Mitosis and the cell cycle: Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria. The DNA replicates to form two copies of each chromosome.

Q: How do I revise Mitosis and the cell cycle: Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria. The DNA replicates to form two copies of each chromosome. for GCSE?

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Q: Is this Mitosis and the cell cycle: Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria. The DNA replicates to form two copies of each chromosome. guide aligned to the AQA specification?

Yes. This guide is linked to the Mitosis and the cell cycle: Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria. The DNA replicates to form two copies of each chromosome. topic in the AQA GCSE specification.

Before division, a cell must prepare so that each daughter cell receives everything it needs.

Study notes

From the checked teaching notes for this specification point.

The idea

Before division, a cell must prepare so that each daughter cell receives everything it needs. During interphase, the cell grows, increasing its cytoplasm and making more sub-cellular structures. Ribosomes are needed for protein synthesis, and mitochondria supply the ATP required for the many reactions of division. The genetic material must also be copied: DNA replication produces two identical copies of every chromosome, each consisting of two sister chromatids held together. For example, a human body cell with 46 chromosomes replicates its DNA so that each chromosome now has two identical chromatids, while the chromosome number remains 46. This ensures that when the nucleus divides, each new cell receives a complete, identical set of chromosomes and enough organelles to function.

What earns the marks

Interphase is the stage before mitosis in which the cell grows and carries out DNA replication.
The cell increases its number of sub-cellular structures, including ribosomes and mitochondria, in preparation for division.
Ribosomes are required for protein synthesis, and mitochondria release energy for the cell's activities, including division.
DNA replication produces two identical copies of each chromosome, so each chromosome consists of two sister chromatids.
After replication, the chromosome number is unchanged; each chromosome has been copied rather than the cell gaining extra chromosome sets.
The copied chromosomes ensure that each daughter cell receives a complete and genetically identical set of genetic material.

Common mistakes and how to put them right

Thinking that the cell doubles its chromosome number during replication.
Put it right: The number of chromosomes stays the same; each chromosome is copied to form two identical chromatids.
Confusing growth with cell division.
Put it right: Growth and DNA replication occur during interphase before mitosis, not during mitosis itself.
Believing that mitochondria and ribosomes are unimportant for division.
Put it right: Mitochondria provide energy and ribosomes make proteins, both essential for the cell to divide successfully.

Exam tips

Use the term interphase when describing the preparation stage before mitosis.
Link each sub-cellular structure to its function: ribosomes for protein synthesis and mitochondria for energy release.
When explaining DNA replication, state clearly that two identical copies of each chromosome are formed and that the chromosome number does not change.

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The start of the Mitosis and the cell cycle: Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria. The DNA replicates to form two copies of each chromosome. lesson, made from checked teaching notes for this specification point.

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Before a cell divides, what happens to the DNA during the cell cycle?

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