DNA mutations and genotypes

• What is karyotype


  It is a visual representation of an individual chromosomes, it is a particular set of chromosomes an individual has
• How do you prepare a karyotype


  To prepare a karyotype, a cell sample is collected and treated to stop cell division during Metaphase of . Then the sample is stained, which produces a branding pattern on the chromosome. Then the chromosomes are observed under a microscope, then they are sorted, paired and arranged.
• What is non-disjunction


  It is the failure of homologous chromosomes or sister chromatids to separate during meiosis, occurs during Anaphase 1 or Anaphase 2 of
• Differentiate between monosomy and trisomy


  Monosomy is the loss of a chromosome as a result of non-disjunction

  WHILE

  Trisomy is the gain of a chromosome a result of non-disjunction
• What is a chromosomal disorder


  A chromosomal disorder is a condition that occurs due to changes or abnormalities to the structure or number of chromosomes
• What is a genetic disorder

  A genetic disorder is a condition that occurs due to abnormalities or mutations to a person's gene or chromosomes
• What are the chromosomal errors

  Deletion,duplication,inversion,translocation
• Deletion

  Definition: Occurs when a part of a chromosome is missing or deleted

  DISEASES ASSOCIATED: Cri-du-chat syndrome, Prader-willi syndrome, Angelman syndrome

  Symptoms: High-pitched cat like sound, low birth weight, widely spaced eyes, recessed chin
• Duplication

  DEFINITION: Occurs when a part of chromosome appears two or more times in a row.

  DISEASES ASSOCIATED: Charcot-Marie tooth disease.

  SYMPTOMS: Muscle weakness; Loss of sensation in lower legs, feet and hands; Behavioural issues.
• Inversion

  DEFINITION: Occurs when a section of a chromosome is inverted, happens only in males.

  DISEASES ASSOCIATED: FG syndrome, Pericentric inversion.

  SYMPTOMS: Intellectual disability; low muscle tone; broad toes and thumbs; delayed motor development.
• Translocation


  DEFINITION: Occurs when a segment of a chromosome becomes attached to another chromosome, mostly between chromosome 9 and 22.

  DISEASES ASSOCIATED: Chronic myeloid leukaemia ( CML ); Down syndrome.

  SYMPTOMS : Abnormal growth; intellectual disability; increased risk of certain types of cancer.