CMMB 403 Final Exam Actual Questions and Answers with complete solution

CMMB 403 Final Exam Actual Questions and Answers with complete solution Which animal's development is chick development most similar to compared to other species? - answerMost similar to humans than other species talked about in lecture (like amphibians and flies) What is the Nieuwkoop Centre (NC)? When does it emerge during embryo development? - answerCentre that induces the formation of the organizer and later the dorsal mesoderm; emerges during the late blastula stage How does the fish organizer and Niewukoop Centre (NC) compare to their amphibian counterparts? - answerThey have similar functions When during embryo development does the organizer develop? Where does the organizer form? - answerGastrula stage; organizer forms opposite to sperm entry What kind of cleavage do zebrafish embryos undergo? - answerDiscoidal meroblastic cleavage What is the fish organizer called? - answerThe embryonic shield What is the fish Nieuwkoop centre (NC)? - answerThe yolk syncytial layer directly below the shield (BUT NOT the entire yolk syncytial layer itself); this area is where nuclear localization of b-catenin is seen as it is what is forming the NC centre What is the key difference between fish zygotes undergoing development versus other zygotes? - answerFish zygotes do NOT undergo cortical rotation The yolk syncytial layer is at the margin between what 2 things in the zebrafish embryo? - answerThe blastoderm (which the organizer is a part of) and the yolk What does B-catenin specifically do in zebrafish development that is similar to its function in amphibians? - answerActivates organizer genes to form the organizer which is where B- catenin is stabilized (up in the dorsal region of the embryo) Where is nuclear B-catenin specifically found in the embryo? - answerBelow the future embryonic shield (in the yolk syncytial layer beneath the future embryonic shield) which is where B-catenin marks as the dorsal side of the embryo What does nuclear localization of B-catenin do and what does it help to form? - answerNuclear localization of b-catenin marks the dorsal side of the Xenopus blastula and helps form its Nieuwkoop center beneath the organizer What happens to the future embryonic shield after nuclear B-catenin is stabiliized below it? - answerFuture embryonic shield above the nuclear B-catenin cells thicken to become the organizer How do the molecules involved in zebrafish development (ie. organizer formation, etc) relate to the ones used in amphibians? - answerThey are homologous What 2 organizer genes does B-catenin activate expression of in zebrafish? What kind of proteins do each of these 2 genes express? Expression of these leads to expression of what molecules? - answerB-catenin activates expression of squint (which is nodal-like) and bozozok (which is a homeodomain that also happens to be siamois ortholog) Squint and bozozok both activate expression of chordino (a BMP inhibitor in zebrafish) as well as noggin, goosecoid, dickkopf (Wnt inhibitors) What is the mechanism of beta catenin accumulation in zebrafish? What movements were found to be not detected? - answerMechanism of beta-catenin accumulation in zebrafish is unknown - no cortical rotation or other morphogenetic movements have been detected Nuclear beta catenin has a direct effect on chordino expression (True/False) - answerFalse, beta catenin affects chordino expression indirectly through squint (nodal-like protein) and bozokok (homeoprotein) homologues What is squint a homologue of? What is bozokok a homologue of? - answerSquint is a homologue of Nodal (TGF beta paracrine factor) Bozokok is a homologue of siamois At the blastula stage, what is going on with the Nieuwkoop center? - answerThere is nuclear beta-catenin accumulation at the Nieuwkoop center Between zebrafish and Xenopus, which has a smaller embryo? - answerZebrafish embryo is smaller Gastrulation in aminiote embryos occurs through what structure? What does this structure contain? - answerA linear structure called the primitive streak (a characteristic feature of all amniote embryos) which contains a groove through which cells ingress to form the endoderm and mesoderm Cells (from the epiblast) that ingress through the primitive streak form what? Cell that don't ingress through the primitive streak form what? - answerCells that ingress through the primitive streak form the mesoderm and the endoderm while cells that DON'T ingress through the primitive streak form the ecto