Genetic Mutations

• This is an agent that causes genetic mutations such as radiation or chemical substances.

  Mutagen
• A mutation, also called chromosomal aberrations, is an alteration in the nucleotide sequence of the genome of an organism, virus, or extrachromosomal DNA, which are inheritable and are permanent.
• This is the change in genetic material.

  Mutation
• The Chromosome segregation occurs at two separate stage during meiosis called anaphase I and anaphase II.
• Mutations that occur in sex cells can be passed from parent to their children.
• Nondisjunction occurs when homologous chromosomes or sister chromatids fail to separate during meiosis, resulting in an abnormal chromosome number.
• What are the two types of cells in a Eukaryotic organism where a mutation can occur?

  Somatic cells, Germ cells
• Somatic mutation occurs in somatic cells. It occurs in non-reproductive cells and will not be passed to the offspring.
• Germinal mutation in an alteration of the nucleotide sequence of the DNA makes up a gene. The germ cells give rise to sex cells that will carry mutations to the next generation when a successful mating happened.
• Insertion is a genetic material added from another chromosome.
• Translocation happens when part of a chromosome breaks off and combined to another chromosome. This type of disorder is due to chromosomal-level mutation.
• Deletion happens when there is a loss of part of a chromosome.
• Inversion happened when the direction of a part of a chromosome is reversed.
• This is a genetic disorder that happens when a child receives two defective genes from each parent.

  recessive disorder
• The Klinefelter's Syndrome has 44 autosomes and sex cells that are XXY. Males who have this syndrome usually have wide hips, long arms and legs, and poor beard growth.
• Sex-linked disorders are more common in men because they only have one X chromosome, so all defective genes on the chromosome will be expressed.
• Color blindness and hemophilia are examples of this type of genetic disorder.

  Sex-linked disorder
• The Turner's syndrome only has an X chromosome that occurs in females.
• Metafemale contains this sex chromosomes in females.


  XXX
• Jacob Syndrome is a genetic condition in which a human male has an extra Y chromosome.
• Down Syndrome is a condition in which a child is born with an extra copy of their 21st chromosome. This is also called trisomy 21.
• Cri du chat is caused by the deletion of part of the short arm of chromosomes 5.
• William Syndrome is the result of the loss of a segment of chromosome 7.
• Edward Syndrome, also known as trisomy 18, happens when there is an extra number 18 chromosome.
• Patau's Syndrome, is caused by the extra copy of 13 chromosome.
• A whole genome is called a Euploidy
• A change in chromosome number is called an Aneuploidy
• When a particular individual has three chromosomes of a particular type, this chromosomal aberration is called a trisomy
• If a cell has 18 chromosomes, how many chromosomes would each daughter cell have after mitosis?

  18
• The causes of genetic mutations are the following:

  • Smoking
  • Effect of old age on offspring
  • Chemotherapy
  • External Influences