Mutation Presentation PDF

MUTATION GENETICS Romel C. Mutya | Instructor Cebu Technological University – Danao Campus What are mutations? MUTATIONS are any changes in the sequence of bases of DNA Mutations  Mutations DO COULD...

MUTATION GENETICS Romel C. Mutya | Instructor Cebu Technological University – Danao Campus What are mutations? MUTATIONS are any changes in the sequence of bases of DNA Mutations  Mutations DO COULD NOT lead lead to to this this Colon cancer cells  most people have dozens or even hundreds of mutations in their DNA Mutations are essential for evolution to occur. ultimate source of all new genetic material - new alleles - in a species Types of Mutations Germline mutations occur in gametes especially significant because they can be transmitted to offspring and every cell in the offspring will have the mutation. Somatic mutations occur in other cells of the body may have little effect on the organism because they are confined to just one cell and its daughter cells cannot be passed on to offspring. What can cause mutations to happen more often? CAUSES OF MUTATIONS Errors in DNA Replication On very, very rare occasions DNA polymerase will incorporate a noncomplementary base into the daughter strand. During the next round of replication the missincorporated base would lead to a mutation. This, however, is very rare as the exonuclease functions as a proofreading mechanism recognizing mismatched base pairs and excising them.  Errors in DNA Recombination DNA often rearranges itself by a process called recombination which proceeds via a variety of mechanisms. Occasionally DNA is lost during replication leading to a mutation.  Gene Mutation a change to a gene's DNA sequence to produce something different creates a permanent change to that gene's DNA sequence Chromosomal Aberrations a disorder characterized by a morphological or numerical alteration in single or multiple chromosomes, affecting autosomes, sex chromosomes, or both TYPES OF GENE MUTATION Class of Mutation Deletion A deletion, resulting in a frameshift, results when one or more base pairs are lost from the DNA If one or two bases are deleted the translational frame is altered resulting in a garbled message and nonfunctional product. A deletion of three or more bases leave the reading frame intact. A deletion of one or more codons results in a protein missing one or more amino acids. This may be deleterious or not.  Cystic Fibrosis A hereditary disorder characterized by lung congestion and infection and malabsorption of nutrients by the pancreas.  Cri du chat Syndrome the characteristics of a newborn with cri du chat syndrome include a high- pitched cry, a small head and a flattened bridge of the Duplications A region of a chromosome is repeated, resulting in an increase in dosage from the genes in that region occurs when a stretch of one or more nucleotides in a gene is copied and repeated next to the original DNA sequence. This type of variant may alter the function of the protein made from the gene.  Charcot- Marie- Tooth Disease one of a group of disorders that cause damage to the peripheral nerves Inversions One region of a chromosome is flipped and reinserted An inversion changes more than one nucleotide in a gene by replacing the original sequence with the same sequence in reverse order.  Opitz- Kaveggia Syndrome an X-linked recessive mental retardation syndrome characterized by dysmorphic features, including relative macrocephaly, hypertelorism, downslanted palpebral fissures, prominent forehead with frontal hair upsweep, and broad thumbs and Translocations A region from one chromosome is aberrantly attached to another chromosome Substitution This type of variant replaces one DNA building block (nucleotide) with another. Substitution variants can be further classified by the effect they have on the production of protein from the altered gene. Missense a type of substitution in which the nucleotide change results in the replacement of one protein building block (amino acid) with another in the protein made from the gene. The amino acid change may alter the function of the protein. Nonsense another type of substitution. Instead of causing a change in one amino acid, however, the altered DNA sequence results in a stop signal that prematurely signals the cell to stop building a protein. This type of variant results in a shortened protein that may function improperly, be nonfunctional, or get broken down. Sickle-cell anemia Insertion The insertion of additional base pairs may lead to frameshifts depending on whether or not multiples of three base pairs are inserted. Combinations of insertions and deletions leading to a variety of outcomes are also possible.  One form of beta- thalassemi a TYPES OF CHROMOSOMAL ABERRATIONS  Abnormal Karyotype Karyotypes can reveal changes in chromosome number associated with aneuploid conditions, such as trisomy 21 (Down syndrome). Careful analysis of karyotypes can also reveal more subtle structural changes, such as chromosomal deletions, duplications, translocations, or inversions. Aneuploidy vs. Polyploidy Chromosome Duplication a type of mutation in which one or more copies of a DNA segment (which can be as small as a few bases or as large as a major chromosomal region) is produced occur in all organisms. Chromosome Inversion occurs when a segment breaks off and reattaches within the same chromosome, but in reverse orientation DNA may or may not be lost in the process. Sex Chromosome Aberrations/Abnormalities a group of disorders that affects the number or the structure of the X and Y chromosomes. Examples include monosomy X or structural abnormalities of the chromosome like isochromosome of the long arm (isochromosome Xq), both leading to Turner syndrome. EFFECTS OF MUTATIONS ON PLANTS EFFECTS OF MUTATION IN ANIMALS/HUMANS  Albinism This rare albino alligator must have the specific "instructions," or DNA, to have this quality. The cause of albinism is a mutation in a gene for melanin, a protein found in skin and eyes. Such a mutation may result in no melanin production at all or a significant decline in the amount of melanin.  Eight-Legged Goat In Croatia, a baby goat was born with a genetic abnormality that resulted in four extra legs. This is because one of the children absorbed one of his brothers or sisters in the womb. Farmer Zoran Papari told reporters that he first thought he would go crazy when he counted the baby's feet, so he had to invite the farmer's neighbour to confirm that he was not deceived with his eyes. The goat, most likely, did not live long, but the farmer planned to keep the animal as a pet if the goat survived.  Plant Mutation also known as sports, breaks, or chimeras, are naturally occurring genetic mutations that can change the appearance of the foliage, flowers, fruit or stems of any plant. BENEFICIAL MUTATION  Trichromatic Vision the ability of humans and some other animals to see different colors, mediated by interactions among three types of color-sensing cone cells  Lactose Tolerance a single point mutation in the DNA near to the lactase gene changes the cytosine (C) nucleotide to a thymine (T) individuals who have the thymine (T) nucleotide are lactose tolerant and can digest milk products in adulthood. MUTATION AND CANCER  p53 gene A gene that makes a protein that is found inside the nucleus of cells and plays a key role in controlling cell division and cell death mutations (changes) in the p53 gene may cause cancer cells to grow and spread in the body.