Mutations A mutation is any change in the DNA sequence.
Mutations in Reproductive Cells Only in gametes can mutations be passed on to offspring
Mutations in Body Cells Somatic (normal/non-sex cells) cannot be passed on to offspring
Types of Mutations Gene mutations- changes to a specific gene. (DNA base pairs) Chromosomal mutations- changes to a portion of the chromosome Can affect many genes
Different Types of Gene Mutations Point mutation-a change in a single base pair in the DNA. THE DOG BIT THE CAT THE DOG BIT THE CAR THE DOG BAT THE CAR THE DIG BAT THE CAR
Point Mutation
Frameshift Mutation a single base pair is added or deleted, causing a shift in how the strand will be read. THE DOG BIT THE CAT THE DO BIT THE CAT THE DOB ITT HEC AT
Chromosome Mutations Deletion-part of a chromosome is left out.
There is a small section of chromosome #5 that has been deleted
Insertion-part of a chromatid breaks off & attaches to its sister chromatid.
Inversion-part of a chromosome breaks off & reinserts backwards.
Translocation-part of one chromosome breaks off & is added to a different chromosome.
Nondisjunction- have an abnormal number of chromosomes Caused by errors in Mitosis or Meiosis Most die before birth Results in either monosomy or trisomy
Down’s Syndrome Traits Down’s Syndrome is an example of nondisjunction Results from trisomy of the 21st pair of chromsomes (3 chromosomes) Mental retardation, short stature, heart defects, most are sterile, and other problems
There is an extra chromosome on the 21st pair Down’s Syndrome There is an extra chromosome on the 21st pair
Turner’s Syndrome Traits Turner’s Syndrome occurs only in females Results from monosomy X People with syndrome are sterile Secondary sex characteristics don’t develop
What causes mutations? spontaneous mistakes environment any agent that can cause a change in DNA is called a mutagen. (x-rays, UV light, asbestos)
DNA Repair enzymes in our cells remove the incorrect nucleotides & replace them with the right ones. this works well, but is not perfect