Quiz 2 cell and systems

Which protein family plays a central role in regulating mitochondrial outer membrane permeabilization during intrinsic apoptosis?

Bcl-2 family

Which caspase is primarily responsible for the execution phase of apoptosis by cleaving cellular substrates?

Caspase-3

Release of which mitochondrial protein into the cytosol triggers apoptosome formation and activation of caspase-9?

Cytochrome c

Which death receptor is commonly associated with the extrinsic apoptotic pathway?

Fas (CD95)

Annexin V binding combined with propidium iodide (PI) staining is used to distinguish which cell populations?

Live, early apoptotic, and late apoptotic/necrotic cells

Ferroptosis is characterized by which biochemical event?

Iron-dependent lipid peroxidation

What morphological feature most strongly distinguishes apoptosis from necrosis?

Nuclear fragmentation and cell shrinkage

Which assay detects DNA fragmentation by labeling free 3'-OH termini and is used as an apoptosis marker?

TUNEL assay

Which Bcl-2 family protein is pro-apoptotic and promotes mitochondrial outer membrane permeabilization?

Bax

Activation of which caspase is most closely associated with the intrinsic apoptotic pathway upstream of executioner caspases?

Caspase-9

Autophagy primarily serves which cellular function under nutrient-deprived conditions?

Degradation and recycling of cellular components

LC3-II formation is a marker for which cellular process?

Autophagosome formation during autophagy

Which feature is characteristic of necrosis but not of classical apoptosis?

Plasma membrane rupture and inflammation

Which molecule acts as an apoptosis repressor by binding and neutralizing pro-apoptotic proteins?

Bcl-2

Which cellular organelle is most directly involved in intrinsic apoptosis signaling?

Mitochondria

Which of the following is a common downstream consequence of mitochondrial outer membrane permeabilization (MOMP)?

Release of pro-apoptotic factors like cytochrome c and SMAC into the cytosol

Which caspase is typically associated with death receptor (extrinsic) pathway activation?

Caspase-8

Which ion is most directly implicated in mitochondrial permeability transition contributing to necrosis?

Calcium

Which molecule inhibits caspases and is often used experimentally as a pan-caspase inhibitor?

Z-VAD-FMK

Which cell death process is most often associated with inflammation due to release of intracellular DAMPs?

Necrosis and necroptosis

An agent secreted by a cell that can influence the properties of another cell is called what?

Ligand

Hormones are signaling molecules of which system?

Endocrine system

In many signaling cascades in prokaryotic and animal cells, what is the second messenger?

cAMP

Which of the following ligands binds to extracellular receptors?

Growth hormones

The largest family of human cell surface receptors is the:

G protein-coupled receptors (GPCRs)

The sequence of changes in a series of different molecules that occurs during cell signaling is called what?

Signal transduction pathway

Chemicals that carry information from one neuron to another neuron are called what?

Neurotransmitters

Which of the following is used for long-distance signaling in both plants and animals?

Hormones

What type of signaling is involved in paracrine signaling?

Chemical signaling

Which statement is true regarding cell signaling?

• Cell signaling has four basic categories

• is used to study the context of human diseases

• in plants cell signaling occurs through phytohormones

Why are target cells of a lipid-soluble hormone such as cortisol able to respond to it?

Only target cells express the appropriate cytosolic receptors

Which signal molecule is NOT used for extracellular signaling?

cAMP

What molecules can directly convert extracellular signals into intracellular signals?

Transmembrane proteins, cell-surface receptors, and GPCRs

How many transmembrane helices are present in GPCRs?

Seven

All steroid hormones are derived from what molecule?

Cholesterol

Which signaling molecules are used by simple nerve reflexes?

Neurotransmitters

Cyclic AMP acts as the second messenger for all of the following EXCEPT which?

Oxytocin

G-proteins have a nucleotide-binding site for what?

GDP/GTP

In the cAMP pathway, the G protein stimulates what enzyme?

Adenylyl cyclase

Synaptic signaling involves what?

Neurotransmitters

All of the following hormones show a negative feedback system EXCEPT which?

Oxytocin

Which of the following is a steroid hormone?

Testosterone