↓

1.2. ↓

• DNA 々 (self replication)(nucleodide) mRNA ㌹ (transcription(polypeptide) ゼ(translation

• mRNA DNA ㌹ (reversetranscription)

DNA(Sequence ofnucleotides)

mRNA(Sequence ofnucleotides)

Polypeptide(Sequence of amino acids)

transcription translationreplication

㌹

• ┞ (A-U, T-A, G-C, C-G) DNAmessenger RNA (mRNA)

• DNA (sense strand 3’ ’) ㌹(antisense strand) DNA々

• RNA㌹ (RNA polymerase) DNA promoter DNA よ ㌹ ㌹

mRNA DNA• RNA㌹ ㌹ (terminator) ㌹

A:adenin:U:uracilG:guanineC:thymine

A T C C G T A T C G C T A A

U A G G C A U A G C G A U U

5’3’

D.L. /E.W./ ┐ゼ

AAAA

• ┷ ㌹ RNA mRNA• 5’❻ Cap• 3’❻ Poly-A tail• さ ( intron) (

exon) ( splicing) ゼmRNA

5’ Cap 3’

AAAA5’ Cap 3’mRNA

splicing

• mRNA (codon)• (triplet)• 64 61 AUG

UAA, UAG, UGA nonsense• 々 degeneracy•• mRNA よ

U U U U U U U U U U U U U U U U U U U U U

Phe PhePhe Phe PhePhe Phe

Phe

Leu

Leu

Ile

Met

Val

Ser

Ser

Pro

Thr

Ala

Tyr

StopStop

Stop

Cys

Trp

Arg

Arg

GlyAsp

Asp

His

Gln

Lys

Glu

• mRNA (ribosome) 々transfer RNA (tRNA) -tRNA ㎲

- tRNA DNA ㌹(anticodon) 3

• ㈻ribosomal RNA (rRNA)

• ゼ mRNA AUG UAA, UAG, UGA• mRNA 々 ゼ

• 3 mRNA• -tRNA tRNA

ゼ

A U G C C C G A A G A A G A A C C C C C C G A AG G GG G G

Glu

C U U

GluGlu

GluPro

Met

ProPro

C U U

Peptide bond

mRNA

tRNA

• mRNA mRNAt-RNA ㎲

よ

↓

↓

• Silent mutationAGG CGG

• Neutral mutationAAA AGA

• Missense mutationGAG GUG

• Nonsense mutation ㈻CAG UAG

• 3 ゼ(frame shift)

A U G A A U C U C U U U G U G G G U A G G

insertion

deletion

A U G A A U G C U C U U U G U G G G U A G G

Met Asn Leu Phe Val Gly Arg

Met Asn Ala Leu Cys Gly Stop

A U G A A U U C U U U G U G G G U A G GMet Asn

Sickle-cell anaemia

Haemoglobin2 αpolypetides (141 amino acids)

2 βpolypetides (146 amino acids)

β-chainHbA (normal): Val-His-Leu-Thr-Pro-Glu-Glu-

GTGCACCTGACTCCTGAGGAG

HbS (abnormal): Val-His-Leu-Thr-Pro-Val-Glu- GTGCACCTGACTCCTGTGGAG

↓

• ↓ ↓• ↓ ↓

• ↓↓ 100

↓• ↓ ↓• X α β γ ㈻

↓ ↓mutagen

• ↓ ⒬ ㈻(carcinogen• ↓• ↓

• ↓ DNA

• DNA freeradical DNA

• ↓ ┞

• DNA thymine dimerDNA ㌹ 々

• っ

• 5-BU DNA ㎲ ぞ

A=T A=BUA=T

G BU

G C

A=BU

substitution

• DNA

• 々proofreading, mismatch repair,

photoreactivating enzyme, excisionrepair DNA々

• オ ┞

error-prone DNA々trasnlesion

DNA synthesis• 々 ↓

↓

G

DNA polymerase

Proofreading