...Introduction The profound importance for microorganisms to operate at a maximum efficiency has lead to adaptations allowing for groups of processes to be functional when resources are available, while on the contrary remaining “dormant” when not in need. This has been accomplished at the molecular level by configuring clusters of genes together on the genome into operons that elicit a processive response in the presence of a specific metabolite. The Lac operon is responsible for the cleaving of the disaccharide lactose into two products. A myriad of components control the expression of the Lac operon when two conditions are met. First, the substrate, lactose, must be present. Second, no better substrate for example, glucose, is present (2). The three structural genes in the Lac operon are lacZ, lacY, and lacA. The gene lacZ encodes the tetramer, ß-galactosidase, which is responsible for hydrolyzing the ß-1,4 glycosidic linkage between galactose and glucose in lactose. The transport of lactose into the cell via the enzyme lactose permease is encoded by the gene lacY. The lacA gene encodes the enzyme, galactoside transacetylase, a trimer that transfers an acetyl group from acetyl-CoA to galactosides. Activation of these genes is dependent on the activity of a promoter and three operators based on the nutritional and environmental conditions available to the cell. The lac operon is a negatively controlled inducible operon that utilizes the product of the regulator gene lacI, to...
Words: 10690 - Pages: 43
...MINICHROMOSOMES: THE NEXT GENERATION TECHNOLOGY FOR PLANT GENETIC ENGINEERING Genetic transformation occurs frequently in nature in prokaryotes. The transfer of genes from one organism to another is termed horizontal gene transfer1. For example, bacteria can acquire virulence factors, as well as antibiotic resistance genes, which may lead to the breakdown of the efficacy of antibiotics. Horizontal gene transfers are rare in higher eukaryotes, but years ago scientists found that a pathogenic bacterium, Agrobacterium, could transfer genes from its genome to its plant hosts, where expression of the transferred genes caused crown gall disease2. The development of Agrobacterium-mediated genetic transformation, and direct transformation by biolistics, i.e., the high velocity delivery of DNA attached to metal particles, led to the first generation of transgenic plants and the rapid application of this technology to crop improvement. Genetic engineering as a driving force for modern agriculture Genetic engineering is a powerful tool for improving crop quality and productivity, and reducing labor and resource utilization of farming. For example, farmers saved up to an estimated 60% of costs for pest control by growing Bt (insect resistance) cotton in certain regions of the US in 1997, according to a USDA report3. The reduction of pesticide spray has other safety benefits for both the environment and humans. Because of these and other benefits, the adoption of three primary GE crops...
Words: 1860 - Pages: 8
...Section B 1. A) What properties of chromosomes suggested to early geneticists that they might harbor the genetic material? What experiments confirmed these suspicions? Chromosomes was known to possess deoxyribonucleic acid. The genetical material was expected to have the stability but still capable of accepting sudden and permanent changes to adapt to evolution. Experiments that confirmed the suspicions were done by: • Griffith- demonstrated non-virulent strains of bacteria turned virulent when mixed with heat-killed pathogenic bacteria • Avery and colleagues- showed that deoxyribonuclease leads destruction of transforming activity • Hershey and Chase- used radioactive labels and bacteriophages to show that only nucleic acid was passed onto progeny not protein B)...
Words: 1206 - Pages: 5
...Chromosome Crossing Over Do you ever wonder why two people besides identical twins are not alike? Our genes determine most of our physical characteristics, the exact combination of genes we inherit, and thus our physical traits is in part due to the process our chromosomes undergo, known as genetic recombination. Biology online states, that during meiosis, when homologous chromosomes are paired together, there are points along the chromosomes that make contact with the other pair. This point of contact is chiasmata, and can allow the exchange of genetic information between chromosomes. This further increases genetic variation. Recombination can occur between any two genes on a chromosome. The amount of crossing over is a function of how close the genes are to each other on the chromosome. If two genes are far apart, at opposite ends of the chromosome, more crossing over is possible. If the genes are closer together fewer crossing over is possible (McClean, 1998). Two types of gametes are possible when following genes on the same chromosomes. If crossing over does not occur, the products are parental gametes. If crossing over occurs, the products are recombinant gametes. The allelic composition of parental and recombinant gametes depends upon whether the original cross involved genes in coupling or repulsion phase. It is easy to determine which gametes are recombinant because they are found in the lowest frequency (McClean, 1998). In the 1930’s Harriet Creighton and Barbara...
Words: 558 - Pages: 3
...the prevailing medical issues of that time. With the discovery of the structure of DNA by Crick and Watson in the early 1950s, the focus on medical research has shifted to the understanding of the genetic cause of a particular disease. Because of this, we are now able to understand the pathophysiology behind much of the diseases that has been a mystery to us before. An example of this is cancer, which was initially untreatable, but now thanks to our ever improving understanding of the genetic and biochemical mechanisms of the disease we are almost a step closer to achieving a reliable cure. In order to understand the progression of a particular disease accurately, scientists need to recreate the symptoms in a controlled environment (e.g. a laboratory) within a living organism. Such organisms are known as model organisms, because they serve as a live model which allows us to explore the workings of the disease. Due to various ethical issues, using humans as model organisms are out of the question, so scientists have looked towards other organisms to fulfil this purpose. Different organisms have been used for different research purposes, with notable examples being the use of organisms such as yeasts, worms and flies for studying the cell cycle and many developmental processes. For genetic diseases, however, a genetically similar organism to humans are required, since the results will be different in...
Words: 2525 - Pages: 11
...Unit II: Genetics Brief Overview Reading: Chapters 3, 4, 9-12, 14 (Note: you have reviewed much of this already) The earth is teeming with living things. We can easily see some of the larger organisms—trees, grass, flowers, weeds, cats, fish, squirrels, dogs, insects, spiders, snails, mushrooms, lichens. Other organisms are everywhere, in the air, in water, soil and on our skin, but are too small to see with the naked eye—bacteria, viruses, protists (single celled eukaryotes such as amoebae), and tiny plants and animals. Life is remarkable in its complexity and diversity, and yet it all boils down to a very simple idea—the instructions for making all this life are written in nucleic acids, usually DNA. Most organisms have a set of DNA that contains the instructions for making that creature. This DNA contains four “letters” in which these instructions are written—A, T, G, and C. The only difference between the code for a dog and the code for a geranium is in the order of those letters in the code. If you took the DNA from a human and rearranged the letters in the right way, you could produce an oak tree—arrange them slightly differently and you would have a bumble bee—arrange them again and you would have the instructions for making a bacterium. Acting through more than two billion years, the process of evolution has taken one basic idea—a molecular code that uses four letters—and used it over and over, in millions of combinations to produce a dazzling array of life forms...
Words: 32016 - Pages: 129
...Genetic Diversity: Mutations, Sexual Reproduction, Migration & Population Size Genetic diversity is scientific term that is used to describe genetic differences. Genetic differences can be caused by a number of things. Mutations, Sexual reproduction, Migration and Population size all affect how diverse genetics can be. Mutation causes many variations in any known species; they introduce new genetic information into a population by modifying the alleles that are already present or ones that have been absent. All different alleles of a trait came from some kind of mutation in the past. Most people when thinking of a mutation expect some obvious type of deformity or cancer; however mutations can be either neutral or harmful. Mutations can have no effect at all as with neutral ones, or stop the gene from functioning completely hence causing a harmful one. Sexual reproduction creates new genetic combinations as each parent passes on 13 chromosomes to the child during fertilization. It’s the process of recombination of cells from both parents. Migration of individuals is an important factor in passing on or subtracting alleles from one local population to another. Whenever one human being leaves one population and enters another, it subtracts its genetic information from its own and joins the one it has entered. As persons continue to add to and leave the population the gene pool will continue to change. Population size is affected by all of the above. Simply put the smaller...
Words: 260 - Pages: 2
...NAME ___ANSWER KEY_____________________________________ CH. 10 STUDY GUIDE-REGULAR SECTION 1: MEIOSIS In your textbook, read about meiosis I and meiosis II. Label the diagrams below. Use these choices: |anaphase I |anaphase II |interphase |metaphase I |metaphase II | |prophase I |prophase II |telophase I |telophase II | | |1. prophase I |2. prophase II |3. telophase II |4. interphase |5. anaphase I | |6. telophase I |7. anaphase II |8. metaphase I |9. metaphase II | 10. Using the pictures & phases above, describe what is happening in each phase: a. Interphase: G1 – cell grows; S-DNA is duplicated; G2 – cells grows & makes sure all the organelles are duplicated. b. Prophase I: nuclear membrane breaks down; nucleolus disappears; centrioles begin to migrate to opposite sides of the cell; spindle fibers begin to form; homologous chromosomes form; crossing over occurs c. Metaphase I: homologous chromosomes are lined up down the middle of the cell d. Anaphase I: homologous chromosomes are pulled apart & sister chromatids are pulled to opposite sides of the cell, cell has gone from diploid to haploid e. Telophase I: nuclear membrane reforms, nucleolus reappears; spindle fibers disappear;...
Words: 1200 - Pages: 5
...Eugenics: Health Benefits 1 Running Head: EUGENICS: HEALTH BENEFITS AND THE FUTURE Eugenics: Health Benefits and the Future Abstract The study of eugenics is propelling the world quickly into the future. Eugenics is the study of genetically engineering enhanced humans. This genetic engineering is done through modification of certain traits on an embryonic level, to create a heritable trait. Once modified, these traits will be passed on to the offspring of this individual, as well as demonstrated in that particular individual. The traits that can be modified are as simple as hair color, eye color, skin color, ability to grow muscle mass, body build, etc. They can be as complex as prevention of cancer and other gene-based diseases. Gene modification to create enhanced humans is an evolutionary necessity. In the day and age where the aspects of oneself can be modified with enough money or enough time, it is only natural that society would progress to the point where they would want to modify their offspring. The prospect of eugenics (literally, "well born") is not new, it spans back to the 1800's, when Sir Francis Galton created the word to define the basis for inheritance of intellect. He theorized that through the process of uncontrolled breeding, the unintelligent were outweighing the intelligent. Galton was not too far off according to movies such as Idiocracy, where the world becomes exclusively populated by morons...
Words: 2771 - Pages: 12
...hypothesize that evolution came about due to the loss of genes, and then, after the loss of genes, recombination occurred. From the work of Roentgen, Stevens, Seguy, Quenisset, and Frieben, related to X-rays, Mavor was able to show, in Drosophila, that exposure to X-rays increased the frequency of nondisjunction. In 1938, Bridges used Painter’s drawings to develop a system for describing each band. After many years of exploring what caused male determination, Jacobs and Strong showed that mammals are, in fact, similar to Melandrium, where the Y is the male-determining chromosome. Lewis showed that position effect is not dependent on how the chromosomes are positioned. From this study, the terms cis and trans were introduced into the genetics vocabulary. Landsteiner’s work with blood determination allowed Decastello and Sturli to form the common ABO blood grouping system. The work of Garrod and metabolic pathways allowed Beadle, Tatum, Winge, Avery, and others to increase our current knowledge on the subject....
Words: 1379 - Pages: 6
...Bio 405 Genetics Mendelian Inheritance This video is talking about the Mendelian genetics. This videos starts off by telling us the meaning of both genetics and heredity. Genetics can be used in many different subjects such as zoology, molecular biology, microbiology and topics dealing life as examples. It then goes on to discuss the father of genetics which is Gregor Mendel who was and Austrian monk that grew up with a family of religious beliefs. Throughout his life Gregor was interested in botany and mathematics. He is known as one of the first scientist applied mathematics to his science research. There was two viewpoints of heredity which where blending and particulate hypothesis. The blending hypothesis didn’t work when the father of evolution, Charles Darwin did not have enough evidence. The particulate hypothesis was then discovered by Gregor Mendel. This video also breaks down the meaning of genes and traits. You have different characteristics for genes and traits such a height, weight, and appearance. It then goes to tell us about the advantages Mendel had with us pea plants in his study. From the hybridization experiments, he induced two generalizations which later became known as Mendel's Principles of Heredity or Mendelian inheritance. The speaker of this video also proceeds to talk about alleles, which are known as variation of different genes. Most alleles are represented as the dominant trait. Mendel’s Principle of Dominance says that the dominant...
Words: 726 - Pages: 3
...modified organisms and it changes the way food is made within the DNA. GM food was originated “between 1997 and 1999, gene-modified (GM) ingredients suddenly appeared in 2/3rds of all US processed foods. This food alteration was fueled by a single Supreme Court ruling. It allowed, for the first time, the patenting of life forms for commercialization. Since then thousands of applications for experimental GM organisms have been filed with the US Patent Office alone, and many more abroad. “ (http://www.disabled-world.com/fitness/gm-foods.php) The first food that was ever grown as a GM food was a tomato and was discharged into the market in 1994. Dr. Mae-Wan Ho states that, "Genetic engineering is inherently dangerous, because it greatly expands the scope for horizontal gene transfer and recombination, precisely the processes that create new viruses and bacteria that cause disease epidemics, and trigger cancer in...
Words: 356 - Pages: 2
...when there is variation of inherited traits within a population. The major sources of such variation are mutation, genetic recombination and gene flow. This process has produced all the diversity of living organisms. Charles Darwin characterized the result as endless forms most beautiful and most wonderful. It has always been debated if there is any evidence of evolution and in what fields, in this report we will give a brief summary concerning: • DNA Evidence of Evolution • Biological Evidence of Evolution DNA Evidence of Evolution: DNA molecules are complex molecules which contain the assembly instructions for every living creature. Certain aspects of DNA have been interpreted as evidence for Darwinian evolution. DNA evidence for evolution includes mutations, genetic similarities among species, so-called “Junk DNA” and “Pseudogenes.” The fact that mutations can corrupt DNA is important for the Darwinian paradigm because in order for an organism to eventually evolve into an entirely different organism, changes must be made to the creature’s genome over time. But Darwinian evolution needs more than just change. It needs an increase in genetic information. Critics point out that genetic mutation does not appear to provide a mechanism for that increase. In fact, there appear to be genetic limitations to the potential for biological change. Genetic similarities between species are also interpreted as DNA evidence for evolution. The fact that human and chimp DNA are...
Words: 1011 - Pages: 5
...Linkage Mapping in Drosophila Introduction Common fruit flies, D. melanogaster, have been found as one of the most useful tools in genetic research. The reason behind that it is a popular experimental organism is due to the high likely hood of producing mutant, visible individuals. Geneticist, Thomas Morgan Hunt, was the first to discover the Drosophila as a model organism to study genetic hereditary. His research showed that the species could randomly obtain genetic mutations that could be visible in the parental generation. Since fruit flies have a diploid chromosome number of 8 (haploid 4), chromosomal types are easily identified. Various genetic crosses are able to determine that the x-linked gene is found on chromosome 1, while the autosomal genes are located on the 2-4 chromosomes. Mapping of unknown mutations by reciprocal crosses can identify if the alleles are x-linked or autosomal and if these alleles are dominant or recessive. Once the type of allele is determined, other genetic crosses can determine the location of the chromosome that the mutagen is one. For the x-linked mutations, a three factor test cross can induce map order and distance. The physical distance separating two genes on the chromosome (map distance) is directly related the frequency of recombination between markers during meiosis. The greater the map distance of the genes, the greater the probability that there is crossing over when the chromosomes segregate in meiosis. ...
Words: 1820 - Pages: 8
...Mendel’s principle of inheritance Principle of segregation Two alleles per offspring, one from each parent Independent assortment Distribution of one pair of alleles does not influence another pair Genes don’t blend Eukaryotic and prokaryotic Prokaryotic – are one celled organisms. Two kinds- bacteria and archaea Cells structure is simple Eukaryotes- every organism that has more than one cell. Cell structure is more complex than prokaryotes Prokaryotes Prokaryotic cells are one celled organisms they were the first organisms on the planet First appeared around 3.7 bya Have a free flowing nucleoid with no nuclear envelope Cytoplasm- gel like, holds all of the cells internal structures (organellas) Ribosomes- you should know. Flagella- used for locomotion as well as a sensory tool (also present in eukaryotes) Pili- help with attaching to surfaces and the transfer of dna Eukaryotic First appeared 1.5 bya Has a nucleus contained in a nuclear membrane Many more organelles Mitochondria Mitochondria Responsible for producing energy Separate dna called, mitochondria dna, which is only passed down through the mother Eukaryotes Two types of cells in complex organisms Somatic cell (body cell) Diploid-has full set of paired chromosomes (46) Gamete cell (sex cell) Haploid-only has half of the chromosomes (23) Cell division Required for an organism to, Grow, Mature, Maintain tissues, reproduce Mitosis and meiosis Mitosis Prophase Metaphase ...
Words: 1021 - Pages: 5
