Chapter+09

Place your questions and answers for Chapter 9 here. A: When Gehring swapped the eyeless and Pax 6 gene between a mouse and a fly, the mouse gene produced a new fly eye, and the mouse gene was able to trigger his formation anywhere; suggesting that the control for eye development was similar between mice and flies, and the eyeless and Pax 6 gene are basically the same. Gene swapping is beneficial to humans in terms of gene therapy, where problematic genes can be replaced with normal functioning genes. This occurs through ex vivo or in vivo therapy to help treat diseases like SCID or cystic fibrosis, which is extremely beneficial to humans affected and touched by these illnesses. (M. Blanchard)
 * Q: What happened when Gehring swapped the //eyeless// gene and the //Pax 6// gene? How is the ability to swap genes beneficial to humans? (T. Gebhart)**

A: Essentially, a light travels to the back of your eye, through several layers such as the lens and cornea. The image is projected onto the retina, where light receptors send signals to the brain, where our brain interprets the image. One way to enhance organism vision would be to add more light-sensing cells to their eyes, in order to enhance their vision and overall survival. (H. Schwarz)
 * Q: What is the process the book describes for processing what your eyes see? What is one way to enhance an organism's vision? (J. Speelman) **

**Q: What type of animal did Shubin say was an ideal subject for finding out what happens when genes are messed with and turned on/off in the wrong places, specifically relating to the eyeless gene? Why do you think that this animal would be the ideal subject for this? (A. Nolan)** A: The fly is an ideal subject for figuring out what happens when genes are messed with, specifically relating to the eyeless gene. Flies would be the ideal subject because they share some of the same genes with humans, so they are good to use in order to see what could happen in humans. They also small, so they are easy to handle, and they are easily accessible/able to be bred with specific mutations. (J. terHorst) A: Shubin mentioned that flies are ideal subjects for genetic research for many different reasons. These reasons include that flies have a short reproductive cycle so the impacts of genetic changes are quickly observed after the change is made, they are relatively inexpensive to keep, a high population of flies can be kept in a laboratory habitat at one time, and, like Janna said, they are genetically similar to humans so genetic changes in fruit flies can be extrapolated to humans. (T. Russell)

**Q: The basic mechanisms of eyes are shared among all complex life that possesses eyes. What are the fundamental features of eyes that are shared? What features are different? What analogy to Shubin use comparing the different types of eyes? (M. Purdon)** A: Almost all organisms with a skull, including fish and mammals, have a camera-like eye like humans. The camera eye is composed of a cornea, iris, lens, and retina which all help to control and reflect light in order for us to see. All organisms use opsin to gather light. Other animals have simple eye patches of specialized cells, like in certain kinds of jellyfish, and eyes with a compound lens similar to those found in flies. Shubin used a Chevy Corvette analogy to explain the common history of our eye organs and parts. (C.Nikolai).

**Q. What is the difference between vertebrate and invertebrate eyes? Which organism bridged this gap and why was that discovery so important?(E.Olson)** A: Invertebrate eyes have multiple folds in their eye tissue while vertebrates have projections extending from the tissue like tiny bristles. The organism that was found to be the bridge between vertebrate and invertebrate eyes was a primitive worm called a Polychaete. This discovery is important because it is again, another link in our evolutionary past. It shows the connection between vertebrates and invertebrates all while further proving Shubin's main point that every animal is somehow related to one another due to a common ancestor in our ancient past. Without this discovery it would just be another one of the missing links needed in order to really know how animals began to transition from one type of structure to another. (L. Bentley)

===**Q: Shubin describes the twisty structure of the specialized conductor used by the molecule opsin to carry information to the inside of a cell in the eye. He then mentions that this "twisty" structure is identical to parts of certain molecules in bacteria. Since this unique twisted path has lasted so long, it must have some significance. What benefit does this twisty path taken by the receptor serve to the organism and its eyesight? What do you think would happen if a mutation occurred that altered this twisty structure into a straight structure? (L. Bercz)**===

A: Shubin discusses the Old World Monkey's and how they used to only eat figs and palms, both of which were similar in color. When the diversity in color grew, that led to the development of new resources as well as better vision. Specifically with the better vision, it allowed organisms to differentiate between different food sources and which might be more beneficial and allowed organisms to better be able to see predators or dangerous situations. Both developments would have aided in organisms survival, allowing them to reproduce and survive over time. (R. Heis)
 * Q: In this chapter, Shubin mentions the change in the color of the Earth millions of years ago. What organism does he specifically mention and how might the greater diversity of color that has progressed to what we find today be responsible for the survival of organisms over time? (O. Heltman)**

A: Andiridia is an eye disorder where there is no iris and because there is no iris it may cause the pupil to be misshapen. In terms of genetics this is caused by mutations in the PAX6 gene and a lack of functional PAX6 genes which will lead to a disruption when forming the eyes. (A. Schmidt)
 * Q: Towards the end of this chapter, Shubin discusses genetic dissorders amongst variuos species. What is andiridia and how does it effect the human body? Explain what this meant in terms of genetics? (E. Bach)**

A: Eyesight is a very important feature for the survival of many animals, but not necessary for some. For example, a blind beetle in the dark caves of the Australian desert do not need vision because it would serve no purpose. Therefore animals such as these, or even nocturnal animals with limited eyesight, would be able to survive without this feature. For the most part, however, eyesight would be a valuable trait that is likely to be passed on to increase the survival of organisms. (N. Sarkar) A: Though eyes can rarely be found in fossils, and their pristine preservation is still rarer, scientists are still able to gather information about these organs. Shubin compares finding information about eyes when there no tangible evidence to that of a car, we are able to trace the history of the eye through information gathered on other organs. Though this eyesight is very important for many organisms, it isn't always necessary. Some animals have a simple photoreceptor system that allows them to differentiate light from dark, and others have no eyes at all. This is because some animals, such as jellyfish and deep-sea animals simply don't have a use for eyes. While it may prove a disadvantage for some environments, it usually doesn't decrease chances of survival unless it is a random mutation that occurred. Otherwise, organisms such as the jellyfish would've died out hundreds of millions of years ago. (I. Perler)
 * Q: In this chapter, Shubin talks about the rarity of finding eyes in the fossil record. Knowing this, how are scientists able to trace and relate sight to other bodily features? If eyesight is such an important ability, how would animals without eyes survive? Would they survive, or would this be a trait that would prove** **disadvantageous to the species and decrease chance of survival? (M. McKinney)**

A: The difference between humans' color receptors and other mammals (such as monkeys) is that humans have three color receptors. This means that organisms can pick up on more colors than those they were competiting whith, who only had one or two color receptors, giving them a much smaller color range. This became advantagous because the color receptors allows organisms to destinguish between preditors or prey. (E. Bach)
 * Q: In this chapter, Shubin discusses how the color receptors in our eyes today can give us insight into which** **organisms are more closely related. What is different between the color receptors in humans and mammals? Why were these changes in color reception advantageous as animals and the world evolved? (C. Sanders)**

A: Humans' camera-type eyes are named such because the image projected onto the optic nerve and thus sent to the brain is supposed to accurately capture what the world looks like in front of us, as a camera does when it takes a picture. This type of eye is found in other species but is not the only kind out there. For instance, many insects posses a compound eye where an image is replicated many times and placed adjacent to itself before being processed. (P. Oakes) A: humans have a camera type eye are called camera type eyes because it captures the light, then sends the information to the brain which deciphers the light information allowing us to see the world the way we do. Like a camera, when it takes a picture it is snapped with a aperture and then the information is sent into the computer of the camera. any species that has a skull. But that does not mean there aren't other types of eyes. (T. McDaniel)
 * Q: Shubin mentions that humans have a "camera type eye". Based on the information about the human eye, can you infer why it is called a "camera-type eye?" Do other species have similar eye setup?(C.King)**

A: He uses the analogy of comparing bodies and organs to Chevy Corvettes. Shubin uses the analogy that are eye have a history as organs just like bodies but also there own individual part have a history. He again use the analogy that you could trace the history of just the tires on the Corvette to see just that one parts history. (C.Hurst)
 * Q: What car does Shubin use for his analogy for bodies and organs? What is the similarity between bodies and organs (particularly the eye in this chapter) and this car, and what is a specific example and description of one of these constituent parts pertaining to the eye? (N. Braun)**