Studying Human Chromosomes
StarAsia Thomas
Mach.31.2012
Benjamin Banneker Academy
Living Environment Pd.2nd
StarAsia Thomas Benjamin Banneker Academy
March.31.2012 Living Enviornment Pd.2nd
Background
The name karyotype is given to the set of chromosomes of an individual, usually when visualized and identified under the microscope. The visualization generally is made with the cells in the initial phases of cell division for the chromosomes to be seen already replicated and condensed.The counting and identification of chromosomes in the karyotype of an individual can diagnose the aneuploidies, diseases caused by alteration in the number of chromosomes in relation to the normal number of the species.Down syndrome is an aneuploidy, i.e., a numeric alteration of chromosomes within the cells compared to the normal number of chromosomes of the species. Affected individuals have in their cells an additional chromosome 21 instead of only one pair. For this reason the condition is also called trisomy 21. The affected person has karyotype with 47 chromosomes: 45 + XY or 45 + XX..
Aneuploidy is an abnormal number of chromosomes in the cells of an individual.The main aneuploidies of the human species and their respective conditions are: the nullisomies (absence of any chromosome pair of the species, often incompatible with life); the monosomies (absence of a chromosome from a pair, for example, Turner’s syndrome, 44 + X); the trisomies (an extra chromosome, for example, the triple X syndrome, 44 + XXX, or the Edwards syndrome, trisomy 18, 45 + XY or 45 + XX).Generally the aneuploidies are caused by impaired assortment of chromosomes during meiosis. For example, when the homologous chromosomes of the pair 21 do not separate gametes with two chromosomes 21 and gametes without chromosomes 21 form. If a gamete with two chromosomes 21 fecundates a normal gamete of the opposite sex the zygote will present trisomy (three chromosomes 21).
The Term Paper on Cell Cycle
?The cell cycle, or cell-division cycle, is the series of events that take place in a cell leading to its division and duplication that produces two daughter cells. In cells without a nucleus, the cell cycle occurs via a process termed binary fission. In cells with a nucleus, the cell cycle can be divided in three periods: interphase—during which the cell grows, accumulating nutrients needed for ...
If a gamete without chromosomes 21 fecundates a normal gamete of the opposite sex there will be a zygote with monosomy (with only one chromosome 21).The defects in the separation of chromosomes during cell division are called chromosomal nondisjunctions. During meiosis nondisjunctions may occur in the anaphase I (nondisjunction of homologous) as well in anaphase II (nondisjunction of sister chromatids).Genetic diseases classify into chromosomal abnormalities and genetic mutations.
Among chromosomal abnormalities there are the aneuploidies, diseases caused by alterations of the normal (euploidy) number of chromosomes of the species. An example of aneuploidy is Down syndrome, or trisomy 21, in which there are three chromosomes 21 instead of the normal pair. In the group of chromosomal abnormalities there are also the deletions (absence of part of a chromosome), the inversions (in which a chromosome breaks and its pieces reconnect in inverse manner) and the translocations (pieces of a chromosome that exchange positions).In the genetic mutation group there are the deletions (one or more DNA nucleotide absent), the substitutions and the insertion.
Genetic mutations are alterations of the genetic material (compared to the normal condition of the species) involving modifications in the normal nucleotide sequence of a gene but without structural or numeric chromosomal changes.These modifications may be deletions (loss of nucleotides), substitutions (exchange of nucleotides by other different nucleotides) or insertions (placement of additional nucleotides in the DNA molecule).Not every gene mutation causes alteration in the composition of the protein the gene codifies. Since the genetic code is degenerated, i.e., there are amino acids codified by more than one different DNA nucleotide triplet, if by chance the mutation substitutes one or more nucleotides of a codifier triplet and the newly formed triplet still codifies the same amino acid codified by the original triplet there will be no modification in the protein made from the gene.
The Essay on Genetic Technology Dna Humans Plant
DNA After staying on the plant Earth reaching the human genetic technology, I have come up with this report the four things I am going to talk about in this report are: 1) What is the chemical basis of the plant Earth 2) What do human mean by " genetic technology' and how is it possible 3) How have human used this technology 4) Are humans concerned about this technology 1) The chemical basis of ...
Too extensive or too frequent genetic mutations generally are deleterious for individuals and species. These mutations often cause important phenotypical changes or defects incompatible with the survival of the body and the continuity of the species.However small genetic mutations that do not cause the appearing of lethal changes are continuously accumulated in the genetic patrimony of the species. These mutations gradually add to each other giving birth to small phenotypical changes in individuals. These small changes are exposed to the selective criticism of the environment (natural selection) and the more favorable for survival and reproduction are preserved (the remaider are eliminated as their carriers have difficulty in surviving and reproducing).
In this manner the combined processes of accumulation of small mutations and of natural selection incorporate new features in the species and they may even lead to speciation (formation of new species) and promotion of biological diversity(Obviously only genetic mutations transmitted by cells that originate new individuals, in sexual or asexual reproduction, have evolutionary effect.)
Mutagenic agents, or mutagens, are physical, chemical or biological factors that can cause alteration in DNA molecules.Examples of well-known or believed to be mutagenic agents are: X, alpha, beta and gamma rays, ultraviolet radiation, nitrous acid, many dyes, some sweeteners, some herbicides, many substances of tobacco, some viruses, like HPV, etc. Small DNA fragments known as transposons can also act as mutagens when incorporated into other DNA molecules.The exposition of a population to mutagenic agents (for example, the people living in the surrounds of the Chernobyl nuclear power plant and exposed to the radiation from the nuclear accident in 1986) increases the cancer incidence in that population. This occurs because the mutagenic agents increase the rate of mutation and the probability of mutant cells to proliferate in pathological manner (cancer).
The Essay on Human Race Genetic Dna Genetics
SHOULD WE GENETICALLY ENGINEER OURSELVES Should we use new genetic information to alter our own DNA to make ourselves more adept Last winter, scientist made a major break through in genetic engineering. They finished a complete map of DNA of a complex organism. Although the animal that they broke down is a simple flat worm, over 40% of its DNA sequence match our own. This is an astounding leap ...
Cancer itself is not a hereditarily transmissible disease. Genetic predispositions for the development of cancer, however, can be inherited.There are enzymes within the cells that detect errors or alterations in DNA molecules and begin a repair of those errors. First, enzymes known as restriction endonucleases, specialized in cutting DNA molecules (also used in genetic engineering), cut the affected piece of DNA. Then polymerase enzymes build correct sequences of nucleotides correspondent to the affected piece taking as template the DNA chain complementary to the affected chain. Finally the new correct sequence is bound in the DNA under repair by specific enzymes.Image Diversity:DNA repairing system[->0].Examples of recessive genetic diseases are: cystic fibrosis, albinism, phenylketonuria, galactosemia, Tay-Sachs disease.Examples of dominant genetic diseases are: Huntington’s disease (or Huntington’s chorea), neurofibromatosis, hypercholesterolemia, polycystic kidney disease.
Severe and early autosomal dominant diseases are rarer than recessive autosomal diseases because in this last group the affected allele may be hidden in the heterozygous individuals and transmitted to the offspring until undergoing homozygosity (actual manifestation of the disease).
In severe dominant diseases the heterozygous manifests the condition and often dies without having offspring. (Some genetic diseases are of later manifestation, like Huntington disease; in these cases the incidence is higher because many individuals have children before knowing that they are carriers of the dominant gene).Consanguineal marriage is the marriage between relatives, i.e., people having common near ancestors.The consanguineal marriage increases the probability of recessive genetic disease in the offspring since it is common for people from the same genetic lineage to be heterozygous carriers of alleles that condition recessive genetic diseases.Genetic disease may be diagnosed in the prenatal period by karyotype analysis, in case of aneuploidies, or by DNA analysis, in case of other diseases.The test is performed by removal of material containing cells of the embryo by amniocentesis (extraction of amniotic fluid) or cordocentesis (puncture of the umbilical cord) or even by chorionic villus biopsy (that can be done earlier in gestation).Ultrasonography is a diagnostic procedure for some genetic diseases that produce morphological variations during the embryonic development. The study of genetic family trees is also an important auxiliary method in the early diagnosis of many genetic diseases.
The Essay on Acondroplasia A Genetic Disorder Growth Individuals
Acondroplasia A Genetic Bone Disorder There are hundreds of reasons why some children never reach expected heights as adults. Many are short in stature because of family or ethnic backgrounds. Others have a wide range of medical conditions, which are often at times genetic, that limit overall growth in all or just specific parts of the body, such as the limbs or the torso. One of the medical ...
Analysis
1. How can normal males and females be identified froma karyotype?
Human females have a homologous pair of X chromosomes (XX), but males have one X and one Y chromosome (XY).
2. Down Syndrome is caused by one etra autosome in each cell. Which pair of autocoms has an extra chromosome?
Autosomes, or sex-linked genes, usually do not have extra chromosomes. The only exception is Kleinfelter’s syndome, which is a male that instead of having the chromosomes XY he has XXY, which could cause him to have some womanly features, such as a smaller height or fuller breasts. It is also common that a man with Kleinfelters is sterile.
3. In Klinefelter’s syndrome, individuals are males with an extra chromosome . What is the extra chromosome?
In Klinefelter’s syndrome the extra chromosome for an individual male is a sex chromosome. An individual has 44 autosomes and 3 sex chromosomes if they are a male that has klinefelter’s syndrome.
4. How do individuals get extra chromosomes?
Individuals gets extra chromosomes beacause normally, a baby inherits 23 chromosomes from each parent, for a total of 46. Each chromosome matches the corresponding chromosome from the other parent, forming 23 numbered pairs.Biological errors can happen during the early stages of cell division, causing some fetuses to develop with 47 chromosomes: Instead of 23 matched pairs, they have 22 pairs plus one set of three, a chromosomal abnormality called trisomy.Most fetuses with trisomy are miscarried during the first trimester. Most of those who survive have Down syndrome, also known as trisomy 21 because it’s caused by an extra chromosome 21.
The Term Paper on Support Individuals With Self-Directed Support
1. Understand self-directed support:- 1.1 Explain the principles underpinning self-directed support and how this differs from traditional support:- The principles underpinning self-directed support and how it differs to traditional support is as follows:- Right to independent living – If someone has an impairment they should be able to get the support they need to live an independent life. ...
[->0] – http://images.google.com/images?svnum=10&hl=en&gbv=2&q=DNA+repair+system
