Download Self-Assessment - Introduction to Animal Development | BIOL 117 and more Quizzes Biology in PDF only on Docsity! BIOL 117 – Spring 2015 Lecture 9 Self-Assessment Lecture 9 – Introduction to Animal Development 1) Within a sperm cell, what is the function of an acrosome? Acrosomes contain enzymes needed to penetrate egg cells 2) How do membrane proteins on both an egg and a sperm cell function to keep fertilization species- specific? They go through a lock and key reaction, when they go through it means they are apart of the same species. 3) Explain the steps of the acrosomal reaction. The discharge of hydrolytic enzymes from the acrosome, a vesicle in the tip of the sperm, when the sperm approaches or contacts an egg. The head contains the nucleus and the enzyme-filled acrosome. Acrosome enzymes allow the sperm to penetrate the egg's barriers.When a sperm head contacts the jelly layer, enzymes from the sperm's acrosome digest through the egg's jelly layer and vitelline envelope. a. How does this reaction help a sperm cell enter an egg cell? 4) Explain the steps of the cortical reaction. RESPONSE OF AN EGG CELL TO ENTRY BY A SPERM CELL THAT CHANGES THE STRUCTURE OF THE OUTER LAYERS, PREVENTING THE PENETRATION BY ADDITIONAL SPERM 1. Sperm enters cell egg 2. The egg releases calcium ions from storage (fertilization envelope begins to lift) 3. Corticol granules fuse with the egg’s cell membrane and release their contents (excess sperm cleared away) a. What element (ion) is the chemical trigger for the cortical reaction to begin? Calcium b. How does this reaction help to prevent polyspermy? o The acrosomal reaction allows one sperm to penetrate the egg, but when the sperm cell unites with the egg plasma, it triggers the cortical reaction leads to a modification of the zona pellucida that blocks polyspermy; enzymes released by cortical granules digest sperm receptor proteins ZP2 and ZP3 so that they can no longer bind sperm, in mammals. 5) Put the following steps of development into order: 1. Fertilization 2. Cell cleavage 3. Gastrulation 4. Organogenesis 6) At what stage of development do the primary germ layers begin to form? GASTRULATION 7) What tissue layer (germ layer) is used to create the neural tube? ectoderm 8) What tissue layer (germ layer) is used to create somite structures? MESODERM
