2019HSCShort answer

Q33 (a)

3 marks

Question

Alzheimer’s disease causes destruction of brain tissue, dementia and eventually death.
The diagram shows the effect of Alzheimer’s disease on the brain.
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.

Try the question before revealing the answer.

Solution

Criteria	Marks
Outlines processes of transcription AND translation	3
Provides features of transcription AND/OR translation	2
Provides some relevant information	1

Sample answer:

The DNA is unzipped and a complementary mRNA strand is transcribed. The mRNA moves to the ribosomes where translation occurs. Each codon is matched to a tRNA molecule with a complementary anticodon and carries a specific amino acid. The amino acids are joined together to form a polypeptide/protein.

Supplied marking guidance · human reviewed

Compare this with your working, not only your final sentence.

Syllabus alignment

Module 5 · Heredity

DNA and Polypeptide SynthesisAnalyse the function and importance of polypeptide synthesis.
DNA and Polypeptide SynthesisModel transcription and translation, including the roles of mRNA and tRNA.

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