Lecture 44: Cell proliferation checkpoints and cell death - Trophic signals Flashcards
1️⃣ What is cell proliferation?
The process by which cells divide and reproduce
essential for growth
2️⃣ What are the key phases of the cell cycle?
G1 Phase: Cell grows and prepares for DNA synthesis
S Phase: DNA replication occurs
G2 Phase: Preparation for mitosis
M Phase: Mitosis (cell division)
3️⃣ What regulates cell proliferation?
Cyclins and cyclin-dependent kinases (CDKs) regulate progression through the cell cycle.
4️⃣ What is the role of checkpoints in the cell cycle?
Ensure DNA is correctly replicated and damage-free before cell division proceeds.
5️⃣ Which checkpoint is the most critical?
G1/S Checkpoint: Determines if a cell proceeds to DNA replication or enters G0 (quiescence).
6️⃣ What is the role of growth factors in cell proliferation?
External signals that stimulate cell division by activating signaling pathways like MAPK and PI3K/AKT.
7️⃣ What happens when proliferation is uncontrolled?
Leads to diseases such as cancer due to excessive cell division.
Mitosis and Cell Division
8️⃣ What are the stages of mitosis?
Prophase: Chromosomes condense
spindle forms.
Metaphase: Chromosomes align in the center.
Anaphase: Sister chromatids separate.
Telophase: Nuclear envelope reforms
cytokinesis begins.
9️⃣ How is mitosis different from meiosis?
Mitosis produces identical cells
meiosis generates genetically diverse gametes.
🔟 What is the significance of cytokinesis?
The physical separation of the cytoplasm
resulting in two daughter cells.
Cell Death Mechanisms
1️⃣1️⃣ What are the main types of cell death?
Apoptosis (programmed cell death)
Necrosis (uncontrolled cell death)
Autophagy (self-digestion for survival or death)
1️⃣2️⃣ What is apoptosis?
A highly regulated process that eliminates damaged or unnecessary cells without inflammation.
1️⃣3️⃣ What are key features of apoptosis?
Cell shrinkage
chromatin condensation
1️⃣4️⃣ What triggers apoptosis?
DNA damage
oxidative stress
1️⃣5️⃣ What are caspases?
Proteases that execute apoptosis by degrading cellular components.
1️⃣6️⃣ What is the intrinsic pathway of apoptosis?
Initiated by mitochondrial stress
leading to cytochrome c release and caspase activation.
1️⃣7️⃣ What is the extrinsic pathway of apoptosis?
Triggered by death receptor activation (Fas
TNF receptors) leading to caspase activation.
1️⃣8️⃣ What is necrosis?
A form of accidental cell death caused by injury
leading to inflammation.
1️⃣9️⃣ How does necrosis differ from apoptosis?
Apoptosis is controlled and non-inflammatory
whereas necrosis is uncontrolled and inflammatory.
2️⃣0️⃣ What is necroptosis?
A regulated form of necrosis that occurs when apoptosis is blocked
involving RIPK1/RIPK3 signaling.
2️⃣1️⃣ What is autophagy?
A survival mechanism where cells degrade and recycle their own components under stress.
2️⃣2️⃣ What is the role of Bcl-2 proteins in apoptosis?
Pro-survival proteins (Bcl-2
Bcl-xL) inhibit apoptosis
Cell Cycle and Cancer
2️⃣3️⃣ What is the relationship between apoptosis and cancer?
Cancer cells evade apoptosis
allowing uncontrolled proliferation.
2️⃣4️⃣ Which gene is known as the “guardian of the genome”?
p53: It detects DNA damage and can trigger apoptosis.
2️⃣5️⃣ What happens if p53 is mutated?
Cells with DNA damage survive and proliferate
increasing cancer risk.
2️⃣6️⃣ How do chemotherapy drugs induce cell death?
By damaging DNA
disrupting mitosis
2️⃣7️⃣ What is senescence?
A state where cells stop dividing but remain metabolically active
acting as a tumor suppression mechanism.
2️⃣8️⃣ How do cancer cells bypass senescence?
By upregulating telomerase
which prevents telomere shortening and enables endless replication.
2️⃣9️⃣ What are tumor suppressor genes?
Genes that regulate cell growth and apoptosis (e.g.
p53
3️⃣0️⃣ What are oncogenes?
Mutated genes that drive uncontrolled proliferation (e.g.
Ras
