From DNA to genomes
The genetic material in the nucleus of a cell is made up of a chemical called Deoxyribonucleic acid. The material inside the nucleus of cells, carrying the genetic information of a living being.. DNA is a A large molecule formed from many identical smaller molecules known as monomers., made of many smaller units called nucleotides. A nucleotide is made of a sugar and a phosphate group, with one of four different bases, A, C, T or G, attached. The nucleotides join together, forming two strands. These, in turn, form a The shape of the DNA molecule, with two strands twisted together in a spiral. structure. The double helix is held together by weak hydrogen bonding between complementary base pairs. Base A always pairs with T, and C always pairs with G forming a twisted ladder structure called a double helix. It carries the The code formed by the order of the bases in DNA that determines an organism's characteristics., which determines the characteristics of a living Living entity, eg animals, plants or microorganisms..
Chromosomes
The cell's The nucleus controls what happens inside the cell. Chromosomes are structures found in the nucleus of most cells. The plural of nucleus is nuclei. contains The structure made of DNA that codes for all the characteristics of an organism.. These are long threads of DNA, which are made up of many The basic unit of genetic material inherited from our parents. A gene is a section of DNA which controls part of a cell's chemistry - particularly protein production..
Genes
A gene is a small section of DNA in a chromosome. Each gene codes for a particular sequence of amino acids in order to make a specific protein. It is the unit of Genetic information that determines an organism's characteristics, passed on from one generation to another. To do with passing genes to an offspring from its parent or parents., and may be copied and passed on to the next generation.
The diagram shows the relationship between the cell, its nucleus, chromosomes in the nucleus, and genes.
Genome
The The complete set of DNA found in an organism. is one copy of all an organism's DNA. In humans this is all the DNA that makes up the 23 pairs of chromosomes found in all diploid body cells. That is all the cells except sex cells or gametes, which only have half of a person's genome.
The Human Genome Project
The Human Genome Project, or HGP for short, was started at the end of the last century. It was very ambitious and had several aims, including:
- to work out the order or sequence of all the three billion base pairs in the human genome
- to identify all the genes
- to develop faster methods for sequencing DNA
The sequencing project was finished in 2001, and work continues to identify all the genes in the human genome. The HGP used the DNA of several people to get a sort of average sequence, but each person has a unique sequence (unless they have an identical twin).
Mapping of a person's genome can help in predicting how likely they are to develop certain conditions. Scientists and doctors are also now beginning to use the information they have discovered in the HGP to help make more effective medicines as the effectiveness of medicines can be affected by variations in alleles.
Discover more about DNA and the genome with Dr Alex Lathbridge
Listen to the full series on 成人快手 Sounds.
In this podcast, learn the key facts about DNA: what it is, how it's made and how it works.