* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Mutation Notes
BRCA mutation wikipedia , lookup
Designer baby wikipedia , lookup
Cancer epigenetics wikipedia , lookup
Deoxyribozyme wikipedia , lookup
Polycomb Group Proteins and Cancer wikipedia , lookup
Epigenetics of human development wikipedia , lookup
Genome evolution wikipedia , lookup
Population genetics wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
Cell-free fetal DNA wikipedia , lookup
Neuronal ceroid lipofuscinosis wikipedia , lookup
Nucleic acid analogue wikipedia , lookup
Epigenetics of neurodegenerative diseases wikipedia , lookup
Skewed X-inactivation wikipedia , lookup
Expanded genetic code wikipedia , lookup
Y chromosome wikipedia , lookup
No-SCAR (Scarless Cas9 Assisted Recombineering) Genome Editing wikipedia , lookup
Koinophilia wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Saethre–Chotzen syndrome wikipedia , lookup
X-inactivation wikipedia , lookup
Genome (book) wikipedia , lookup
Neocentromere wikipedia , lookup
Oncogenomics wikipedia , lookup
Microevolution wikipedia , lookup
Genetic code wikipedia , lookup
MUTATIONS How mistakes are made… Mutations Mutations are defined as “a sudden genetic change in the DNA sequence that affects genetic information”. They can occur at the molecular level (genes) and change a single gene, or at the chromosome level and affect many genes. Things that can cause mutations are called “mutagens”. Known mutagens are ultraviolet light, cigarette smoking, some viruses, certain chemicals like PCB’s. Mutagens often result in cancer. Inheritability of Mutations It depends on where it occurs i. Germ mutations – occur in gametes. Inheritable (colorblindness, hemophilia) ii. Somatic mutations – affect body cell, not inheritable (CAN RESULT IN cancer) Effects of Mutations Not all mutations have effects. Silent mutations - have no effect on the expression of the gene. Causes for this type of mutation: It is in a non-coding region It does not change the amino acid sequence The change does not affect the folding of the protein Types of Mutations a) Point Mutations – effects a single gene i. Substitution ii. Frameshift a. deletion b. insertions b) Chromosomal Mutations – most drastic, change in structure or # of chromosomes (affects many genes) III. Point Mutations a) Substitution – one base exchanges for another, affects 1 amino acid (Ex. GCA-TCA GCT-TCA The Effects of Point Mutations ►A point mutation is a change in a single base pair in DNA. A change in a single nitrogenous base can change the entire structure of a protein because a change in a single amino acid can affect the shape of the protein. Normal mRNA Protein Replace G with A Point mutation Stop mRNA Protein Stop Effects of substitution mutations Missense mutations – causes a change in the amino acid coded for Nonsense mutations – causes a stop codon to occur prematurely Sickle cell anemia Tay-Sachs Frameshift Mutations ►What would happen if a single base were lost from a DNA strand? ►A mutation in which a single base is added or deleted from DNA is called a frameshift mutation because it shifts the reading of codons by one base. As a result, every codon after the deleted base would be different. Deletion of U mRNA Protein Frameshift – affects several amino acids -Insertion – 1 base is inserted, affects several amino acids Ex. (GCA-TCA GCA-GTC-A -Deletion – base is removed, affects several amino acids Ex. (GCA-TCA GCT-CA X Cystic fibrosis Chromosome mutations Nondisjunction – incomplete chromosome division during meiosis; results in gametes with too many or too few chromosomes. Ex: Down syndrome is caused by an extra #21 chromosome Polyploidy Aneuploidy Down’s Syndrome •Trisomy 21 •1 in 700 births •Mental retardation •Vision problems •Heart problems Likelihood of chromosomal mutations 1 in 1700 for mothers under 20. 1 in 1400 for mothers between 20 and 30. 1 in 750 for mothers between 30 and 35. 1 in 16 for mothers over 45. Sex chromosome disorders – occurs as a result of nondisjunction of the sex chromosomes Ex: Turner’s syndrome – X-; Klinefelter’s syndrome – XXY. Klinefelter’s Syndrome •XXY •1 in 1,000 •Usually sterile because of low sperm count •Tall, sparse body hair •Suffer from gynecomastia- male breast tissue •Testosterone treatments Turner’s Syndrome •XO genotype—Monosomy X •1 in 2,500 births •Short, sterile •75% result in non-disjunction from the father XYY-Jacob’s Syndrome a.k.a. “Super Males” • 1 in 1,000 men •Normal appearance, very tall •Low IQ, prone to violence Patau’s Syndrome •1 out of 6,000 births •Trisomy 13 •80-90% do not survive past 1 yr old Edward’s Syndrome •Trisomy 18 •Second most common trisomy after down’s syndrome •Only 5% live to age 1 •1 out of 8,000 births •Severely retarded, many die from malformed heart •Polydactyly or syndactyly Other Chromosomal Mutations Affect many different genes Caused by errors in meiosis or environmental disturbances. Translocation – occurs when a piece of one chromosome breaks off and attaches to a nonhomologous chromosome Inversion – occurs when a piece of one chromosome breaks off, flips, and reattaches to the same chromosome Deletion – occurs when a piece of a chromosome breaks off and is lost Duplication – occurs when a segment of a chromosome is repeated Cri du Chat “Cry of the Cat” •1 in 50,000 births •A piece of chromosome 5 is missing •Severe mental retardation, nonverbal •Does not run in families