Mitosis and Meiosis, the defining differences.
Mitosis and Meiosis, the defining differences. The cell theory was first proposed by Schleiden in 1838 and Schwann in 1839. This theory was then extended upon by Rudolf Virchow in 1855 declaring that new cells only came from pre-existing cells. Shortly after, in 1887, Weismann suggested a specialist form of division occurred in the manufacture of gametes. These two forms of division are called Mitosis and Meiosis respectively. By definition, Mitosis and Meiosis are very similar, both being methods of cell division. However, the way in which the daughter cell is produced in these processes vary. The biological differences in these two processes lie between Mitosis and Meiosis I, as Meiosis II is almost identical to Mitosis. Mitosis As a consequence of Mitosis, a parent nuclei divides into two daughter nuclei, each with the same number of chromosomes as the parent nucleus. The division of the whole cell follows this. In order to accomplish this chromosome firstly replicate themselves during interphase. The two replicate chromosomes are known as chromatids and separate during mitosis. Cell division is a continuous process with no sharp distinction between the phases. There are 3 main stages: Interphase: this is the episode of synthesis and growth. The cell produces many materials essential for its own growth and for carrying out all its functions. DNA replication occurs
Discuss the role of Genetics in modern society
Discuss the role of Genetics in modern society Genes by definition are information we inherit from our parents, they contain chromosomal information which codes for every physical and mental attribute a human, animal or plant has. Modern society has come to realise by finding the gene that causes the illness they can remove it. They then can insert the correct gene to replace it. Genes are arranged like beads on a piece of string, they occur in a fixed order. Modern day society has also realised that by learning about genes and increasing their understanding many useful tasks can be carried out. For example, solving crimes; if a suspect has been identified, a sample of that's persons DNA can be checked against DNA (a long thread- like molecule found in every living cell) which may have been found at the crime scene. This process is done use of a genetic code. Although every human may have the same basic components in a double helix of DNA, base, sugar, and phosphate: The type of sugar may vary, further more the order of complimentary base pairs may occur in a different order. Thus, meaning an almost infinite number of combinations. As our genes allow every person to have their own DNA code, a definite match of DNA would mean that person could without doubt be linked to the scene. All that is needed to extract DNA is one cell - a speck of blood, a swab of saliva or a
The Theory of Evolution
The theory of evolution, as set forth by Charles Darwin in 1859, stated that all plant and animal life evolved over long periods of time from simple to more complicated forms through mutation and adaption. He also taught that only the fittest on each species would survive. This concept is called "Evolution by Natural Selection". Natural selection is that the strongest survive and propagate and therefore increase in the strength of the species. On the Galapagos Islands, the various species established themselves and determined territories. Evolution then set in and many unique species, such as Darwin's finches, resulted. These finches probably descended from one type of ancestor and then, due to isolation and through chance, different climates and natural forces such as food availability and type, they evolved into thirteen different types of finches. So in short, based on the food availability and types, certain fiches survived. The process of their evolution would probably have began with immigrates from the mainland. As they dispersed to different islands, new populations would be formed. Every time these satellite populations dispersed, there would be greater differences between the individual species. Natural selection works as follows: . Variations exist in any population. 2. In and generation there are individuals that do not reach maturity and reproduce. Their
DNA Fingerprinting.
DNA Fingerprinting This is a way of making a pattern from pieces of DNA cut with restriction enzymes. Everybody has a different DNA, so the pattern or fingerprint is unique to each individual. DNA is a long chain, double-helix molecule composed of building units called nucleotides. Each nucleotide consists of a sugar, a phosphate and a nitrogenous base. There are four types of nitrogenous base: adenine, guanine, cytosine and thymine. The genetic information carried by a DNA molecule is contained in the sequence of these four bases. A gene is a length of DNA that codes for a specific protein or polypeptide. They are organised into chromosomes and located within the nucleus in human cells. Only 2% of the DNA of a human cell contains genes. The rest consists of non-coding sequences of bases called introns, which occur between or within a gene. Introns can be between 60 and 100 000 bases long. A single gene can contain 50 introns between exons (coding parts of the DNA molecule). The function of introns is unknown. Within non coding regions between genes there are short sequences of bases called core sequences that repeat themselves over and over again, sometimes up to 100 times. These repeated regions of DNA are called mini-satellites or variable number tandem repeats. Different people have different numbers of repeated core sequences; therefore they have different sized
The human genome project notes
The human genome project notes The Basics: * Fred Sanger first developed a technique for DNA sequencing process in 1977. * This process involved DNA being used as a template for DNA fragments. * The Segments were separated using gel electrophoresis, and are different in size by only 1 base. * Identifying this base at the end of each fragment allowed sequencing to take place. * This allows us to work out the entire sequence of bases and identify the location of genes along the DNA The Human Genome Project: • The human genome project is an organisation that was set up in 1986, who's aim is to sequence the genome for the entire human body. • It was originally a partnership between the US and UK was predicted to take 20 years to fully sequence the human genome. • In 1992, Japan and the rest of Europe joined the project and with sophisticated computerised techniques, the progress was more rapid. • The human genome project did not only attempt to sequence human DNA but also the DNA of other organisms. • In 1996, the bases sequence for yeast was published with the sequence for a nematode worm following 2 years later. • In 1999, the first complete chromosome, chromosome 22, was successfully sequenced. • There are over 3 billion chemical base pairs that make up the human DNA, and there are approximately 30-40,000 genes. • 2 years later in 2001, the
Sexual vs. asexual reproduction: scientists find sex wins.
Sexual vs. asexual reproduction: scientists find sex wins (Santa Barbara, Calif.) Why are most organisms sexual? The question of why most species reproduce sexually and others reproduce asexually has stymied biologists for years (particularly since asexual reproduction has many advantages including producing more offspring.) The question is answered in part in this week's Science Magazine, published on Friday, October 19. Studies by scientists at the University of California, Santa Barbara show that sexual reproduction wins out, in an evolutionary sense, over asexual reproduction in a major study that included 34 experiments with the common fruit fly Drosophila melanogaster. Specifically, they discovered that the rate of progressive evolution (the accumulation of beneficial mutations) is faster in populations that reproduce sexually. "However, there is a high cost associated with producing males," said William R. Rice, first author and professor of biology at the UC, Santa Barbara. "Just do the math and you will see. And yet, look out the window and almost every organism you see reproduces sexually." The math is simple: with four asexual adults (females) you get eight offspring, but with two males and two females you get only four offspring. In other words, the asexual population grows twice as fast as the sexually reproducing one. The second part of the
Genetic Screening
The Application of DNA Technology in the Diagnosis and Treatment of Disease This essay is going to look at genetic engineering and genetic screening. The first section will focus on what each of these things are and how they are used in the diagnosis and treatment of diseases. The second section will concentrate on the use of both the nuchal translucency scan and the Guthrie test. The third section will talk about the application of genetic engineering in the production of insulin, and the final section will look at the ethical issues raised by genetic engineering. There are many different forms of genetic engineering, for example stem cell, which is the process of removing unused cells from embryos which are then produced into tissue. This is a process that is still being researched and could eventually treat or quash many diseases and conditions. The first step is to insert a short piece of foreign DNA into a host organism. This is called gene splicing. For example to insert a piece of DNA from a human into bacterium, you have to break open the ring of DNA from a bacterial plasmid and insert into the human DNA. For the gene splicing to take place it relies on a group of enzymes known as restriction endonticleases. These enzymes will cut the host organism at a specific site which is determined by the bases sequence in that region. It will also cut foreign DNA where there
Dangers of Genetically Engineered Foods.
Dangers of Genetically Engineered Foods Proposed new food regulations will not protect the public from health hazards Hundreds of genetically engineered foods, food additives and ingredients that contain genes derived from animals, fish, insects, viruses, and bacteria will appear in New Zealand shops, unless the public voice their concerns about proposed government regulations which will allow their sale without labelling, even though many genetic scientists say these foods will permanently damage your health. Here's how: Unpredictable mutation of the genetic blueprint of life Given the huge complexity of genetic coding, even in very simple organisms such as bacteria, no one can possibly predict the effects of introducing new genes into any plant. Therefore there is no way of knowing the overall, long-term effect on health. This is because: * the transposed gene may act differently when working within its new host * the original genetic intelligence of the host will be disrupted * the new combination of the host genes and the transposed gene will have unpredictable effects Unnatural gene transfers from one species to another are dangerous Biotechnology companies erroneously claim that their manipulations are similar to natural genetic changes or traditional breeding. However, the cross-species transfers being made, such as between fish and tomatoes, or between
Genetic disorders that can be revealed by kariotype analysis.
Genetic disorders that can be revealed by kariotype analysis Among the numerous genetic disorders that contemporary medicine knows about are some that are caused by changes in number and structure of chromosomes. Therefore, they can be investigated by kariotype analysis. I would like to describe some of the most well-known disorders caused by numerical aberrations in chromosomes. First of all, numerical changes can be either: * Polyploidy - condition in which there are more than two complete sets of corresponding chromosomes. Triploidy and tetraploidy are the most common forms of polyploidy. It is naturally occurring in plants. In humans, polyploidy is lethal. * Aneuploidy - condition in which in one pair of chromosomes there is one more (trisomy) or one fewer (monosomy) chromosome than there should be. It is the most common form of chromosomal aberrations (1/200 newborns) and some of them will be described here. The interesting fact is that it is estimated that chromosomal aberrations occur in some 7.5% of all zygotes. Most of them is lethal though, as e.g. 60% of miscarriages occurring spontaneously in first three months of pregnancy are caused by chromosomal aberrations. Only 0.5% of newborns show such genetic disorders. The most common general symptoms of aneuploidy are general development retardation, many developmental defects. Generally in trisomy the symptoms
Manipulating Reproduction - Have we gone too far?
Manipulating Reproduction - Have we gone too far? Manipulating reproduction has come a long way. It has created many branches from genetic engineering and many more. We have technology where we can clone whole organisms. This development has been already tested on a sheep called dolly. The nucleus from the egg, which came from dolly, was removed and placed into another empty egg with no nucleus. In the end, dolly gave birth to baby who had same genetics as her. And also more progression has been made in genetic engineering. We can now clone tissues and we have technology to select embryo and this is the branch of genetics I will be discussing (4 + 8) Embryo Selection Since the discovery of DNA in the late 1950´s, the possibility of genetic modification of animals and plants has become a reality. However is the reality of designer babies going to far? The term 'designer babies' has become very popular these days. A designer baby is that which an egg from the ovaries of a mother is genetically selected because it does not contain any gene faults or any evidence that future child will have any diseases. The issue has been argued in the media for a considerable amount of time, but is time for the debate now running out or can it be justified to use PGD (Preimplantation Genetic Diagnosis)? (4) The first step to PGD is the creation of embryos outside the body by in vitro
