SCIENCE IN ACTION
MICHAEL JOHN UGLO
WELCOME to our second lecture combining the vast topics of living things and microscopes. When we talk about living things we have to navigate outside parameters as well as within.
These will be from the molecular level to the organisms and species, then to populations and to the ecosystems and the biomes and biosphere at large as a functioning realm. Areas such as the professions each organism holds at the species levels are defined in the studies of ecological niches.
The use of microscopes particularly unveils detailed information about delicate intertwined structures and morphology revealing detailed anatomy with biochemistry and warrants studies in sciences such as molecular biology with the ecosystem parameters. Also horizontal transfer of genes by microbes from the environment are one such area in the entire natural selection process to give rise to the biological diversity we have on earth.
Living things include both plants and animals as well as micro-organisms also known as microbes. Living things are basically those which have life and those individuals which are called organisms. Organisms are able to send and receive signals. These are also open systems which are also self-sustaining processes. They maintain a positive and negative feedback mechanism called homeostasis to maintain a balanced system. Organisms have metabolism, have life cycles, are made of cells and adapt to different environmental and climatic conditions. They can grow, move, reproduce, respond to stimuli and excrete.
Organisms are said to evolve from the abiogenesis process – from non-living mater to living matter which is also called spontaneous generation. The synthesis of the building block of the living matter in the RNA (ribonucleic acid) and DNA (deoxyribonucleic acid) as the molecule for life come about to form proteins from the amino acids. Through the process of polymerisation in these different combinations of amino acids including adenosine, thymine, cytosine and glutamine genes and chromosomes are formed.
Different forms of complex organic molecules are found in the solar system and in the interstellar space providing a hint that life must have evolved from non-living matter. Also at the atomic level, there is the protein’s ability to bind metals for the transfer of electrons in biological systems. The inclusion of inorganic elements such as carbon, hydrogen, oxygen, nitrogen and sulfur are synthesised from inorganic compounds for protein formation. The building blocks for proteins are amino acids that make all the complex life forms such as plants and animals as well as microbes.
The different life forms that come in bacteria, archaea, plants, animals, protists and fungi are derived from two kinds of cells called the prokaryotes and the eucaryotes. Prokaryotes are guessed to be the beginning of all life forms because they are unicellular and have a very simple structure compared to eukaryotes. These cells have a nucleoid that is like a nucleus and contains the genetic information in their DNA that are bundled together. The structure of their DNA is circular. They have a cytoplasm with few cell organelles such as nucleoid, ribosomes, cell walls, cell membrane also known as plasma membrane, capsule, pili, fimbriae and flagella. Bacteria and archaea are said to be procaryotic. Other organisms are eukaryotic and include all multi-cellular organisms. Prokaryotic cells do not have mitochondria also known as the power house for the eucaryotic cells.
Eucaryotic cells have very detailed cell organelle structures that are membrane-bound like the nucleus while the prokaryote is not. All the multi-cellular organisms including plants, animals, algae, fungi and even unicellular organisms such as protozoa are eukaryotic cells. They have a membrane-bound nucleus and within the nucleus is the section called nucleolus that produces the ribosomal RNA. They have cytoplasm, ribosome, vacuole and vesicles, endoplasmic reticulum, nucleus, nucleolus, plasma membrane or cell membrane, cytosol, mitochondria and cell wall.
Procaryotic and the eucaryotic cells have in common the cytoplasm, cell membrane or plasma membrane, DNA and the ribosomes. Ribosomes are responsible for the synthesis of proteins.
2.2 – The Microscope
The microscope is a laboratory device and instrument that is made to see very small things indivisible to the eye especially biological specimen, fungi and algae. Microscopes enabled man to discover the cells being the basic building block for all the living things. The detailed parts of the cells called the cell organelles are discovered and known in detail. That also goes on to the
discovery of the genes which is the molecule that contains the genetic information called the DNA, short for deoxyribonucleic acid and also the RNA whose function is to convert the information contained in the DNA into proteins. Further on, the transfer RNA (tRNA) then carries the appropriate amino acids to the ribosome to be included in the synthesis of the new protein. All these information is discovered with the use of the microscopes when the detailed structures of the cells are discovered. Types of microscopes used are namely a light microscope, an electric microscope and an electron microscope. A light microscope uses sunlight to see through the subjects known as the specimen prepared and placed on what is called a slide placed on the stage and clipped for grip. The electric microscope has the electric light as its light source to pass through the specimen for viewing. The electron microscope does not use the sunlight as in the light microscope or electric light as in the electric microscope but uses the electromagnetic fields to magnify the objects under study. Subjects that are have the diameter in micrometers such as to see viruses or bacteria or objects that have sizes approaching the electrons, then the electron microscopes are used. With electron microscopes, the DNA and RNA macromolecular structures are unfolded with the nucleotides as the monomers and the amino acids as the building blocks for the proteins to make different cells and hence tissues and organisms.
A microscope has a piece of convex lense placed at each end through a light source to enlarge images according to the power of the lenses. The two lenses used in combination to magnify the image of a specimen are namely the eyepiece lens also called the ocular lens and the objective lens.
The eyepiece lens has a power of 10 and 15 times. Thus, when you look at an object through an eyepiece lens, it will be enlarged 10 to 15 times. The objective lens has a power ranging from 4, 10, 40 to 100 times. The eyepiece tube is the eyepiece holder. It carries the eyepiece lens just above the objective lens. The nose piece or the revolving turret normally has these four lenses attached to their sites circularly on the turret. They are rotated and aligned to any specific magnification you want. Hence, when the power of 10 eyepiece lens and the power of 4 objective lenses are aligned, the magnification of the subject on the specimen will be 10 x 4 so the object will be 40 times bigger than it really is.
In another combination, say if the eyepiece is 15 times and the objective lens is 100 times, then the specimen will be enlarged 15 by 100 times which will equal to 1,500 times enlargement. This means the object will be magnified 1,500 times its normal size when viewed through the microscope’s lense system.
The microscope has three parts, namely head (body), arm and base. The head carries all the optical system of the microscope. The base provides the support of the microscope. It has all the illuminators that ensure that the specimen is adequately illuminated for viewing from the body’s lenses system.
The arm of the microscope supports the microscope’s body tube. The arm has the coarse adjustment knob for adjusting the subject for clarity and the fine adjustment knob helps to fine-tune for even detailed clarity. Without the adjustment knobs, the subject on the specimen could be blurred and it would be very difficult to get fine details.
The stage of the microscope is where all the specimens are prepared on slides and placed there for viewing held in grip by the clips. The stage can be moved by the mechanical knobs.
The diaphragm of the microscope is also known as the iris or the iris diaphragm. It is located under the stage and controls the amount and the intensity of light that enters the specimen. Aperture is the hole through the stage through which light enters the specimen. The microscopic illuminator is the light source for the microscope from the base of the microscope captured from another light source of about 100 volts. The condenser of the microscope are the lenses used to collect and focus light onto the specimen for more clarity. These are located next to the diaphragm and produce much clarity of the image of the specimen up to 400 times. Sometimes with advanced Abbe condenser up to about a thousand (1000x) magnification.
My Prayer for PNG today is: “The Lord is my shepherd. I want to follow, where ever He leads me, where ever He goes, Over the mountains, the valleys and byways. He promised to be there. He’s waiting for me…”
Next week: Nutrition in science and technology
- Michael Uglo is a science textbook author and lecturer in Avionics, Auto-piloting and Aircraft Engineering. Please send comments to: [email protected]