BICD 130 DevelopmentFall 2021Dr. Michael PerryDiscussion Problem Set 2Makeup submission due by 12pm Saturday 10/9Reminder: you have two ways to get full points for this assignment.1. Attend your discussion section and meaningfully contribute to the class discussion of theproblem set for full participation points.OR2. If you miss the discussion section, work on these problems on your own and submitwritten answers on Canvas by noon on Saturday. IAs are available to help at officehours.Lecture 3: Find It, Lose It, Move It1. You are an alien from another planet who has very little understanding of human culture.You notice that humans have peculiar hinged rectangles on their buildings, which theycall doors, but you really don’t understand what the purpose of these “doors” are.Thankfully, you are a developmental biologist on your home planet. How would you useFind It, Lose It, Move It to figure out what doors do?2. In the context of experimental developmental biology:a. What is necessity and sufficiency?b. Which part of find it, lose it, move it tells us about each?3. Give examples of common biological techniques used for each step of inquiry ofdevelopmental gene function:a. Find it:b. Lose it:c. Move it:4. Body axes: sketch a simple Bilaterian and label the following axes: anterior-posterior,dorsal-ventral, left-right, medial-lateralLecture 4: Cleavage and Polarity in Sea Urchins1. What is a developmental fate map? What do they show and why are they important?2. Cleavage is characterized by the early embryonic cell divisions that increase cell numberwhile keeping a constant total volume. Draw the normal somatic cell cycle, thenhypothesize what the cell cycle looks like during cleavage and draw that beside it.3. Sketch the sea urchin embryo at the following stages, marking the cleavage plane thatproduced each stage:a. 4-cellb. 8-cellc. 16-cell4. Establishing asymmetry:a. Sketch a summary of Horstadius’s two unfertilized sea urchin egg experimentsfrom the video we watched:i. In one, he divided unfertilized eggs along the future animal-vegetal axisand fertilized one half or the other. What happened?ii. In the next, he instead divided the egg perpendicular to theanimal-vegetal axis and fertilized either half.b. Next sketch a summary of the experiment where Horstadius divided an 8-cellstage embryo into animal and vegetal halves and grew each separately.c. What do the outcomes of these experiments tell us about axis specification in theearly embryo? When is positional information first present?5. We now know some of the molecules involved in animal-vegetal polarity in sea urchins.Using our framework of Find It, Lose It, Move It, describe how we know the role ofβ-catenin in vegetal fate formation in sea