Biology (school) · Part 05
Genes and inheritance
How instructions pass from parents to children and how cells divide.
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- DNAA long molecule shaped like a twisted ladder that carries the instructions for building and running a living thing.
- GeneA short section of DNA that holds the instructions for making one protein.
- ChromosomeA long, coiled strand of DNA containing many genes. Human body cells have 23 pairs.
- AlleleA different version of the same gene. For example, a gene for eye colour has more than one allele.
- Dominant and recessive allelesA dominant allele shows up even if you have only one copy. A recessive allele shows only if you have two copies.
- Genotype and phenotypeGenotype is the alleles an organism has. Phenotype is the feature you can see, such as eye colour.
- Punnett squareA grid that shows all the possible combinations of alleles from two parents and how likely each is.
- MitosisCell division that makes two identical cells. It is used for growth and for repairing the body.
- MeiosisCell division that makes four different sex cells, each with half the usual number of chromosomes.
- Sex chromosomesThe pair of chromosomes that decides whether a person is female (XX) or male (XY).
- Inherited disorderA condition caused by faulty alleles passed from parents to children.