PROTEIN SYNTHESIS

Four Main Stages

1. Synthesis of Amino acid

2. Transcription (formation of RNA)

3. Amino acid activation

4. Translation

Synthesis of Amino acid

IN PLANT

• occurs in mitochondria and chloroplasts

Synthesis of Amino acid

NITRATE

AMINO GROUPS

REDUCTION

AMINO ACIDS

COMBINATION WITH

A CARBON SKELETON

Synthesis of Amino acid

IN ANIMAL

• amino acids are mostly obtained through their food supply

• some amino acids can be synthesized inside their body

TRANSCRIPTION

T CAT G A T T A

A G T A C A A A T

Transcription takes place inside the nucleus.

Part of a DNA unwinds.

A G T A C A A A T

A

G

C

U

G AC G

G UU

U

Only one strand acts as a template.

A G T A C A A A T

A

G

C

U

G AC G

G UU

U

Exposed base attracts complementary RNA.

RNA POLYMERASE

A G T A C A A A T

A

G

C

G AC G

G U

U

U U

The enzyme RNA polymerase adds one complementary RNA

nucleotide to the existing one.

A G T A C A A A T

A

G

C

G AC G

G U

U

U U

The enzyme RNA polymerase moves along the DNA.

A G T A C A A A T

G

C

G AC G

G U

U

U U A

The enzyme RNA polymerase moves along the DNA.

A G T A C A A A T

G

C

G AC G

U

U

GU U A

Complementary RNA nucleotide is added to the growing chain of

mRNA one by one.

A G T A C A A A T

G

C

G AC G

U

GU U A U

Complementary RNA nucleotide is added to the growing chain of

mRNA one by one.

A G T A C A A A T

G

C

G AC G

GU U A U U

Complementary RNA nucleotide is added to the growing chain of

mRNA one by one.

A G T A C A A A T

G

C

G AC G

GU U A U U A

Complementary RNA nucleotide is added to the growing chain of

mRNA one by one.

A G T A C A A A T

G

C

G

C G

GU U A U U A U

Complementary RNA nucleotide is added to the growing chain of

mRNA one by one.

A G T A C A A A T

G

G

C G

GU U A U U A U C

Complementary RNA nucleotide is added to the growing chain of

mRNA one by one.

A G T A C A A A T

G

G

C G

GU U A U U A U C

Complementary RNA nucleotide is added to the growing chain of

mRNA one by one.

A G T A C A A A T U CAU G A U UA

mRNA

CYTOLPLASM

mRNA leaves the nucleus through the nuclear pore.

NUCLEOPLASM

Nuclear pore

A G T A C A A A T

U CAU G A U UA

mRNAmRNA leaves the nucleus through the nuclear pore.

CYTOPLASM

NUCLEOPLASM

U CAU G A U UA

mRNA

CODON CODON CODON

AMINO ACID ACTIVITION

A A U

Leucine

AC U

Aspartic

Acid

AU G

Threonine

TRANSFER RNA

AMINO ACIDS

A A U

Leucine

AC U

Aspartic

Acid

AU G

Threonine

Amino acids combine with the tRNAs using the energy from the splitting of ADP.

A A U

Leucine

AC U

Aspartic

Acid

AU G

Threonine

Amino acids combine with the tRNAs using the energy from the splitting of ADP.

A A U

Leucine

AC U

Aspartic

Acid

AU G

Threonine

ANTICODON

TRANSLATION

U CAU G A U UA

mRNA

CYTOPLASM

U CAU G A U UA

A A U

Leucine

AC U

Aspartic

Acid

RIBOSOME

mRNA attaches to the ribosome.

U CAU G A U UAA A U

Leucine

AC U

Aspartic

Acid

Complementary anticodon of the tRNA is attracted to the codon of the mRNA .

U CAU G A U UA

A A U

Leucine

AC U

Aspartic

Acid

AU G

Threonine

Complementary anticodon of the tRNA is attracted to the codon of the mRNA .

U CAU G A U UA

A A U

Leucine

AC U

Aspartic

Acid

AUG

Threonine

Peptide bond forms between the two adjacent amino acids.

U CAU G A U UA

A A U

Leucine

AC U

Aspartic

Acid

AU G

Threonine

Ribosome moves along the mRNA. Another complementary tRNA is attracted to the codon. The first tRNA is released back to cytoplasm.

U CAU G A U UA

A A U

Leucine

AC U

Aspartic

Acid

AU G

Threonine

Amino acid is linked to the previous amino acids with peptide bond.

U CAU G A U UA

A A U

Leucine

AC U

Aspartic

Acid

AU G

Threonine

A tripetide is formed.

U CAU G A U UA

A A UAC U AU G

LeucineAsparticAcid

Threonine

mRNA and tripeptide are released to cytoplasm.

SCIENCE UNIT CURRICULUM DEVELOPMENT INSTITUTE

EDUCATION DEPARTMENT

SO Chi-shing

Curriculum Officer (Biology)