AQA · GCSE · Combined Science

    Course version: 8464 · Version from Sept 2018

    Meiosis: copies of the genetic information are made

    Before a cell divides by meiosis, its genetic information must be copied so that each new cell receives a complete set.

    Checked against the AQA 8464 specification (opens in a new tab) on .

    • Point 4 of 7
    • 4 key terms

    Study notes

    From the checked teaching notes for this specification point.

    The idea

    Before a cell divides by meiosis, its genetic information must be copied so that each new cell receives a complete set. The genetic information is the DNA packaged into chromosomes, found in the nucleus of the cell. Before division, the DNA is replicated, so each chromosome forms two identical copies. This copying is essential because meiosis involves two divisions, producing four gametes. Without replication, the four gametes could not each receive a single set of chromosomes.

    For example: A human body cell has 46 chromosomes; after copying, there are still 46 chromosomes but each consists of two identical copies, ready for the first meiotic division.

    What earns the marks

    • Genetic information is carried as DNA in chromosomes in the nucleus.
    • The DNA is copied before meiosis begins.
    • After copying, each chromosome consists of two identical copies of the DNA.
    • The number of chromosomes is unchanged by copying, but the amount of DNA is doubled.
    • Copying ensures each of the four gametes can receive one full set of chromosomes.

    Common mistakes and how to put them right

    • Thinking the chromosome number doubles during copying.

      Put it right: The number of chromosomes stays the same, but each chromosome now has two identical copies of DNA.

    • Confusing copying with the first meiotic division.

      Put it right: Copying happens before division begins.

    • Believing gametes are produced directly from the original cell without replication.

      Put it right: Replication must occur first so that four gametes each receive a complete set.

    Exam tips

    • Link copying to the need for four gametes each with a single set of chromosomes.
    • Clearly state that the genetic material is copied before the cell divides.
    • State that copying occurs before meiosis, not during it.

    Try the lesson

    The start of the Meiosis: copies of the genetic information are made lesson, made from checked teaching notes for this specification point.

    Have a go first

    What happens to the genetic information in a cell immediately before meiosis begins?

    Listen

    Before a cell divides by meiosis, its genetic information must be copied so that each new cell receives a complete set. The genetic information is the DNA packaged into chromosomes, found in the nucleus of the cell. Before division, the DNA is replicated, so each chromosome forms two identical copies. This copying is essential because meiosis involves two divisions, producing four gametes. Without replication, the four gametes could not each receive a single set of chromosomes. For example, a human body cell has 46 chromosomes; after copying, there are still 46 chromosomes but each consists of two identical copies, ready for the first meiotic division. A strong answer earns marks for these points. Genetic information is carried as DNA in chromosomes in the nucleus. The DNA is copied before meiosis begins. After copying, each chromosome consists of two identical copies of the DNA. The number of chromosomes is unchanged by copying, but the amount of DNA is doubled. A common slip: Thinking the chromosome number doubles during copying. Instead, the number of chromosomes stays the same, but each chromosome now has two identical copies of DNA. Exam tip: Link copying to the need for four gametes each with a single set of chromosomes.

    See it

    A vertical flowchart with six boxes linked by arrows. The first box says the genetic information is DNA in chromosomes in the nucleus. An arrow leads to the second box, which says the DNA is copied before meiosis begins. An arrow leads to the third box, which says each chromosome now has two identical copies of the DNA. An arrow leads to the fourth box, which says the number of chromosomes is unchanged but the amount of DNA is doubled. An arrow leads to the fifth box, which says meiosis involves two divisions. An arrow leads to the final box, which says four gametes each receive one full set of chromosomes.
    It shows that the DNA is copied before meiosis so that each of the four gametes can receive a full set of chromosomes.

    Put it in order

    Put these steps in the order they happen.

    1. 1. Each chromosome now has two identical copies of the DNA
    2. 2. DNA is copied before meiosis begins
    3. 3. Genetic information is DNA in chromosomes in the nucleus
    4. 4. Four gametes each receive one full set of chromosomes
    5. 5. Meiosis involves two divisions
    6. 6. Number of chromosomes unchanged, amount of DNA doubled

    Key words

    Say what each word means before you turn the card.

    DNA replication

    Try answering aloud or in your head before turning the card.

    Chromosomes and DNA

    Try answering aloud or in your head before turning the card.

    Cell cycle and copying

    Try answering aloud or in your head before turning the card.

    Genetic continuity

    Try answering aloud or in your head before turning the card.

    See every definition
    DNA replication
    The DNA is copied before meiosis begins, so each chromosome forms two identical copies.
    Chromosomes and DNA
    Genetic information is carried as DNA in chromosomes in the nucleus.
    Cell cycle and copying
    Copying happens before division begins, and the number of chromosomes is unchanged by copying.
    Genetic continuity
    Copying ensures each of the four gametes can receive one full set of chromosomes.

    Label the diagram

    Some boxes have lost their names. Pick the right name for each number.

    The diagram again, with 3 boxes numbered instead of named. A vertical flowchart with six boxes linked by arrows. The first box says the genetic information is DNA in chromosomes in the nucleus. An arrow leads to the second box, which says the DNA is copied before meiosis begins. An arrow leads to the third box, which says each chromosome now has two identical copies of the DNA. An arrow leads to the fourth box, which says the number of chromosomes is unchanged but the amount of DNA is doubled. An arrow leads to the fifth box, which says meiosis involves two divisions. An arrow leads to the final box, which says four gametes each receive one full set of chromosomes.

    • 1Box 1

    • 2Box 2

    • 3Box 3

    0 of 3 labelled

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