Download Protein Synthesis

Protein Synthesis
Comparison of
DNA and RNA
DNA
Found in
nucleus
Double
strands
Bases – A, T,
G, C
Deoxyribose
sugar
RNA
Found in
nucleus and
cytoplasm
Single strand
Bases – A, U,
G, C
Ribose sugar
Insulin
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Hormone made in the pancreas
Controls blood sugar levels
Glucose
Glycogen
Encoded for by gene found on 11th chromosome
2 chains (A and B) joined by bonds
Transcription
Part of chain B
sequence.
Uncoiled DNA
double helix
which has split
exposing bases
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First stage of protein synthesis
Occurs in the nucleus
Double helix uncoils
Double strands split
DNA strand acts as template for formation of mRNA
(messenger RNA)
Transcription
Single strand
of DNA
coding for
Chain B
Strand of
mRNA copied
from DNA
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Free RNA nucleotides in the nucleus base pair with
DNA nucleotides A-T, T-U, G-C, C-G
Strong bonds form between phosphate group and
ribose sugar of neighbouring RNA nucleotides
Catalysed by enzyme RNA polymerase
mRNA moves out of nucleus through nuclear pore
Translation
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Second stage of protein synthesis
 Occurs on ribosomes in cytoplasm
 Code on mRNA is used to make protein chain
Translation
Role of Rough Endoplasmic
Reticulum
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Network of
membranes
Found in cytoplasm
Has ribosomes on
surface
Proteins produced
during translation pass
into ER
Role of Golgi Apparatus
Found in cytoplasm
 Flattened sacs
which are
continually formed
 Involved in
processing and
packaging proteins
 Vesicles bud off
with processed
protein
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Secretion
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Also called exocytosis
Vesicle which has pinched off Golgi apparatus moves
towards cell membrane
Membrane of vesicle fuses with cell membrane
Insulin secreted from cell
Comparison of mRNA and
tRNA
mRNA
 Messenger RNA
 Made in nucleus
during transcription
 Moves to cytoplasm
 Codes for protein
 Base triplets - codons
tRNA
 Transfer RNA
 Found in cytoplasm
 Involved in translation
 Assembles amino acids
into correct order for
proteins
 Anti-codons present