back exam questions

Question 1

Explain production and assembly of collagen fibers by local cells

Answer 1

1. pro collagen alpha formed
2. hydroxylation of some residues
3. glycosylation of those residues
4. self assemble 3 pro collagen chains
5. form a triple helix
6. secretion out of the cell
7. cleavage of peptides
8. formation of aggregates
9. formation of fibrils

Question 2

how does increase in LOX in cancer cells contribute to cancer progression

Answer 2

1. Lox adds aldehydes to lysine residues on collagen and elastin fiber precursors
2. these aldehydes can cross link with each other and normal lysine residues
3. this creates a more stiff ECM
4. a stiffer ECM can increase integral signaling and integral clustering leading to the progression of cancer

Question 3

explain intergrin structure and activation

Answer 3

• intergrins are heterodimers that form triple helixes
• intergrins are transmembrane and when in active form are bent with their tails together but inactive, they are not bent, heads are up and tails are separate
• they can be activation from the inside out by tyrosine kinases receptors as well as G-protein coupled receptors leading to the binding of Talin and activation
• they can also be activated by the outside in by binding to a ligand and changing conformation

Question 4

explain how integrin receptors generate signaling complexes that regulate cell function

Answer 4

-after the integrin is activated by binding to talon, talin recruits adaptor proteins. The adaptor proteins bind to talin and expose FAK sites. FAK binds and is a tyrosine kinase so it cross phosphorylates itself and exposes more binding sites for other molecules

Question 5

Name two basic function of the basal lamina and explain

Answer 5

1. selective filter: stops macromolecules in the blood from entering urine
2. mechanical support by forming a riding surface rich in Gags, proteoglycans, collagen etc.
3. compartmentalize tissues- protects tissues from harsh environments
4. scaffold protein for regenerating tissues
5. acts with integrins to regulate signaling

Question 6

describe two characteristics you would expect a stem cell to have

Answer 6

1. be able to self renew

2. be able to differentiate

Question 7

where are stem cells located when they interact with the niche

Answer 7

near the basement membrane, here they are continuously produced

Question 8

after performing a label retention assay, why would adult stem cells have less BrdU incorppration

Answer 8

After a short pulse, actively dividing cells can incorporate BrdU while older, less dividing, more quiescent cells need a longer exposure to incorporate the BrdU. These cold dividing cells (adult stem cells) slowly dilute the dye as they proliferate while during fetal development, the cells are dividing more and diluting the dye less

Question 9

how would you generate autologous dopamine neurons? what kinds of cells would you get from patients and general steps to produce neurons

Answer 9

start with pluripotent cells, then expose them to the correct factors to turn them into neuronal cells (neuronal induction) then through a couple steps of neuronal patterning and finally differentiate them into dopamine producing neurons. This take months to do
and domaine production would be the marker to prove you generated what you wanted

Question 10

how would you test transplantation and function after introducing cells into a patient

Answer 10

dopamine would be the best markers. To prove that the transplant worked, I would dissect the cells that were labeling during culture/transplantation and observe if they produce dopamine
to check the function, I would test the neuronal abilities of the cells by exciting them with things like glutamate or KCl

Question 11

advantages and challenges of using autologous cells

Answer 11

advantages:
- no ethical issues
- do not require immune compromise

challenges:
- ES have greater self renewal potential
- ES cells are more potent

Question 12

what are primary and secondary outcomes trials of phase 1 clinical trials

Answer 12

1. safety: make sure transplantation does not produce negative side affects
2. efficiency: ensure that the neurons are functioning through neuronal sensations

Question 13

what is open label masking

Answer 13

during phase I clinical trials, where all participants receive treatment and the observer and patient are aware they all have transplants

Question 14

inclusions and exclusions of a Parkinson’s clinical trial

Answer 14

include all genders, exclude young people and healthy people (no controls)