mutations (káren krmoyan)
TRANSCRIPT
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MUTATIONSKáren Krmoyan
IB Standard Level BiologyMrs. Mariam Ohanyan
22 December, 2015
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What is a MUTATION?A mutation is a change that occurs in our DNA sequence, either due to mistakes when the DNA is copied or as the result of environmental factors such as UV light and cigarette smoke.
Source: http://learn.genetics.utah.edu/content/variation/mutation/images/mut1.jpg
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Genetic DiversityMost commonly, a single base is
substituted for another. Sometimes a base
is deleted or an extra base is added.
Fortunately, the cell is able to repair most
of these changes. When a DNA change
remains unrepaired in a cell that will
become an egg or a sperm, it is passed
down to offspring. Thanks to mutation, we
all have some new variations that were
not present in our parents.Source:
http://knowgenetics.org/wp-content/uploads/2012/12/amanda1.png
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BENEFICIAL OR NOT?People commonly use the terms "mutant" and mutation" to describe something undesirable or broken. But mutation is not always bad. Most DNA changes fall in the large areas of the genome that sit between genes, and usually they have no effect. When variations occur within genes, there is more often a consequence, but even then mutation only rarely causes death or disease. Mutation also generates new variations that can give an individual a survival advantage. And most often, mutation gives rise to variations that are neither good nor bad, just different.
Source: https://starksbiology.wikispaces.com/file/view/Mutation_3.jpg/132029845/413x365/Mutation_3.jpg
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Mutation generates new allelesThe whole human family is one species
with the same genes. Mutation creates slightly different versions of the same genes, called alleles. These small differences in DNA sequence make every individual unique. They account for the variation we see in human hair color, skin color, height, shape, behavior, and susceptibility to disease. Individuals in other species vary too, in both physical appearance and behavior. Source:
http://www.yourgenome.org/sites/default/files/images/illustrations/mutation_types1_01.png
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Once new alleles arise, meiosis and sexual
reproduction combine different alleles in new
ways to increase genetic variation.
Source: http://learn.genetics.utah.edu/content/variation/mutation/images/mut6.jpg
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Mutation versus variationWe often refer to a mutation as a thing—the genetic variation itself. This approach can be useful when it comes to a gene associated with a disease: the disease allele carries a mutation, a DNA change that compromises the protein's function. However, this approach gives mutation a bad name.
Source: http://learn.genetics.utah.edu/content/variation/mutation/images/mut2.jpg
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Proteins & SwitchesMutation creates variations in protein-coding portions of genes that can affect the protein itself. But even more often, it creates variations in the "switches" that control when and where a protein is active and how much protein is made.
Source: http://learn.genetics.utah.edu/content/variation/mutation/images/mut3.jpg
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Other Drivers of Mutation: Environmental AgentsRadiation, chemicals, byproducts of
cellular metabolism, free radicals, ultraviolet rays from the sun—these agents damage thousands of nucleotides in each of our cells every day. They affect the nucleotides themselves: converting one base to another, knocking a base off its backbone, or even causing a break in the DNA strand. Source:
http://learn.genetics.utah.edu/content/variation/mutation/images/mut4.jpg
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DNA RepairMost of the time, mutation is reversed. DNA
repair machines are constantly at work in our
cells, fixing mismatched nucleotides and
splicing broken DNA strands back together. Yet
some DNA changes remain. If a cell
accumulates too many changes—if its DNA is
so damaged that repair machinery cannot fix it
—it either stops dividing or it self-destructs. If
any of these processes go wrong, the cell could
become cancerous.Source:
http://learn.genetics.utah.edu/content/variation/mutation/images/mut5.jpg
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GENE MUTATIONS
Hereditary Acquired
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Hereditary MutationsThey are inherited from a parent and are present throughout a person’s life in virtually every cell in the body. These mutations are also called germline mutations because they are present in the parent’s egg or sperm cells, which are also called germ cells. When an egg and a sperm cell unite, the resulting fertilized egg cell receives DNA from both parents. If this DNA has a mutation, the child that grows from the fertilized egg will have the mutation in each of his or her cells.
Source: http://www.iianthropology.org/images/mistakes.gif
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Acquired MutationsThey occur at some time during a person’s life and are present only in certain cells, not in every cell in the body. These changes can be caused by environmental factors such as ultraviolet radiation from the sun, or can occur if a mistake is made as DNA copies itself during cell division. Acquired mutations in somatic cells (cells other than sperm and egg cells) cannot be passed on to the next generation.
Source: http://www.iianthropology.org/images/acquired.gif
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Chromosomal MutationsStructural changes in chromosomes are also
caused by radiation, chemicals, and even by some
virus infections.
Changes occur in the structure of chromosomes,
during cell division. When homologous
chromosomes pair up, linked genes on the
chromosomes may break apart. The genes may
join another chromosome, or they may be lost. Source: http://cdn.yourarticlelibrary.com/wp-content/uploads/2013/07/clip_image002_thumb4.jpg
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Chromosomal Mutations (Deletion)A deletion involves the loss of a piece of
chromosome. If a chromosome breaks and the
parts do not reattach, the pieces may be lost.
This is the most serious kind of chromosome
mutation. Here, bits of genetic information are
not available to the offspring.
Source:http://www.embryology.ch/images/kimgchromaber/02abweichende/k2c_deletion.gif
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Chromosomal Mutations (Duplication)
Duplication occurs when one extra,
but identical piece of chromosome is
added to the normal chromosome.
Source:https://upload.wikimedia.org/wikipedia/commons/7/72/Gene-duplication.png
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Chromosomal Mutations (Inversion)When an inversion occurs, the pieces of
chromosome break apart and pieces rejoin the
same chromosome in a different order. Usually
inversions have no harmful effects on the
offspring.
Source:http://web2.mendelu.cz/af_291_projekty2/vseo/files/26/1377.png
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CASE STUDY: SICKLE CELL
ANEMIA
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SICKLE CELL ANEMIASickle cell anaemia is caused by a mutation
in a gene called haemoglobin beta (HBB), located on chromosome 11.
It is a recessive genetic disease, which means that both copies of the gene must contain the mutation for a person to have sickle cell anaemia.
If an individual has just one copy of the mutated gene they are said to be a carrier? of the sickle cell trait.
If both parents are carriers there is a chance
their child could be born with sickle cell
anaemia.Source:
http://www.yourgenome.org/sites/default/files/images/illustrations/sickle_cell_anemia-01.png
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SICKLE CELL
ANEMIA (25 %
chance if both
parents are
carriers)Source:
http://www.babycentre.co.uk/i/imagegallery/categories/diagrams/sickle-cell-tree.jpg
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Sickle Cell Anemia (VIDEO)
Source: https://www.youtube.com/watch?v=R4-c3hUhhyc
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BibliographyN/A. "What Is a Mutation?" Your Genome. Genome Campus, 2015.
Web. 19 December 2015.
N/A. "What Is a Sickle Cell Anemia?" Your Genome. Genome Campus, 2015. Web. 19 December 2015.
N/A. "What Is Mutation?." Genetic Science Learning Center. Learn.Genetics. 2015. Web. 19 December 2015.
N/A. "What Is a Gene Mutation and How Do Mutations Occur?" Genetics Home Reference. 14 December 2015. Web. 19 December 2015.
Pujari, Saritha. “Types of Mutations: Gene & Chromosomal Mutations”. YourArticleLibrary. Your Article Library. N/D. Web. 22 December 2015.
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Thank You!