Presentation on theme: "Mutations and other genetic issues"— Presentation transcript:
1 Mutations and other genetic issues Genetics Unit
2 Mutations Changes in the genetic material. Any deviation from the normal chromosomal complimentTwo types:Spontaneous mutations-occur randomly; no cause can be determinedInduced mutations are caused by some traceable artificial factor: exposure to chemicals, alcohol, drugs, radiation
3 MutationsMutations that produce changes in a single gene are gene mutations.Mutations that produce changes in a whole chromosome are chromosomal mutations.
4 Gene MutationsPoint mutation-change in one or just a few nucleotides. So named because it occurs at a single point.SubstitutionsDeletionsInsertions
5 Gene MutationsFrameshift mutation—shift the reading frame of the genetic codeCan alter a protein so much that it can’t perform its job.
6 Chromosomal Mutations Involve a change in the number or structure of the chromosomeSome change the location of some genes on the chromosomeSome may change the number of copies of some genes.
7 Chromosomal Mutations Four main types of mutations:DeletionDuplicationInversiontranslocation
8 Deletion The permanent loss of a segment of chromosome Can be found anywhere on the chromosomeCan be caused by heat, radiation, viruses, chemicals, errors
12 Causes of abnormalities NondisjunctionThe failure of the chromosome pairs to separate during Meiosis I or Meiosis IIResult will be a zygote with too many or too few chromosomesTwo types: Primary and secondary nondisjunction
22 AmniocentesisAn invasive test that obtains amniotic fluid surrounding the fetus using a needle
23 Amniocentesis Pros and Cons Able to determine fetus’ gender and/or any abnormalitiesCan’t be done before 16th week of pregnancyCan cause infection to mother and/or fetusCan cause premature delivery and birth
25 CVS Pros and ConsCan determine fetus gender and any genetic abnormalitiesCan be done after 10 weeksCan cause leakage of amniotic fluidCan cause premature labor and delivery
26 Recessive Disorders Must be inherited from BOTH parents Autosomal recessive disorders (non-sex cells)Tay-SachsPKUCystic fibrosis
27 Recessive DisordersTay-Sachs—lipid accumulation in the brain; mental deficiency; blindness, death in early childhoodPKU-phenylketonuria—accumulation of phenylalanine in tissues; lack of normal skin pigment; mental retardationCystic fibrosis—excess mucus in lungs, digestive tract, liver; increased susceptibility to infections; often die young
28 Dominant DisordersCan get the disorder by inheriting only one dominant alleleHuntington’s diseaseAchondroplasia
29 Dominant Disorders Huntington’s Disease Achondroplasia Mental deterioration and uncontrollable movementsDoesn’t appear until middle ageAchondroplasiaOne form of dwarfism
30 Sex Linked DisordersIs there a pattern of inheritance for genes located on the X or Y chromosome? YES especially on the XMany times it is male children that inherit these disorders from their mothers because They inherit their X from their mom’sMany sex linked genes are on the XColorblindnessHemophiliaDuchenne Muscular Dystrophy
31 Sex Linked Disorders Colorblindness Most often found in males Females have to inherit from both parents1 in 100 femalesMost common is red-green colorblindness
32 Sex Linked Disorders Hemophilia Two genes on the X chromosome control blood clottingMany times it is male children that inherit this from their mom’s X chromosome1 in 10,000 malesA bleeding disorder; can cause death in severe cases
33 Sex Linked Disorders Duchenne Muscular Dystrophy 1 in 3000 males Progressive weakening and loss of skeletal muscleCaused by defective version of gene that codes for a muscle protein