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EMBRYO SQ 19-20.docx

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BIOL 302
Catherine Studholme

Study question lectures 19-20 Aaron 1. What are the four major regeneration mechanisms? Briefly (one sentence) describe each of them. L19S17, P560 a. Epimorphosis – amputation cause dedifferentiation of cells and formation of undifferentiated mass of cells (blastema) which re-specifies into lost part of body (e.g. salamander limb) b. Morphallaxis – regeneration via repatterning/rearrangement of existing structures with little new growth (hydra repattern after loss of limb to reform) c. Compensatory Regeneration – differentiated cells divide to form cells similar to itself but maintain differentiated functions and therefore do not come from stem cells or dedifferentiated adult cells (liver) (intermediate form of regeneration) d. Stem-cell mediated Regeneration – regrowth of certain organs or tissues lost (e.g. bone marrow replace blood cells, hair) 2. Salamanders can reconstruct a complete limb, if necessary. Which parts of the limb are getting reconstructed after amputation? How do we call this type of regeneration? a. Reconstruction of missing parts of limb after amputation b. Epimorphosis regeneration of proximal to distal limb portion 3. Describe the process of limb regeneration in salamander. P561, S17 a. Amputation b. Plasma clot form c. Surrounding epidermis cover wound to form wound epidermis (no scar tissue) d. Wound epidermis proliferate into apical ectodermal cap (AEC) – prevent scar formation e. Under AEC dedifferentiation and proliferation form regeneration blastema f. Cells undergo respecification to form new structures 1 Study question lectures 19-20 Aaron 4. What are the similarities between apical ectodermal ridge and apical ectodermal cap? What are the differences? (Define both of them first). Apical Ectodermal Ridge Apical Ectodermal Cap -produced in limb formation of embryogenesis -produced in limb regeneration -area underneath is progress zone (constant -area underneath known as regeneration blastema proliferation, determine distal part + what limb -stimulate growth of blastema by release fgf8 developed) (P563) -proximal to distal formation -maintains zone dedifferentiation and -secrete fgf8 for PZ proliferation maintenance proliferation -prevents early cartilage formation -prevents early cartilage formation -induced by fgf10 -requires fgf10, fgf8, shh -important for limb bud formation -fgf2 for angeiogenesis -signalling centre -proximal to distal respecification -maintain mesenchyme proliferation for proximal distal growth - expression of molecules that make AP axis -interact w/ protein that make AP DV axes for differentiation coordination 5. What is the role of nerves in salamander’s limb regeneration? S22 P563 a. Nerves release factors that drive proliferation of blastema cells from AEC i. Glial growth factor? ii. Newt anterior gradient protein – allow blastema cells proliferate 6. Explain the following statement: Blastema is heterogeneous population of restricted progenitor cells. S24P561 a. The cell population in the blastema retain their specification and there are multiple kinds of cells b. old Dermis and skeleton cells can only give rise to dermis orskeleton c. Old Muscle, Schwann and epidermis cells can only become new muscle, Schwann and epidermis d. Restricted Progenitors are not fully undifferentiated and are not multipotential i. Progenitors have a restricted set of redifferentiation fates (blastema retain specification) 7. What are the major steps in mammalian liver compensatory regeneration? P570 S29 a. Removal of liver lobe b. Metalloproteases digest ECM to separate/loosen hepatocytes 2 Study question lectures 19-20 Aaron c. Lipopolysaccharides activate non-hepatocytes to secrete Paracrine factors to induce hepatocytes to re-enter cell cycle d. Stellate cells release hepatocyte growth factor (HPF) and TGF-beta i. HPF activated by metalloproteases e. Proliferation of remaining tissue i. Hepatocytes, bile duct, kupffer, endothelial, Ito cells divide f. All cell types retain identity (no dedifferentiation occurs) 8. Briefly describe the differences between three types of IVF we talked about in class. L20S3 Gamete Intrafallopian Transfer GIFT Zygote Intrafallopian Intracytoplasmic Sperm Transfer ZIFT Injection ICSI -sperm injected into oviduct at ovulation -fertilization in dish, zygotes -single sperm injected into egg -sperm don’t have to travel placed in fallopian tube not cytoplasm -internal fertilization uterus -remove egg from ovary, place -at least one fallopian tube open -external fertilization fertilized egg into uterus -used when cervical/immunological -fertilization confirmation -use when low viable sperm factors hinder sperm count 9. From the table below choose three genes encoding human transcription factors involved in embryonic development and discuss the consequences their mutations would have during embryogenesis (this question will be on the exam, but I will not provide the part of the table that tells what is the mutation phenotype! You can choose the genes in advance and have the answers ready for the exam.) S9 a. Androgen Receptor - Androgen Insensitivity Syndrome – mutation alter RNA longevity, no uterus but have vagina, testes don’t descend (sterile) b. Estrogen Receptor – growth regulation problems, sterility c. SRY – male sex reversal to female 10. What are the possible consequences of mutation in a regulatory part of the gene? In an intron? In a sequences which will be transcribed into 5’ and 3’ UTRs of the mRNA? In a coding sequence? Would you be able to give one example for each of these mutations? a. Mutation in regulatory part of gene can have large effect on protein the gene codes for b. Mutation in intron can result in i. new splice site, convert intron to exon ii. remove splice site, change exon iii. change affinity of splice site for specific splice factors 3 Study question lectures 19-20 Aaron c. Mutation in 5’ UTR of mRNA = i. change translation efficiency ii. form new start codon which extends N-terminus iii. remove original start codon = shorten N-terminus d. mutation in 3’ UTR of mRNA =
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