Turn to your notes Turn to your notes page after page after yesterday’s sheet!yesterday’s sheet!

Read & do those Read & do those questions…questions…

Quick, quick quick, Quick, quick quick, 10 minutes!10 minutes!

Happy Thursday!!! Happy Thursday!!! 10/27/201110/27/2011

Today!! Today!! GO over mutations!GO over mutations!

Tomorrow:Tomorrow:

Review for test!Review for test!

MONdayMONday: : TestTest

Don’t forget…if you want some extra Don’t forget…if you want some extra help or if you’ve been absent, help or if you’ve been absent,

PLEASE come see me tomorrow PLEASE come see me tomorrow during B lunch! Grab lunch & bring during B lunch! Grab lunch & bring

it in here!it in here!

Mutation background . . . . . . .

•Mutation = the alteration of an Mutation = the alteration of an organism’s DNA!!organism’s DNA!!•A malfunction during the process of A malfunction during the process of meiosis meiosis

•From exposure to a physical or a From exposure to a physical or a chemical agent, a mutagen.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 insertion OR deletion of large segments of DNAsegments of DNA

• But not to But not to worry . .. . . worry . .. . .

• Most mutations are automatically Most mutations are automatically repaired by the organism’s repaired by the organism’s enzymesenzymes and therefore have no effect!!!and therefore have no effect!!!

• If not, the mutation can be passed If not, the mutation can be passed on . . . . . . on . . . . . .

8.7 KEY CONCEPT 8.7 KEY CONCEPT Mutations are changes in DNA that Mutations are changes in DNA that may or may not affect may or may not affect phenotypephenotype!!!!!!

Whoa, what’s THAT?Whoa, what’s THAT?It’s “how something It’s “how something looks” or its PHYSICAL looks” or its PHYSICAL appearance.appearance.Don’t freak out…we’ll Don’t freak out…we’ll learn more about this learn more about this next week…genetics! next week…genetics!

Some mutations affect a single Some mutations affect a single genegene, , while others affect an entire while others affect an entire chromosomechromosome. .

• mutation = change in an organism’s mutation = change in an organism’s DNA.DNA.

• Many kinds of mutations can occur, Many kinds of mutations can occur, especially during replication!!!!especially during replication!!!!

mutatedbase

• Affects a single geneAffects a single gene

• point mutation = point mutation = substitutes 1 nucleotide substitutes 1 nucleotide for another.for another.

• frameshift mutation frameshift mutation insertsinserts or or deletesdeletes a a nucleotide in the DNA nucleotide in the DNA sequence!!!sequence!!!

Remember the Remember the READING FRAME READING FRAME

from Friday?from Friday?A frameshift A frameshift

mutation mutation SHIFTSSHIFTS the reading the reading FRAMEFRAME! !

Affect entire Affect entire chromosome, chromosome, manymany genes!!!genes!!!– @ Crossing over - @ Crossing over -

exchange of exchange of unequal segments unequal segments

– Translocation – Translocation – moving of a piece moving of a piece of 1 chromosome of 1 chromosome to a to a nonhomologous nonhomologous part!! part!!

More details on this when More details on this when we study MEIOSIS we study MEIOSIS ……My-Oh-My-Oh-

Sis!Sis!

• Translocation Translocation results from the exchange of results from the exchange of DNA segments between nonhomologous DNA segments between nonhomologous chromosomes!!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!!!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 Some gene mutations DO NOT affect phenotype.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…

CGUCGACGCCGG

ALL FOUR CODONS CODE

FOR WHICH AMINO ACID??

LOOK IT UP!!

Mutations can be caused by several factors.

• Replication errors Replication errors can can cause mutations. cause mutations.

• Mutagens, such as Mutagens, such as – UV rays and chemicals, UV rays and chemicals,

cause mutations.cause mutations.• Some cancer drugs Some cancer drugs useuse

mutagenic properties to mutagenic properties to kill cancer cells.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!