BIOLOGY 205/SECTION 7 DEVELOPMENT- LILJEGREN. Third Examination April 2, 2009

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1 BIOLOGY 205/SECTION 7 DEVELOPMENT- LILJEGREN Third Examination April 2, 2009 Please put your name at the top of each page. Read each question carefully before answering- i.e. read the instructions. Be as specific as possible, while respecting the amount of space allotted for each answer. No regrades for exams done in pencil. 1.) (4 pts) Name the key biological processes that generate each of the following molecules, and specify the starting molecules: RNA protein 2.) (5 pts) We talked about rules of evidence in Developmental Biology. Why do correlative experiments provide the weakest evidence for figuring out a gene s function? What type of evidence do each of the following experiments or findings represent? Using a fibronectin competitor to block frog gastrulation Observing that the blastopore always forms 180º from the site of sperm entry Finding that the blastopore forms next to the site of sperm entry in experimentally rotated eggs 3.) (3 pts) The size of a human skin cell compared to that of a human egg cell is like which of the following relationships: (more than one answer may be correct) Write letter(s) here Size of frog egg compared to a snake egg Size of snake egg compared to a frog egg Length of the average gene (unwound) to the diameter of the average protein Size of fruit fly genome compared to mouse genome (E) Size of mouse genome compared to fruit fly genome (F) Diameter of the average protein to the length of the average gene (unwound) 4.) (4 pts) Order the following events in human development from the earliest to the latest. Compaction (E) Implantation in the uterus Gastrulation (F) Formation of blastocyst Sperm formation begins (G) First differentiation event Oocyte formation begins (H) Fusion of egg and sperm earliest < < < < < < < latest 1

2 5.) (2 pts) If an egg is experimentally manipulated so that it has double the amount of cytoplasm compared to a normal egg, how many cell divisions would you expect for an organism that normally undergoes four cell divisions before the mid-blastula transition? Three Write letter here Four Five Eight Explain in terms of the N/C ratio. 6.) (2 pts) Each germ layer contributes to specific organs within our bodies. Which of the following are correct? Write letter(s) here The ectoderm gives rise to the brain The mesoderm gives rise to the lungs The endoderm gives rise to the gonads The ectoderm gives rise to the bones 7.) (4 pts) We ve talked about the key contributions of several scientists to our understanding of development. Match the names of the following scientists to their respective discoveries. Some names will not be used as answers. Pieter Nieuwkoop William Harvey Hilde Mangold (E) Wilhelm Roux Karl Ernst von Baer (F) Hans Driesch Cells can adjust their fates based on interaction with their neighbors. Transplantation of the dorsal blastopore lip can induce formation of a second body axis. Ex ovo omnia Dorsal vegetal cells can induce formation of the organizer 8.) (2 pts) Drosophila nurse cells and follicle cells provide support to the developing oocyte. Which of the following are correct statements? Write letter(s) here Nurse cells form an epithelium that surrounds the egg. Follicle cells produce nutrients that are pumped into the oocyte via gap junctions. Nurse cells produce mrnas that are pumped into the oocyte via gap junctions. Follicle cells produce nutrients that are delivered into the oocyte via cytoplasmic bridges. (E) Follicle cells are mitotic sisters of the oocyte, and are derived from the germline. (F) Nurse cells are meiotic sisters of the oocyte, and are derived from the germline. 2

3 9.) (18 pts) Mark each of the following questions as T or F and for any that is/are false, indicate briefly why in the space below. a. T F During cleavage, the embryo rapidly increases in size. b. T F When Xenopus animal pole cells are cultured with vegetal pole cells, the vegetal pole cells are induced to make mesoderm. c. T F All cell types express the same proteins. d. T F Exocytosis of the acrosomal vesicle propels the sperm toward the egg. e. T F In worms, the PAR-2 protein is asymmetrically localized during the first cell division. f. T F Injection of Noggin mrna into UV-irradiated frog eggs is able to rescue formation of ventral structures. g. T F Activation of the epithelial Na+ channel (ENaC) is controlled by a protein kinase. h. T F Proto-oncogenes often play roles in normal cell growth or cell division. i. T F Gain-of-function mutations that activate a tumor suppressor gene can lead to cancer. 10.) (6 pts) For each protein below, indicate which of the following categories best describes its job in the cell where its expressed: (Categories may be used more than once or not at all.) a. Membrane-bound signal e. Cytoskeletal protein b. Transcription factor f. Cell adhesion protein c. Secreted signal g. Ion channel protein d. Transmembrane receptor h. Protein kinase Resact Wingless E-cadherin CFTR Bindin Actin 3

4 11.) (2 pts) Through a famous transplantation experiment, it was discovered that transplantation of a region called Hensen s node from a quail embryo to a chick embryo resulted in the formation of two body axes in the chick embryo. Why did this experiment demonstrate that this region can be considered an organizer? Write letter here Quail cells participate in forming the second body axis Quail cells participate in forming the original axis Chick cells participate in forming the original axis Chick cells participate in forming the second body axis 12.) (8 pts) Draw pictures and describe in order from earliest to latest any TWO of the first four cell movements that occur during sea urchin gastrulation. Draw/describe what happens, specify the type of cell movement each event represents, the identity of the cells, and which germ layer they become part of. 13.) (4 pts) Draw pictures and describe ONE of the types of cell movements that occur during gastrulation in frogs but not in sea urchins. Draw/describe what happens during this event, specify the type of cell movement, the identity of the cells, and which germ layer they become part of. 14.) (3 pts) During human gastrulation, epiblast cells from the inner cell mass move through the primitive streak. What type(s) of cell movements do these cells undergo and what is the first germ layer that they contribute to? 4

5 15.) (4 pts) Molting is initiated by pulses of in an insect s blood. If this molecule is present and produced by the is present at high levels, the insect will. 16.) (2 pts) A scientist transplants dorsal vegetal cells from a donor embryo to the ventral side of a host embryo. What would you expect to happen if cells of the host embryo exhibited regulative development and cells of the donor embryo exhibited mosaic development? Write letter(s) here The host embryo gastrulates normally with one head and body axis. The host embryo does not gastrulate and forms a ventral belly piece with no head or body axis. The host embryo gastrulates at two spots, forms a secondary body axis, and develops two heads. The donor embryo gastrulates normally with one head and body axis. (E) The donor embryo does not gastrulate and forms a ventral belly piece with no head or body axis. (F) The donor embryo gastrulates at two spots, forms a secondary body axis, and develops two heads. 17.) (3 pts) In fly eggs, the embryo s dorsal/ventral axis is established by signaling between the oocyte and surrounding follicle cells. Which of the following would you expect to happen if scientists engineered a fly egg with uniformly localized Pipe protein in the surrounding follicle cells? Write letter(s) here The embryo would develop normally A dorsalized embryo would develop A ventralized embryo would develop The Torpedo receptor would be synthesized in all follicle cells (E) The Torpedo receptor would be synthesized only in ventral follicle cells (F) The Torpedo receptor would be synthesized only in dorsal follicle cells. (G) The Torpedo receptor would not be synthesized in any follicle cells. (H) Dorsal would enter both dorsal and ventral nuclei of the developing embryo, resulting in all cells of the embryo becoming specified as dorsal cells. (I) Dorsal would enter both dorsal and ventral nuclei of the developing embryo, resulting in all cells of the embryo becoming specified as ventral cells. (J) Dorsal would not enter any nuclei of the developing embryo, resulting in all cells of the embryo becoming specified as dorsal cells. (K) Dorsal would not enter any nuclei of the developing embryo, resulting in all cells of the embryo becoming specified as ventral cells. 5

6 18.) (1 pt) Which of the following would you expect to happen if scientists engineered a a fly egg with uniformly localized Pipe protein in the surrounding follicle cells in an egg which was maternally-deficient for the Torpedo receptor? The embryo would develop normally A dorsalized embryo would develop A ventralized embryo would develop Write letter(s) here 19.) (2 pts) What model organism was used to demonstrate that the Splunc1 protein was sufficient to inhibit conductance through the epithelial Na+ channel (ENaC)? Arabidopsis Write letter here Xenopus C. elegans Drosophila (E) Mouse 20.) (2 pts) Cystic fibrosis patients have trouble breathing because of a thick mucus layer coating their lungs and severely reduced airway surface liquid (ASL) volume. The Splunc1 protein was demonstrated to regulate ASL volume by which of the following experiments? Write letter here (E) (F) Human Splunc1 knockout bronchial cell cultures were found to have reduced ASL height compared to normal bronchial cell cultures. Human Splunc1 knockout bronchial cell cultures were found to have increased ASL height compared to normal bronchial cell cultures. Splunc1 knockout mice were found to have increased ASL height compared to wildtype mice. Splunc1 knockout mice were found to have reduced ASL height compared to wildtype mice. Wildtype mice treated with a Splunc1 inhibitor were found to have reduced ASL height compared to control mice. Wildtype mice treated with a Splunc1 inhibitor were found to have increased ASL height compared to control mice. 21.) (3 pts) Under which of the following conditions can an oncogene be activated? (E) (F) Write letter(s) here A new gain-of-function mutation occurs A new loss-of-function mutation occurs It is duplicated, so one more copy of the gene is present It is deleted, so one less copy of the gene is present A chromosomal rearrangement results in decreased expression A chromosomal rearrangement results in increased expression 22.) (2 pts) Why is p53 normally able to prevent formation of tumors? 6

7 23.) (4 pts) Which of the following proteins are well-known for their ability to become oncogenes or to suppress tumors? Label the oncogenes as O, tumor suppressors as TS, and neither as N. Rb Roy Ras Myc 24.) (10 pts) Mark each of the following questions as T or F and for any that is/are false, indicate briefly why in the space below. a. T F Dicty cells with a loss-of-function mutation in gp150 form smaller slugs and fruiting bodies than wildtype. b. T F In flies, the cell cycle is much shorter before the mid-blastula transition. c. T F After puberty, monthly surges of LH and estrogen are produced by the pituitary gland. d. T F Sperm can t fuse to an egg when it has a negative membrane potential. e. T F In sea urchin, the cleavage plane forms perpendicular to the contractile ring. I certify that I have performed my work on this examination in full conformity with the provisions of the Honor Code. Signature Extra credit.) (1 pt) What was one of the early misconceptions about sperm? 7