Exam 3 Flashcards
What binds to start signal transduction by RTKs?
a protein with SH2 domain to a tyrosine on the receptor
What is the Ras family composed of?
small G-protiens
What drives over 30% of all human cancers?
Ras genes
How do signals pass from activated Ras?
Ras to Raf to MEK to MAPK
What regulates the activity of many transcription factors that control early response genes?
MAP kinase (MAPK)
In unstimulated cells, where is PKB?
cytosol
In unstimulated cells, what inhibits PKB activity?
catalytic kinase domain bound to pH domain of PKB
What leads to the activation of PI-2 kinase & PKB?
hormone stimulation
Disrupted JAK/STAT signaling can lead to what diseases?
skin conditions, cancer, immune system disorders
What are cytokines important in?
cell signaling
Examples of cytokines?
chemokines
interferons
interleukins
lymphokines
tumor necrosis factors
transforming growth factor
How can the same signal induce different responses in different cells?
different types of cells have different collections of proteins that lead to different cellular events
ex. epinephrine simulates liver for breakdown of glycogen but stimulates heart to contract faster
What causes termination of the cell signal?
- concentration of signal decreases
- G-protein hydrolyzes
- cAMP to AMP
- phosphorylated kinases inactivated
- GRK desensitizes receptors
4 phases of the cell cycle
- G1 (gap stage 1)
- S (synthesis)
- G2 (gap stage 2)
- M (mitosis)
What drives cell cycle progression and initiates centrosome splitting?
CDK
What drives CDK activity?
positive & negative feedback loops
What guarantees each cell cycle step is completed correctly before going to the next step?
checkpoint pathway surveillance mechanisms
How do cells reproduce?
cell division
How do cells produced from mitosis look?
identical to their parent
How do cells produced from meiosis look?
have half the genetic content of the parent
3 main features of cell cycle
- cell growth & DNA replication
- chromosome segregation
- cell division
What cells lack the ability to divide?
nerve, muscle & red blood cells
What cells have a high level of mitotic activity?
stem cells
What cells can be induced to begin DNA synthesis?
liver cells & lymphocytes