Download - CHANGES IN THE GENETIC CODE. Ectrodactyly
What do they all have in common?What do they all have in common?
They’re all mutations!They’re all mutations!
MUTATIONSMUTATIONS
a change in the DNA codea change in the DNA code
causes a different (sometimes causes a different (sometimes wrong) type of protein to be madewrong) type of protein to be made
may or may not be good for the may or may not be good for the organismorganism
ALONG THE WAYALONG THE WAY
good changes occurgood changes occur
bad changes occurbad changes occur
changes that don’t matter either waychanges that don’t matter either way
CHANGE IS NECESSARYCHANGE IS NECESSARY
without changes we would all look alikewithout changes we would all look alike
without changes we would not evolvewithout changes we would not evolve
without changes we would not develop without changes we would not develop immunities to diseaseimmunities to disease
SO… Is change/variation a good SO… Is change/variation a good thing???thing???
YES!YES!
Causes of VariationCauses of Variation
Crossing OverCrossing OverMutationsMutations– Some happen randomly Some happen randomly – Some caused by Mutagens (agents that Some caused by Mutagens (agents that
cause mutations)cause mutations)Nuclear RadiationNuclear RadiationUltraviolet LightUltraviolet LightX RaysX Rayshttp://learn.genetics.utah.edu/units/disorders/sloozhttp://learn.genetics.utah.edu/units/disorders/sloozeworm/mutationbg.cfmeworm/mutationbg.cfm
CROSSING OVERCROSSING OVER
occurs when homologous occurs when homologous chromosomes trade segmentschromosomes trade segments
occurs during Prophase I of Meiosis occurs during Prophase I of Meiosis
entire gene is switchedentire gene is switched
involves the variation of a single traitinvolves the variation of a single trait– gene for big ears exchanges with gene for big ears exchanges with
gene for small earsgene for small ears
AdvantagesAdvantages
variation of offspring from parentsvariation of offspring from parents
allows for “good” changesallows for “good” changes
Better chance of passing on genes Better chance of passing on genes for survivalfor survival
3 TYPES OF MUTATIONS3 TYPES OF MUTATIONS
Chromosomal mutationsChromosomal mutations
Gene mutationsGene mutations
Somatic mutationsSomatic mutations– these usually occur during mitosis and these usually occur during mitosis and
involve a chromosomal mutationinvolve a chromosomal mutation– involved with body cells, not sex cellsinvolved with body cells, not sex cells– tumors are the result tumors are the result
Research your mutationResearch your mutation
1. Answer these questions1. Answer these questions– What does the name of the mutation mean?What does the name of the mutation mean?– What happens to the chromosome?What happens to the chromosome?– What is an example?What is an example?
CHROMOSOMAL CHROMOSOMAL MUTATIONSMUTATIONSNONDISJUNCTIONNONDISJUNCTION
DELETIONDELETION
INVERSIONINVERSION
DUPLICATIONDUPLICATION
TRANSLOCATIONTRANSLOCATION
INSERTIONINSERTION
NONDISJUNCTIONNONDISJUNCTION
failure of homologous pairs to failure of homologous pairs to separate during meiosisseparate during meiosis
correct number of chromosomes are correct number of chromosomes are not present in the gametenot present in the gamete
after fertilization, diploid number is after fertilization, diploid number is not restorednot restored
ExamplesExamples
Trisomy 21(Down Syndrome)- 3 Trisomy 21(Down Syndrome)- 3 copies of chromosome 21copies of chromosome 21
Klinefelters Syndrome- XXYKlinefelters Syndrome- XXY
Turner Syndrome- XTurner Syndrome- X
““Supermales” - XYYSupermales” - XYY
ExamplesExamples
Cri-du-chat syndrome- “cry of the Cri-du-chat syndrome- “cry of the cat”- deletion of piece of cat”- deletion of piece of chromosome #5chromosome #5
Angelman Syndrome- deletion of Angelman Syndrome- deletion of piece of chromosome #15piece of chromosome #15
Prader-Willi Syndrome- deletion of Prader-Willi Syndrome- deletion of piece of chromosome #15piece of chromosome #15
ExampleExample
Translocation Down SyndromeTranslocation Down Syndrome
Instead of being 3 separate copies of Instead of being 3 separate copies of chromosome 21, the extra copy is chromosome 21, the extra copy is actually attached to another actually attached to another chromosomechromosome
GENE MUTATIONSGENE MUTATIONS
POINT MUTATIONSPOINT MUTATIONS
FRAME SHIFTFRAME SHIFT– insertionsinsertions– deletionsdeletions
INVERSIONSINVERSIONS
LETS MUTATE!LETS MUTATE!
Start with an original strand of DNAStart with an original strand of DNA
GCC TTA CGT TTA CGA CTG TAC GTAGCC TTA CGT TTA CGA CTG TAC GTA
CGG CGG AATAAT GCAGCA AATAAT GCTGCT GAC ATG CAT GAC ATG CAT
A B C DA B C D
lets assume this strand codes for a lets assume this strand codes for a proteinprotein
AMINO ACIDS
POINT MUTATIONSPOINT MUTATIONS
TTA CGT TTA CGATTA CGT TTA CGA
AAT AAT GCAGCA AAT GCT AAT GCT ORIGINALORIGINAL
1 base is replaced with another base1 base is replaced with another base
TTA CTTA CTTT TTA CGAT TTA CGA
AAT AAT GGAAAA AAT GCT AAT GCT MUTATIONMUTATION
B
E
ExampleExample
Sickle Cell Anemia- changing 1 base Sickle Cell Anemia- changing 1 base causes mutation that codes for valine causes mutation that codes for valine instead of glutamate in the protein instead of glutamate in the protein hemoglobinhemoglobin
Individuals produce different type of Individuals produce different type of hemoglobinhemoglobin
Red Blood Cells become sickle shaped and Red Blood Cells become sickle shaped and don’t pass thru blood vessels as easilydon’t pass thru blood vessels as easily
Cells die sooner than normalCells die sooner than normal
Individuals don’t get as much oxygenIndividuals don’t get as much oxygen
http://www.montgomerycollege.edu/~wolehttp://www.montgomerycollege.edu/~wolexik/Sickle%20Cell%20Anemia%20400x.jpxik/Sickle%20Cell%20Anemia%20400x.jpgg
FRAME SHIFTSFRAME SHIFTS
TTA CGT TTA CGATTA CGT TTA CGAAATAAT GCAGCA AATAAT GCTGCT ORIGINALORIGINAL A B C DA B C D
TTA CGT TTA TTA CGT TTA AACG ACG AAATAAT GCAGCA AATAAT TTGCGC T TINSERTION-base is INSERTION-base is
insertedinserted A B C FA B C F
TTA CGT TTA CGT TACTAC GA GAAATAAT GCAGCA ATGATG CT CT DELETION- base is DELETION- base is
deleteddeleted A B G A B G
INVERSIONSINVERSIONS
TTA CGT TTA CGATTA CGT TTA CGA
AATAAT GCAGCA AATAAT GCTGCT ORIGINALORIGINAL A B C DA B C D
Codon is found in reverse orderCodon is found in reverse order
TTA TTA TGCTGC TTA CGA TTA CGA
AATAAT ACGACG AATAAT GCTGCT INVERSIONINVERSION A H C DA H C D
ConsequencesConsequences
Sometimes mutations are bad and Sometimes mutations are bad and cause for different proteins to be cause for different proteins to be mademadeBut- if you look at the amino acid But- if you look at the amino acid chart- several different codons code chart- several different codons code for the same amino acidsfor the same amino acidsMutations can occur but wouldn’t be Mutations can occur but wouldn’t be noticednoticedSome mutations are masked by other Some mutations are masked by other genesgenes