Mutations Flashcards
Mutation
Permanent change to a gene or chromosome leading to a new characteristic in an organism, Can be caused by changing base sequences in a section of DNA which changes the proteins that will be synthesised by the body, Advantageous or disadvantageous
Mutant
Organism with a characteristic resulting from a mutation
Mutagens
Agents known to increase the rate at which mutations occur, Eg UV light, X-rays, radiation, chemicals such as sulfur dioxide or antibiotics
Somatic mutation
Mutation in a body cell, reproductive cells aren’t affected and once the organism dies, the mutation is lost
Germline mutation
Mutation in the gametes, individual isn’t usually affected however they produce gametes with changed DNA
Gene mutations
When there is a change in a single gene, Occur during DNA replication before cell division, If DNA copies are incorrectly changed, changed DNA continues to be copied in all future divisions, If a single base is changed in a gene the DNA may code for a new amino acid and thus a different protein or causing a protein to not be created at all however there may be no change
Point mutation
Change in just one base
Albinism
Point mutation, Results from a missing protein, Protein responsible for the pigment of hair, skin and eyes is missing
Duchenne muscular dystophy
Point mutation (deletion), Caused by missing the protein dystrophin, Results in wasting of the leg muscles and later the arms, shoulders and chest, Individuals generally experience muscle weakness as the ages of 3-5 years, Eventually death occurs due to failure of respiratory muscles, Boys who contract the disease don’t live past 25 years
Frameshift mutation
When a single base is added or deleted from DNA which shifts the reading of codons by one base
Cystic fibrosis
Results from changes to DNA of the CFTR gene resulting in different amino acids in the CFTR protein, CFTR protein regulates the development of the chloride channels in the cell membrane, Without the CFTR protein a person cannot transport chloride ions and the movement of water into and out of cells, Without the correct version of the CFTR protein the person suffers from salty tasting skin, persistent ocughing, wheezing and digestive problems
Lethal recessive
When a recessive mutation isn’t masked by a dominant (normal) allele, Can occur if both partners carried the same recessive mutation, Cause the death of the embryo or foetus by miscarriage or abortion
Chromosomal mutations
Occur when there is a change in the whole or part of a chromosome causing a change in a few nucleotide bases, Can affect genes
Aneuploidy
Change in the chromosome numbers
Causes of chromosomal mutations (5)
Deletion where part of a chromosome is loss, Duplication where a section of a chromosome occurs twice, Inversion when a break occurs in the chromosome and the broken piece joins back in but inverted (the wrong way around), Translocation when part of a chromosome breaks off and is re-joined to the wrong chromosome, Non-disjunction- during meiosis when a chromosome pair doesn’t separate meaning one daughter cell has one less chromosome (monosomy) and on has one extra (trisomy, down syndrome)
