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Question 21 (3 marks) (a) Identify the components of a nucleotide - HSC - SSCE Biology - Question 21 - 2023 - Paper 1
Question 21
Question 21 (3 marks) (a) Identify the components of a nucleotide. .................................................................................. (b) A sectio... show full transcript
Worked Solution & Example Answer:Question 21 (3 marks) (a) Identify the components of a nucleotide - HSC - SSCE Biology - Question 21 - 2023 - Paper 1
Step 1
Identify the components of a nucleotide.
Answer
A nucleotide is composed of three main components:
- Sugar: This is a five-carbon sugar known as deoxyribose in DNA.
- Phosphate group: This group connects the sugars of different nucleotides together, forming the backbone of the DNA strand.
- Nitrogenous base: This can be one of four types — adenine (A), thymine (T), cytosine (C), or guanine (G).
Step 2
Complete the diagram labelling the complementary mRNA strand formed from CAGT.
Answer
The complementary mRNA strand generated during transcription from the DNA sequence CAGT would pair nucleotides based on base pairing rules:
- C pairs with G
- A pairs with U (since RNA contains uracil instead of thymine)
- G pairs with C
- T pairs with A
Thus, the complementary mRNA strand would be: G U C A.