Bio chemical genetics

1. DEPARTMENT OF GENETICS AND PLANT BREEDING
C C S UNIVERSITY MEERUT
Submitted by
Mr.R P MAURYA
M. SC. (Ag), Department of
Genetics & Plant Breeding,
Chaudhary CharannSingh
University, Meerut
Submitted to
DR. S S GAURAV
Asstt. Professor, Department
of Genetics & Plant Breeding,
Chaudhary Charan Singh
University, Meerut

2. Content:
 Introduction.
 One gene one enzyme hypothesis
 Inborn errors of metabolism in man
 Phenyketoniriya
 Alkaktonuriya
 Albinism
 Goitrous certinism
 Eye transplantation in drosophila
 Bio chemical mutation in neurospora
 REFERENCES

3. Introduction
BIO CHEMICAL GENETICS CAN BE DEFINED AS THE
STUDY THE RELATIONSHIP BETWEEB GENES AND
ENZYME SPECIFOCALLY THE ROLE OF GENES IN
CONTROLLING THE STEPS BIO CHEMICAL PATHWAYS
The Foundation bio Chemical Genetics was laid by Sir
Archibald Edward Garrod in 1902 was english Physicion .he
studied Gene action in men
G.W,Beadle and F.L Tatum [both Nobel Prize winners in1958]
was proposed in 1941 a concept called ONE GENE ONE
ENZYME HYPOTHESIS
Beadle and Ephrussi in1957 studied metabolic pathway for
Eye Colour in Drosophila.

4. The One-Gene-One Enzyme Hypothesis
George Beadle and Edward
Tatum were among the first
to investigate biosynthetic
pathways
They studied growth
variants of the fungus,
Neurospora crassa
Their proposal, the one-
gene-one enzyme
hypothesis came out of their
experiments

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6. One gene one enzyme
Precursor Product A Product B
Product
C
Product n

8. Phenylketonuria
Autosomal recessive metabolic genetic
disorder
Mutation in the gene for phenylalanine
hydroxylase(PAH).
When PAH activity is reduced, phenylalanine
accumulates and is converted into
phenylpyruvate(phenylketone), which can be
detected in the urine.

9. Overview
 Autosomal recessive disorder caused by
mutation in PAH gene
 Located on 12th chromosome.
 PKU is rare – it is estimated to affect 1 in
every 10,000 babies.

10. SYMPTOMS
 Most babies with phenylketonuria appear
healthy at birth.
 Symptoms usually only develop due to
complications that arise if the condition is not
treated properly.
 If it isn't treated, damage to the brain and
nervous system can lead to:
1. learning disabilities
2. behavioural difficulties
3. epilepsy

13. Alkaptonuria
 also called black urine disease
 is an inherited genetic disorder of
phenylalanine and tyrosine metabolism.
 This condition is rare, affecting 1 in 250,000
to 1 million people worldwide. Alkaptonuria is
more common in certain areas of Slovakia
(where it has an incidence of about 1 in
19,000 people) and in the Dominican
Republic.
 Mutations in the HGD gene

14. SYMPTOMS
 Urine in an infant's diaper may darken and can turn
almost black after several hours. However, many persons
with this condition may not know they have it until mid-
adulthood (around age 40), when joint and other
problems occur.
 Arthritis (especially of the spine) that gets worse over time
 Darkening of the ear
 Dark spots on the white of the eye (sclera) and cornea

17. ALBINISM
 Albinism is caused by a genetic lack of
melanin
 Melanin is synthesized from the amino acid
tyrosine
 Tyrosinase breaks down tyrosine
 People with albinism have been passed
down a nonfunctional tyrosinase allele, which
does not allow them to produce melanin

20. Gene Action in Drosophila | Biochemical
Genetics
 Beadle and Ephrussi (1937) studied metabolic
pathway for eye colour in Drosophila. There are
three eye colours in the fruitfly, viz. wild,
vermillion and cinnabar.
 The imagine disc or primordia was transplanted
from one larva on to the abdomen of other larva.
Reciprocal eye transplantation was made
among wild, vermillion and cinnabar larvae. The
eye colour was examined when the larvae,
became adult.

22. Biochemical Pathway in Neurospora
Beadle and Tatum studied biosynthetic
pathway of arginine in Neurospora. They
reported that biosynthesis of arginine involves
several sequential steps and each step is
controlled by specific enzyme. The end product
of one biochemical reaction serves as a
precursor for the next

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