developmental biology 1 Flashcards
development of metazoans (multicelluar) includes:
- gametogenesis
- fertilization
- embryonic period
- fetal period
- growth
- later development
gametogenesis
- formation of gametes: egg and sperm
fertilization
- fusion of male and female gametes to form a zygote
embryonic period:
- first 8 weeks of human development
- formation of all precursors
- developing organism = embryo
embryonic age vs gestational age
- gestational: time that has passed since onset of last menstruation
- embryonic: measures the actual age of the embryo or fetus from the time of fertilization
describe the fetal period
- prenatal period between embryonic stage and birth; fetus; extensive growth and continued development of organ systems
describe the fetal period in organisms other than mammals
- replaced with larval stages, followed by metamorphosis
describe the growth period
- neonatal and child development period
describe later “development” period
- tissue maintenance
- wound healing
- aging
- cancer/diseases related to development
draw the fertilization age scale
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what is required for embryonic development?
- cell proliferation
- cell differentiation
- pattern formation and morphogenesis
what is the cell cycle?
- sequences of stages through which a cell passes between one cell division and the next
- G1, S, G2, mitosis
What are checkpoints in the cell cycle?
- cells make a decision about moving forward in the cell cycle
G1/R checkpoint (general)
- trying to decide if cell cycle should continue
- monitoring external/internal conditions
- monitoring DNA damage
S/G2 and M phase checkpoint
- constant monitoring of internal conditions…
- S: if replication is complete… if DNA has been screened to remove error
G2: cell size adequate… chromo replication complete - monitoring status of DNA… is it being replicated properly
M monitoring mitotic spindle is properly formed
G1 checkpoint cells are responsive to…
- nutrient levels
- anchorage dependence
- mitogenic growth factors
- anti-mitogenic TGF- beta signals
Choices prior to / at R checkpoint:
- remain in active proliferation
- exit cell cycle (G0 or post-mitotic phase)
- apoptosis
What has the cell committed to after completing R checkpoint?
- completing the cell cycle
- if deregulated, becomes cancer
G0 phase in detail
- monitor external/internal conditions
- 3 states:
- reversible
1. Quiescent: resting, inactive - irreversible
2. Senescent (not really resting or active.. dont die but dont rlly do anything)
3. Differentiated (not inactive)
terminally differentiated cells such as nerve and muscle cells
What are the two types of genes that regulate the cell cycle?
- proto-oncogenes
- tumor suppressors
proto-oncogenes
- stimulate cell cycle progression
- mutation in cancer: gain of function
- proto-oncogene = wt; oncogene = mutant
tumor suppressors
- inhibit cell cycle progression
- mutation in cancer: loss of function
why is maintaining genome integrity important?
- to make sure daughter cells dont inherit damages DNA
What gene is activated in response to DNA damage
- tumor supressor p53
what are the p53 pathways responsible for?
- halting the cell cycle until damage is repaired
- initiating apoptosis
What is p53 pathway? (draw )
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why are CDK and cyclins important?
- CDK phosphorylates, and are dependent on the presence of cyclin
- regulate passage through the checkpoints
cell cycle regulation pathways converging on the R checkpoint
mitogen –> cyclin –> CDK –> repress pRb… unless repressed by Growth factors….
pRb is repressed due to phosphorylation
