* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download NAME: NWAIWU ROSEMARY DEPT: BIOCHEMISTRY COURSE
Gene therapy of the human retina wikipedia , lookup
United Kingdom National DNA Database wikipedia , lookup
Human genome wikipedia , lookup
Neuronal ceroid lipofuscinosis wikipedia , lookup
Molecular cloning wikipedia , lookup
Genealogical DNA test wikipedia , lookup
Genome evolution wikipedia , lookup
Population genetics wikipedia , lookup
Epigenomics wikipedia , lookup
Nucleic acid double helix wikipedia , lookup
Genetic engineering wikipedia , lookup
Genome (book) wikipedia , lookup
DNA vaccination wikipedia , lookup
Epigenetics of neurodegenerative diseases wikipedia , lookup
DNA supercoil wikipedia , lookup
Zinc finger nuclease wikipedia , lookup
Nutriepigenomics wikipedia , lookup
Saethre–Chotzen syndrome wikipedia , lookup
Extrachromosomal DNA wikipedia , lookup
Genetic code wikipedia , lookup
Cre-Lox recombination wikipedia , lookup
Cancer epigenetics wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
DNA damage theory of aging wikipedia , lookup
Nucleic acid analogue wikipedia , lookup
Deoxyribozyme wikipedia , lookup
No-SCAR (Scarless Cas9 Assisted Recombineering) Genome Editing wikipedia , lookup
Genome editing wikipedia , lookup
Vectors in gene therapy wikipedia , lookup
Designer baby wikipedia , lookup
Oncogenomics wikipedia , lookup
Non-coding DNA wikipedia , lookup
History of genetic engineering wikipedia , lookup
Cell-free fetal DNA wikipedia , lookup
Therapeutic gene modulation wikipedia , lookup
Microsatellite wikipedia , lookup
Helitron (biology) wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Microevolution wikipedia , lookup
NAME: NWAIWU ROSEMARY DEPT: BIOCHEMISTRY COURSE: BIO 201 MUTATION: A CURSE OR A BLESSING. MUTATION: A mutation is a permanent change to DNA. These changes occur when DNA repair mechanisms fail to repair damage, when DNA replicates incorrectly, or form the deletion or insertion of DNA segments. Some mutations occur within the lifetime of a single organism. These somatic mutations involve direct damage to an organism’s DNA from an environmental source. For example, damage from ultraviolet rays damages DNA in a way that gives rise to cancerous cells. Other mutations are heritable and pass from one generation to another. One particular heritable mutation causes a deletion of 32 base pairs affecting the human CCR5 protein. Research suggests that people with this gene possess immunity to bubonic plague or small pox, a very beneficial mutation to people at various periods in human history. Because of higher survival rates of people with the CCR5 mutation, the mutation persists into the present day. For modern humans, a CCR5 mutation means resistance to HIV. Mistakes occur constantly during the replication, translation and transcription of DNA. Fortunately, nearly 98 percent of human DNA is noncoding DNA with no apparent functions and mutations in noncoding DNA have no effect. TYPES OF MUTATION MISSENSE MUTATION- This type of mutation is a change in one DNA base pair that results in the substitution of one amino acid for another in the protein made by a gene. (i.e. a change in a single “chemical letter” such as switching an A to a G) such a substitution could change a codon to one that encodes a different amino acid and cause a small change in the protein produced. For example, sickle cell anemia is caused by a substitution in the beta-haemoglobin gene, which alters a single amino acid in the protein produced. NONSENSE MUTATION- A nonsense mutation is also a change in one DNA base pair. Instead of substituting one amino acid for another, however, the altered DNA sequence prematurely signals the cell to stop building a protein. This type of mutation results in a shortened protein that may function improperly or not at all. INSERTION- An insertion changes the number of DNA bases in a gene by adding a piece of DNA. As a result, the protein made by the gene may not function properly. DELETION- A deletion changes the number of DNA bases by removing a piece of DNA. Small deletions may remove one or a few base pairs with a gene, while larger deletions can remove an entire gene or several neighboring genes. The deleted DNA may alter the function of the resulting protein(s) DUPLICATION- A duplication consists of a piece of DNA that is abnormally copied one or more times. This type of mutation may alter the function of the resulting protein. FRAMESHIFT MUTATION- This type of mutation occurs when the addition or loss of DNA bases changes a gene’s reading frame. A reading frame consists of groups of 3 bases that each code for one amino acid. A frameshift mutation shifts the grouping of these bases and changes that code for amino acids. The resulting protein is usually nonfunctional. Insertions, deletions, and duplications can all be frameshift mutations. REPEAT EXPANSION- Nucleotide repeats are short DNA sequences that are repeated a number of times in a row. For example, a trinucleotide repeat is made up of 3-base-pair sequences, and a tetranucleotide is made up of 4-base-pair sequences. A repeat expansion is a mutation that increases the number of times that the short DNA sequence is repeated. This type of mutation can cause the resulting protein to function improperly. Mutations happen, they happen with great regularity. Almost all mutations are neutral and whether they are helpful/harmful depends on the environment (circumstances). Advantages of Mutation SURVIVAL- Mutations have allowed humans to adapt to their environment. For instance, lactose tolerance is a specific external mutation that was advantageous in societies that raised cows and goats. Mutations have been responsible for antibiotic resistance in bacteria, sickle cell resistance to malaria, and immunity to HIV, among others. A rare gene mutation leading to unusual shortness of height has proven to be advantageous for a particular Ecuadorian community, the Ecuadorian community with the rare gene mutation known as Laron syndrome are protected against cancer and diabetes. DIVERSITY- Originally we all had brown eyes but a genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a “switch”, which literally turned off the ability to produce brown eyes. This explains that things like hair colour, baldness, freckles, and beauty spots are all brought about by mutations. Disadvantages of Mutation DISEASE- As much as mutations have helped humans, mutations are also the cause of certain diseases. For instance, a particular mutation relatively common on the Indian subcontinent predisposes people to heart disease, many other diseases, such as cancer, diabetes and asthma, are linked to genetic mutations. GENETIC DISORDER- A genetic disorder is a disease that is cause by abnormality in an individual’s DNA. Abnormalities can range from a small mutation in a single gene to the addition or subtraction of an entire chromosome or set of chromosomes. Non-disjunction is one of the most common types of mutations. Down syndrome is a non-disjunction and a common genetic disorder that has other consequences such as developmental delays. Mutation can also be errors in all or part of a chromosome. Humans normally have 23pairs of chromosomes, and an extra chromosome can have a tremendous negative impact. For example, there should be two of chromosome 21, as with all other chromosomes, but if there are three, the result is Down syndrome. People with Down syndrome have a unique physical appearance and are developmentally disabled. Nor is an extra chromosome the only chromosomal abnormality that causes problems: if chromosomes 9 and 22 exchange materials, a phenomenon known as translocation, the result can be a certain type of leukemia. Down syndrome also results from translocation. CLASSIFICATION OF MUTATION. 1.By effect on structure The sequence of a gene can be altered in a number of ways. Gene mutations have varying effects on health depending on where they occur and whether they alter the function of essential proteins. 2. by effect on fitness 3. by inheritance 4. by impact of protein synthesis.