Genetics in technology

SCIENCE IN ACTION

By MICHAEL JOHN UGLO
THIS being our 12th lecture, it is my pleasure to welcome you all.
As an anology, a computer memory emulates containment of information fed to it and because of the silicon solidstate computer memory, the binary logic device in the NAND, NOT, OR XOR, NOR and AND gates play pivotal roles.
Perfection is achieved by the latches in the toggling of the counting or progression of the binary numbers to pass on messages from one vertex to another via an edge.
If an error condition is experienced, then it should be corrected with a prompt as a feedback corrective action.
The structures to effect this function can be the repeated bits of data from the sender as a built-in from the message known as the checksum or the parity bits as software error correction codes. Or it can be an instrumentation from the hardware.
In this eventual moment, there is the message transmission or storage as intended by the programmer or it can be the user who stores his or her information in the memory of the computer.
The above scenario can be used to relate to the most perfect quarternary code that transmits via the chromosomal genes to new living things that are seen around us including both plants and animals. This is studied in the field of genetics.

Genetics
Genetics is the scientific study of the passing down of genes and traits from parents to their offspring or their progeny.
It is heredity whereby genes containing the information about their parents are transmitted to their progeny that have every information expressed by the progeny.
These include the information about their physical features such as their height, eye colours, gender and even their characters.
The information is contained in structures called chromosomes. Chromosomes are found inside the nucleolus of a cell’s nucleus.
There are two kinds of cells that the chromosomes are located in. These are the somatic cells and the germ cells. Somatic cells are any of the ordinary body cells with the diploid chromosomes.
Germ cells are the gametes which are the sperm cells and the egg cells in animals.
In plants the gametes are the pollen and the egg cells from the ovary. The sex cells are haploid and that is they contain half of the chromosomes which they form during meiosis process of cell division.
For instance, there are 46 chromosomes in humans so an egg cell or a sperm cell will contain half of that chromosome pair which is 23 chromosomes after the meiotic cell division. Chromosomes that contain the bigger polymer molecules for life are called the nucleic acids.
The two types of these molecules are known as DNA short for deoxyribonucleic acid and RNA short for ribonucleic acid.

DNA strands
There are two long strands of the DNA with a long sugar phosphate backbone helical structure that harbours four nucleobases also called the nitrogen bases. The nitrogen bases of the DNA are namely adenine, guanine, cytosine and thymine. Each paired nucleobase has a three-nucleotide structure known as a codon which has a specific coding for a particular amino acid.
This amino acid coding is the genetic coding that provides the information for the formation of a specific protein with for a specific polypeptide chain.
An example of a specific protein is the hemoglobin which is the red pigment that gives the blood its characteristic red color that adjusts it surface to attach oxygen molecule to transport it around the body.
The nucleotides house a gene that has the alleles for particular traits to be expressed by a protein.
A gene has two alleles which are one from each parent.
The RNA has a single strand of sugar phosphate backbone. It has an unpaired nucleobase or nitrogen base. In the special RNA’s case the three nuclides which are adenine, cytosine, guanine are similar but and it has uracil as its fourth nitrogen base which is different from DNA.
It is like thymine is replaced by uracil. In RNA uracil is its fourth nucleobase while in DNA thymine is its fourth nucleobase.
The RNA is seen to be present in prokaryotes and is the means by which genes are carried. In eukaryotes, the DNA is the method of gene transmission and formation of proteins. In eukaryotes, the DNA produces the RNA known as the messenger RNA (mRNA) and transfer or transport RNA (tRNA).
The messenger RNA carries the message about the from the DNA and what protein is to be made by the ribosome.
The tRNA carries the amino acid specified by the gene to the ribosome for the kind of protein that is to be made. The direction of this information is only unidirectional which means that this information about the production of a particular protein is sent from DNA to the ribosome for the production of the protein with a specific function. The information does not flow in the reverse direction.
The external environment plays an important part in influencing the genes to trigger certain effects.
Specifically, the gene transcriptions are switched on or off depending on the intracellular and extracellular conditions.
For instance, a plant seed of the same genes sown in different climatic conditions such as one in a colder temperate region and another in a hot or an arid climate will experience different growths.
The one in the colder climate will have more nutrients and water than the one in the arid condition so it will grow much taller as expressed in the phenotype than the one in the arid climate.
Their genotypes are similar but the phenotypes are different. Phenotypes are the physical expressions or manifestations seen as being tall or short or as being dark or light.

In the base pair of a five sugar phosphate strand of DNA, there are hundreds of millions of them to contain the genetic information as a molecule.
A combined sequence of this DNA or the heredity material of the chromosome is called its genome.
This DNA sequence is copied by the messenger RNA retaining the original sequence to transfer to the new copy that is replicated as a diploid pair and this happens during mitosis.
The diploid pair in meiosis is halved and there are four haploid chromosomes.
From the DNA sequence, the mRNA replicates that maintaining the nucleotide sequence which produces the particular amino acid sequences which then leads to producing the different kinds of polypeptide chain bearing the different proteins.
These various proteins produce various proteins for the body’s different functions.
There can be chromosomal cross-overs that will produce recombinant genes and chromosomes which provide the linkages to trace any genetic defect such as mutation or diseases with genetic linkages.
That is the genes have alleles that cross to another loci during meiosis or meiotic cell division and hence produce haploid cells.
The haploid cells are the germ cells that include spermatozoa (sperm cells), eggs and pollen.
The genotypes are the sets of alleles for any living organism contained as a gene. A homologous pair contains two similar alleles containing one from each parent at the same locus of the two chromosome pairs.
The one allele that has its observable traits expressed on the phenotype is called a dominant allele while the allele that does not show any traits and is dormant is called a recessive allele.
Some alleles show co-dominance characters when they show their phenotypic characters that are intermediate or in between. That is both alleles show their characters and neither being recessive nor dominant.

My Prayer for PNG today is: “Every day, every hour, every moment has been blessed by the strength of God’s love. At the turn of each tide God is there at my side, with a touch that is gentle as silence…”

Next week: Evolution in science and technology

• Michael John Uglo is the author of the science textbook “Science in PNG, Pacific, Asia and Caribbean” and a lecturer in Avionics, Auto- Piloting and Aircraft Engineering. Please send comments to: [email protected]