Week 5 Flashcards
What does transcription factor X do after it has been translated?
It migrates back to to the nucleus, and binds to specific regions of the Dna
Affects the transcription of other genes;
In this case it turns on genes A, B, C and E and it turns off gene D
What are the four classes of proteins that are products housekeeping genes?
House keeping genes are crucial for the maintenance of cells
The genes translate to the following proteins:
For gene expression
- Ribosomal
- RNA polymerase related protein
Metabolism
- mitochondrial proteins
- citric acid cycle related
Structural proteins
- cytoskeleton related
What are the three stages of differentiation? Briefly describe each stage.
Remember SDD.
- Specification
- Determination
- Differentiation
- Fate of cell is not completely determined and it can change
- Fate is fixed at this point and the environment can’t change it
- The structure and function of the cell begins to change.
Cells that are differentiated are genetically identical but they just express different genes. How does differential gene expression occur?
regulatory molecules such as transcription factors
Cytoplasmic determinants
External signals (growth factors, hormones etc)
Synthesis of a function protein occurs in a series of steps, outline these.
Remember TPTTM. To paint the wall man.
Transcriptional control
Processing (splicing of introns, capping of RnA, polyadenylation)
Transport (mRNA through nuclear pore, dependent on splicing)
Translation (protein synthesis, ribosomes on 5’, tRNA synthetase)
Modification (protein folding, disulphide bond formation, pretty much formation of tertiary protein)
How do transcription factors influence gene expression?
By IBA.
Interacting with the promoter region of the Gene
Binding to DNA, this affecting its structure
Affecting the activity of a second transcription factor
** transcription factors can also regulate their own production, to maintain the expression of certain genes **
What is cell determination?
Cell fate is progressively being limited as ‘memory’ of previous developmental decisions are kept, and this memory is maintained during cell division
What affects gene expression in terms of the DNA itself? How do these mechanisms work?
- Chromatin structure
- Heterochromatin (seen as dark and dense on the electro micrograph) condensed and transcriptionally inactive form of chromatin
- Euchromatin (seen as white and bitsy on “) unwound and transcriptionally active form of chromatin - DNA methylation
What is DNA methylation and why is it important?
DNA methylation is the addition of a methyl group on cytosine on DNA.
Methylation leads to transcriptional repression or locking genes into the switched off mode.
It is essential for cell differentiation and embryonic development… Abnormal patterns of methylation are linked to several diseases
What are totipotent cells
Cells that can differentiate into all cell types
Toti- like total
What are pluripotent cells?
Cells capable of forming more than one differentiated cell type
What are multi potent cells?
Cells that can differentiate into just one cell type
Check a better definition out
How do cells lose their totipotency
- Altered gene expression
Regulation by transcription factors changes - Terminal differentiation
Cells lose their cell division capacity because they become too specialised (muscles, neurones) - Gross DNA rearrangement or even loss of DNA
B cells splice genes encoding for IgG heavy chain
RBCs enucleate
Describe the two types of cloning?
Reproductive
Placing embryo inside mother
Therapeutic
Cells from early embryo transferred from to a culture dish
What is hematopoiesis?
Process of blood cell production and maturation in the bone marrow
- begins with pluripotent stem cell
- myeloid or lymphoid cell depending on cytokines
Infection causes macrophages to release cytokines, this leads to increased hematopoietic activity
