Genetic Mutations

Mutations In__________________, a mutation is a change in the structure or amount of the genetic material of an organism. A genetic _____________is an individual whose DNA or chromosomes differ from some previous or normal state. Every unique allele of every gene began as a mutation of an existing gene.

A mutation may have no effect, or may harm or help in some way. Mutations occur naturally as accidental changes to __________or to chromosomes during the cell cycle. A mutation may have no effect, or may harm or help in some way. The effect depends on where and when the mutation occurs.

Kinds of Mutations ________mutations When one nitrogen base in mRNA is replaced with another. Ex: Sickle Cell Anemia For example…The dog bit the cat The dog bit the car

Kinds of Mutations 2. ________________________Mutations An insertion or deletion can shift the reading frame, or cause a frameshift. For example…The dog bit the cat The dob itt hec at

______________________Mutations In eukaryotic cells, the process of meiosis creates the chance for mutations at the chromosomal level. Recall that during this process, chromosomes pair up and may undergo crossover.

4 Types 1. __________________A deletion occurs when a piece of a chromosome is lost. At the end of meiosis, one of the cells will lack the genes from that missing piece. Such deletions are usually harmful.

2. ______________________: occurs when a piece remains attached to its homologous chromosome after meiosis. One chromosome will then carry both alleles for each of the genes in that piece.

3. ___________________________: occurs when a piece reattaches to its original chromosome, but in a reverse direction.

4. __________________________A translocation occurs when a chromosome piece ends up in a completely different, non-homologous chromosome.

Chromosomal Mutations ____________________________(NAHN dis JUHNK shuhn) a failure of homologous chromosomes to separate during meiosis I or the failure of sister chromatids to separate during mitosis or meiosis II. Polyploidy (PAH lee PLOY dee) an abnormal condition of having more than two sets of chromosomes.

Trisomy 21 – Down Syndrome (ex: Nondisjunction) Most people with Down syndrome have an extra copy of chromosome 21. The extra chromosome can be seen in a karyotype.

Chromosomal Mutations Other Examples: Turner’s Syndrome – woman with only one X chromosome Klinefelter’s Syndrome – man with extra X chromosome

Turner’s Syndrome - XO

Klinefelter Syndrome - XXY

Effects of Mutations The results of genetic mutations may be harmful, beneficial, or__________________; Most changes are neutral and may not be passed on to offspring. Mutations that occur in gametes can be passed on to offspring, but mutations in body cells affect only the individual in which they occur.

Mutations are caused by error in… –Replication –Transcription –Cell division –External agents (_____________________)