A hand book of life sciences/Printable version


A hand book of life sciences

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EXCRETORY SYSTEM

The removal of harmful and unwanted waste material from the body is called excretion.Those organ which help in the process of excretion called excretory organs.



CLASSICAL GENETICS

PEDIGREE ANALYSISEdit

=== PATTERNS OF INHERITANCE ===[1]

AUTOSOMAL DOMINANTEdit

  • Each affected person has an affected parents.
  • It occurs in every generation.
  • There is male to male transmission.

Ex: Huntington's chorea,Neurofibromatosis,Achondroplasia,Familial hypercholesterolemia

AUTOSOMAL RECESSIVEEdit

  • Most affected individuals have unaffected parents.
  • Both parents of unaffected persons are carriers but offsprings are affected.
  • Trait often skips generations.

Ex:Sickle cell anemia,Cystic fibrosis,Phenylketonuria,Tay-Sachs disease

X-LINKED DOMINANTEdit

  • Females are more frequently affected from mothers.
  • Affected females comes from affected mothers or fathers.
  • If the male is affected then all of his daughters would be affects but non of his sons are affected.
  • If the female is affected then about half of her sons are affected.
  • It present in each generation.

Ex:Hypophatemic rickets (vitamin-D resistant rickets), Ornithine Transcarbamylase deficiency

X-LINKED RECESSIVEEdit

  • Most affected individuals are male.
  • Affected males comes from mother who are affected or carriers.
  • Affected females comes affected father and affected or carrier mother.
  • Affected males present in each generation.

Ex:Hemophilia A,Duchenne Muscular Dystrophy,Colour blindness, Night blindness,Fragile X-syndrome

Y-LINKED INHERITANCEEdit

  • It is also known as holandric inheritance.
  • Affects only Males.
  • Affected males always have an affected father.
  • If the fathers will affected,all of his sons will be affected.

Ex:Flatfoot and hair loss

MITOCHONDRIAL DISORDERSEdit

  • This inheritance can affect both males and females.But only passed on by females.
  • It can appear in every generation.

Ex:Mitochondrial myopathy, Diabetes mellitus and deafness(DAD)

referenceEdit


  1. https://www.ncbi.nlm.nih.gov/books/NBK115561/