Biology · Paper 1
Cell Division
How cells copy themselves. Chromosomes, genes and DNA, the cell cycle and mitosis, and stem cells: what they are, where they are found and how they could be used in medicine and in farming. Matches AQA Biology topic 4.1.2, and the mitosis and stem cell sections of Edexcel and OCR. Every lesson is for both Combined Science and separate Biology, at Foundation and Higher.
Lessons
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1
Chromosomes, Genes and DNA
Every cell nucleus holds a full set of instructions for building the organism. This lesson shows how those instructions are stored, from the nucleus down to a…
9 terms -
2
The Cell Cycle and Mitosis
New cells are made when existing cells divide. This lesson follows a cell through the cell cycle, shows what happens to the chromosomes in mitosis, and…
10 terms -
3
Stem Cells
A stem cell has not yet decided what to become. This lesson explains what makes a cell a stem cell, where stem cells are found in embryos, in adult animals and…
8 terms -
4
Using Stem Cells
Stem cells could be used to replace cells the body has lost, and plant stem cells are already used to make copies of useful plants. This lesson covers how…
8 terms
Key terms in this chapter
All 35, gathered from every lesson.
- Nucleus
- The part of a eukaryotic cell that contains the genetic material and controls the cell's activities.
- Chromosome
- A long, coiled molecule of DNA in the nucleus that carries a large number of genes.
- DNA
- The molecule that stores genetic information, made of two strands twisted into a double helix.
- Gene
- A short section of DNA that contains the instructions for making a particular protein.
- Double helix
- The shape of a DNA molecule: two strands twisted around each other.
- Body cell
- Any cell of the body other than the sex cells (egg and sperm). It has chromosomes in pairs.
- Pair of chromosomes
- Two chromosomes of the same size that carry the same genes, one inherited from each parent.
- Genome
- All of the genetic material in an organism.
- Genetic material
- The DNA that carries the instructions for building and running an organism.
- Cell cycle
- The series of stages a cell goes through to grow, copy its DNA and divide into two cells.
- Mitosis
- The stage of the cell cycle in which one set of chromosomes is pulled to each end of the cell and the nucleus divides.
- DNA replication
- The copying of DNA, so that there are two identical copies of each chromosome.
- Daughter cell
- One of the two cells formed when a cell divides.
- Genetically identical
- Having exactly the same genes.
- Clone
- An organism, or cell, that is genetically identical to its parent.
- Growth
- An increase in the number of cells (and so in the size of an organism).
- Repair
- Replacing damaged cells with new ones made by mitosis.
- Asexual reproduction
- Reproduction with one parent only, using mitosis, so the offspring are genetically identical to it.
- Sub-cellular structure
- A structure inside a cell, such as a nucleus, a mitochondrion or a ribosome.
- Stem cell
- An undifferentiated cell that can divide to make more cells of the same type and can differentiate into specialised cells.
- Undifferentiated
- Not yet specialised for any particular job.
- Differentiation
- The process by which a cell changes to become specialised for its job.
- Specialised cell
- A cell with structures that suit it to doing one job, such as a nerve cell or a red blood cell.
- Embryo
- An organism in the earliest stage of development, before it is born or hatched. A human embryo begins as a ball of cells.
- Embryonic stem cell
- A stem cell from an early embryo, able to become most types of human cell.
- Bone marrow
- The soft tissue inside bones, where stem cells make blood cells.
- Meristem
- Plant tissue at the tips of shoots and roots that contains stem cells and can become any type of plant cell.
- Therapeutic cloning
- Making an embryo with the same genes as a patient, so that its stem cells can be used in treatment without being rejected.
- Rejection
- When the body's immune system attacks cells or tissue that it recognises as foreign.
- Clone
- An organism, or cell, that is genetically identical to another.
- Diabetes
- A condition in which the body cannot control the level of glucose in the blood, because not enough insulin is made or it does not work.
- Paralysis
- Loss of the ability to move part of the body, often because nerve cells have been damaged.
- Ethical objection
- A moral argument against doing something, such as destroying an embryo.
- Viral infection
- A disease caused by a virus. Stem cell treatments risk passing one on.
- Disease resistance
- The ability of a plant to avoid or withstand a particular disease.