MUTATIONSKáren Krmoyan

IB Standard Level BiologyMrs. Mariam Ohanyan

22 December, 2015

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

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

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

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

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

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

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

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

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

GENE MUTATIONS

Hereditary Acquired

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

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

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

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

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

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

CASE STUDY: SICKLE CELL

ANEMIA

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

SICKLE CELL

ANEMIA (25 %

chance if both

parents are

carriers)Source:

http://www.babycentre.co.uk/i/imagegallery/categories/diagrams/sickle-cell-tree.jpg

Sickle Cell Anemia (VIDEO)

Source: https://www.youtube.com/watch?v=R4-c3hUhhyc

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.

Thank You!