mRNA and Protein Synthesis Overview

mRNA is a type of ribonucleic acid (RNA) that carries genetic information from DNA to ribosomes, where proteins are made
mRNA is single-stranded and contains codons, which are sequences of three nucleotides that specify particular amino acids
mRNA functions as a messenger molecule for protein synthesis

A codon is a sequence of three nucleotides within mRNA that corresponds to a specific amino acid
There are 64 possible codons, but only 20 amino acids, resulting in multiple codons coding for the same amino acid

The genetic code refers to the relationship between codons and their corresponding amino acids
The genetic code is universal, meaning it’s largely the same across all living organisms, with few exceptions

Transcription is the process of copying genetic information from DNA to mRNA, which happens in the nucleus
Translation is the process of converting the mRNA code into a protein, which occurs at ribosomes in the cytoplasm
The mRNA molecule serves as a template for protein synthesis
The codons on the mRNA are read by ribosomes, which recruit specific amino acids to build the protein chain
The process of translation is driven by ribosomes and requires specific transfer RNA (tRNA) molecules, which deliver the correct amino acid to the ribosome based on the codon being read

The relationship between mRNA codons and the amino acids they encode is known as the genetic code
This code is essential for protein synthesis, which is the basis for all living organisms
The genetic code is degenerate, meaning that multiple codons can encode for the same amino acid
The genetic code is also unambiguous, meaning that a single codon will only ever encode for one specific amino acid
Understanding the genetic code is critical for understanding how genetic information is translated into proteins, which are the building blocks of life

During replication, the leading strand is synthesized continuously, in the same direction as the replication fork, meaning it is easier to replicate
The lagging strand is synthesized discontinuously, in the opposite direction of the replication fork
Due to the direction of replication, the lagging strand is synthesized in short fragments called Okazaki fragments
Okazaki fragments are then joined together by DNA ligase to form a continuous strand

The process of protein synthesis involves two main steps: transcription and translation
Transcription is the copying of DNA's genetic information into mRNA, which acts as a template for protein synthesis
Translation is the decoding of the mRNA code into a protein, which occurs on ribosomes
The sequence of amino acids in a protein is determined by the sequence of codons in the mRNA molecule
The process of protein synthesis is meticulously controlled and ensures the production of accurate proteins, essential for all cellular functions.

tRNA, also known as transfer RNA, plays a critical role in protein synthesis.
tRNA acts as a molecular adaptor between mRNA and amino acids.
tRNA binds to mRNA codons using its anticodon, and delivers the corresponding amino acid to the ribosome.
tRNA molecules exhibit variability in structure and function.
Each tRNA molecule has a specific structure that enables it to bind to a single amino acid and its corresponding mRNA codon.

tRNA is a small, single-stranded RNA molecule.
tRNA is typically 70-90 nucleotides long.
tRNA is folded into a three-dimensional structure.
tRNA contains a distinctive cloverleaf shape when viewed in two dimensions.
tRNA contains a specific region called the anticodon loop which contains three nucleotides that complementarily bind to the mRNA codon.
tRNA has a specific site for attachment of the corresponding amino acid.
tRNA interacts with multiple enzymes involved in protein synthesis.

The genetic code is a set of rules that define the correspondence between codons and amino acids.
Each codon consists of three nucleotides.
Each codon specifies a particular amino acid.
The genetic code is degenerate, meaning that there is more than one codon for most amino acids.
The genetic code is virtually universal, meaning that it is the same in all organisms.
The genetic code is non-overlapping, meaning that a single nucleotide can be a part of only one codon.

Translation is the process of converting the genetic code contained in mRNA into a protein sequence.
Translation occurs on ribosomes, which are complex molecular machines.
Translation requires several factors, including tRNA, mRNA, ribosomes, and protein factors.
During translation, tRNA brings amino acids to the ribosome, where they are linked together to form a polypeptide chain.
The polypeptide chain folds into a specific three-dimensional structure, which is the functional protein.

Transcription is the process of copying genetic information from DNA into mRNA.
Transcription occurs in the nucleus of eukaryotic cells.
Transcription requires the enzyme RNA polymerase.
During transcription, RNA polymerase reads the DNA sequence and synthesizes a complementary mRNA strand.
The mRNA strand is modified and then transported to the cytoplasm, where it is translated into protein.

The non-coding strand (also known as the template strand) is the strand of DNA that serves as a template for transcription.
The non-coding strand is not directly translated into protein.
The non-coding strand is complementary to the mRNA sequence.

During Translation, mRNA’s codons are read by tRNA.
Codons are three-nucleotide sequences that specify which amino acid is to be added to the growing polypeptide chain.
The sequence of codons in mRNA determines the order of amino acids in the protein.