Bio 2B03 EXAM QUESTIONS WITH
100% CORRECT ANSWERS
When will Dictyostelium differentiate into a slug? - correct answer ✔✔ starved amoeba will
secrete cAMP, other amoebas have cAMP GPCRs which activate actin reorganization into
Fimbriae to move toward the signal location
When will slug differentiate into amoebas ? - correct answer ✔✔ When nutrients are availble.
Post cells= body, ant cells= stalk
JAK-STAT pathway accomplishes what? - correct answer ✔✔ Inhibit apoptosis, promote
differentiation
JAK STAT signal is? - correct answer ✔✔ Epo from kidneys
JAK STAT Pathway steps? - correct answer ✔✔ 1. EpoR dimerizes bound to signal
2. docking sites to come closer, cytoplasmic JAK kinase dimerizes =autophosphorylation of
activation lip tyrosines =active
3. JAK kinases will phosphorylate docking sites tyrosines
4. STAT (SH2 domain) transferred to the docked phosphorylated tyrosines,
5. STAT becomes phophorylated by JAK
6. STAT-p dimerizes
7. NLS signal revealed
8. TF activator for genes like bcl-xl to inhibit apoptosis
Short term Deactivation - correct answer ✔✔ SHP1 (2 SH2 domains) migrate to cytosolic
docking site by phoph. tyrosines. Dephosphorylates JAk kinase
,Long term Deactivation - correct answer ✔✔ SOCS has SH2 domain to migrate and works 2
ways
1. accumulates on docking site to block STAT access
2. will ubiquitinate JAK for degradation
to remake JAK is why its "longterm"
effect of truncated EpoR on negative regulators? - correct answer ✔✔ decreased sensitivity to
regulators bc of shorter docking site therefore higher hematocrit
Receptor Tyrosine Kinase signals ? - correct answer ✔✔ RTKs bind to hormones like NGF, EGF,
insulin, hGH,
RTK receptor has what type of activity on the cytosolic face ? - correct answer ✔✔ weak kinase
activity
signal binding causes what interaction btw receptors? - correct answer ✔✔ Dimerization and
kinase activty activation on the cytosolic face. Autophosph. of the neighbouring activity lip=
more tyrosine residues phosph.
Next steps in pathway... - correct answer ✔✔ 1.GRB2's SH2 domain binds to phosphorylated
tyrosine residue
2. 2 SH3 domains recognize SOS proline rich seqence
3. SOS binds to Ras G protein, SOS has intrinsic GEF activity, Will replace GDP with GTP = active
Ras
4. Ras activates Raf via regulatory domain
5. GTP hydrolysis dissociates Ras-Raf
6. Raf aka MAP kinase kinase kinase (Serine/threonine)
, 7. MEK (map kinase kinase) serine/tyrosine kinase
8. MAP kinase activated (phosph TFs) (serine/threonine)
9. MAPK dimerizes
10. MAPK phosph p60 (RSK), they both enter nucleus for TF activation/phosphorylation
11. TFs are SRF (serum response factor) and TCF (Ternary complex factor)
12.TFs bind to enhancer SRE (serum response element) which promotes many genes like cfos
gene.
13. cfos gene enhances cell division
GDI does what? - correct answer ✔✔ Guanine dissociation inhibitor, keeps GDP bound to G
protein
Breast Cancer HER2 (RTK) defect is? - correct answer ✔✔ always dimerized therefore Ras always
active, so p60 and MAPK dimer always phosph. SRF and TCF which activate enhancer region SRE
which upreg cfos gene leading to uncontrolled cell division
GPCRs - correct answer ✔✔ Structure = 7 TM domains which create :
4 extracellular signal binding domains
4 cytosolic domains (trimer)
Function= adrenergic receptors
beta: glycogenolysis/lipolysis liver (stimulatory)
alpha: reduce blood flow to periphery
(inhibitory)
Steps in GPCR adrenergic response - correct answer ✔✔ 1. signal binding induces cc on GPCR to
bind to alpha subunit of G trimer- GDP
2. cc on G trimer by receptor causes GTP binding
100% CORRECT ANSWERS
When will Dictyostelium differentiate into a slug? - correct answer ✔✔ starved amoeba will
secrete cAMP, other amoebas have cAMP GPCRs which activate actin reorganization into
Fimbriae to move toward the signal location
When will slug differentiate into amoebas ? - correct answer ✔✔ When nutrients are availble.
Post cells= body, ant cells= stalk
JAK-STAT pathway accomplishes what? - correct answer ✔✔ Inhibit apoptosis, promote
differentiation
JAK STAT signal is? - correct answer ✔✔ Epo from kidneys
JAK STAT Pathway steps? - correct answer ✔✔ 1. EpoR dimerizes bound to signal
2. docking sites to come closer, cytoplasmic JAK kinase dimerizes =autophosphorylation of
activation lip tyrosines =active
3. JAK kinases will phosphorylate docking sites tyrosines
4. STAT (SH2 domain) transferred to the docked phosphorylated tyrosines,
5. STAT becomes phophorylated by JAK
6. STAT-p dimerizes
7. NLS signal revealed
8. TF activator for genes like bcl-xl to inhibit apoptosis
Short term Deactivation - correct answer ✔✔ SHP1 (2 SH2 domains) migrate to cytosolic
docking site by phoph. tyrosines. Dephosphorylates JAk kinase
,Long term Deactivation - correct answer ✔✔ SOCS has SH2 domain to migrate and works 2
ways
1. accumulates on docking site to block STAT access
2. will ubiquitinate JAK for degradation
to remake JAK is why its "longterm"
effect of truncated EpoR on negative regulators? - correct answer ✔✔ decreased sensitivity to
regulators bc of shorter docking site therefore higher hematocrit
Receptor Tyrosine Kinase signals ? - correct answer ✔✔ RTKs bind to hormones like NGF, EGF,
insulin, hGH,
RTK receptor has what type of activity on the cytosolic face ? - correct answer ✔✔ weak kinase
activity
signal binding causes what interaction btw receptors? - correct answer ✔✔ Dimerization and
kinase activty activation on the cytosolic face. Autophosph. of the neighbouring activity lip=
more tyrosine residues phosph.
Next steps in pathway... - correct answer ✔✔ 1.GRB2's SH2 domain binds to phosphorylated
tyrosine residue
2. 2 SH3 domains recognize SOS proline rich seqence
3. SOS binds to Ras G protein, SOS has intrinsic GEF activity, Will replace GDP with GTP = active
Ras
4. Ras activates Raf via regulatory domain
5. GTP hydrolysis dissociates Ras-Raf
6. Raf aka MAP kinase kinase kinase (Serine/threonine)
, 7. MEK (map kinase kinase) serine/tyrosine kinase
8. MAP kinase activated (phosph TFs) (serine/threonine)
9. MAPK dimerizes
10. MAPK phosph p60 (RSK), they both enter nucleus for TF activation/phosphorylation
11. TFs are SRF (serum response factor) and TCF (Ternary complex factor)
12.TFs bind to enhancer SRE (serum response element) which promotes many genes like cfos
gene.
13. cfos gene enhances cell division
GDI does what? - correct answer ✔✔ Guanine dissociation inhibitor, keeps GDP bound to G
protein
Breast Cancer HER2 (RTK) defect is? - correct answer ✔✔ always dimerized therefore Ras always
active, so p60 and MAPK dimer always phosph. SRF and TCF which activate enhancer region SRE
which upreg cfos gene leading to uncontrolled cell division
GPCRs - correct answer ✔✔ Structure = 7 TM domains which create :
4 extracellular signal binding domains
4 cytosolic domains (trimer)
Function= adrenergic receptors
beta: glycogenolysis/lipolysis liver (stimulatory)
alpha: reduce blood flow to periphery
(inhibitory)
Steps in GPCR adrenergic response - correct answer ✔✔ 1. signal binding induces cc on GPCR to
bind to alpha subunit of G trimer- GDP
2. cc on G trimer by receptor causes GTP binding
