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Mystery Sequence

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Problem Set 4

Study Question 3

What is the minimum number of bases to specify the number of different amino acids found in protein?

G A C T

1 base fixed length nonoverlapping

Study Question 3

What is the minimum number of bases to specify the number of different amino acids found in protein?

2 base, fixed length, nonoverlapping

Study Question 3What is the minimum number of bases to specify the

number of different amino acids found in protein?

3 base, fixed length, nonoverlapping

Growth of E. coli on a plate

Growth of E. coli on a plate

Growth of E. coli on a plate

Growth of E. coli on a plate

Growth of E. coli on a plate

Growth of E. coli on a plate

Growth of E. coli on a plate

Infection by phage T4

Infection by phage T4

Infection by phage T4

Growth of E. coli B + phage T4

Seed plate withE.coli B and

phage T4(not visible)

Growth of E. coli B + phage T4

Growth of E. coli B + phage T4

Growth of E. coli B + phage T4

Growth of E. coli B + phage T4

Growth of E. coli B + phage T4

rII region of phage T4

rII rII

T4 rII+ T4 rII -

T4 DNA T4 DNA

rIIA rIIB rIIA- rIIB

Distinguishing T4 rII+ from rII-

T4 rII+

T4 rII -E. coli B x T4 rII+

T4 rII -E. coli K() x

T4 rII - cannot grow on E. coli K()

Why is T4rII- defective?

T4 rII -

T4 rII+

E. coli K()

E. coli K()

No infection

Lysis

Crick et al frameshift experiment

rIIA-

rIIA-

rIIA-

rIIA+

proflavin

proflavin

proflavin

How to explain frameshift results?Role of proflavin in experiment

CACTCGGATA

CACTCG??GATA

GTGAGC

GTGAGCAC

Proflavin causes one base insertions

(or deletions)

How to explain frameshift results?Wild type rIIA

rIIA+

… THE FAT CAT ATE THE BIG RAT...

Wld type rIIA

How to explain frameshift results?Single frameshift

rIIA-

THE FAT CAR TAT ETH EBI GRA …

… THE FAT CAT ATE THE BIG RAT...

How to explain frameshift results?Double frameshift

rIIA-

… THE FAT CAR TAT ETH EBI GRA …

… THE FAT CAT ATE THE BIG RAT...

… THE FAT CAR TAR TET HEB IGR …

How to explain frameshift results?Triple frameshift

rIIA-

… THE FAT CAR TAT ETH EBI GRA …

… THE FAT CAT ATE THE BIG RAT...

… THE FAT CAR TAR TET HEB IGR …

… THE FAT CAR TAR TOE THE BIG ...

Study Question 7

When will proflavin-induced mutation suppress?

Study Question 8

Results of frameshift experiment if variable length code?

This is a variable length code

This is a varitable length code

Variable length code with GATC?