Genes expression

• Gene is a section of the DNA that carries the code to make a specific molecule, typically a protein
• Protein is made up of amino acids joined together by peptide bonds.
• The sequence of amino acids determines the shape and function of the protein.
• Codon is a group of 3 nucleotides in DNA and RNA which acts as a code in the placing of an amino acid in a protein molecule
• Triplets is the sequence of 3 nucleotides that forms a unit of genetic code in a DNA or RNA molecule. Each triplet, also called a codon encodes a specific amino acid or a stop signal.
• START CODON (codes for the amino acid methionine): AUG
• STOP CODON (doesn't code for a specific amino acid): UAA, UAG, UGA
• Genetic code is a series of rules that define how genetic information stored within nucleotides is transcribed and translated into functional proteins.
• The genetic code works like a recipe with 3 letter "words"/triplets/codons that tell cells how to make proteins. Each "words" stands for an ingredient (amino acid) in the protein. Some "words" start or stop the process. The order of these "words" decides the order of ingredients in the protein.
• Transcription is the first step in process of cells producing proteins. The structures of the cell identify the start and the end of a gene and read the DNA sequence between them (A-T and C-G) to create a matching mRNA message resembling single-stranded RNA
• Translation is the second step in the process of cells producing proteins. A ribosome receives the mRNA molecule and begins to build a chain of amino acids (the ribosome used mRNA to make proteins). The ribosome 'reads' the mRNA in sets of 3 letters (codons), following the instructions to add specific amino acids in a chain, creating a protein.
• Gene expression is the process of reading the information stored within a gene to create a functional product, typically a protein or even non-coding strands of RNA.
• Gene expression is crucial for maintaining life because it allows living organisms to produce proteins and products.
• For rRNA and tRNA, only transcription and RNA processing occurs when making a protein chain/polypeptide
• PROCESS OF GENE EXPRESSION:

  1: Transcription - copies the DNA into pre-mRNA

  2: RNA processing - modifies the pre-mRNA molecule to produce mRNA

  3: Translation - deciding of the mRNA strand into a polypeptide/protein chain
• The process of transcription can be broken down to INITIATION, ELONGATION, and TERMINATION.
• Initiation involves the binding of an enzyme called RNA polymerase to the promoter region on the DNA template strand. This causes the double helix structure to unwind slightly so that one of the two strands can serve as a template for synthesizing a complementary copy of itself.
• Termination refers to the end of the transcription process where the newly formed RNA molecule separates from the DNA template strand and detaches from the RNA polymerase.
• During elongation, the RNA polymerase moves along the DNA template strand, adding nucleotides to the growing RNA chain according to base pairing rules. As the RNA polymerase continues moving along the DNA template strand, it reads the sequence of bases and adds corresponding nucleotides to the growing RNA chain.
• In eukaryotes, there are three types of RNA polymerases involved in transcription: RNA polymerase I, II, and III.