Cell Signalling- Richard

Question 1

Which of the following best describes steroid hormone receptors?
A. Located on the plasma membrane
B. Activate G-proteins directly
C. Bind hydrophilic ligands
D. Directly influence gene transcription
E. Activate second messengers like cAMP

Answer 1

D. Directly influence gene transcription

Question 2

Which second messenger is released from the endoplasmic reticulum in response to IP₃?
A. DAG
B. cAMP
C. Calcium ions
D. PKA
E. cGMP

Answer 2

C. Calcium ions

Question 3

What is the main second messenger produced by adenylate cyclase activation?
A. IP₃
B. DAG
C. cAMP
D. Ca²⁺
E. ATP

Answer 3

C. cAMP

Question 4

Which of the following results from Gs protein activation?
A. Decreased cAMP
B. Inhibition of adenylate cyclase
C. Activation of phospholipase C
D. Activation of adenylate cyclase
E. Increased IP₃

Answer 4

D. Activation of adenylate cyclase

Question 5

Which receptor type typically involves tyrosine kinase activity?
A. GPCR
B. Ionotropic receptors
C. RTKs
D. Steroid receptors
E. Enzyme-linked receptors using serine kinases

Answer 5

C. RTKs

Question 6

Which of the following statements about Kd is true?
A. A high Kd indicates high affinity
B. A low Kd indicates low affinity
C. Kd is the concentration that gives 100% receptor occupancy
D. Kd = [Ligand] at 50% receptor occupancy
E. Kd can only be used for enzyme kinetics

Answer 6

D. Kd = [Ligand] at 50% receptor occupancy

Question 7

In a Scatchard plot, what does the slope represent?
A. Receptor concentration
B. -1/Kd
C. Ligand affinity directly
D. The Hill coefficient
E. Maximal response (Emax)

Answer 7

B. -1/Kd

Question 8

Which of the following indicates positive cooperativity in a Hill plot?
A. Hill coefficient = 1
B. Hill coefficient < 1
C. Hill coefficient > 1
D. Flat binding curve
E. No receptor-ligand interaction

Answer 8

C. Hill coefficient > 1

Question 9

In obesity, insulin signalling is often disrupted due to:
A. Enhanced insulin secretion
B. Overexpression of adiponectin
C. Abnormal phosphorylation of IRS
D. Increased glucagon signalling
E. Increased adipocyte browning

Answer 9

C. Abnormal phosphorylation of IRS

Question 10

Which tissue normally uses insulin to inhibit gluconeogenesis?
A. Muscle
B. Adipose tissue
C. Brain
D. Liver
E. Pancreas

Answer 10

D. Liver

Question 11

Chronic inflammation in obesity is mainly caused by increased expression of:
A. Adiponectin
B. IL-10
C. TNF-α
D. Insulin
E. PPARα

Answer 11

C. TNF-α

Question 12

What is the function of adiponectin?
A. Stimulates appetite
B. Increases β-oxidation and insulin sensitivity
C. Inhibits lipolysis
D. Enhances gluconeogenesis
E. Promotes pro-inflammatory signalling

Answer 12

B. Increases β-oxidation and insulin sensitivity

Question 13

Which of the following is reduced in obesity?
A. TNF-α
B. Plasma triglycerides
C. Adiponectin
D. Leptin resistance
E. IRS phosphorylation

Answer 13

C. Adiponectin

Question 14

Which best describes leptin’s normal role?
A. Increase food intake
B. Stimulate gluconeogenesis
C. Inhibit insulin secretion
D. Promote satiety via hypothalamic neurons
E. Increase visceral adipocyte size

Answer 14

D. Promote satiety via hypothalamic neurons

Question 15

Which best describes insulin resistance?
A. Decreased insulin secretion
B. Increased glucose uptake in muscle
C. Failure of insulin to act on target tissues
D. Overexpression of insulin receptors
E. Elevated adiponectin levels

Answer 15

C. Failure of insulin to act on target tissues

Question 16

Which of the following is a common metabolic consequence of insulin resistance?
A. Hypoglycaemia
B. Ketogenesis suppression
C. Hyperglycaemia
D. Decreased plasma lipids
E. Increased glucose oxidation

Answer 16

C. Hyperglycaemia

Question 17

Glycation of proteins occurs in hyperglycaemia and leads to:
A. Enhanced receptor binding
B. Protein activation
C. Improved metabolic efficiency
D. Structural and functional disruption
E. Receptor recycling

Answer 17

D. Structural and functional disruption

Question 18

Which molecule builds up in the liver during dyslipidaemia and contributes to cholesterol synthesis?
A. Acetyl-CoA
B. NADH
C. Pyruvate
D. Oxaloacetate
E. ATP

Answer 18

A. Acetyl-CoA

Question 19

Which pathway is activated by insulin binding to its receptor?
A. JAK/STAT pathway
B. MAPK cascade
C. PI3K-Akt pathway
D. PLC-DAG pathway
E. β-arrestin signalling

Answer 19

C. PI3K-Akt pathway

Question 20

Atherosclerosis in type 2 diabetes results from:
A. Increased HDL production
B. Enhanced glycolysis
C. Glycated LDL accumulation in arteries
D. Increased adiponectin
E. Enhanced vasodilation

Answer 20

C. Glycated LDL accumulation in arteries

Question 21

Which of the following drugs acts as a PPARγ agonist to improve insulin sensitivity?
A. Metformin
B. Insulin
C. Glucagon
D. Rosiglitazone
E. Statins

Answer 21

D. Rosiglitazone

Question 22

What is the natural ligand for PPARγ?
A. Still unknown
B. Glucose
C. Insulin
D. Free fatty acids
E. Cortisol

Answer 22

A. Still unknown

Question 23

What’s a key feature of cardiac muscle energy metabolism?
A. Uses anaerobic glycolysis primarily
B. Relies heavily on glycogen breakdown
C. Prefers ketone bodies even in fed state
D. Requires continuous oxygen supply
E. Functions best under hypoxic conditions

Answer 23

D. Requires continuous oxygen supply

Question 24

A high Hill coefficient indicates:
A. Single ligand binding
B. No cooperativity
C. Negative cooperativity
D. Positive cooperativity
E. High Kd

Answer 24

D. Positive cooperativity

Question 25

Which of the following is a consequence of leptin resistance in obesity? A. Increased satiety B. Reduced food intake C. Increased adiponectin levels D. Increased appetite E. Decreased TAG storage

Answer 25

D. Increased appetite

Question 26

Which of the following pathways is linked to IP₃ production? A. Adenylate cyclase pathway B. Phospholipase C pathway C. Tyrosine hydroxylase pathway D. JAK-STAT pathway E. Ras-Raf pathway

Answer 26

B. Phospholipase C pathway

Question 27

In calcium imaging, which fluorescent dye is commonly used? A. GFP B. Ethidium bromide C. FURA-2 D. FITC E. Luciferase

Answer 27

C. FURA-2

Question 28

Capacitative calcium entry occurs when: A. Calcium stores are full B. GPCRs are inactive C. ER calcium stores are depleted D. Mitochondria release ATP E. IP₃ levels drop

Answer 28

C. ER calcium stores are depleted

Question 29

What happens when DAG is produced at the plasma membrane? A. Binds to PKA B. Triggers calcium release from ER C. Activates PKC D. Inhibits cAMP synthesis E. Stimulates gluconeogenesis

Answer 29

C. Activates PKC

Question 30

Which of the following is a defining feature of metabolic syndrome? A. Hyperthyroidism B. Chronic hypoglycaemia C. Elevated insulin sensitivity D. Co-occurrence of obesity, hyperglycaemia, and dyslipidaemia E. Autoimmune destruction of β-cells

Answer 30

D. Co-occurrence of obesity, hyperglycaemia, and dyslipidaemia