INTRODUCTION TO
BIOLOGY
BIOLOGY
Biology - the study of the many varieties of life or living
organisms, e.g. E. coli, tree fern, gazelle, and beetle
Bio from Greek bios means life; logos means study of
first coined by Gottfried Reinhold Treviranus
examines the structure, function, growth, origin, evolution,
distribution and classification of all living things
Unifying principles that formed the foundation of modern
biology:
cell theory
Evolution
gene theory
Energy
homeostasis
Disciplines of biology
Botany - the study of plants
Zoology - the study of animals
Microbiology - the study of microorganisms
Biochemistry examines the fundamental chemistry of life
Molecular biology studies the complex interactions of
systems of biological molecules
Cellular biology examines the basic building block of all
life, the cell
Physiology examines the physical and chemical functions
of the tissues and organ systems of an organism
Ecology examines how various organisms interrelate with
their environment
Principles of Biology
Cell theory
Evolution
Genes
Homeostasis
Energy
All living organisms are made of one or more cells, the basic
living unit of function in organisms.
All cells come from preexisting cells that multiply through cell
division.
Through natural selection and genetic drift, a population's
inherited traits change from generation to generation.
A living organism's traits are encoded in DNA. Segments of
DNA that specify a trait are known as genes
Traits are passed on from one generation to the next through
genes
All information transfers from the genotype, the unobservable
genetic traits, to the phenotype, the observable physical or
biochemical characteristics of the organism
Although the phenotype expressed by the gene may adapt to
the environment of the organism, that information is not
transferred back to the genes
Only through the process of evolution do genes change in
response to the environment
The physiological processes that allow an organism to maintain
its internal environment notwithstanding its external
environment
The attribute of any living organism that is essential for its
state. (e.g. required for metabolism
Cell theory
The cell is the fundamental unit of life.
All living things are composed of one or more cells or
the secreted products of those cells, such as shells.
Cells arise from other cells through cell division
In multicellular organisms, every cell in the organism's
body is produced from a single cell in a fertilized egg.
The cell is considered to be the basic part of the
pathological processes of an organism.
Evolution
Life changes and develops through evolution and that all
life-forms known have a common origin
Introduced by Jean-Baptiste de Lamarck in 1809
Charles Darwin established evolution 50 years later as a
viable theory by articulating its driving force: natural
selection
Alfred Russel Wallace as the co-discoverer
Darwin theorized that species and breeds developed through the
processes of natural selection and artificial selection or selective
breeding
Genetic drift was embraced as an additional mechanism of
evolutionary development in the modern synthesis of the theory
Phylogeny - the evolutionary history of the species
together with its genealogical relationship to every other
species
include the comparisons of DNA sequences conducted within molecular
biology or genomics, and comparisons of fossils or other records of ancient
organisms in paleontology
Biologists organize and analyze evolutionary relationships
through various methods, including phylogenetics,
phenetics, and cladistics
Spontaneous generation, the belief that life forms could
appear spontaneously under certain conditions, was
widely believed (19th century)
This misconception was challenged by William Harvey's diction that
"all life [is] from [an] egg" (from the Latin "Omne vivum ex ovo"), a
foundational concept of modern biology, means that there is an
unbroken continuity of life from its initial origin to the present time
Genetics
Genes are the primary units of inheritance in all
organisms and are made of DNA. Widely different
organisms, including bacteria, plants, animals, and fungi,
share the same basic machinery that copies and
transcribes DNA into proteins.
e.g : bacteria with inserted human DNA may, under the right
circumstances, manufacture a human protein
All the genes in an organism or cell are together known as
the genome, which is stored on one or more
chromosomes
Chromosome - an organized structure consisting of DNA
and protein
Cells transcribe a DNA gene into an RNA version of the gene, and
a ribosome then translates the RNA into a protein
Homeostasis
Homeostasis - the ability of an open system to regulate
its internal environment to maintain a stable condition by
means of multiple dynamic equilibrium adjustments
controlled by interrelated regulation mechanisms.
All living organisms, whether unicellular or multicellular, exhibit
homeostasis.
It exists at the cellular level (e.g. cells maintain a stable internal
acidity (pH); warm-blooded animals maintain a constant internal
body temperature
It is also used in association with ecosystems (e.g. the roots of
plants help prevent soil from eroding, which helps to maintain the
ecosystem.
Tissues and organs can also maintain homeostasis.
It is also the maintenance of stability of numbers of individuals
within a population.
Energy
Survival depends on the continuous input of energy
Chemical reactions that are responsible for its structure and function
are tuned to extract energy from substances that act as its food and
transform them to form new cells and sustain them.
Mostly, energy needed for life processes originates from the Sun
plants and other autotrophs convert into chemical energy (organic
molecules) via photosynthesis in the presence of water and
minerals
Few ecosystems depend entirely on energy extracted from methane,
sulfides, or other inorganic molecules by chemosynthetic
microorganisms
Captured energy is used to produce biomass to sustain life and
provide energy for its growth and development.
A part of this energy is lost as heat and waste molecules.
The common processes for converting energy in chemical substances
into energy useful to sustain life are metabolism and respiration.
Fields of Biology
Molecular biology is the study of biology at a molecular
level
overlaps with other areas of biology, particularly genetics and
biochemistry
chiefly concerns itself with understanding the interactions between
the various systems of a cell, including the interrelationship of DNA,
RNA, and protein synthesis and learning how these interactions are
regulated
Cell biology studies the physiological properties of cells,
as well as their behaviors, interactions, and environment
done both on a microscopic and molecular level
researches both single-celled organisms like bacteria and
specialized cells in multicellular organisms like humans
similarities and differences between cell types s provide a
unifying theme, allowing the principles learned from
studying one cell type to be extrapolated and generalized
to other cell types
Genetics is the science of genes, heredity, and the
variation of organisms
Genes encode the information necessary for synthesizing proteins,
which in turn play a large role in influencing the final phenotype of
the organism
provides important tools in the investigation of the function of a
particular gene, or the analysis of genetic interactions
Genetic information generally is carried in
chromosomes, where it is represented in the chemical
structure of particular DNA molecules.
Developmental biology studies the process by
which organisms grow and develop
Originating in embryology, modern developmental biology studies
the genetic control of cell growth, differentiation, and
"morphogenesis," which is the process that gives rise to tissues,
organs, and anatomy
Model organisms for developmental biology includes:
round worm Caenorhabditis elegans
fruit fly Drosophila melanogaster
zebrafish Brachydanio rerio
mouse Mus musculus, and the weed Arabidopsis thaliana
Physiology studies the mechanical, physical, and
biochemical processes of living organisms by attempting to
understand how all of the structures function as a whole
Divided into plant and animal physiology
It is universal, e,g what is learned about the physiology of
yeast cells can also apply to human cells
The field of animal physiology extends the tools and
methods of human physiology to non-human species.
Plant physiology also borrows techniques from both
fields.
Anatomy is an important branch of physiology and
considers how organ systems in animals, such as the
nervous, immune, endocrine, respiratory, and circulatory
systems, function and interact. The study of these systems
is shared with medically oriented disciplines such as
neurology and immunology.
Taxonomy
A phylogenetic tree of all living things, based on rRNA
gene data, showing the separation of the three domains
bacteria, archaea, and eukaryotes as described initially
by Carl Woese.
Classification is the province of the disciplines of
systematics and taxonomy.
Taxonomy places organisms in groups called taxa, while
systematics seeks to define their relationships with each
other
This classification technique has evolved to reflect advances in
cladistics and genetics, shifting the focus from physical similarities
and shared characteristics to phylogenetics
Living Things Kingdom
Traditional
Classification
1. Monera
2. Protista
3. Fungi
4. Plantae
5. Animalia
Modern
Classification
1. Archaea (originally
Archaebacteria)
2. Bacteria (originally
Eubacteria)
3. Eukarya (including
protists, fungi, plants,
and animals.)
Each kingdom is broken down continuously until each
species is separately classified, in the ffg order:
1. Domain
2. Kingdom
3. Phylum
4. Class
5. Order
6. Family
7. Genus
8. Species
Intracellular parasites
1. Viruses
2. Viroids
3. Prions
The scientific name of an organism is obtained from its
genus and species
E.g: humans would be listed as Homo sapiens
Homo would be the genus and sapiens is the species
Whenever writing the scientific name of an organism:
capitalize the first letter in the genus and put all of the species in
lowercase
the entire term would be italicized or underlined
Naming of organisms
The dominant classification system is called
Linnaean taxonomy
Governed by international agreements
International Code of Botanical Nomenclature (ICBN)
International Code of Zoological Nomenclature (ICZN)
International Code of Nomenclature of Bacteria (ICNB)
Ecology
Ecology studies the distribution and abundance of living
organisms, and the interactions between organisms and their
environment
The environment of an organism includes both its habitat,
which can be described as the sum of local abiotic factors such
as climate and ecology, and the other organisms that share its
habitat.
Ecological systems are studied at several different levels, from
individuals and populations to ecosystems and the biosphere.
Population biology is often used interchangeably with
population ecology
Population biology is more frequently used when studying diseases,
viruses, and microbes
Population ecology is more commonly when studying plants and
animals
Ethology
Ethology studies animal behavior (particularly that of
social animals such as primates and canids), and is
sometimes considered a branch of zoology
Ethologists have been particularly concerned with the
evolution of behavior and the understanding of behavior in
terms of the theory of natural selection
The first modern ethologist was Charles Darwin, whose book "The
Expression of the Emotions in Man and Animals" influenced many
ethologists.
Biogeography studies the spatial distribution of
organisms on the Earth, focusing on topics like plate
tectonics, climate change, dispersal and migration, and
cladistics
Every organism interacts with other organisms and its
environment
For any given species, behaviors can be co-operative,
aggressive, parasitic or symbiotic
Matters become more complex when two or more
different species interact in an ecosystem. Studies of this
type are the province of ecology.
