Protein Synthesis

 Introduction

Synthesis itself means to "make something". So, protein synthesis means to make protein.

( protein.https://dictionary.cambridge.org/dictionary/english/synthesis )

DNA has the genetic information that codes for the color of our eyes and hair. Let's take eye color as an example. To have that pigment, you have genes, which are portions of DNA, that can code for proteins that help make that pigment. So, if we're talking about Protein Synthesis. It's talking about how DNA can lead in the making of Protein. 

Proteins do a lot more stuff than giving the pigment to our eyes. The structural support, biochemical catalysts, hormones, enzymes, building blocks, initiators of cellular death, and many more. 

In protein synthesis, we can look at two major steps. One is transcription and the other is translation. Remember, transcription always comes first, then translation.

Genes

A polypeptide is coded for by a gene, which is defined as a sequence of nucleotide bases that forms part of a DNA molecule. While there are some genes that are unusually small or large, most are around 1000 to 2000 nucleotide bases in length.

Although it is not quite true in males, owing to the existence of the Y chromosome , humans have 23 different chromosomes, with two copies of each one,

making 46 in all. The position of a gene on a chromosome is called its locus. For example, the gene that determines the structure and function of the B-chain polypeptide of the haemoglobin molecule is found on chromosome 11

Transcription

Transcription is when they 'transcribe' the DNA into a message through RNA. DNA is valuable, it'll be a problem if it got damaged, the cell does not have correct instructions for making proteins, and is likely to die. So, the DNA is kept in the nucleus. Basically "DNA ->RNA".

In order to make proteins, RNA must do a 'master copy' carried and transferred to the ribosomes, which are found in the cytoplasnm. To do this copy or 'master copy' the RNA must copy the gene of the DNA, called the primary RNA transcript, or "Primary Transcript" for short. It's also can be called pre-mRNA, 'M' stands for messenger.

As we now the structure of RNA is similar to that of a single strand of DNA.

(https://www.genome.gov/genetics-glossary/Transcription)

1. DNA helicase, an enzyme that catalyes or unwinds the double helix by breaking of hydrogen bonds between the DNA strands

2. The bases of free RNA nucleotides then join, by complementary base pairingm with the exposed DNA bases on the template strand.

3. Another enzyme, RN polymerase will connect complementary RNA bases to the DNA. As the RNA polymerase moves along the template strande, it produces a single-stranded molecule of RNA called the primary transcript or pre-mRNA.

    And pre-mRNA matures into mRNA by an enzyme called RNA polymerase II catalyze the formation of a pre-mRNA molecule, which is then processed to form mature mRNA.

Translation

    Then the messenger RNA (mRNA) go out from the nucleus into the cytoplasm where it's going to attach to a ribosome. Ribosome make protein. The ribosome is made of rRNA, the 'r' stands for ribosomal RNA. The ribosome is where protein synthesis takes place, the next step which is translation!

    The ribosome reads the code in the messenger RNA to produce a chane made up of amino acids. There are 20 different types of amino acids.

    In translation, the code on the mRNA is used to assemble the amino acids of the protein on correct order. This involves another type of RNA, called transfer RNA (tRNA). Every cell contains thousands of RNA nucleotides, folded round to make three lobes, held together by hydrogen bonds between complementary base pairs. The tRNA molecules are often described as being shaped like a clover leaf. Each tRNA has three unpaired bases, anticodon, usually shown at the base of the molecule.

Book pg. 172&173

( https://www.youtube.com/watch?v=gG7uCskUOrA )

After the codons are paired the amino acids gathered up together and turns into a polypeptide

Many ribosomes often work together on the same length of mRNA, each treanslating a particular part of it,

( https://www.youtube.com/watch?v=oefAI2x2CQM&t=252s )

This is the mRNA codon Chart. THis is how we now what kind of amino acids.

AUG is also considered a start codon as methionine is typically going to be the first amino. Some combination of bases act as 'START' and 'STOP' codons when transcribed into RNA.