State means to give a specific name, value or other brief answer without explanation or calculation.
The chromosome is composed of two main molecules.
a) DNA
b) Proteins called histones.
This image was taken shortly after DNA a replication but before the prophase. It is composed of two daughter chromatids joined at the centromere.
The chromosome is super coiled by a factor around x16,000. The DNA molecule is about 1.8m long but is located in the nucleus which is only 10um in diameter!
4.1.2 Define gene, allele and genome. (1)
Define means to give the precise meaning of a word, phrase or physical quantity.
Gene:a heritable factor that controls a specific characteristic.
Allele: one specific form of a gene, differing form other alleles by one or a few bases only and occupying the same gene locus as other alleles of that gene.
Genome: the whole genetic information of the organism.
4.1.3 Define gene mutation. (1)
Define means to give the precise meaning of a word, phrase or physical quantity.
Gene mutation is a change in the base sequence of an allele.
The changed base sequence may produce a different amino acid sequence in the protein translated.
The changed base sequence may not change the protein because of the degenerate nature of the genetic code.
The expression of the mutated gene may or may not be beneficial to the organism.
Substances that cause mutation are called mutagens and include chemicals and radiation.
Mutation was coined by Hugo de Vries a dutch researcher who at the time was testing the work of mendel. His research at the begriming of the 20th Century even suggested that sudden changes in gene might explain an evolutionary 'jumping' mechanisms rather than the gradual mechanisms suggested by Darwinism. Subsequently it has been shown that the plant that de Vries was working on has unusual genetic behaviour.
Mutations are not rare, even as you