Lecture 1- Introduction Flashcards
What is developmental biology?
- How do cells acquire different characteristics?
- How do cells organise themselves into organs?
- What controls the behaviour of cells will underpin how the organism will form and be maintained
- How do cells communicate with each other and provide precision and accuracy?
Why does the UK population provide new challenges to our modern society?
The population is aging faster than its growth
What are 3 concepts underpin developmental decisions?
- Cell behaviour
- Genetic programme
- Cell-cell communication
What are the 2 theories of developmental biology?
- Epigenesis: organisms develop progressively over time through the generation of new structures and forms
- Preformationism: organisms develop from miniature versions of themselves
What is the cell theory?
- All organisms are composed of one or more cells
- The cell is the most basic unit of structure, function and organisation in all organisms
- All cells arise from pre-existing living cells
Outline the germ plasm determinants theory
- Suggests the nucleus of the zygote contains special factors called determinants
- Whilst the fertilised egg underwent rapid cycles the cell division cleavages, the determinants would be distributed unevenly to the discrete cells and would control the cells future development
- The fate of each cell was predetermined in the egg by the factors it received during cleavage
- These unequal distributions make daughter cells different from each other
How was the germ plasm determinants theory experimented and what was concluded?
- Experiment with frog embryos
- Concluded the development of the frog is based on mosaic mechanisms, the cells having their character and fate determined at each cleavage
What 2 theories contributed to advances in developmental biology?
- Aristotle’s epigenesis theory
2. Weismann’s germ plasm theory
What is true about the expression of genes and proteins in every cell?
- All cells have the same DNA so will all have the same genes present
- However the gene will only be expressed in certain cells and therefore the proteins will only be expressed in certain cells
- The presence of certain proteins in a cell under pins it’s identify and function
Why do gene mutations only show as phenotypes in certain tissues?
- A mutated gene will mean every cell in the body will carry the mutation
- However, the gene is only transcribed and translated (expressed) into proteins in certain cells/tissues
- So, mutations will only be ‘visable’ in the tissues where the protein is needed and therefore normally expressed
What is the different between cells differentiating by intrinsic or extrinsic cues?
Intrinsic cues: a cell differentiates into another
Extrinsic cues: a cell is influenced/instructed by another cell when differentiating
How do cells acquire new properties and change their behaviours?
- Cell differentiation
- Cell survival
- Cell division
- Cell adhesion
- Cell shape
- Cell migration
- Cell death
What is a key way in which differences between cells are generated/how does one cell tell another cell to become different?
Through cell-cell communication
Give 3 examples of cell-cell communication
- Paracrine signalling
- Autocrine signalling
- Juxtacrine signalling
What is paracrine signalling?
- Communication through the release of chemical messengers over a relatively short distance
- Cell A may make a secrete protein which is released and binds to receptor on cell B (telling cell B to become different/change)
Which is autocrine signalling?
- Cell signals to itself my releasing a ligand which binds to its own receptor
- Cell A makes a signal which is released and stimulates its own receptors on its own cell to change/differentiate itself
What is juxtacrine signalling?
- Cell signal is directly passed from ine cell to another that is in direct or close contact with another cell
- The signal does not freely diffuse
What are some key points about cell signalling?
- Signal reception require cells to be competent to allow signalling pathway to operate/activate
- Signals can be instructive or permissive
- Signals can acts a morphogens
- Transmission of the signal to the nucleus involves a signal transduction cascade
What is the difference between an instructive and permissive signal?
Instructive: signal which initiated a new programme
Permissive: signal which provides a favourable environment for a specific programme
How can a signal acts as a morphogen?
Instructs district cell fates according to the concentration of the signal/morphogen
What are common features in signal transduction pathways?
- Reception: the ligand binds to a cell surface receptor and activates it
- Transduction: receptor activation induced the transduction of the signal from the membrane to the nucleus via a cascade of secondary messenger activation
- Response: transcription factor is activated and induces the transcription of specific target genes
At which levels can a gene programme be controlled?
- The production of mRNA
- The processing/stability of mRNA
- The production of proteins
- The activity of proteins
How can the genetic programme being controlled at the level of gene transcription?
- Differential gene expression
- Enhancer-mediates control of gene expression
- Control at the level of chromatin and miRNAs can regulate enhancer control elements
How does cell signalling results in changes in the gene expression profile of a cell?
Changes operate mainly at the level of mRNA synthesis through the activity of specific transcription factors
