POINT MUTATIONS Not like XMen MUTATION n Any

POINT MUTATIONS Not like X-Men

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

POINT MUTATIONS n Occurs n These at 1 single point in DNA could cause one amino acid to change, which would change the protein that is being produced.

POINT MUTATIONS n BASE SUBSTITUTION: – A nucleotide is replaced with a different nucleotide. – Three examples: n Transversion mutation n Transition mutation n Silent mutation

BASE SUBSTITUTION Examples: n Transversion – happens when one purine (A, G) is swapped with a pyrimidine (C, T). DNA: m. RNA: AA: CTT GAA Glu to to to C AT G UA Val

Transversion Substitution

BASE SUBSTITUTION Examples: n transition mutations – happen when one purine is swapped with the other purine or a pyrimidine is swapped with a pyrimidine. DNA: m. RNA: AA: CTT to CCT GAA to GGA Glu to Gly

BASE SUBSTITUTION Examples: n Silent mutations – happen when a base codon is changed but both code for the same amino acid. DNA: m. RNA: AA: GAA CUU Leu to GAC to CUG to Leu

POINT MUTATIONS n FRAMESHIFT: Because of a point mutation, there is a shift in the “reading frame” of genetic message – Almost always affect all the amino acids after the mutation, which will affect the entire protein.

Frameshift Mutation Examples: n Insertion – Shifts the reading to the right – DNA: from GCATCG to GCC ATC – m. RNA: from CGU AGC to CGG UAG – Amino Acid: from Arg Ser to Arg STOP

Point Mutation n Deletion – Shifts the reading to the left – DNA: from GCATCG to GAT CG – m. RNA: from CGU AGC to CUA GC – Amino Acid: from Arg Ser to 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 MUTATIONS

INVERSION and TRANSLOCATION n Inversion: 2 sections of the chromosome are reversed n Translocation: 1 part of a chromosome breaks off and attaches to another part of a chromosome n Duplication: Part of chromosome is copied

Examples n ORIGINAL CHROMOSOME: – ABCDEFG – where the letters are representing genes on the chromosome. n Inversion – ABGFEDC n Translocation – ABCDXYZ n Duplication – ABBBCDEFG

Inversion Brenden 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 12 th 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 n Acute Promyelocytic Leukemia – caused by a rearrangement of genetic material between chromosome 9 and 22.

Translocation Examples n 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

Translocation A chromosome 5; 12 translocation causes severe skeletal and composite cardiac malformations.

Duplication

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

Chromosome New Chromosome Mutation Abcd. EFghijklm Abcdkjlm 1 Abcd. EFghijklm Abihg. FEdcjklm 2 Abcd. EFghijklm Acd. EFghijklm 3 Abcd. EFghijklm Abcd. EFghi. Wx. Yz 4 Abcd. EFghijklm Abcdbcd. EFghijklm 5 Abcd. EFghijklm Abcd. EFkjihglm 6 Abcd. EFghijklm 7 Abcd. EFghijklm Abcdmlkjhg 8

Chromosome New Chromosome Mutation Abcd. EFghijklm Abcdkjlm 1 Deletion & Inversion Abcd. EFghijklm Abihg. FEdcjklm 2 Inversion Abcd. EFghijklm Acd. EFghijklm 3 Deletion Abcd. EFghijklm Abcd. EFghi. Wx. Yz 4 Translocation Abcd. EFghijklm Abcdbcd. EFghijklm 5 Duplication Abcd. EFghijklm Abcd. EFkjihglm 6 Inversion Abcd. EFghijklm 7 Duplication Abcd. EFghijklm Abcdmlkjhg 8 Deletion &

http: //www. chemistryexplained. com/Ma. Na/Mutation. html http: //embryology. med. unsw. edu. au/Defect/p age 21. htm http: //www. biology. arizona. edu/human_bio/ac tivities/karyotyping. html http: //www. docstoc. com/docs/38810096/Muta tions