Alzheimer’s disease causes destruction of brain tissue, dementia and eventually death. Amyloid beta protein is produced in the human brain throughout life. In people with Alzheimer’s disease, it accumulates in excessive amounts. Outline the main steps that brain cells use to make proteins such as amyloid beta.

SSCE HSC Biology DNA and polypeptide synthesis: Alzheimer’s disease causes destr

Transcription: The process begins in the nucleus of the brain cell where the DNA is unzipped to expose the gene that encodes the amyloid beta protein. RNA polymerase then transcribes this gene into a messenger RNA (mRNA) strand.
Processing of mRNA: The mRNA strand undergoes modification, including the addition of a 5' cap and a poly-A tail, and splicing to remove non-coding regions (introns), resulting in a mature mRNA strand ready for translation.
Translation: The mature mRNA exits the nucleus and enters the cytoplasm, where it binds to a ribosome. The ribosome reads the mRNA in codons, which are sets of three nucleotides. Each codon is matched with a specific transfer RNA (tRNA) that carries a corresponding amino acid.
Amino Acid Chain Formation: As the ribosome moves along the mRNA, amino acids are linked together in the order specified by the codons, forming a polypeptide chain.
Protein Folding and Modification: The nascent polypeptide chain then folds into its functional three-dimensional shape. Post-translational modifications may also occur, which can include glycosylation or phosphorylation.
Amyloid Beta Production: Specifically for amyloid beta, the protein is a derivative of a larger precursor protein called APP (amyloid precursor protein). The cleavage of APP by enzymes results in the formation of amyloid beta peptides, which may accumulate abnormally in Alzheimer's disease.