A mutagen is a physical or chemical agent creating the mutation. Common mutagens that cause mutations are X-rays and UV radiation Changes can be either beneficial or harmful depending upon the change that is made. Chromosome Mutations portions of chromosomes are switched, – added or deleted, etc. p. 245 (limited info in text) and powerpoint; – good link here: Crossing Over p 184 exchange of corresponding – segments on homologous chromosomes during synapsis. chiasma point where crossing over occurs – recombinants chromosomes resulting from – crossing over they have been recombined. – Translocation attachment of chromosome fragment – to a non-homologous chromosome Ex: segments on Chromosome 22 and Leukemia – Chromosome 9 switch activating the gene for the most common form of leukemia Inversion fragment breaks off and reattaches to the – original chromosome but in the opposite direction fragment breaks off and is lost Deletion – Ex: Cri du Chat Syndrome deletion in chromosome – 5 creates a child who is mentally retarded and has cry. Death occurs in infancy. Nondisjunction chromosome pair fails to separate in – meiosis. Not in your book but it is in online activity and at list under Your Genome link at top of chromosome mutations list. one gamete has too many chromosomes, another gamete doesn’t have enough chromosomes – neither produces and offspring Trisomy 21 Down’s Syndroms – Offspring has three of the 21st chromosome. Has a rounded face, flattened features, short stature, is susceptible to heart disease and infections Klinefelter’s Syndrome XXY – Offspring has male sex organs but is sterile. Exhibits breast enlargement and is of normal intelligence Turner Syndrome XO – Offspring has short stature, a web of skin between the neck and shoulders, is sterile and of normal intelligence
A mutagen is a physical or chemical agent creating the mutation. Common mutagens that cause mutations are X-rays and UV radiation Changes can be either beneficial or harmful depending upon the change that is made. Chromosome Mutations – portions of chromosomes are switched, added or deleted, etc. – p. 245 (limited info in text) and powerpoint; good link here: Crossing Over p 184 – exchange of corresponding segments on homologous chromosomes during synapsis. chiasma – point where crossing over occurs recombinants – chromosomes resulting from crossing over – they have been recombined. Translocation – attachment of chromosome fragment to a non-homologous chromosome Ex: Leukemia – segments on Chromosome 22 and Chromosome 9 switch activating the gene for the most common form of leukemia Inversion – fragment breaks off and reattaches to the original chromosome but in the opposite direction Deletion – fragment breaks off and is lost Ex: Cri du Chat Syndrome – deletion in chromosome 5 creates a child who is mentally retarded and has cry. Death occurs in infancy. Nondisjunction – chromosome pair fails to separate in meiosis. Not in your book but it is in online activity and at list under Your Genome link at top of chromosome mutations list. one gamete has too many chromosomes, another gamete doesn’t have enough chromosomes – neither produces and offspring Trisomy 21 – Down’s Syndroms Offspring has three of the 21st chromosome. Has a rounded face, flattened features, short stature, is susceptible to heart disease and infections Klinefelter’s Syndrome – XXY Offspring has male sex organs but is sterile. Exhibits breast enlargement and is of normal intelligence Turner Syndrome – XO Offspring has short stature, a web of skin between the neck and shoulders, is sterile and of normal intelligence