Module 11 Flashcards
(38 cards)
How can dUTP be incorporated in the nicks of apoptotic cells? (TUNEL assay of digit development)
by the addition of terminal deoxynucleotide transferase enzyme which allows for the detection of cells undergoing apoptosis
what does an increase in thyroid hormone do to frogs?
this induces metamorphosis that occurs in the tails that are induced to disappear
why do some nerve cells survive and others don’t?
only certain cells receive sruvival factors, those who do not undergo apoptosis
how many neurons originally produced in the brain must undergo apoptosis?
half of the original cells
what cells in the brain must undergo apoptosis?
I) cells that have faulty connections
II) cells that have not achieved a synaptic connection
true or false: the number of nerve cells match the number of target cell?
true
What are the results of TOO much cell death?
neurodegenerative disorders
- alzheimers (hippocampus + cerebral cortex)
- huntingtons (striatum)
- parkinsons (dopamine neurons in substantia nigra)
- DMD (muscular degeneration)
Describe necrosis
during this process cells swell up and release its content in nearby tissue which may lead to infection and is potentially dangerous
Describe apoptosis
this is PROGRAMMED cell death, the cell disposes of its cellular debris and does so without causing damage to the surrounding cells, the contents are rather contained and recycled by surrounding cells
Apoptosis works by execution, engulfment and clearance of its cellular debris
what visible changes appear in the cell during apoptosis?
- the cell gets smaller
- blebbing occurs: protrusions/bulges appear in the cell
- the mitochondria lose permeability
- nucleus breaks down into vesicles which will be phagocytized
how many somatic and apoptotic cells can be seen in C elegans
947 somatic cell
- 131 cells undergo programmed cell death
what does a mutation in the ced-1 gene of C. elegan do?
the ced-1 gene usually allows the cell to undergo apoptosis
a mutation in this gene, the cell still undergoes apoptosis but lacks the ability to engulf cells by phagocytosis
what does a mutation in the ced-3 gene of C. elegan do?
with a ced-1 and ced-3 mutation NO APOPTOSIS occurs
the ced-3 gene is said to be essential for the apoptotic pathway
what 4 genes are essential for the apoptotic pathway?
I) Ced-3
II) Ced-4
III) Ced-9
IV) Egl-1
what are the human homologs of the Egl1 protein?
Bid and Bim, they are part of the BH3 family of proteins
what is the Bcl2-protein
this is the human homolog of Ced-9 nad is bound to the mitochondrial membrane, it is in control of related proetins: Bak and Bax
what is the caspase holoenzyme?
a complex formed between ced-4 and ced-3 proteins
it is a protease that targets a variety of proteins
what time of mutations prevent apoptosis?
loss of function mutations in ced-3 or ced-4
what happens in a loss of function mutations in ced-9?
all of the cells die by inhibition of the caspase holoenzyme
what happens in a loss of function mutation in ced-3 or ced-4?
apoptosis is prevented
how does Egl-1 signal apoptosis?
by inhibiting the inhibitor (ced-9) it is able to induce the apoptotic pathway
what do we call the human version of the caspase holoenzyme?
the apoptosome, it contains direct homologs of the ced-4 (Apaf1) and ced-3 (Caspase-9)
both the function of the apoptosome and the caspase holoenzyme lead to cell degradation and cell death
how does ced-9 inhibit apoptosis?
by binding to ced-4 dimers and keeping them inactive
how is ced-4 released?
by Egl1 binding to Ced-9, once released ced-4 binds to ced-3 to form the caspase holoenzyme
