channel

Question 16

What is the initial event in G protein-coupled receptor signaling?

Accepted Answer

Ligand binding to the receptor

Answer

GDP-GTP exchange on the G protein

Answer

Activation of an effector protein

Answer

Termination of signaling

Question 17

Which of the following is a downstream effector of activated tyrosine kinase receptors?

Accepted Answer

Phospholipase C

Answer

Protein kinase A

Answer

Guanylyl cyclase

Answer

Adenylyl cyclase

Question 18

Which of the following disorders is caused by a mutation in a G protein-coupled receptor?

Accepted Answer

Cystic fibrosis

Answer

Sickle cell anemia

Answer

Huntington's disease

Answer

Alzheimer's disease

Question 19

Which of the following is NOT a mechanism by which cell surface receptors are desensitized?

Accepted Answer

Ligand-independent activation

Answer

Phosphorylation

Answer

Internalization

Answer

Ubiquitination

Question 20

Explain the role of the epidermal growth factor receptor (EGFR) in cancer development. Describe how its overexpression contributes to tumor formation.

Accepted Answer

EGFR, a tyrosine kinase receptor, plays a crucial role in cancer development. Its overexpression leads to uncontrolled cell proliferation and survival through the activation of downstream signaling pathways, ultimately promoting tumor growth.

Answer

EGFR, a G protein-coupled receptor, is involved in regulating cellular metabolism and differentiation. Its overexpression can disrupt normal cellular processes, potentially contributing to cancer development.

Answer

EGFR is not a significant player in cancer development. Its overexpression has minimal impact on cellular processes and does not contribute to tumorigenesis.

Question 21

Which of the following is not a characteristic of cell surface receptors?

Accepted Answer

They are located inside the nucleus.

Answer

They bind to specific ligands.

Answer

They initiate signal transduction pathways.

Answer

They are membrane-associated proteins.

Question 22

Which of the following is the primary mechanism of signal transduction for G protein-coupled receptors?

Accepted Answer

Activation of heterotrimeric G proteins.

Answer

Ligand-gated ion channel activation.

Answer

Ion channel opening.

Answer

Tyrosine phosphorylation.

Question 23

Which of the following is the primary mechanism of signal transduction for tyrosine kinase receptors?

Accepted Answer

Tyrosine phosphorylation of receptor and downstream targets.

Answer

Ligand-gated ion channel activation.

Answer

Ion channel opening.

Answer

G protein activation.

Question 24

Which of the following is NOT a common downstream effector of tyrosine kinase receptor signaling?

Accepted Answer

Protein kinase C.

Answer

Extracellular signal-regulated kinase (ERK).

Answer

Signal transducer and activator of transcription (STAT).

Answer

Phosphoinositide 3-kinase (PI3K).

Question 25

Which of the following is an example of a ligand that binds to a G protein-coupled receptor?

Accepted Answer

Epinephrine.

Answer

Platelet-derived growth factor (PDGF).

Answer

Epidermal growth factor (EGF).

Answer

Insulin.

Question 26

Which of the following is NOT a type of cell surface receptor that initiates intracellular signal transduction?

Accepted Answer

Nuclear receptor

Answer

G protein-coupled receptor

Answer

Tyrosine kinase receptor

Question 27

In the signal transduction pathway of G protein-coupled receptors, which of the following steps is crucial for initiating downstream signaling?

Accepted Answer

Activation of G protein

Answer

Autophosphorylation of receptor

Answer

Phosphorylation of receptor

Answer

Dimerization of receptor

Question 28

Select the characteristic that accurately describes tyrosine kinase receptors:

Accepted Answer

Transmit signals across the plasma membrane

Answer

Activate G proteins

Answer

Linked to ion channels

Answer

Bind to DNA

Question 29

Which of the following consequences results from receptor desensitization?

Accepted Answer

Reduced response to subsequent stimuli

Answer

Increased receptor expression

Answer

Activation of alternative signaling pathways

Answer

Increased affinity for ligand

Question 30

Which of the following molecules is commonly used as a second messenger in receptor signaling pathways?

Accepted Answer

cAMP

Answer

Insulin

Answer

Growth factor

Question 31

Identify the disease that is primarily caused by a mutation in a receptor gene:

Accepted Answer

Cystic fibrosis

Answer

Alzheimer's disease

Answer

Parkinson's disease

Answer

Diabetes type 2

Question 32

In the context of cancer treatment, which of the following therapeutic approaches targets receptor signaling?

Accepted Answer

Receptor tyrosine kinase inhibitor

Answer

Antibiotic

Answer

Statin

Answer

Antipsychotic

Question 33

Which of the following is NOT a mechanism of signal transduction used by cell surface receptors?

Accepted Answer

Direct activation of transcription factors

Answer

Second messenger signaling

Answer

G protein-coupled signaling

Answer

Tyrosine kinase signaling

Question 34

Which of the following is a key structural feature of G protein-coupled receptors?

Accepted Answer

Seven transmembrane domains

Answer

Single transmembrane domain

Answer

Ligand-gated ion channel

Answer

Intracellular tyrosine kinase domain

Question 35

The initial step in tyrosine kinase signaling typically involves:

Accepted Answer

Autophosphorylation of the receptor

Answer

Direct activation of transcription factors

Answer

Inhibition of adenylyl cyclase

Answer

Activation of a G protein

Question 36

Which of the following diseases is caused by a mutation in a cell surface receptor?

Accepted Answer

Cystic fibrosis

Answer

Alzheimer's disease

Answer

Huntington's disease

Question 37

The discovery of receptor signaling has had a significant impact on the development of:

Accepted Answer

Targeted therapies

Answer

Imaging techniques

Answer

Antibiotics

Answer

Vaccines

Question 38

Which of the following is NOT a type of cell surface receptor?

Accepted Answer

Enzymes

Answer

Ligand-gated ion channels

Answer

G protein-coupled receptors

Answer

Cytokine receptors

Question 39

What is the primary mechanism of signal transduction for G protein-coupled receptors?

Accepted Answer

Activation of heterotrimeric G proteins

Answer

Direct ion channel opening

Answer

Phosphorylation of serine residues

Answer

Guanylate cyclase activation

Question 40

What is the primary role of second messengers in receptor signaling?

Accepted Answer

To amplify and propagate the signal within the cell

Answer

To activate transcription factors

Answer

To bind directly to the receptor

Answer

To inhibit the receptor from further signaling

Question 41

What is the primary function of scaffolding proteins in receptor signaling?

Accepted Answer

To facilitate the assembly of signaling complexes

Answer

To transport the signal to the nucleus

Answer

To directly bind to the receptor

Answer

To amplify the signal by phosphorylation

Question 42

Which of the following can lead to the activation of receptor tyrosine kinases?

Accepted Answer

Ligand binding

Answer

G protein activation

Answer

Dephosphorylation

Answer

Second messenger production

Question 43

What is the role of ubiquitination in receptor signaling?

Accepted Answer

To target proteins for degradation

Answer

To inhibit receptor binding

Answer

To transport receptors to the nucleus

Answer

To activate signaling pathways

Question 44

Which of the following is NOT a type of cell surface receptor?

Accepted Answer

Ribosome

Answer

Ion channel receptor

Answer

Tyrosine kinase receptor

Answer

G protein-coupled receptor

Question 45

Which of the following is a G protein-coupled receptor (GPCR)?

Accepted Answer

Beta-adrenergic receptor

Answer

Insulin receptor

Answer

Nicotinic acetylcholine receptor

Answer

EGF receptor

Question 46

Which of the following is NOT a step in the G protein signaling pathway?

Accepted Answer

Receptor phosphorylation

Answer

Effector activation

Answer

Signal termination

Answer

GTP-GDP exchange on G protein

Question 47

Which of the following is a tyrosine kinase receptor?

Accepted Answer

Insulin receptor

Answer

Glutamate receptor

Answer

Adenosine receptor

Answer

Dopamine receptor

Question 48

Which of the following is a downstream effector of the Ras pathway?

Accepted Answer

MAP kinase

Answer

Phospholipase C

Answer

Adenylyl cyclase

Answer

Protein kinase A

Question 49

Which of the following is a mechanism of signal termination in receptor signaling pathways?

Accepted Answer

Receptor internalization

Answer

Ligand binding

Answer

Effector phosphorylation

Answer

G protein activation

Question 50

Which of the following is a potential disadvantage of using multiple intracellular signaling pathways?

Accepted Answer

Increased potential for cross-talk between pathways

Answer

Greater energy efficiency

Answer

Enhanced signal specificity

Answer

Faster response time

Question 51

Which of the following is a key characteristic of receptor desensitization?

Accepted Answer

Decreased receptor number on the cell surface

Answer

Enhanced signal transduction

Answer

Increased receptor affinity for the ligand

Answer

Prolonged receptor activation