1 / 9

Insertion Mutations

Insertion Mutations. What is an insertion mutation?. Mutations caused by the insertion of DNA bases or fragments This can happen when DNA is copied incorrectly ( frameshift mutation) One or two bases are added This can also happen when large fragments move from one place to another.

nolcha
Download Presentation

Insertion Mutations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Insertion Mutations

  2. What is an insertion mutation? • Mutations caused by the insertion of DNA bases or fragments • This can happen when DNA is copied incorrectly (frameshift mutation) • One or two bases are added • This can also happen when large fragments move from one place to another

  3. Barbara McClintock • Genes and chromosomes were originally described as “beads on a string”; it was thought that genes occupied a fixed position on a chromosome • Barbara McClintock received a Nobel prize in 1983 for her workdiscovering transposable elements or “jumping genes”: DNA fragments that can move from one chromosome to another. • Today we know that 65% of the human genome is composed of transposable elements

  4. McClintock’s Observations: • McClintock discovered transposons by studying colour pattern in Indian corn • She found that corn kernels which should have been brown or purple according to their genotype, would often show patches of white • She correctly predicted that this happened if a transposon inserted itself and disrupted the pigment producing gene. • Also seen in hosta plants

  5. Viruses • Viruses contain genetic information, but are not living things. • In order to make copies of themselves, they rely on cell machinery of the host • Viruses insert their DNA into the host’s genome, so the host will transcribe and translate viral genes in order to make viral proteins

  6. Viruses • Throughout evolution, our DNA has acquired many relics of past viral infection. • Once the human genome was sequenced in 2000, it was found that ~ 8% of our genome is from viruses! • Like transposons, when viral DNA is inserted in the middle of a human gene, its function will be disrupted. • Viral insertions usually occur in regulatory genes, which increase or decrease the function of another gene

  7. Negative effects of viral insertions • Insertions can be harmful • If viral genes disrupt genes that regulate cell growth, infection may cause cancer = oncovirus • HPV (Human Papilloma Virus) • Hepatitis C Virus • Prior infection with certain viruses has been linked to the development of other diseases. • Bornavirusschizophrenia and other mood disorders. • Herpes virus 1 Alzheimer’s

  8. Benefits of viral insertions • Insertions can be beneficial • Viral insertions have activated some digestive enzymes in human saliva by disrupting suppressor genes • Infection by less harmful virus prevents infection by more dangerous strains. • Vaccinia prevents small pox • Viral machinery can be manipulated to insert helpful genes into cells (gene therapy)

  9. Genetics and Probability Homework • 0.50 that 1st child will be brown-eyed (depends on inheriting B from dad: Bb) 2. a) 0.25 (both are HRHW, 0.50 that each pass on HR allele) b) 0.50 ( 0.25 probability of each combination, 2 combinations produce roan cattle) • a) cross 1: 0.50; cross 2: 0.00; cross 3: 0.25 b) cross 1: 0.50; cross 2: 0.50; cross 3: 0.50 c) cross 1: 0.00; cross 2: 0.50; cross 3: 0.25 • a) affected son: 0.50 affected daughter: 0.00 b) affected son: 0.25 (50% mom is a carrier x 50% she will pass on alllele); affected daughter: 0.25 • man: Rr bb woman: rr BB a) left handed child: 0.50 b) left handed with brown eyes: 0.50 (probability of brown eyes is 1.00) 6. Condition is recessive; 0.50 that carrier female will pass on affected allele, 0.67 that man is a carrier, 0.50 that man will pass on affected allele 0.50 x 0.67 x 0.50 = ~ 0.18 that they will have an affected child.

More Related