POINT MUTATIONS Not like X-Men. MUTATION Any change in the genetic sequence (DNA) that affects the...

POINT MUTATIONSPOINT MUTATIONS

Not like X-MenNot like X-Men

MUTATIONMUTATION

Any change in the Any change in the genetic sequence genetic sequence (DNA) that affects the (DNA) that affects the genetic informationgenetic information


Occurs at 1 single point in Occurs at 1 single point in DNADNA

These These couldcould cause one cause one amino acid to change, which amino acid to change, which would change the protein would change the protein that is being produced.that is being produced.


BASE SUBSTITUTIONBASE SUBSTITUTION::– A nucleotide is replaced with a A nucleotide is replaced with a

different nucleotide.different nucleotide.

– Three examples:Three examples: Transversion mutationTransversion mutation Transition mutationTransition mutation Silent mutationSilent mutation

BASE SUBSTITUTIONBASE SUBSTITUTIONExamples:Examples: TransversionTransversion – happens when – happens when

one purine (A,G) is swapped with one purine (A,G) is swapped with a pyrimidine (C,T).a pyrimidine (C,T).

DNA:DNA: CTT to C CTT to CAATT

mRNA: GAA to GmRNA: GAA to GUUA A

AA: Glu to AA: Glu to ValVal

Transversion Transversion SubstitutionSubstitution

BASE SUBSTITUTIONBASE SUBSTITUTIONExamples:Examples: transition mutations transition mutations – happen – happen

when one purine is swapped with the when one purine is swapped with the other purine or a pyrimidine is other purine or a pyrimidine is swapped with a pyrimidine.swapped with a pyrimidine.

DNA:DNA: CTT to C CTT to CCCTT

mRNA: GAA to GmRNA: GAA to GGGA A

AA: Glu to AA: Glu to GlyGly

BASE SUBSTITUTIONBASE SUBSTITUTIONExamples:Examples: Silent mutations Silent mutations – happen when – happen when

a base codon is changed but both a base codon is changed but both code for the same amino acid.code for the same amino acid.

DNA:DNA: GAA to GA GAA to GACC

mRNA: CUU to CUmRNA: CUU to CUGG

AA: Leu to LeuAA: Leu to Leu


FRAMESHIFT:FRAMESHIFT: Because of a point Because of a point mutation, there is a mutation, there is a shiftshift in the in the “reading frame” of genetic “reading frame” of genetic messagemessage

– Almost always affect all the amino Almost always affect all the amino acids after the mutation, which will acids after the mutation, which will affect the affect the entireentire protein. protein.

Frameshift Mutation Frameshift Mutation Examples:Examples: InsertionInsertion

– Shifts the reading to the rightShifts the reading to the right

– DNA: from GCATCG to GCDNA: from GCATCG to GCC C ATCATC– mRNA: from CGU AGC to CGmRNA: from CGU AGC to CGGG UAGUAG– AminoAmino

Acid: from Arg Ser to Acid: from Arg Ser to Arg STOPArg STOP

Point MutationPoint Mutation

DeletionDeletion– Shifts the reading to the leftShifts the reading to the left

– DNA: from GCATCG to GAT CGDNA: from GCATCG to GAT CG– mRNA: from CGU AGC to CUmRNA: from CGU AGC to CUAA GCGC– AminoAmino

Acid: from Arg Ser to Acid: from Arg Ser to Leu Leu

A New Subtype of Brachydactyly Type B Caused by Point Mutations in the Bone Morphogenetic Protein Antagonist NOGGIN

Hutchinson-Gilford progeria syndrome The disease is caused by a small point mutation on a single gene known as LMNA. Almost all cases are caused by the substitution of only one base pair out of the approximate 25 000 DNA base pairs that compose the LMNA gene. This gene codes for the protein lamin A, which is important to determine the shape of a cell’s nucleus. It is vital in providing support to the nucleus’ inner membrane. The mutation in the LMNA gene causes an abnormal form of the lamin A protein. That malformed protein makes the inner cell membrane unstable and little by little damages the nucleus; this makes cells more prone to die prematurely. Researchers are still trying to figure out how exactly this leads to the phenotypes associated with progeria.

CHROMOSOMAL CHROMOSOMAL MUTATIONSMUTATIONS

INVERSION and INVERSION and TRANSLOCATIONTRANSLOCATION

Inversion:Inversion: 2 sections of the 2 sections of the chromosome are reversedchromosome are reversed

Translocation:Translocation: 1 part of a 1 part of a chromosome breaks off and attaches chromosome breaks off and attaches to another part of a chromosometo another part of a chromosome

Duplication:Duplication: Part of chromosome is Part of chromosome is copiedcopied

ExamplesExamples ORIGINAL CHROMOSOME:ORIGINAL CHROMOSOME:

– ABCDEFG ABCDEFG – where the letters are – where the letters are representing representing genesgenes on the chromosome.on the chromosome.

InversionInversion – AB – ABGFEDCGFEDC

TranslocationTranslocation – ABCD – ABCDXYZXYZ

Duplication Duplication –– AABBBBBBCDEFGCDEFG

InversionBrenden Adams abnormal growth

rate is due to an inversion in chromosome-12, a growth gene defect that skyrocketed his growth rate.

In Brenden’s case, his 12th chromosomes don’t match. Experts don’t know why, but the middle of one of them broke off, flipped around and re-attached at the zygote stage of development, disrupting a critical gene that controls growth.http://www.kimatv.com/news/local/11161021.html?tab=video

Translocation Examples Acute

Promyelocytic Leukemia – caused by a rearrangement of genetic material between chromosome 9 and 22.

The section on 15 is responsible for suppressing tumors (control growth). The section on 17 is responsible for helping white blood cells mature. When the two are translocated, tumors can grow and white blood cells cannot mature.

It is aquired not inherited.

Translocation Examples

Translocation

Translocation

A chromosome

5;12 translocation causes severe skeletal and composite

cardiac malformations

.

Duplication

DeletionDeletion

a portion of one chromosome is a portion of one chromosome is lost lost during cell division. That during cell division. That chromosome is now missing chromosome is now missing certain genes. When this certain genes. When this chromosome is passed on to chromosome is passed on to offspring the result is usually offspring the result is usually lethal due to missing genes.lethal due to missing genes.

ChromosomChromosomee

New New ChromosomeChromosome

MutationMutation

AbcdEFghijklAbcdEFghijklmm

AbcdkjlmAbcdkjlm 11


AbihgFEdcjklmAbihgFEdcjklm 22


AcdEFghijklmAcdEFghijklm 33


AbcdEFghiWxYzAbcdEFghiWxYz 44


AbcdbcdEFghijklmAbcdbcdEFghijklm 55


AbcdEFkjihglmAbcdEFkjihglm 66


AbcdEFdEFghijklmAbcdEFdEFghijklm 77


AbcdmlkjhgAbcdmlkjhg 88

ChromosomChromosomee

New New ChromosomeChromosome

MutationMutation


AbcdkjlmAbcdkjlm 11 Deletion & Deletion & InversionInversion


AbihgFEdcjklmAbihgFEdcjklm 22 Inversion Inversion


AcdEFghijklmAcdEFghijklm 33 Deletion Deletion


AbcdEFghiWxYzAbcdEFghiWxYz 44 TranslocationTranslocation


AbcdbcdEFghijklmAbcdbcdEFghijklm 55 Duplication Duplication


AbcdEFkjihglmAbcdEFkjihglm 6 6 InversionInversion


AbcdEFdEFghijklmAbcdEFdEFghijklm 7 7 DuplicationDuplication


AbcdmlkjhgAbcdmlkjhg 88 Deletion & Deletion & InversionInversion

http://www.chemistryexplained.com/Ma-Na/Mutation.html

http://embryology.med.unsw.edu.au/Defect/page21.htm

http://www.biology.arizona.edu/human_bio/activities/karyotyping/karyotyping.html

http://www.docstoc.com/docs/38810096/Mutations

POINT MUTATIONS Not like X-Men. MUTATION Any change in the genetic sequence (DNA) that affects the...

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