M1. review and basic concept Flashcards
How does a single cell divide and change to form a multicellular organism?
- cell division
- cells become different
- form organized structures such as tissues and organs
- coordination of cell communication, gene expression, cell fate, cell migration, cell proliferation, cell and tissue shape changes
genes control _____ and _____ by controlling the __________
cell properties, behaviour, protein expression
gene expression
transcription, nuclear processing, nuclear-cytoplasmic transport, mRNA translation, protein modification and protein stability
Control regions of Genetic loci
- enhancers and promoters are acted on by transcription factors (TF) to activate or repress transcription
- TF binding sites within enhancers dictate levels and spatial/temporal control of expression of that gene
Differential gene activity is regulated at ____ levels.
several
what does differential gene activity control?
development
- determines where and when proteins are synthesized
- transcription factors, signalling proteins, cytoskeletal proteins, cell cycle proteins and enzymes
- full complement of protein determines cell identity and behaviour
- gene expression is dynamic
- past and current patterns of expression define a cell’s fate
Genes expression responds to different combinations of ?
inputs
-a gene can have many different control regions
a combination of inputs control final ______ pattern.
expression
- cellular signalling
- transcription factor levels
- developmental history -can determine if areas of the genome are in a open or closed configuration (heterochromatin vs. euchromatin)
how is gene expression regulated?
control regions
genetic equivalence
somatic cells contain identical genetic information
differential gene expression
differences in cells are generated by differences in gene activity
positive and negative feedback regulatory loops
genes are usual part of complex interdependent gene networks
cell communication
- exchange/transmission of signals
- can involves many cells or immediate neighbours
- induction
- competence
- intercellular communication
- permissive signalling
- instructive signalling
- antagonist signalling
exchange/transmission of signals
- secreted diffusible molecules
- surface molecule receptor
- gap junction
indcution
process by which signals from one (group) of cell(s) influences the development of another
competence
the state of being able to respond to inductive signals
intercellular communication
allows cells to communicate
permissive signalling
cells make only one kind of response to a signal when a required level of a signal is reached
instructive signalling
cells respond differently to different levels of a signal (tells them what response to make depending on the signal)
antagonist signalling
inhibition of a signal
intracellular signalling
1) alter gene expression in the nucleus and / or 2) activate or change activity of intracellular molecules through a relay type response (ie. signal transduction)
when a signal (ie a ligand) is transmitted from the membrane (transmembrane receptor) to the cell’s interior (cytoplasm and or nucleus)
intracellular signalling
Fibroblast growth factor (FGF) pathway
- a diffusible ligand (extracellular signalling molecule) activates a membrane bound receptor (FGF) receptor)
- protein kinases (intracellular signalling proteins) initiate a relay of protein phosphorylations [P] called a “signalling cascade”
- phosphorylation of a transcription factor changes it into an active form
The Wnt and transforming growth factor (TGF)-beta pathways
- a diffusible ligand (Wnt or TGF-beta) activates a membrane bound receptor
- the activity of a signalling complex associated with a transcription factor (TF) activates or inactivates TF
- TF can enter nucleus and activate or repress trancription
notch signalling pathway
- requires direct cell-cell contact
- membrane bound ligand (Delta) binds membrane bound receptor (Notch) of adjacent cell
- ligand binding induced proteolytic cleavage of notch to create a co-activator
- co-activator (cleaved notch) translocates into the nucleus and controls transcription factor activity
