Amyloid beta protein is produced in the human brain throughout life - HSC - SSCE Biology - Question 33 - 2019 - Paper 1
Question 33
Amyloid beta protein is produced in the human brain throughout life. In people with Alzheimer's disease, it accumulates in excessive amounts.
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Worked Solution & Example Answer:Amyloid beta protein is produced in the human brain throughout life - HSC - SSCE Biology - Question 33 - 2019 - Paper 1
Step 1
Step 1: Transcription
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The process begins in the nucleus, where the DNA containing the gene for amyloid beta protein unwinds and unzips. This allows for the synthesis of a complementary messenger RNA (mRNA) strand, which serves as a template.
Step 2
Step 2: mRNA Processing
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Once synthesized, the pre-mRNA undergoes processing. Introns (non-coding regions) are spliced out, and a 5' cap and poly-A tail are added to the mRNA for stability and export from the nucleus.
Step 3
Step 3: Translation
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The processed mRNA exits the nucleus and enters the cytoplasm, where it binds to ribosomes. Here, the mRNA is read in codons, and each codon corresponds to a specific amino acid, delivered by transfer RNA (tRNA) molecules.
Step 4
Step 4: Protein Synthesis
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Amino acids are linked together in a specific sequence as dictated by the mRNA, forming a polypeptide chain. This chain then folds into the functional amyloid beta protein, which may be secreted or maintained within the cell.
Step 5
Step 5: Protein Accumulation in Alzheimer's Disease
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In Alzheimer's disease, the regulatory mechanisms governing protein production and clearance are disrupted, leading to excessive accumulation of amyloid beta protein, which can form plaques and contribute to neuronal damage.
