A glossary of genetic terms

Gregory Mendel studied inheritance in common garden peas. He established the fundamentals of genetics in the 1850s. He only discovered the changes from parent to offspring. He worked in Austria in a monetary.

DNA – deoxyribonucleic acid

RNA – ribonucleic acid

Both RNA and DNA are genetic codes which hold information about the plants. RNA reads DNA base genes.

DNA is made up of 4 chemical building blocks called bases. Each base has two parts, a glucose component which is the same in all four bases linked to a nucleotide. There are four nucleotides in DNA monocles giving the four different bases. The initial letters are (A) adenine, (C) cytosine, (G) guanine and (T) thymine are commonly used to identify the bases. The glucose components link each base together. The bases form into strings of tremendous length, reflecting the large quality of information they store. DNA is in a double helix shape and if unravelled it would reach 1.7 metres long containing about 10,000 genes.

A simple three letter code is called a codon which represent amino acids. A protein consists of a string of amino acids anything from about 100 to several hundred. There are 20 naturally occurring amino acids which are presented by a least one distinct codons. There are several amino acid methionine which identifies the start of a gene and there several codons that can mark the end of a gene.

Tell plant cells – contained in the RNA like a second wave of genes which help to read. It can also switch on and off cells.

Regulatory or control sequences – control overall DNA and help to sort the genetic information and regulates how much a plant cell reads the genes.

Protein coding sequences – create bases like writing down information.

DNA is read by a cluster of enzymes that physically move along the DNA strand, and under the direction of the regulatory sequences make copies of RNA. This copying process is called transcription. As RNA and DNA function in the same way making multiple identical copies if the genes.

These new copies distribute to another type of enzyme cluster, which reads the RNA. Recognises each group of 3 nucleotides and matches to the appropriate amino acid to each codon. These enzymes are translating the genetic codes into proteins. Not all DNA creates proteins; some even create some of the key chemical components in the transcription/translation apparatus.

Transcription factors in regulation

They copy RNA and DNA prior to protein synthesis

They produce flowers in K C A and G. (Look in Flower Formulae).

Copies of genomes are called haploids.

Polyidisation resulting in multiple copies of genomes in plants. Some chemicals can induce polypoids which increase cell division.

Triploids – three copies of genomes.

Hexapliods – six copies of genomes.

Colchicines – a naturally occurring toxic compound found it autumn crocus is used to induce polypoids. Some breeders have used polyploidisation to try to produce new varieties. Polypoids are usually associated with large flowers and later flowering. Many cultivated plants contain polypoids such as potatoes, daffodils and cyclamen.

Most plant cells contain two copies of genomes. In developing flowers, buds, eggs and pollen. Forming gametes or germ cells. These cells go through meiosis this ensures that only one (genome) copy is passed on to the daughter cells.

A fertilised egg with pollen is called zygote, which contains two copies of the genomes. The fertilised egg undergoes mitosis the moist common cell division.

Meiosis has a second function that ensure that both parent genomes mix their information before gamete formation is called recombination. In new plant cells the parent chromosomes split and join with the opposite kind and mix to become a new DNA strand.

The active and inactive forms of genes are called allelic. Trait controlled by the two alleles is called allelic variation.

Gardeners know mutation as sports. It occurs when errors happen in the copying process in DNA. They maybe induce by natural or artificial radiation. Viruses and or transposable elements.

In the 1960s and 1970s the groundbreaking work of Barbara McLintock on unstable genetic traits in maize lead to the understanding of transposons. They are naturally occurring fragments of DNA that are able to move around the genome by cutting themselves out of DNA and in again elsewhere. Encoding a few genes they are special sequence of the base at each end. They have influences on flower colours, which make variegation such as strips and stops.

Hetero and homozygosity – plant cells contain two copies of gemones, cross species are not included. These genes will be the same, controlling the same characteristics and in the same location long the DNA. Most are inbred.

Genetic locus – where the alleles are present at each location in DNA.

Plants in which two gemones carry identical alleles at all gene louci are described as homozygoisous (homo meaning the same).

F1 plants are all the same.

F2 inherit most genes from their grandparents.

Dominate alleles – they mask the recessive alleles, these control the main genes.

Recessive alleles – these types of genes come back every other generation, for example grandparent’s genes to grand children’s. Allele relationships are not that straight forward and can be complex.

Genotype – a main controller in appearances from plant genes, phenotype main contributors to flowers.

Heterozygous species tend to be perennials.

Inbreeding may lead to loss of vigour, size and fertility.

Homozygous species are in breeders, they are adapted to self pollination which are highly adaptive.