Mutations Slides PDF

Mutations A mutation is a change in the structure or amount of an organism’s genetic material. This mutation can by a tiny change in DNA structure or can be a large scale change in chromosome structure or number When a change in genotype produces a change in phenotype, the individual i...

Mutations A mutation is a change in the structure or amount of an organism’s genetic material. This mutation can by a tiny change in DNA structure or can be a large scale change in chromosome structure or number When a change in genotype produces a change in phenotype, the individual is called a mutant 1  Gene Mutations = Alteration of the base or sequence Here there is a change in one or more of the nucleotides in a strand of DNA When one or more of the nucleotides (letters) are changed, it can cause a change in the amino acids which then can cause a different protein to be made 2  Point mutations Change in one base For a protein to work properly it must have the correct sequence of amino acids. If there is a change it usually brings about a minor change (i.e. one different amino acid).Here organism is affected only slightly or not at all. However if the substituted amino acid occurs at a critical point in the amino acid a major defect may arise e.g. sickle cell anaemia. 3  Sickle Cell Anemia Sickle cell anemia Image Credit: http://explore.ecb.org/ Blood smear (normal) Image Credit: http://lifesci.rutgers.edu/~babiarz/  Sickle Cell Disease Results from a Base Change in Beta Globin Gene  Sickle Cell Anemia Mutation encodes valine in place of glutamic acid Creates sickle shape of red blood cells (RBC) Sickling causes anemia, joint pain, and organ damage when RBC become lodged in small blood vessels Sickle cell disease is particularly common in people with an African or Caribbean family background. Is there a positive? People with Sickle Cell Anemia are more resistant to Malaria (disease spread by mosquitos)  Chromosomal Abnormalities Chromosomes can be affected by mutations which bring about large scale changes to the genetic material. One type happens during meiosis in humans when unusual gametes can be formed which contain 22 or 24 chromosomes instead of the normal 23 7  Down’s Syndrome-Chromosomal Abnormality Due to an extra chromosome at position #21. An extra copy of chromosome 21 is seen in the karyotype of someone with Down’s syndrome. They have 47 chromosomes instead of 46 The affected individual is characterised by mental impairments and distinctive physical features Egg mother cells of older women (80% due to age) tend to be more prone to this occurring 8  Down’s Syndrome (trisomy 21) Karyotype 9  Mutagenic agents – Increases mutation rate. These include – A variety of chemicals act as mutagens. E.g. Peroxides and mustard gas, chemically modify DNA. – Exposure to high-energy radiation (or ultraviolet light can have a similar effect). 10 SELECTIVE BREEDING The selection of certain seeds or animals for reproduction in order to influence the traits inherited by the next generation.  SELECTIVE BREEDING The Liger is the result of breeding a female Tiger to a male Lion. On their hind legs, ligers stand approximately 12 feet tall. At most, ligers may weigh up to 1,000 pounds. The Cama is the result of breeding a Llama to a Camel. GENETIC ENGINEERING The selective, deliberate change of genes (genetic material) by science The technique of removing, modifying or adding genes to a DNA molecule in order to change the information it contains.  Cure For Sickle Cell Anemia? A new treatment being given in the UK is designed to work by editing the faulty gene in a patient's bone marrow stem cells so that the body produces functioning haemoglobin. To do this, stem cells are taken out of bone marrow, edited in a laboratory and then infused back into the patient after which the results have the potential to be life-long. 16