Cell division, death and specialisation Flashcards
What is the result of mitosis?
2 identical daughter cells from 1 parent cell
What is the result of meiosis?
4 genetically diverse cells from one parent cell
What is a centromere?
Region of repetitive DNA sequences
Place where sister chromatids attatched
What is a kinetochore?
Specialised structure on centromere where spindle fibers attach during mitosis
Why is the cell cycle controlled?
To replace injured or dead cells
Must be controlled to regulate cell division
What are CDK?
Cyclin-dependent kinase
Form complex with cyclins
What do CDKs and cyclins do?
Control and coordinate cell division
What are cyclins?
Proteins that have cyclic fluctuating concentrations
What is the G1 checkpoint?
Go ahead and start process
Stop: enter non-diving G0 phase
What is the G2 checkpoint?
Ensure DNA is replicated
What is the M checkpoint?
Sister chromatids are attached to spindle microtubules
What are the types of stem cells?
Embryonic
Somatic: undifferentiated cells located in “mature” tissue
Induced pluripotent stem cells
What do tumor cells express?
Express the CHEMOKINE RECEPTOR CXCR4
What does the bone marrow express?
Naturally high expression of CHEMOKINE CXCL12
How do chemokines and chemokine receptor influence tumor cells?
Tumor cells migrate towards high concentrations of CXCL12
What are cell junctions?
Specialized regions of plasma membrane that connect cells
What are the types of cell junctions?
Desosomes
Tight junctions
Gap junctions
Explain tight junctions
Seal cells together
Allow small molecules to move through
Explain gap junctions
Mediate passage of chemicals or electrical signals
Have channels to allow passage
What is apoptosis?
Programmed cell death
Explain the process of apoptosis
Nucleus shrinks
Chromatin condenses
DNA fragments
Cell detaches from neighbors
Cell “round up”
Cell shrinks
Cell fragments burst out
Neighbor cells/macrophages eat fragments
What is the intrinsic pathway of apoptosis
Response to internal damage
Controlled by release of cytochrome C from mitochondria
What is the extrinsic pathway of apoptosis?
Triggered by immune system
Binds to cell-surface death receptors
What is necrosis?
Disruption of membranes
What are a few causes of necrosis?
O2 deprivation
Infectious agents
Chemical agents
DNA disruption
Nutritional imbalance
What are ROS?
Reactive oxygen species
By products of normal cellular respiration
What are the cell defence mechanisms against oxidative stress?
Antioxidants and enzymes
What is ischemia?
Lack of blood supply to organs
What is reperfusion?
Tissue damage after blood supply returns after period of O2 lack
