| Transcription | Process by which a DNA sequence is used as a template to make an mRNA copy of a gene |
| mRNA | Single-stranded molecule of mRNA that corresponds to the genetic sequence of a gene and is read by a ribosome in the process of synthesising a protein |
| Process of mRNA Production | 1. Initiation: RNA polymerase binds to the promoter region of a gene on the DNA template in the nucleus.
2. Elongation: RNA polymerase moves along the DNA strand, unwinding it and adding complementary RNA nucleotides (A, U, G, C) to the growing mRNA strand.
3. Termination: Transcription concludes as RNA polymerase reaches the terminator sequence, causing mRNA and RNA polymerase to detach from the DNA template.
4. mRNA Processing: In eukaryotes, pre-mRNA undergoes modification, including capping at the 5' end and addition of a poly-A tail at the 3' end, along with removal of introns by splicing.
5. Export: Processed mRNA exits the nucleus and enters the cytoplasm. |
| mRNA Translation | Converting nucleic acid in the form of mRNA into a protein. A polypeptide is formed according to the sequence of codon. |
| Process of mRNA Translation | 1. Initiation: The small ribosomal subunit binds to the mRNA near the start codon (AUG), followed by the attachment of the initiator tRNA with the complementary anticodon (UAC).
2. Elongation: The ribosome moves along the mRNA in a 5' to 3' direction. Each new tRNA brings an amino acid, forming a peptide bond between adjacent amino acids. The ribosome shifts, translocating the mRNA and tRNAs.
3. Termination: When a stop codon (UAA, UAG, or UGA) is reached, release factors bind to the ribosome, causing the completed protein to detach.
4. Protein Folding: The newly synthesized polypeptide undergoes folding, guided by its amino acid sequence and cellular environment.
5. Protein Function: The mature protein carries out its specific role in cellular processes.
This process occurs on ribosomes in the cytoplasm and synthesizes proteins based on the mRNA sequence. |
| Gene Expression | Process by which information stored in a gene is used to synthesise a functional gene product |
| Gene Regulation | Process of controlling which genes are expressed by which cells, when they are expressed, and in what quantity
[which, when and what] |
| Transcription Factors | Proteins produced by regulatory gene |
| Translation Factors | mRNA finds a complementary mRNA and an enzyme then breaks it |
| Gene Cascades | Chain reaction in which the expression of one gene causes subsequent gene expression [Due to gene 1 producing a transcription factor to trigger gene 2] |
| Phenotypic Expression | The expression of physically observable traits |
| Epigenome Factors affecting Phenotypic Expression | Produce tags which determine which genes are ex/repressed. |
| Environmental Factors affecting Phenotypic Expression | External conditions, like temperature, nutrition, light, chemicals, stress, and social interactions, can alter gene activity and protein function - influences how traits encoded by genes are expressed |
| Differentiation Cell Regulation | Process by which different types of stem cells become specialised in order to perform different functions [affected by transcription and growth factors] |
| HOX Genes | Group of genes that control the body plan and segment identity during development. They regulate the spatial arrangement of body structures along the anterior-posterior axis in organisms. Produce transcription factors in a specific order |
| Sex-Determining Region Y | Located on the short arm of the Y chromosome, codes for SRY protein. Transcription factor to promote genes associated with testes formation and inhibits genes linked with female reproduction. [Transcription of SOX-9] |
