Degeneracy in genetic code

1. POWERPOINT PRESENTATION BY:
SNEHA SUSAN MATHEW (15MSI0065)
*DEGENERACY IN
GENETIC CODE

2. *

3. *TRANSLATION
 THE PATHWAY OF PROTEIN
SYNTHESIS IS CALLED
TRANSLATION BECAUSE THE
LANGUAGE OF NUCLEOTIDE
SEQUENCE ON mRNA IS
TRANSLATED IN TO THE
LANGUAGE OF AMINO ACID
SEQUENCE.
 THE PROCESS OF
TRANSLATION REQUIRES A
GENETIC CODE, THROUGH
WHICH THE INFO CONTAINED
IN THE NUCLEIC ACID
SEQUENCE IS EXPRESSED TO
PRODUCE A SPECIFIC
SEQUENCE OF AMINO ACID.

4. *
 SET OF RULES BY
WHICH
INFORMATION
ENCODED WITHIN
GENETIC MATERIAL
IS TRANSLATED INTO
PROTEINS.
 TERM GIVEN BY
GEORGE GAMOW.

5. SALIENT FEATURES OF
GENETIC CODE

6. *
THREE ADJACENT
NITROGEN BASES
CONSTITUTE A CODON
WHICH SPECIFIES THE
PLACEMENT OF ONE
AMINO ACID IN A
POLYPEPTIDE.
1 CODON = 1 AMINO
ACID

7. *
*ONE CODON CODES FOR ONLY
ONE AMINO ACID.
*EXAMPLE: AUG CODES FOR
METHIONINE.

8. *
*THE CODE IS NEARLY UNIVERSAL.
*AUG – METHIONINE
*AUG -- VALINE
*FOR EXAMPLE: FROM BACTERIA
TO HUMANS UUU WOULD CODE
FOR PHENYLALANINE ( phe ).

9. *
*THE GENETIC CODE IS
CONTINOUS AND DOES NOT
POSSESS PAUSES AFTER THE
TRIPLETS.
*IF A NUCLEOTIDE IS ADDED OR
DELETED, THE WHOLE GENETIC
CODE WILL READ DIFFERENTLY.

10. THERE ARE 64
POSSIBLE
COMBINATIONS OF 3
LETTER NUCLEOTIDE
SEQUENCES .
61 REPRESENTS AMINO
ACIDS AND 3 ARE STOP
CODONS.
NIRENBERG AND HAR
GOBIND KHORANA
PREPARED THE
GENETIC CODON
TABLE FOR VARIOUS
AMINO ACID.

11. *CODON TABLE

12. *
*SOME AMINO ACIDS MAY BE INFLUENCED
BY MORE THAN ONE CODON.
*AMINO ACIDS ARE SPECIFIED BY TWO TO
SIX CODONS.
*EXAMPLE: phe – UUU, UUC
*Arginine- CGU,CGC,CGA,AGA,AGG.
*DEGENERACY RESULTS THERE ARE MORE
CODONS TO ENCODE 20 AMINO ACIDS.

13. *DEGENERACY
*GUU = VALINE GUA = VALINE
* GUC = VALINE GUG = VALINE

14. UUU: XYU
UUC: XYC
UUA: XYA
UUG: XYG

15. *IN DEGENERATE
CODONS,GENERALLY THE
FIRST TWO NITROGEN
BASES ARE SIMILAR
WHILE THE THIRD ONE IS
DIFFERENT.

16. *
*ACCORDING TO THIS HYPOTHESIS,
ONLY THE FIRST TWO BASES OF THE
CODON HAVE A PRECISE PAIRING WITH
THE BASES OF THE ANTICODON OF
mRNA WHILE THE PAIRING BETWEEN
THE THIRD BASES OF CODON AND
ANTICODON MAY WOBBLE(NON-
SPECIFIC).

17. Nucleotide
at 5' end of
anticodon
Nucleotide
at 3' end of
anticodon
G U or C
C G
A U
U A or G
I (indosine) A, U or C

18. *
*ANY CHANGE IN THE
IN THE GENETIC CODE
CAUSES MUTATION.

19. *
*AUG GUG AGC AGG ADDITION
*AUG GUG ACG CAG G

20. *THANKYOU