Earth And Life Science 2, Second Quarter Notes PDF

EARTH AND LIFE SCIENCE 2 SECOND QUARTER GENETIC ENGINEERING is the artificial manipulation, modification, and recombination of DNA or other nucleic acid molecules in order to modify an organism or population of organisms. The term genetic en...

EARTH AND LIFE SCIENCE 2 SECOND QUARTER GENETIC ENGINEERING is the artificial manipulation, modification, and recombination of DNA or other nucleic acid molecules in order to modify an organism or population of organisms. The term genetic engineering initially referred to various techniques used for the modification or manipulation of organisms through the processes of heredity and reproduction term embraced both artificial selection and all the interventions of biomedical techniques, among them artificial insemination, in vitro fertilization (e.g., “test-tube” babies), cloning, and gene manipulation. GENE SPLICING Is the process in which fragments of DNA from one or more different microorganism are combined to form rDNA (recombinant DNA) and are made to function within the cell 2 Highly Significant Techniques: ◦ Gene transfer - transferring the gene from one source to another subject. ◦ Gene therapy - correcting defective gene that are responsible for disease development. Plasmid - A circular form of DNA often used as a vector in genetic engineering. Vector – an organism/ chemical that is used to transport a gene to the host cell. Host cell – the cell into where the new gene is transplanted Enzymes used: Endonucleases – enzymes that cut DNA molecule at some given location Exonucleases – enzyme that removes one nitrogen base unit at a time Ligases – enzyme that join two DNA segments together 5'GAATTC3' - a restriction site of a widely used restriction enzyme which produces sticky ends. The enzyme is ECO R1. RDNA Recombinant DNA, or rDNA, is DNA that is formed by combining DNA from different sources through a process called genetic recombination. Often, the sources are from different organisms. Generally speaking, DNA from different organisms has the same general chemical structure. rDNA Products 1. Insulin- produced by “Genetech”, first genetic engineering company, founded by Robert Swanson and Herbert Boyer - obtain a copy of insulin gene (can be from natural source or manufactured) - inserting the insulin gene into the vector - the hybrid plasmid can now be inserted to the host cell. This is the manufactured insulin that is injected to a diabetic patient 2. Human growth hormone- for children, whose growth is insufficient because of genetic problems 3. Interleukin-2 – for treatment of cancer 4. Factor VIII- needed by hemophiliacs for blood clotting 5. Erythropoietin- for treatment of anemia 6. Tumor necrosis factor- for treatment of tumors 7. Tissue plasminogen activator – use to dissolve blood clots REPRODUCTION OF ANIMALS  1. Asexual reproduction - Type of reproduction that does not need two parents to produce an individual. - Therefore, the offspring produced is the exact copy of the parent animal. - Common among lower form of animals COMMON FORMS Fission- two individuals will form as the parents divides in half. Bacteria, amoeba, sea anemone Fragmentation- the breaking of body parts into fragments, is always followed by regeneration and regrowth of lost parts. Even if the animal is broken into many pieces, each piece will grow into a new individual. Planarians, sponges, cnidarians, sea squirts Budding- is when an outgrowth called bud grows and develops from the parent animal and would eventually separate to become a new individual. Coral and hydra 2. Sexual reproduction - Needs two parents to produce an offspring - Combination of the genes from both parents increases the chances of species variation. Therefore, species extinction is highly unlikely. Fertilization could happen internally or externally External fertilization- union of sperm and egg occurs outside the female reproductive organ. Common among species of bony fish and amphibians. Internal Fertilization Oviparity- after the eggs are fertilized internally, it would complete its development outside the mother’s body. The egg would receive its nourishment through its yolk. This is found in some bony and cartilaginous fish (including clown fish and blue tangs), most reptiles, some amphibians, all birds, and a few mammals (monotremes). Ovoviviparity- the eggs are also fertilized internally and receive its nourishment through its yolk. However, eggs will complete its development within the mother. They are then fully developed when they are hatched and released by the mother. This is common in some bony fish (including mollies, guppies, and mosquito fish), some cartilaginous fish, and many reptiles. Viviparity- the eggs are developed internally and receive nourishment directly from the mother’s blood through placenta rather than from the yolk. This can be found in most cartilaginous fish (including lemon sharks), some amphibians, a few reptiles, and almost all mammals including humans. EVOLUTION -populations and species of organism change overtime -Darwin proposed that species can change over time, that new species come from pre-existing species and that all species share a common ancestor -Darwin did not just propose that organisms evolved. He also proposed a mechanism for evolution: natural selection. This mechanism was elegant and logical, and it explained how populations could evolve (undergo descent with modification) in such a way that they became better suited to their environments over time. CHARLES DARWIN In the 1850, he wrote an influential and controversial book, “Origin of Species by Means of Natural Selection” In it, he proposed that species evolve (or, as he put it, undergo "descent with modification") and that all living things can trace their descent to a common ancestor. SURVIVAL OF THE FITTEST Only those who are tough enough will endure any given situation DARWIN’S CONCEPT OF NATURAL SELECTION WAS BASED ON SEVERAL KEY OBSERVATION 1. Traits are often heritable  In living organisms, many characteristics are inherited, or passed from parent to offspring. (Darwin knew this was the case, even though he did not know that traits were inherited via genes.) 2. More offspring are produced than can survived Organisms are capable of producing more offspring than their environments can support. Thus, there is competition for limited resources in each generation. 3. Offspring vary in their heritable traits The offspring in any generation will be slightly different from one another in their traits (color, size, shape, etc.), and many of these features will be heritable. Based on these simple observations, Darwin concluded the following: In a population, some individuals will have inherited traits that help them survive and reproduce (given the conditions of the environment, such as the predators and food sources present). The individuals with the helpful traits will leave more offspring in the next generation than their peers, since the traits make them more effective at surviving and reproducing. Because the helpful traits are heritable, and because organisms with these traits leave more offspring, the traits will tend to become more common (present in a larger fraction of the population) in the next generation. Over generations, the population will become adapted to its environment (as individuals with traits helpful in that environment have consistently greater reproductive success than their peers). OTHER MECHANISM OF CHANGE ❖ Mutations Evolution by mutation occurs whenever a mistake in the DNA occurs in the heritable cells of an organism. Mutations occur at random in the genome, but mutations of large effect are often so bad for the organism that the organism dies as it develops, so mutations of smaller effect or even neutral mutations are theoretically more common in a population. Because mutation rates are low relative to population growth in most species, mutation alone does not have much of an effect on evolution. But mutation combined with one of the other mechanisms of evolution, can result in meaningful changes in allele frequencies in a population. ❖ Gene flow (Migration) Gene flow — also called migration — is any movement of individuals, and/or the genetic material they carry, from one population to another. Gene flow includes lots of different kinds of events, such as pollen being blown to a new destination or people moving to new cities or countries. This variable flow of individuals in and out of the group not only changes the gene structure of the population but can also introduce new genetic variation to populations in different geological locations and habitats. ❖ Genetic Drift Genetic drift is the term biologists use to describe the gradual loss of certain genes from a species–genes that may have been very important for that species’ survival. In each generation, some individuals may, just by chance, leave behind a few more descendants (and genes) than other individuals. The genes of the next generation will be the genes of the “lucky” individuals, not necessarily the healthier or “better” individuals. That, in a nutshell, is genetic drift. It happens to all populations—there is no avoiding the off chance. ❖ Artificial Selection Long before Darwin and Wallace, farmers and breeders were using the idea of selection to cause major changes in the features of their plants and animals over the course of decades. Farmers and breeders allowed only the plants and animals with desirable characteristics to reproduce, causing the evolution of farm stock. This process is called artificial selection because people (instead of nature) select which organisms get to reproduce. ❖ Systematics is the scientific study of diversity of organisms and their evolutionary relationships. The branch of systematics that involves the study of naming, describing, and classifying organisms is called taxonomy. ❖ Taxonomists perform classification, a method of arranging organisms into groups based on their similarities. Carl or Carolus Linnaeus’s System of Classification Rules in Designating Scientific Names of Organisms Organisms are named using the binomial nomenclature system. It is a system in which an organism is given a two-part name consisting of genus and species. In scientific name, the genus starts with a capital letter while the species starts with a small letter (e.g., Felis catus). Scientific names are set in italics (e.g., Felis catus). When scientific names are handwritten, each word should be underlined (e.g., Felis catus). Importance of Scientific Name The use of scientific names avoids confusion among scientists. Scientific names allow the use of universal names which helps scientists clarify particular organism they are referring to. Scientific names also provide organisms identity and indicate their true nature. Common names do not tell the exact nature of an organism (e.g., sea horse is not a horse but a fish; a sea lion is not a cat but a seal; and whale shark is not even a mammal). POPULATION - the whole number of inhabitants occupying an area such as a country or the world VARIABLES ACCOUNTED FOR CHANGES IN POPULATION SIZE BIRTH- the process of bearing or bringing forth offspring DEATH- end of life IMMIGRATION- act of leaving one’s country and moving to another country which they are not natives or citizen EMIGRATION- relocation; leaving one country to reside in another BIOTIC POTENTIAL - The ability or capacity of a population of a species to grow or propagate under ideal environmental conditions--- given sufficient food supply, no diseases and no predators present. - It is said that the primary factors that determine biotic potential include an organism’s rate of reproduction and the number of offspring produced at one birth. ENVIRONMENTAL RESISTANCE Prevents populations from reaching their full biotic potential  The combination of all factors to limit growth of a population These factors include abiotic and biotic factors that limit the organism from endlessly increasing its population. Biotic factors include predation, competition, parasitism, and diseases. Abiotic factors include climatic conditions, fire, and temperature. Most are density-dependent DENSITY-DEPENDENT their effects are most pronounced when the population density increases beyond a certain level, in other words, whose effects on the size or growth of the population vary with the population density. The types of density dependent factors include availability of food, predation, disease, and migration. However, food availability is considered as the main factor. DENSITY-INDEPENDENT can affect the population without being necessary based on the density. They include natural disasters (droughts, floods, hurricanes, and fires), temperature, sunlight, seasonal cycle, human activities, and levels of acidity, cited among many others. ✓ Together, biotic potential and environmental resistance determine the carrying capacity ✓ Carrying capacity- is defined as the maximum population of a given species that a particular habitat can sustain indefinitely without being degraded. The growth rate of a population decreases as its size nears the carrying capacity of its environment because resources such as food, water, and space begin to dwindle.