Genetics terminology

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  • Created on: 07-01-14 18:41
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Genetics terminology
DNA- is the molecule which contains genes. It is shaped like a double helix.
Chromosomes- X-shaped structures which are found in the cell nucleus. The
arms are made up of long coils of DNA, so chromosomes also contain genes.
Chromatids- the separate arms of the X-shaped chromosome
Centromere- the bit in the middle of the chromosomes where the arms join
Gene- a section of DNA molecule that codes for a particular protein
Allele- an alternative form of a gene
Dominant- this refers to an allele or a gene. The dominant allele is the one
which will determine the characteristic which appears.
Recessive- the allele which does not usually affect how the organism turns out
because it's dominated by the dominant allele
Homozygous- an individual with two alleles the same for that particular gene
e.g. HH or hh
Heterozygous- an individual with two alleles different for that particular gene
Genotype- a description of the genes you have e.g. Mm or RR
Phenotype- is the outward expression of the genotype. It is the description of
your physical attributes due to the genes in question.
Mitosis- is the process of cell division where one cell splits into two identical
Meiosis- is the process of cell division which creates sperm or egg cells. It only
happens in the ovaries or the testes.
Diploid- the description of cells which have all 46 chromosomes (pairs of 23)
Haploid- the description of cells which only have half the chromosomes (23)
Gamete- is either a sperm or an egg cell. All gametes are haploid.
Zygote- the name given to the newly formed human life after the gametes
have fused together at fertilisation.


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