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BIO351 |! Module |! 4 |! Exam |! with |! verified |!
detailed |! solutions
Mesodermal |! cells |! at |! the |! site |! of |! the |! limb |! buds |! respond |! to |! beads |! soaked |! in |! FGF8 |! and |! grow |! out |! along |! the |! proximal-distal |! axis. |! If |! beads |! expressing |! FGF8 |! are |! placed |! under |! the |! epithelium |! of |! the |! back |! there |! is |! no |! outgrowth. |! This |! experiment |! demonstrates |! which |! of |! the |! following?
- |! Permissive |! induction
- |! Proliferation
- |! Competence
- |! Gastrulation
- |! Differentiation |! - |! Correct |! answer |! ✔- |! Competence LEC |! 1.3 |! Slide |! 6 "Competence: |! a |! cell's |! ability |! to |! respond |! to |! an |! inductive |! signal." Think |! about |! this: |! the |! soaked |! Fgf8 |! beads |! are |! transplanted |! 'under |! the |! epithelium |! of |! the |! BACK |! ... |! [and] |! there |! is |! NO |! outgrowth." Because |! there |! is |! no |! outgrowth |! when |! this |! is |! translated, |! this |! means |! the |! cells |! of |! the |! back |! are |! not |! competent. |! Meaning, |! their |! signals |! are |! there/present |!
from |! Fgf8, |! however, |! the |! cell's |! (of |! the |! back) |! ability |! to |! comprehend |! and |! exact |! the |! goals |! of |! the |! Fgf8 |! signal |! is |! inadequate |! or |! incompetent. |! textbook: Cells |! of |! the |! responding |! tissue |! must |! have |! both |! a |! receptor |! protein |! for |! the |! inducing |! factor |! and |! the |! ability |! to |! respond |! to |! the |! signal. |! The |! ability |! to |! receive |! and |! respond |! to |! a |! specific |! inductive |! signal |! is |! called |! competence |! (Waddington |! 1940). Researchers |! were |! examining |! the |! role |! of |! SHH |! on |! patterning |! the |! digits |! in |! the |! limb |! bud. |! They |! predict |! a |! gradient |! of |! SHH |! along |! the |! rostral/caudal |! axis |! is |! required |! to |! pattern |! the |! digits |! (left |! panel). |! Ablation |! of |! the |! Zone |! of |! Polarizing |! Activity |! (ZPA) |! lead |! to |! the |! SHH |! concentrations |! in |! the |! right |! panel. |! Based |! on |! this |! model, |! which |! pattern |! of |! digits |! (A-E) |! is |! expected.
- |! C
- |! D
- |! E
- |! A
- |! B |! - |! Correct |! answer |! ✔- |! D LEC |! 1.3 |! Slides |! 14, |! 17- As |! can |! be |! seen |! in |! the |! 'real' |! image |! (not |! depicted |! here), |! there |! are |! 2 |! thresholds |! for |! red, |! white, |! and |! blue |! for |! particular |! digits.
|! (EMT), |! and |! its |! various |! regions |! become |! committed |! to |! forming |! only |! certain |! cell |! types |! (see |! Figure |! 17.2A-D). |! These |! mature |! somites |! contain |! two |! major |! compartments: |! the |! sclerotome |! and |! the |! dermomyotome |! (see |! Figure |! 17.2D,E). quiz |! question:
|! The |! somites |! derive |! from |! which |! of |! the |! early |! embryonic |! tissues? |! = |! mesoderm Which |! of |! the |! following |! signaling |! pathways |! controls |! cyclical |! gene |! transcription |! in |! the |! segmentation |! clock?
- |! SHH
- |! Hox
- |! Notch
- |! BMP |! - |! Correct |! answer |! ✔- |! Notch LEC |! 4.2 |! Slides |! 8- "Segmentation |! [clock] |! is |! regulated |! by |! 2) |! cycling |! expression |! of |! Notch |! pathway |! genes..." quiz |! question:
|! The |! diagram |! below |! shows |! the |! phenotype |! of |! a |! mouse |! with |! a |! genetic |! mutation. |! This |! phenotype |! is |! most |! likely |! to |! result |! from |! disruption |! of |! which |! of |! the |! following |! processes? |! = |! segmentation |! clock |! notes |! "The |! Segmentation |! Clock: |! prepatterning |! in |! the |! presomitic |! mesoderm |! through |! gradients |! & |! oscillators." "Failures |! of |! Notch |! signaling |! can |! lead |! to |! disruptions |! of |! the |! segmentation |! clock." The |! diagram |! shows |! that |! when |! the |! _____________ |! is |! removed, |! the |! limb |! bud |! no |! longer |! receives |! _______ |! that |! is |! required |! for |! proximal |! to |! distal |! growth. |! Fill |! in |! the |! blanks |! with |! the |! best |! option |! below.
- |! Apical |! ectodermal |! ridge |! (AER), |! SHH
- |! Dorsal |! ectoderm, |! WNT7A
- |! Apical |! ectodermal |! ridge |! (AER), |! FGF
- |! Zone |! of |! polarizing |! activity |! (ZPA), |! SHH |! - |! Correct |! answer |! ✔- |! Apical |! ectodermal |! ridge |! (AER), |! FGF LEC |! 4.7 |! Slide |! 17 "The |! AER |! is |! removed |! and |! replaced |! a |! synthetic |! bead |! soaked |! in |! Fgf8. |! [Prediction:] |! Fgf8 |! is |! sufficient |! to |! induce |! the |! underlying |! mesenchyme |! to |! grow |! distally |! and |! is |! the |! inductive |! factor |! in |! the |! AER."
- |! Retinoic |! acid, |! Notch |! signaling |! - |! Correct |! answer |! ✔- |! Retinoic |! acid, |! FGF8 |! and |! Wnt LEC |! 4.2 |! Slide |! 3 "There |! are |! gradients |! of |! inducing |! factors |! (Fgf8 |! and |! retinoic |! acid |! (RA)) |! within |! the |! presomitic |! mesoderm |! that |! determine[s] |! where |! segmental |! boundaries |! will |! eventually |! form. |! This |! 'decision |! zone' |! is |! called |! the |! determination |! zone." "Segmentation |! is |! regulated |! by |! 1) |! gradients |! of |! inducing |! factors |! FGF8/WNT3a |! and |! RA"... |! and |! 2) |! cycling |! expression |! of |! Notch |! pathway |! genes In |! the |! diagram |! B |! points |! to |! the |! _______________ |! and |! D |! points |! to |! the |! __________ |!. |! Pick |! the |! best |! answer |! to |! fill |! the |! blanks.
- |! Ventral-lateral |! lip, |! dorsal-medial |! lip |! of |! the |! dermomyotome
- |! Ventral-Lateral |! lip |! of |! the |! dermomyotome, |! syndetome |!
- |! Notochord, |! neural |! tube
- |! Dorsal-medial |! lip |! of |! the |! dermomyotome, |! Sclerotome |! - |! Correct |! answer |! ✔- |! Dorsal-medial |! lip |! of |! the |! dermomyotome, |! Sclerotome LEC |! 4.3 |! Slide |! 6 In |! the |! image: |!
|! A: |! neural |! tube |! B: |! DML |! (dorsal-medial |! lip) |! C: |! VLL |! (ventral-lateral |! lip) |! D: |! Sclerotome Based |! on |! your |! understanding |! of |! how |! Hox |! group |! 9, |! group |! 10, |! group |! 11, |! group |! 12, |! and |! group |! 13 |! paralogues |! regulate |! the |! specification |! of |! proximal |! to |! distal |! regions |! of |! the |! extremities, |! which |! of |! the |! following |! would |! you |! expect |! from |! a |! loss |! of |! Hoxa11 |! and |! other |! group |! 11 |! genes?
- |! affects |! the |! stylopod |! (humerus |! and |! femur)
- |! affects |! the |! zeugopod |! (radius/ulna |! and |! tibia/fibula)
- |! affects |! the |! autopod |! (hand |! and |! foot)
- |! affects |! only |! the |! upper |! extremities |! (arms) |! but |! not |! lower |! (legs) |! - |! Correct |! answer |! ✔- |! affects |! the |! zeugopod |! (radius/ulna |! and |! tibia/fibula) LEC |! 4.6 |! Slide |! 13 As |! stated |! in |! the |! lecture: |!
|! STYLOPOD |! = |! HOX |! 9- |! ZEUGOPOD |! = |! HOX |! 10- |! AUTOPOD |! = |! HOX |! 12-
Humans |! homozygous |! for |! a |! HOXD13 |! mutation |! show |! abnormalities |! of |! the |! hands |! and |! feet |! wherein |! the |! digits |! fuse |! (FIGURE |! 19.3D), |! and |! humans |! with |! homozygous |! mutant |! alleles |! of |! HOXA13 |! also |! have |! deformities |! of |! their |! autopods |! (Muragaki |! et |! al. |! 1996; |! Mortlock |! and |! Innis |! 1997). |! In |! both |! mice |! and |! humans, |! the |! autopod |! (the |! most |! distal |! portion |! of |! the |! limb) |! is |! affected |! by |! the |! loss |! of |! function |! of |! the |! most |! 5′ |! Hox |! genes. Scientists |! have |! created |! a |! transgenic |! chick |! embryo |! that |! expresses |! Tbx4 |! in |! both |! the |! forelimb |! and |! hindbud |! regions |! but |! no |! Tbx5. |! What |! would |! you |! expect |! in |! the |! resulting |! chicken?
- |! A |! chicken |! with |! 1) |! legs |! instead |! of |! wings |! and |! 2) |! wings |! instead |! of |! legs
- |! A |! chicken |! with |! 4 |! wings
- |! A |! chicken |! with |! 4 |! legs
- |! A |! chicken |! without |! any |! extremities |! - |! Correct |! answer |! ✔- |! A |! chicken |! with |! 4 |! wings LEC |! 4.6 |! Slides |! 15-
|! FORELIMB |! = |! Tbx |! HINDLIMB |! = |! Tbx THUS: |! if |! there |! is |! no |! Tbx5 |! then |! only |! forelimbs |! will |! be |! produced.
Hypoxia, |! a |! state |! of |! low |! oxygen |! levels |! in |! tissues, |! is |! known |! to |! cause |! a |! disruption |! of |! somitogenesis. |! If |! a |! mouse |! embryo |! were |! temporarily |! exposed |! to |! low |! levels |! of |! oxygen |! during |! the |! final |! stages |! of |! somitogenesis, |! what |! would |! you |! expect |! to |! see |! in |! the |! vertebral |! column |! of |! the |! newborn |! mouse?
- |! Defects |! of |! the |! cervical |! (neck) |! vertebrae
- |! Defects |! of |! the |! caudal |! (tail) |! vertebrae
- |! Defects |! of |! the |! thoracic-lumbar |! (trunk) |! vertebrae
- |! The |! entire |! vertebral |! column |! is |! missing. |! - |! Correct |! answer |! ✔- |! Defects |! of |! the |! caudal |! (tail) |! vertebrae LEC |! 4.1 |! Slide |! 7 "Somites |! are |! formed |! in |! rostral-caudal |! order, |! with |! the |! head |! somites |! first |! ... |! neck |! ... |! then |! thoracic, |! lumbar, |! and |! finally |! sacral |! and |! coccygeal |! somites." B/c |! of |! this, |! if |! the |! embryo |! is |! already |! partially |! developed |! before |! being |! exposed |! to |! low |! amounts |! of |! oxygen, |! then |! the |! tail |! or |! the |! final |! stages |! of |! somitogenesis |! will |! be |! undeveloped. |! "Presomitic |! mesoderm |! cells |! are |! dividing |! and |! pushing |! cells |! forward |! and |! new |! cells |! bud |! off |! at |! the |! end |! and |! lengthen." Which |! of |! the |! following |! cells |! makes |! the |! greatest |! contribution |! to |! bone |! length |! during |! development?
- |! Fusion |! of |! myoblasts |! into |! primary |! myotubes |! - |! Correct |! answer |! ✔- |! Fusion |! of |! myoblasts |! into |! primary |! myotubes LEC |! 4.4 |! Slides |! 9- There |! are |! 2 |! waves |! of |! myotube |! formation: |! 1) |! the |! First |! Wave |! & |! 2) |! the |! Second |! Wave. The |! First |! Wave |! occurs |! all |! at |! once |! and |! results |! in |! the |! fusion |! of |! existing |! myoblasts |! to |! form |! primary |! myotubes. The |! Second |! Wave |! occurs |! in |! an |! ongoing |! asynchronous |! fashion |! and |! results |! in |! the |! formation |! of |! muscle |! fibers. |! Since |! the |! Q |! is |! saying |! that |! there |! is |! an |! INHIBITION |! of |! the |! formation |! of |! neuromuscular |! junctions; |! we |! know |! that |! these |! junctions |! form |! during |! the |! Second |! Wave. |! Because |! there |! is |! this |! inhibition |! then |! the |! Second |! Wave |! will |! be |! BLOCKED. |! Thus, |! the |! last |! step |! achieved |! was |! the |! "Fusion |! of |! myoblasts |! into |! primary |! myotubes." Which |! compartment |! of |! the |! somite |! will |! give |! rise |! to |! tendons?
- |! Sclerotome
- |! Myotome
- |! Syndetome
- |! Dermomyotome |! - |! Correct |! answer |! ✔- |! Syndetome
LEC |! 4.4 |! Slide |! 12 "Scleraxis |! is |! expressed |! in |! tendon |! progenitors." Tendons |! develop |! from |! the |! syndetome |! which |! lies |! btwn |! the |! sclerotome |! and |! myotome. textbook:"Dorsal |! regions |! forms |! tendons |! (syndetome)." Quiz |! Q |! from |! 4.4 |!
|! Match |! the |! somite-derived |! compartment |! with |! the |! correct |! adult |! tissues |! that |! derive |! from |! it. |! = |! - |! syndetome, |! tendons Which |! statement |! is |! correct |! regarding |! the |! patterning |! of |! the |! sclerotome.
- |! SHH |! secreted |! from |! the |! notochord |! induces |! Pax1 |! expression |! in |! that |! will |! become |! the |! sclerotome
- |! BMP4 |! secreted |! from |! the |! dorsal |! epidermis |! induces |! Pax1 |! expression |! in |! cells |! that |! will |! become |! the |! sclerotome.
- |! The |! sclerotome |! is |! marked |! by |! expression |! of |! Pax3 |! and |! MyoD.
- |! Wnt1 |! and |! NT3 |! from |! the |! neural |! tube |! induce |! Pax1 |! in |! cells |! that |! will |! become |! the |! sclerotome |! - |! Correct |! answer |! ✔- |! SHH |! secreted |! from |! the |! notochord |! induces |! Pax1 |! expression |! in |! that |! will |! become |! the |! sclerotome
The |! proliferating |! myoblasts |! are |! characterized |! by |! Pax3 |! and |! Pax7 |! and |! are |! induced |! by |! Wnts |! in |! the |! epidermis. |! (After |! G. |! Cossu |! et |! al. |! 1996. |! Trends |! Genet |! 12: |! 218-223.) During |! limb |! bud |! outgrowth, |! FGF8 |! in |! the |! AER |! moves |! distally |! away |! from |! the |! RA |! source. |! This |! allows |! FGF8 |! to |! reinforce |! FGF10 |! signaling |! in |! the |! adjacent |! mesoderm. |! FGF10 |! is |! important |! for |! _______. |! Choose |! the |! best |! answer.
- |! establishing |! polarity
- |! MET
- |! proliferation
- |! inhibiting |! TBX4/5 |! - |! Correct |! answer |! ✔- |! proliferation LEC |! 4.6 |! Slides |! 14- "Fgf10 |! bead |! included |! ectopic |! limb |! that |! had |! both |! forelimb |! structures |! anterior |! and |! hindlimb |! structures |! posterior." ^ |! This |! experiment |! just |! displayed |! the |! fact |! that |! Fgf10 |! is |! incredibly |! important |! for |! proliferation |! and |! limb |! growth. textbook: "Downstream |! of |! the |! regulatory |! function |! of |! these |! transcription |! factors |! is |! Fgf10, |! the |! primary |! inducer |! for |! limb |! bud |! formation |! through |! the |! initiation |! of
|! cell |! shape |! changes |! and |! proliferation |! for |! outgrowth, |! as |! discussed |! below |! (FIGURE |! 19.8B,C)." There |! are |! many |! recurring |! themes |! involved |! in |! patterning |! a |! developing |! organism. |! Which |! of |! the |! following |! themes |! below |! definitionally |! relies |! on |! a |! concentration |! threshold |! to |! regulate |! cell |! specification.
- |! asymmetric |! division
- |! EMT/MET
- |! morphogen |! gradients
- |! Hox |! gene |! expression |! - |! Correct |! answer |! ✔- |! morphogen |! gradients LEC |! 1.3 |! Slide |! 15 "Morphogen |! gradients |! can |! regulate |! the |! activity/expression |! of |! specific |! transcription |! factors" Cell |! fate |! is |! specified |! based |! on |! the |! morphogen |! gradient |! induction |! (based |! on |! a |! cell's |! threshold). Chose |! the |! answer |! from |! the |! dropdown |! menus. In |! bone |! remodeling: |! ________________ |! remove |! bone, |! ______________ |! deposit |! bone. OPT |! #1: |! ["osteoclasts", |! "osteocytes", |! "osteoblasts"]
MyoD's |! goal |! is |! to |! bring |! about |! Determination |! and |! Differentiation |! of |! myoblasts. |! We |! know |! that |! determination |! is |! IRREVERSIBLE. Osteopetrosis |! is |! associated |! with |! an |! increase |! in |! _________________ |! due |! to |! a |! failure |! of |! the |! ________________.
- |! bone |! frailty; |! osteoblasts
- |! collagen |! deposition; |! osteoclasts
- |! bone |! density; |! osteoclasts
- |! collagen |! deposition; |! osteoblasts |! - |! Correct |! answer |! ✔- |! collagen |! deposition; |! osteoclasts LEC |! 4.5 |! Slide |! 18 "Osteopetrosis |! is |! a |! defect |! in |! bone |! resorption |! by |! osteoclasts. |! Radiographic |! findings |! in |! a |! patient |! with |! increased |! bone |! density |! versus |! normal." This |! is |! due |! to |! a |! decrease |! in |! "osteoclast |! activity."
