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  • A Protein is a long chain-like molecule that is made up of small units known as amino acids, joined together by peptide bonds.

  • The word protein is derived from the Greek word 'proteios' which means "primary" or "in the lead".

  • Protein is essential for life, it is crucial to all cells in the body playing a key role as enzymes in a cell. After water, protein is the most plentiful substance in the body.

  • Proteins grow, maintain, and replace the tissues in our bodies. Therefore our muscles, organs, and immune systems are mostly made of protein.

  • Once protein is digested it is broken down into its amino acids. These amino acids can then be reused to make the proteins your body needs to maintain muscles, bones, blood, and body organs.

  • There are over 20 slightly differing amino acids. Our bodies can produce around 13 of these, but there are 9 amino acids that our body cannot make itself. These are called essential amino acids and we obtain these by eating certain protein-rich foods.

  • Like the other energy sources, carbohydrates and fat, too much protein can also lead to weight gain.

The first step in making a protein is called transcription. This is when the cell makes a copy (or "transcript") of the DNA. The copy of DNA is called RNA because it uses a different type of nucleic acid called ribonucleic acid. The RNA is used in the next step, which is called translation. 

The next step in making a protein is called translation. This is when the RNA is converted (or "translated") into a sequence of amino acids that makes up the protein. 

The translation process of making the new protein from the RNA instructions takes place in a complex machine in the cell called the ribosome. The following steps take place in the ribosome.

 

  • The RNA moves to the ribosome. This type of RNA is called the "messenger" RNA. It is abbreviated as mRNA where the "m" is for messenger.

  • The mRNA attaches itself to the ribosome.

  • The ribosome figures out where to start on the mRNA by finding a special three letter "begin" sequence called a codon.

  • The ribosome then moves down the strand of mRNA. Every three letters represents another amino acid molecule. The ribosome builds a string of amino acids based on the codes in the mRNA.

  • When the ribosome sees the "stop" code, it ends the translation and the protein is complete.

     

     

     

     

     

     

     

     

     

mRNA is the nucleic acid that brings the genetic info to the Ribosome.  Inside the Ribosome, the tRNA will bring the amino acid that matches the mRNA code.  Every 3 counterpart nucleotides will equal an amino acid.  These 3 nucleotides that make an amino acid are togother called a Codon.    When the amino acides are hooked together like a train, they are called a protein.  Proteins are held together by peptide bonds.  Peptide bonds are covalent.  (They share electrons.)

Unlocking the Code

Why does Uracil take the place of Thymine in mRNA?

 

A better question may be: Why does thymine replace uracil in DNA? Since it takes energy to convert uracil to thymine (by adding a methyl group), why do cells expend the energy required to methylate uracil to thymine for use in DNA?

One reason is to protect the DNA. Methylation of bases protects the DNA by making it unrecognizable to many nucleases—enzymes that can break down DNA—and thus defending it from attack by invaders like bacteria and viruses. Since RNA is shorter-lived than DNA, it can get by with the energetically “cheaper” uracil. Also, adding the hydrophobic methyl group changes the shape of the DNA molecule and allows thymine to base-pair only with adenine, whereas uracil would base-pair less selectively. Finally, using thymine allows more effective recognition and repair of potentially harmful cytosine to uracil mutations, as explained by Dr. Greg Freyer.

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