In this part II of history and evolution of life on
earth, we learned about systematics, taxonomy and classification. Evolution produces
biodiversity of organisms. What is Systematics? Systematics is the study of
biological diversity and its evolution. Taxonomy, a subdivision of systematics
is the science of biological classification- identification, nomenclature and
making into a system. This classification systems help to clarify the
relationship among organisms. It also helps us to remember organisms and their
traits. This system enable us to communicate clearly about the identity of
organisms being studied. If there is no classification system, it will make the
communication between scientists or people who studied in this field become
difficult as there will be miscommunication in order to differentiate one
organism from another species. There are many ways to classify the animals by
seeing their forms, colour, size, chemical structure and genetic make up but
now focus is more on molecular similarities, proteins, DNA and genes. Caralus Linnaeus,
a Swedish botanist was first to develop and publish the first comprehensive and
consistent classification system for both plants and animals. Each species is
given a unique scientific name. For this semester, the syllabus for cell
biology class and microbiology class are almost the same. In microbiology
class, we also learned about taxonomy, classification and so on. What I can
relate to this topic from microbiology class is about the scientific name. From
the scientific names of a microbe, we can know its shape, who is the founder of
the microbe, what kind of nutrient that it gets, and what diseases can be
caused by the microbe. It is really useful and interesting. I got really
excited actually when the first time I knew that we can get those information
from the name of the microbes.
Furthermore, there are 7 taxa which are kingdom,
phylum, class, order, family, genus and species. Next, we learned about
phylogenetics which is the study of evolutionary relationships among and
between species. The relationships usually presented as a phylogenetic tree or
cladogram. Each branch of the cladogram is called as clade. Classic phylogenetics
dealt mainly with physical or morphological features. Modern phylogeny uses
information extracted from genetic material which is mainly DNA and protein
sequences.
Other than that, we studied about prokaryotic cells,
virus, viroid and prions. First of all, we read about the discovery of cell. The
first person who discovered cell was Robert Hooke while looking at a slice of
cork. He described cells as tiny boxes or honey combs. He also thought cells
only existed in plants and fungi. On 1673, Anton van Leeuwenhoek used his hand
microscope to view samples from a pond and discovered single cell organisms. There
are three basic cell theory which are:
1) All living things are made up of cells.
2) The cell is the basic unit of life in all living
things.
3) New cells arise from the pre-existing cells.
After that, there are four additional statements
which are the
cell contains hereditary information which is passed on from cell to cell
during cell division, all
cells are basically the same in chemical composition and metabolic activities, all
basic chemical and physiological functions are carried out inside the cells and cells
activities depends on the activities of subcellular structures within the cell.
I have been learning about prokaryotes and
eukaryotes since in secondary school and the basic about the cells. In the
lecture, I have been introduced more details about the structure of the cells
such as the materials that made up the cell wall, the important to distinguish
between gram positive and negative bacteria, the features of the cell membrane
and the structure of nucleoid region in bacteria. The new things for me are
virus, viroid and prion.
Viruses can be classified according to their genetic,
shape, symmetry of the capsid, presence and absence of envelope and type of the
host. Viruses reproduce in 2 ways, lytic cycle and lysogeny cycle. Lytic cycle
is virus will lysis and rupture the host and distribute its particle. In lysogeny
cyle, the virus will grow together with the host. Then, DNA’s virus enters the
host and integrate the host chromosome. For viroid, it is a small circular RNA
molecules without a protein coat. It infects plant and lead to dramatic
economic losses in agriculture and horticulture worldwide. The last one is
prions. Prion is an infectious agent that is composed primarily of protein.
It propagates
by transmitting a mis-folded protein state. This mis-folded protein can lead to
mad cow disease and Alzheimer.
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