What happens in cells (and what do cells need)? — OCR GCSE Biology
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What happens in cells (and what do cells need)? explained
Deoxyribonucleic acid (DNA) is a macromolecule categorized as a polymer, which means it consists of a long chain formed by linking numerous smaller repeating molecular units termed monomers.
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In nucleic acids, these individual monomers are nucleotides. Thousands of nucleotides link covalently along their sugar and phosphate groups to produce a continuous, alternating sugar-phosphate backbone. Because polymers can extend over millions of monomer units, DNA possesses the immense molecular length required to store extensive genetic information encoding all cellular proteins within an organism.
Your focus
- Define DNA as a biological polymer composed of repeating monomers.
- Identify nucleotides as the monomer units of nucleic acids.
- Describe how nucleotides link to form the sugar-phosphate backbone.
What happens in cells (and what do cells need)? exam tips
Marking Points
- defining a polymer as a large molecule made of many repeating monomer units
- identifying nucleotides as the monomer subunits that join to build DNA
- describing the repeating sugar-phosphate backbone formed by linked nucleotides
Examiner Tips
- 💡Explicitly define polymer when asked to describe DNA as one: mention repeated nucleotide monomers linked together.
- 💡Link the polymer nature of DNA to its capacity to store vast amounts of hereditary code.
Common Mistakes
- confusing the monomers of DNA (nucleotides) with the monomers of proteins (amino acids)
- calling DNA a monomer and nucleotides polymers, reversing the relationship