Your Inner Fish


Terms in this set (...)

why the Inner Fish title for the book?
Because humans share such body parts as wrists, ribs, ears, and skeleton anatomies with Tiktaalik, scientist, like Shubin, have proved that humans share a history with this animal. Tiktaalik marks the beginning of land animal evolution. With distinct shoulders and a detached head, Tiktaalik and humans share certain features that help them survive out of water. While humans have developed more organs to adapt to their land environment, the similarities in appearance and certain organs suggests that our bodies have evolved from this intermediary creature. Shubin suggests that Tiktaalik is a common ancestor of the human.
Describe the "pattern" to the skeleton of the human arm that was discovered by Sir Richard Owen in the mid-1800s. Relate this pattern to his idea of exceptional similarities.
All humans have one bone, the humerus, in their upper arms, two bones in their forearms, nine smaller bones at the wrists, and five rods that create fingers. Yet, the exceptional similarity is the anatomical similarity in the skeletal pattern of limbs. Despite the different functions, all limbs must have this same basic structure to function properly.
How did Charles Darwin's theory explain these similarities that were observed by Owen?
Charles Darwin suggested that all organisms share a common ancestor. Thus, all the similarities in design exist and can be traced to a common lineage. While individual populations and organisms evolve, similarities in their anatomical structures and patterns can be found. Darwin explains the different number of toes and function of limbs as occurring due to mutation. The bone and size shape differences occur after the common ancestor due to natural selection and adaptation. Darwin's theory allows Owen's theory to find the exact spot of descent and compare ancestry.
What did further examination of Tiktaalik's fins reveal about the creature and its lifestyle?
Shubin and his team noticed that, like the human limb skeletal pattern, Tiktaalik's fin has a joint at the end which connects to other bones. Tiktaalik appeared to be the first creature with a wrist bone, a vital characteristic of human anatomy. Like humans, Tiktaalik's wrist bone moved in conjunction with the elbow. Tiktaalik's bone showed that it was a primitive ancestor of the 1-2 bone limb tendency. Tiktaalik's appendage also seemed to be a cross between a fin and limb. The fin investigation further supported the idea that Tiktaalik was an intermediary animal. With a shoulder, elbow, and wrist, Tiktaalik was capable of performing many functions associated with humans today, such as a push-up. The wrist was able to lie flat against the ground in Tiktaalik. Tiktaalik's flat structure suggests that likely, in the predator waters filled with fish, Tiktaalik could easily delve deep and swim along the bottom of streams and ponds to increase its fitness. Tiktaalik's strong chest muscles also suggest that it could go onto the mudflats of the bank to avoid predators. Thus, Tiktaalik's mutation increased its fitness and was successfully passed onto its descendants such as humans.
Hedgehog gene
During embryological development, the hedgehog gene helps facilitate specialization, growth, and formation. In the fruit fly, the hedgehog gene ensured that one end of the fly's body segment differed completely in look from the other. Because the hedgehog gene was first discovered in flies, it was given this name because in those animals that had a mutation in this DNA sequence, bristle like structures appeared. The hedgehog gene, within every living organism, can be found in the ZPA tissue. When vitamin A is injected into the chick, the hedgehog gene becomes active on both sides of the limb. By remaining active and inactive at the appropriate times, the hedgehog gene controls the making and shaping of limbs. Thus, the hedgehog gene accounts for the different shapes and sizes of those bones such as fingers. Even in a shark, the fin, or main appendage, houses the hedgehog gene and it becomes active in both sides when injected.
Teeth make great fossils. Why are they "as hard as rocks?"
Shubin discovered that teeth make reliable fossils due to the high concentration of the molecule hydroxyapatite found within the tooth. Hydroxyapatite can be found in the enamel and within the inner dentine layer of the tooth. By encompassing the molecular and cellular structure of the tooth, hydroxyapatite helps teeth build an immunity to damage caused by things such as eating or weathering to which rocks fall immune. Teeth stronger than the food they tear. Sheen makes them locatable
What are conodonts?
First version of modern teeth (attached to organisms with no hard bones)
Shubin writes that "we would never have scales, feathers, and breasts if we didn't have teeth in the first place." Explain what he means by this statement.
During development, two tissue layers interact to create teeth. The outer and inner cell layers create a fold that secretes the molecules and prompts the organ formation. A similar and nearly identical process occurs during the formation of scales, feathers, and breasts; the two tissue layers secrete to form these new organs. Because all reptiles and mammals had teeth before they had scales, feathers, or breasts, scientists discovered that the tooth formation process was modified and changed to create these new, specialized organs. The tooth formation process was repurposed and, because it increased fitness, was passed onto new populations and organisms. Thus, if we did not have teeth, these process would never have modified to create these other organs.
Why are the trigeminal and facial cranial nerves both complicated and strange in the human body?
Within the head are twelve cranial nerves that branch into a series of networks within the head. Simple cranial nerves serve only one function, and, thus they only attach to one muscle or organ in a clear path. Yet, the trigeminal and facial cranial nerves both have their own complex path and conjunction of networks. Whereas other cranial nerves have one function, the trigeminal and facial cranial nerves process sensation and action, transmitting information to different branches and paths throughout the head. By processing sensation and sending it from the face to the brain, the trigeminal cranial nerve controls muscles, such as those inner ear muscles. When something touches the face's skin, the trigeminal cranial nerves deliver this information to the brain. Some trigeminal cranial nerves even lead to pathways in tooth roots. The facial cranial nerve is responsible for those muscles involved in facial expression. Frowning and smiling both occur because of the facial cranial nerve. Both the trigeminal and facial cranial nerves appear complicated and strange because they have extensive branches and pathways. Though seemingly unrelated, these two cranial nerves both deliver information to adjacent muscles in the ear and appear to cross paths while relaying information.
List the structures that are formed from the four embryonic arches (gill arches) during human development.
Development begins with the fertilization of an egg. All of our organs and structures are formed as this single cell develops and specializes. The first arch tissue is responsible for the formation of the upper and lower jaws, the malleus and incus ear bones, and the vessels and muscles that supply or aid these structures. The second arch forms the stapes, the last small ear bone, a small bone in the throat, and facial expression muscles while the third arch forms a lot of the bones, muscles, and nerves found deeper in the throat. The fourth arch finishes forming some of the deeper throat structures such as a portion of the larynx and all those muscles and vessels around it.
What are the Hox genes and why are they so important?
Found in the back of the head, Hox genes determine the body plan of an animal and organize the head-tail formation of an organisms. Hox genes and their complements differ in each gill arch of an organism. Yet, all Hox genes help instruct cells to create different portions of the body and head. Thus, without Hox genes, the body would not be organized and laid out correctly. If the Hox genes were changed, the structures in the arch would also change. Hox genes ensure the body is properly arranged.
Amphioxus is a small invertebrate yet is in an important specimen for study. Why?
Though an invertebrate, the amphioxus shows many similarities to vertebrate animals. Like a vertebrate, such as fish, amphibians, and mammals, an Amphioxus has a nerve cord running along the length of its back along with a notochord, or rod, that runs the length of its body, lying parallel to the nerve cord. Within the notochord, a jelly fluid provides stability and support. During human development, a notochord is also present, but it dissolves and integrates itself into the disk between our vertebrate. Also like humans, Amphioxus have gill arches supported by cartilage. Because the human head and back structure share so many similarities with the Amphioxus, the structure of the human head was likely restructured or repurposed.
Early embryonic experiments in the 1800s led to the discovery of three germ layers. List their names and the organs that form from each.
In the 1800s, embryonic experimenters discovered that the same structures, such as lungs and tissues, emanated from one of three layers within the body. While reptiles and mammals may be vastly different in size, shape, and diet, as embryos, all organisms experience the same stages of development. The three germ layers remain consist in all animals. The outer layer, the ectoderm, is responsible for forming the outer skin and the nervous system. The inner germ layer, the endoderm, has the inner body structure forming form it such as the digestive tract and the glands associated with these tracts. The tissue between the guts and skin of our skeleton and muscles form from the middle layer, the mesoderm. In all organisms, organs consistently form from the same germ layer.
Describe the blastocyst stage in embryonic development.
Once the sperm fertilizes the egg, the egg undergoes a series of divisions. Once a few of these divisions occur, a ball, or mass, of cells form into a spherical wall that houses a fluid center. The blastocyst has no front or back and has not reached a stage of development to have organs or tissues yet. The blastocyst's main task is to attach to the mother's uterus. By doing so, the mother and the embryo share the same bloodstream, allowing the embryo to further development with the mother's nourishment.
What is meant by "ontogeny recapitulates phylogeny?"
Developing looking like embryonic history
What type of gene is Noggin and what is its function in bodies?
Noggin is a type of Organizer gene. Because Noggin helps organize the body during body axis development, it is necessary to facilitating position on the top-bottom axis. While Noggin's most notable role is in body axis development, it also works and hosts other organs. Yet, Noggin only function in tandem with other genes to organize the body. Alone, Noggin can not instruct any cell in the embryo; it is only when multiple genes work together that Noggin can successfully position organs along the top-bottom axis. For example, the BMP-4 gene can not work when Noggin is on. Thus, it is not that Noggin tells cells to form at the top of the body, but rather that it turns off their ability to become bottom cells that makes it important.
Sea anemones have radial symmetry while humans have bilateral symmetry but they still have "similar" body plans. Explain.
Sea anemones are good research tools for scientists because of their primitive bodies. The long central stump branches off into tentacles. Although sea anemones have radial symmetry while humans have bilateral symmetry, they still have a head-anus axis and similar belly-to-back genes as humans. The activity and organization along an axis show similarities, but unlike humans and animals, the axis does not provide a pattern to organ development. Sea anemones yet still have this directive axis comparable to humans; their existence shows that bilateral symmetry evolved from versions of radial symmetry such as this one.
What is the most common protein found in the human body? Name and describe it.
The most common protein found in the human body is collagen. The molecule looks like a fiber rope. When stretched, collagen is strong, yet if it is compressed the molecule becomes weak. Collagen most commonly appears between bone cells. While collagen is strong when pulled, hydroxyapatite is strong when compressed. The contrast in their desirable forms accounts for the bone strength as they excel under different conditions and thus tend to be functional in all circumstances.
Explain how cell "stick" to one another. Give one example.
Small molecular rivets allow cells to stick together. Yet, cells have many different methods to sticking. In some cases, one molecule will attach to the outer membrane of another cell which then attaches to the outer membrane of another cell endlessly. Other cells will only stick or attach to the same kind of rivet or cell. For example, bone cells sonly stick to bone cells and skin cells only stick to skin cells; a bone and skin cell will not stick. This type of sticking or attaching helps the body organize itself and maintain order.
How do cells communicate with one another?
Cells communicate with one another by sending each other molecules. Many cells will signal, sending the molecule to attach to the membrane of the receiving cell. The information within the transported molecule is often sent to the nucleus, which houses the DNA. The sent molecule may then cause certain genes to become active or inactive. The sent molecule has the capability to control and alter the receiving cell's activity or behavior. In a sense, the emitted molecule is much like the words used by humans.
What are choanoflagellates and why have they been studied by biologists?
Choanoflagellates are single-celled microbes; they are the most recent common ancestor of animals with bodies as well as placozoans and sponges. Biologists study choanoflagellates because most of this microbe's active genes also operate and are active in animals. The choanoflagellate controls such functions as cell adhesion and cell communication. Choanoflagellates may also contain molecule parts from the matrix a cell forms with molecular cascades. Choanoflagelaates connect to a signal that operates both outside and inside the cell. Often, biologists used them as a way to compare the human bodybuilding apparatus to other microbes, looking for signs of evolution, common ancestry, and overall similarities and differences.
What are some of the reasons that "bodies" might have developed in the first place?
Many theories exist regarding the development of bodies. Some scientists believe that the body developed as a defense mechanism. When, microbes learned to eat each other, the body, big in form, provided a defense to avoid being eaten. Microbes attach to other microbes and invade them as food source; the molecules that a microbe uses to engulf their pray show similarities to the molecules that are rivet attachments for body cells. Thus, it is likely that the microbe increased the production of this molecule. Under different experiments, scientists found that when a unicellular organisms fears a predator, often, it may divide to become cell clumps.
Briefly explain how we perceive a smell.
The genes we use to smell are contained in DNA. Because DNA is in the nucleus of the cell and houses directions, the genes for smell appear in every body cell. Yet, these genes only become active in the nasal. Our brains perceive molecules floating in the air as smell; different substances or things release different molecules, accounting for the variance of smells. These molecules that we "smell" are small and light; they easily float and renal stationary in the air. The molecules enter into our body through our nostrils. Behind the nose, the mucous lining of the nasal passage allows these molecules to pass through. Within the mucous lining, the nerve cells send signals to the brain, and we register these signals as smell and odor.
Jawless fish have a very small number of odor genes while mammals have a much larger number. Why does this make sense and how is it possible?
While jawless fish have a single nostril, mammals have two nostrils. Jawless fish use their odor genes in a vastly different capacity than do humans. While jawless fish take odor from water, humans perceive odor from the air. Although now there are distinct land odor genes and distinct water smelling genes, jawless fish had odor genes before this clear distinction existed. Thus, overtime, the human odor genes have increased, accounting for our large number in comparison. By duplication, the human odor genes have surpassed those possessed by primitive species. Also, humans have more odor genes because many of them are unused; the jawless fish had less of a surplus of odor genes.
Humans and Old World monkeys have similar vision- explain the similarity and reasons for it.
Like humans, Old World monkeys use three different light receptors to respond to various light frequencies. Both humans and old monkeys possess this detailed color vision. While two of the human's three receptors are more like one of the two in other mammals, our vision is stronger and more complete like Old World monkeys. Based on evidence, it is likely that color vision began for us when one of the light genes in other mammals duplicated; as it increased the human's fitness, it specialized and became effective in different light sources. Likely, Old World monkeys have these three receptors due to a mutation that also increased fitness. As Old World monkeys relied on plants and fruits for their diet, color vision helped them avoid poisonous or less satisfying options.
What do eyeless and Pax 6 genes do and where can they be found?
Like other embryonic development genes, eyeless and Pax 6 genes help control the formation of tissues and organs. The eyeless and Pax 6 genes control eye development. When the DNA sequence appears for these genes, eyes form, but, when it does not, they do not develop. Scientists attribute the eyeless and Pax 6 genes to being the major components of eye formation. When the gene is mutated, small eyes or no eyes appear. The Pax 6 and eyeless genes have the ability to form an eye anywhere the gene is found, regardless of the section of the body. Although all animals with these genes look different, the genetic information that forms the eyes remains consistent.
List the three parts of the ear. Which part is unique to mammals?
The three parts of the ear are the external, middle, and inner portions. The external ear is the visible part we see on mammals, the middle houses our little ear bones, and the inner ear houses sensory cells, a fluid, and tissue. The external ear is unique to mammals. While mammals have pinnae, class mammal is the only class to have this. Also, while mammals have three bone in the inner ear, reptiles and amphibians only have one. The mammal ear structure can be distinguished from that of all other classes' ear structures.
An early anatomist proposed the hypothesis that parts of the ears of mammals are the same thing as parts of the jaws of reptiles. Explain any fossil evidence that supports this idea.
Mammals have three inner ear bones: the malleus, the incus, and the stapes. These ear bones originate from gill arches. While the stapes comes from the second arch, the malleus and incus come from the first arch. Yet, reptiles do not have these three inner ear bones; they only have one. During research, scientists discovered that two ear bones of mammals correlated to the jaw bone pieces of reptiles. The malleus and incus originate from the first gill arch, but so do parts of the reptile jaw. Also, reptiles only have one bone in their middle ear, but this is the same as the stapes of mammals as both originate form the second arch. What is called hyomandibula in a reptile is equivalent to the stapes of a mammal. Fossil evidence indicates that the malleus and incus were once part of the reptile jaw, but, undergoing shrinkage, they moved into the ear. Thus, fossil evidence suggests that the jaw bones were repurposed to create the class mammalia. Likely, this mutation occurred during the transition to land as hearing on land requires different structures than does hearing in water.
What is the function of the Pax 2 gene?
Inner ear formation The Pax 2 gene can also remain active in the head and the neuromasts. The Pax 2 gene shows similarities with the Pax 6 gene as both prompt organ and issue formation by working in conjunction with other gene activities.
What is Shubin's biological "law of everything" and why is it so important?
Shubin's biological "law of everything" recognizes that all living things have parents, or, more specifically, came from parental DNA or genetic information. Shubin also notices that all living organisms show modification of their parent's genetic information. Thus, Shubin's law of everything addresses the idea of descent with modification. Though not all living organisms are exact copies of their parents, all living things show some degree of similarity and modification of their parents. Shubin shows that characters and features are the proof of this descent with modification.
What is the author trying to show with his "Bozo" example?
Shubin uses his "Bozo" example to show descent with modification. Because descent with modification leaves a clear trace of characters, descent with modification can build a family tree or lineage. In the Bozo example, descent with modification leaves recognizable features such as red noses, orange hair, and big feet that reflect generations. The Bozo example further supports Shubin's assertion that all living things show traces of their parental DNA and genetic information. Though the parental generation and second generation look vastly different in the Bozo example, the lineage is traceable through characters.