Protein Synthesis
These are brain cells, neurons. Here you can see proteins being released at the synapse. These are carried there in vesicles carried by motor proteins
To make a protein 2 organelles are involved: the Nucleus and the Endoplasmic reticulum
To export it, it must be packaged into a vesicle, this happens in the Golgi Organelle
To power this, glucose is combined with oxygen to make carbon dioxide and water. This process releases energy, that is then trapped in ATP
Three Proteins are powered by this ATP and are involved in the creation, building and export of this protein: RNA Polymerase, Ribosome and the Motor Protein
There are 23 Pairs of Chromosomes - Each Chromosome is like a 'book'
Each Chromosome contains between 1000 and 2000 genes
Each gene is the instructions for building something
Because the Books or Chromosomes are precious, and also very very large, copies of the instructions are made
The Copies are written as messenger RNA, or mRNA
This is called messenger as it is a message that is sent from the Nucleus to the Endoplasmic Reticulum
Here we can see the protein RNA Polymerase copying the instructions from the chromosome
The RNA Polymerase is called a polymerase as it is an Enzyme (-ase) that makes polymers (long chain).
The RNA is powered by energy released from ATP
The RNA polymerase transcribes the DNA gene into a RNA message
The bases are paired up with complimentary base pairing
- if it is a C in DNA, then it is paired with a U or RNA
- DNA G is paired with C from RNA
- DNA T is paired with A from RNA
- DNA A is paired with U from RNA (not T, rather U)
The copying of the DNA Gene into mRNA by RNA polymerase is called Transcription
Transcription is to Transcribe something, that is, to make a copy
The messenger RNA is sent out of the Nucleus to the Endoplasmic Reticulum
Here there is a Ribosome - the Builder of Proteins
The Ribosome Translates the message from the language of the Nucleic Acids into the language of Amino Acids
This is called, Translation
There are only 20 amino acids, but 4x4x4 = 64possible combination of bases in a codon
So there are several possible codes for each amino acid - this is referred to as Redundancy
The Ribosome starts to read the messenger RNA
Every 3 mRNA letters is a codon
On the Transfer RNA, or tRNA, there is an Amino Acid and a 3 letter anti-codon
The Ribosome matches the 3 letter codon on the mRNA to the 3 letter anti-codon of the Transfer RNA
The Amino Acids are joined together using a Peptide Bond
As the Amino Acids join together the transfer RNA detaches.
The tRNA floats off to reattach to another amino acid in the cytoplasm
The amino acids get to the cytoplasm from these get here from the diet - eat, digest, absorb from Small intestine into bloodstream, into the intercellular space then into the cells.
The amino acid chain is now a protein
It is sent to the Golgi where it is packaged into a vesicle
The Vesicle is then carried by a Motor Protein
The Motor Protein carries the Vesicle along the Cytoskeleton to the Cell Membrane
At the Cell Membrane, the Vesicle fuses with the membrane and releases its protein into the intercellular space
It is by this way that the protein exits the cell, this is called Exocytosis
Protein Synthesis
Protein synthesis is the creation of proteins, the synthesis of proteins
There are two parts, the making of mRNA and the making of the protein
This follows the central dogma of Biology
DNA to RNA to Protein
DNA is transcribed into a messenger RNA copy.
The mRNA copy is then translated into a sequence of amino acids
These then fold up to make the structure of the protein
The structure of the protein determines its function
Transcription
RNA Polymerase unwides part of the DNA double helix to access 1 of the 2 strands of DNA
The strand that is copied is called the DNA template strand
RNA polymerase makes a copy of a gene - from DNA into RNA
To do this RNA uses complimentary base paring his has complimentary base par
G=C
T=A
A=U
The finished messenger RNA is sent out of the Nucleus
Translation
The Ribosome binds to the mRNA
The anticodon of the tRNA binds with the codon on the mRNA
A peptide bond forms between the first amino acid and the second, this continues for all subsequent amino acids forming a polypeptide chain
The tRNA releases its amino acid, the Ribosome moves along the mRNA and the tRNA is released
This proceeds until a stop codon is read
Then the Polypeptide is released
The polypeptide then folds up into a shape determined by the sequence of amino acids
This is now a Protein
The proteins function is determined by its shape and its sequence of amino acids
The Triplet Code is 3 RNA letters for each one Amino Acid
Transcription DNA is transcribed (copied) into a message called messenger RNA
Transcription RNA is translated into an Amino Acid sequence using the Triplet Code
The amino acid sequence folds up into a protein. The structure of this determines its function
How can building Lego work as an analogy for protein synthesis?
Have a look at "Truck Genes"
... what a suave Ribosome
