Turn to your notes page after yesterday’s sheet! Read & do those questions… Quick, quick quick, 10 minutes! Happy Thursday!!! 10/27/2011

Today!! GO over mutations! Tomorrow: Review for test! MONday: Test Don’t forget…if you want some extra help or if you’ve been absent, PLEASE come see me tomorrow during B lunch! Grab lunch & bring it in here!

Mutation background Mutation = the alteration of an organism’s DNA!! Mutation = the alteration of an organism’s DNA!! A malfunction during the process of meiosis A malfunction during the process of meiosis From exposure to a physical or a chemical agent, a mutagen. From exposure to a physical or a chemical agent, a mutagen. Can be a Can be a change in one base pair change in one base pair insertion OR deletion of large segments of DNA insertion OR deletion of large segments of DNA

But not to worry..... But not to worry..... Most mutations are automatically repaired by the organism’s enzymes and therefore have no effect!!! Most mutations are automatically repaired by the organism’s enzymes and therefore have no effect!!! If not, the mutation can be passed on If not, the mutation can be passed on......

8.7 KEY CONCEPT Mutations are changes in DNA that may or may not affect phenotype!!! Whoa, what’s THAT? It’s “how something looks” or its PHYSICAL appearance. Don’t freak out…we’ll learn more about this next week…genetics! Don’t freak out…we’ll learn more about this next week…genetics!

Some mutations affect a single gene, while others affect an entire chromosome. mutation = change in an organism’s DNA.mutation = change in an organism’s DNA. Many kinds of mutations can occur, especially during replication!!!!Many kinds of mutations can occur, especially during replication!!!! mutated base

Affects a single gene Affects a single gene point mutation = substitutes 1 nucleotide for another.point mutation = substitutes 1 nucleotide for another. frameshift mutation inserts or deletes a nucleotide in the DNA sequence!!!frameshift mutation inserts or deletes a nucleotide in the DNA sequence!!! Remember the READING FRAME from Friday? A frameshift mutation SHIFTS the reading FRAME! A frameshift mutation SHIFTS the reading FRAME!

Affect entire chromosome, many genes!!! Crossing over - exchange of unequal segments –Translocation – moving of a piece of 1 chromosome to a nonhomologous part!! More details on this when we study MEIOSIS …My-Oh-Sis!

Translocation results from the exchange of DNA segments between nonhomologous chromosomes!!Translocation results from the exchange of DNA segments between nonhomologous chromosomes!!

IF in a body cell, the cell with the mutation is affected, & daughter cells (from mitosis) can be affected by the altered DNA, but the mutation will not be passed on to your kids!!!! ○ Aging, cancer IF in a gamete (sperm or egg cell), the altered DNA will be transmitted to embryo and may be passed to subsequent generations (genetic disorders)!!!! ○ If the mutation affects a single gene, it is known as a gene mutation. –Sickle cell anemia, Tay-Sachs disease, Huntington’s disease, cystic fibrosis, or albinism. –More on ALL of this next week when we study GENETICS! Mutation Fun Facts!!!

Chrom mutations tend to have a big effect…WHY? Some gene mutations change phenotype. –may cause an “early” stop codon –may change protein shape or active site. –may change gene regulation blockage no blockage Some folks have a mutation that increases cholesterol Cystic Fibrosis is caused by a deletion – too much mucous, no cure! 

Some gene mutations DO NOT affect phenotype. –may occur in a noncoding region (you have “extra DNA” that is never transcribed…) –may not affect protein folding or the active site, so the protein may still function normally –SOME amino acids are coded by several codons… CGU CGA CGC CGG ALL FOUR CODONS CODE FOR WHICH AMINO ACID?? LOOK IT UP!!

Mutations can be caused by several factors. Replication errors can cause mutations.Replication errors can cause mutations. Mutagens, such asMutagens, such as –UV rays and chemicals, cause mutations. Some cancer drugs use mutagenic properties to kill cancer cells.Some cancer drugs use mutagenic properties to kill cancer cells.

For the rest of the period: Rice Krispy DAY 1: work hard, do the paper part of this activity today…and if you WORK STEADILY & EFFICIENTLY! MAKE RICE KRISPY TREATS TOMORROW!