Evolution is the process by which organisms change over time. Mutations
produce genetic variation in populations, and the environment interacts with this
variation to select those individuals best adapted to their surroundings. The best-
adapted individuals leave behind more offspring than less well-adapted individuals
do. Given enough time, one species may evolve into many others.
The oldest verified sample of DNA has been pulled from soil deep within the
permafrost of Siberia. The DNA belonged to grasses, sedges and shrubs estimated to
be between 300,000 and 400,000 years old.
The most ancient identified animal genetic material is about 50,000 years old.
Although there is evidence of plants and animals dating back hundreds of millions of
years, DNA from such specimens has not been identified because it has degraded.
Paleomicrobiology is an emerging field that is devoted to the detection,
identification and characterization of microorganisms in ancient remains. Data
indicate that host-associated microbial DNA can survive for almost 20,000 years, and
environmental bacterial DNA preserved in permafrost samples has been dated to
400,000-600,000 years. In addition to frozen and mummified soft tissues, bone and
dental pulp can also be used to search for microbial pathogens. Various techniques,
including microscopy and immunodetection, can be used in paleomicrobiology, but
most data have been obtained using PCR-based molecular techniques. Infections
caused by bacteria, viruses and parasites have all been diagnosed using
paleomicrobiological techniques. Additionally, molecular typing of ancient pathogens
could help to reconstruct the epidemiology of past epidemics and could feed into
current models of emerging infections, therefore contributing to the development of
appropriate preventative measures.
Selection in biology, the preferential survival and reproduction or preferential
elimination of individuals with certain genotypes (genetic compositions), by means of
natural or artificial controlling factors.
The theory of evolution by natural selection was proposed by Charles Darwin
and Alfred Russel Wallace in 1858. They argued that species with useful adaptations
to the environment are more likely to survive and produce progeny than are those
with less useful adaptations, thereby increasing the frequency with which useful
adaptations occur over the generations. The limited resources available in an
environment promotes competition in which organisms of the same or different
species struggle to survive. In the competition for food, space, and mates that occurs,
the less well-adapted individuals must die or fail to reproduce, and those who are
better adapted do survive and reproduce. In the absence of competition between
organisms, selection may be due to purely environmental factors, such as inclement
weather or seasonal variations. (See natural selection.)
Artificial selection (or selective breeding) differs from natural selection in that
heritable variations in a species are manipulated by humans through controlled
breeding. The breeder attempts to isolate and propagate those genotypes that are
responsible for a plant or animal’s desired qualities in a suitable environment. These
qualities are economically or aesthetically desirable to humans, rather than useful to
the organism in its natural environment.
In mass selection, a number of individuals chosen on the basis of appearance
are mated; their progeny are further selected for the preferred characteristics, and the
process is continued for as many generations as is desired. The choosing of breeding
stock on the basis of ancestral reproductive ability and quality is known as pedigree
selection. Progeny selection indicates choice of breeding stock on the basis of the
performance or testing of their offspring or descendants. Family selection refers to
mating of organisms from the same ancestral stock that are not directly related to
each other. Pure-line selection involves selecting and breeding progeny from superior
organisms for a number of generations until a pure line of organisms with only the
desired characteristics has been established.
Darwin also proposed a theory of sexual selection, in which females chose as
mates the most attractive males; outstanding males thus helped generate more young
than mediocre males.
Evolutionary development (evolution of development or informally, evo-devo)
is a field of biology that compares the developmental processes of different
organisms to determine the ancestral relationship between them, and to discover how
developmental processes evolved. It addresses the origin and evolution of embryonic
development; how modifications of development and developmental processes lead
to the production of novel features, such as the evolution of feathers the role of
developmental plasticity in evolution; how ecology impacts development and
evolutionary change; and the developmental basis of homoplasy and homology.
Although interest in the relationship between ontogeny and phylogeny extends
back to the nineteenth century, the contemporary field of evo-devo has gained
impetus from the discovery of genes regulating embryonic development in model.
General hypotheses remain hard to test because organisms differ so much in shape
Nevertheless, it now appears that just as evolution tends to create new genes
from parts of old genes (molecular economy), evo-devo demonstrates that evolution
alters developmental processes to create new and novel structures from the old gene
networks (such as bone structures of the jaw deviating to the ossicles of the middle
ear) or will conserve (molecular economy) a similar program in a host of organisms
such as eye development genes in mollusks, insects, and vertebrates. Initially the
major interest has been in the evidence of homology in the cellular and molecular
mechanisms that regulate body plan and organ development. However, subsequent
approaches include developmental changes associated with speciation.
In the past, human interaction with nature, although often having a disruptive
effect on nature, often also enriched the quality and variety of the living world and its
habitats - e.g. through the creation of artificial landscapes and soil cultivation by local
Today, however, human pressure on natural environments is greater than
before in terms of magnitude and efficiency in disrupting nature and natural
landscapes, most notably:
- Intensive agriculture replacing traditional farming; this combined with the
subsidies of industrial farming has had an enormous effect on western rural
landscapes and continues to be a threat.
- Mass tourism affecting mountains and coasts.
- the policies pursued in the industry, transport and energy sectors having a
direct and damaging impact on the coasts, major rivers (dam construction and
associated canal building) and mountain landscapes (main road networks).
- The strong focus of forestry management on economic targets primarily
causes the decline in biodiversity, soil erosion and other related effects.
Human Impact On The Natural Environment
Human impact on the environment or anthropogenic impact on the
environment includes impacts on biophysical environments, biodiversity, and other
resources. The term anthropogenic designates an effect or object resulting from
human activity. The term was first used in the technical sense by Russian geologist
Alexey Pavlov, and was first used in English by British ecologist Arthur Tansley in
reference to human influences on climax plant communities. The atmospheric
scientist Paul Crutzen introduced the term "AAnthropocene" in the mid-1970s. The
term is sometimes used in the context of pollution emissions that are produced as a
result of human activities but applies broadly to all major human impacts on the
impacts, which according to the I = PAT equation is measured as resource use or
pollution generated per unit GDP. Environmental impacts caused by the application
of technology are often perceived as unavoidable for several reasons. First, given that
the purpose of many technologies is to exploit, control, or otherwise “improve” upon
nature for the perceived benefit of humanity while at the same time the myriad of
processes in nature have been optimized and are continually adjusted by evolution,
any disturbance of these natural processes by technology is likely to result in negative
environmental consequences. Second, the conservation of mass principle and the first
law of thermodynamics (i.e., conservation of energy) dictate that whenever material
resources or energy are moved around or manipulated by technology, environmental
consequences are inescapable. Third, according to the second law of
thermodynamics, order can be increased within a system (such as the human
economy) only by increasing disorder or entropy outside the system (i.e., the
environment). Thus, technologies can create “order” in the human economy (i.e.,
order as manifested in buildings, factories, transportation networks, communication
systems, etc.) only at the expense of increasing “disorder” in the environment.
According to a number of studies, increased entropy is likely to be correlated to
negative environmental impacts.
A common concern for the life and composition of the cell brings biologists
and chemists together in the field of biochemistry-molecular biology. The vast and
complex array of chemical reactions occurring in living matter and the chemical
composition of the cell are the primary concerns of the biochemist. Life processes
occurring at the molecular level, including the storage and transfer of genetic
information and the interactions between cells and the viruses that infect them, are
the investigatory concerns of the molecular biologist.
Biochemistry and molecular biology are sub-disciplines within the larger, more
general area of biological sciences. The study of biochemistry and molecular biology
requires that students be genuinely interested and able to perform successfully in the
"quantitative" sciences and that they have acquired a solid foundation in biology,
chemistry, mathematics, and physics in their high school or community college
Students planning to major in biochemistry-molecular biology enter as a
biological sciences premajor and take a common core curriculum consisting of
introductory biology, general chemistry, physics, organic chemistry, a full year of
calculus and an additional mathematics course, preferably differential equations.
Students should complete this preparatory work in their freshman and sophomore
years. Following successful completion of seven of these courses, students may
advance from biology premajor to full major status. The Biochemistry-Molecular
Biology major requires completion of 48 upper-division quarter units, including
coursework in biochemistry, physical chemistry, general and molecular genetics, plus
electives. Students should review the full requirement sheet for the major and plan
their schedules accordingly.
Throughout the Biochemistry-Molecular Biology program, students encounter
and work with the sophisticated techniques and equipment that allow them to
penetrate what one scientist refers to as "the boundaries between what we know and
what we do not know, between our current understanding and what we are seeking to
understand." At UCSB, students learn not only in the classroom, but also in the
laboratory. There they actively engage in research with faculty and routinely interact
with graduate students and postdoctoral research fellows. A continuing series of
seminars conducted by outside researchers, as well as seminars on advanced topics
conducted by department faculty, supplement the curriculum.
Cell biology (formerly called cytology, from the Greek
κυτος, kytos, "vessel")
and otherwise known as molecular biology, is a branch of biology that studies the
different structures and functions of the cell and focuses mainly on the idea of the cell
as the basic unit of life. Cell biology explains the structure, organization of the
organelles they contain, their physiological properties, metabolic processes, signaling
pathways, life cycle, and interactions with their environment. This is done both on a
microscopic and molecular level as it encompasses prokaryotic cells and eukaryotic.
Knowing the components of cells and how cells work is fundamental to all biological
sciences it is also essential for research in bio-medical fields such as cancer, and other
diseases. Research in cell biology is closely related to genetics, biochemistry,
molecular biology, immunology, and developmental biology. Chemical and
The study of the cell is done on a molecular level; however, most of the
processes within the cell is made up of a mixture of small organic molecules,
inorganic ions, hormones, and water. Approximately 75-85% of the cell’s volume is
due to water making it an indispensable solvent as a result of its polarity and
suitable environment for the cell to carry out metabolic reactions and signaling. The
cell shape varies among the different types of organisms, and are thus then classified
into two categories: eukaryotes and prokaryotes. In the case of eukaryotic cells -
which are made up of animal, plant, fungi, and protozoa cells - the shapes are
generally round and spherical, while for prokaryotic cells – which are composed of
bacteria and archaea - the shapes are: spherical (cocci), rods (bacillus), curved
(vibrio), and spirals (spirochetes).
Cell biology focuses more on the study of eukaryotic cells, and their signaling
pathways, rather than on prokaryotes, which is covered under microbiology. The
main constituents of the general molecular composition of the cell includes: proteins
and lipids which are either free flowing or membrane bound, along with different
internal compartments known as organelles. This environment of the cell is made up
of hydrophilic and hydrophobic regions, which allows for the exchange of the above-
mentioned molecules and ions. The hydrophilic regions of the cell are mainly on the
inside and outside of the cell, while the hydrophobic regions are within the
phospholipid bilayer of the cell membrane. The cell membrane consists of lipids and
proteins which accounts for its hydrophobicity as a result of being non-polar
substances. Therefore, in order for these molecules to participate in reactions, within
the cell, they need to be able to cross this membrane layer to get into the cell. They
accomplish this process of gaining access to the cell via: osmotic pressure, diffusion,
concentration gradients, and membrane channels. Inside of the cell are extensive
internal sub-cellular membrane-bounded compartments called organelles.
Biological techniques used to enhance products
Biotechnology (sometimes shortened to "biotech") is a field of applied biology
that involves the use of living organisms to enhance crops, biofuels, household
products, and medical treatments. Modern biotechnology may involve the use of
genetic engineering technology to permanently alter the genetic makeup of living
Biotechnology is the use of living systems and organisms to develop or make
products, or "any technological application that uses biological systems, living
organisms or derivatives thereof, to make or modify products or processes for
specific use" (UN Convention on Biological Diversity, Art. 2). Depending on the
tools and applications, it often overlaps with the (related) fields of bioengineering,
biomedical engineering, bio manufacturing, etc.
For thousands of years, humankind has used biotechnology in agriculture, food
production, and medicine.
The term is largely believed to have been coined in 1919
biotechnology has expanded to include new and diverse sciences such as genomics,
recombinant gene techniques, applied immunology, and development of
pharmaceutical therapies and diagnostic tests.
Some of the earlier studies in biophysics were conducted in the 1840s by a
group known as the Berlin school of physiologists. Among its members were
pioneers such as Hermann von Helmholtz, Ernst Heinrich Weber, Carl F. W. Ludwig,
and Johannes Peter Muller. Biophysics might even be seen as dating back to the
studies of Luigi Galvani.
The popularity of the field rose when the book What Is Life? by Erwin
Schrödinger was published. Since 1957 biophysicists have organized themselves into
the Biophysical Society which now has about 9,000 members over the world.
What do biophysicists study?
Biophysicists study life at every level, from atoms and molecules to cells,
organisms, and environments. As innovations come out of physics and biology labs,
biophysicists find new areas to explore where they can apply their expertise, create
new tools, and learn new things. The work always aims to find out how biological
systems work. Biophysicists ask questions, such as:
How do protein machines work? Even though they are millions of times
smaller than everyday machines, molecular machines work on the same principles.
They use energy to do work. The kinesin machine shown here is carrying a load as it
walks along a track. Biophysics reveals how each step is powered forward.
In biology, an organism is any contiguous living system, such as an animal,
plant, fungus, archaeon, or bacterium. All known types of organisms are capable of
some degree of response to stimuli, reproduction, growth and development and
homeostasis. An organism consists of one or more cells; when it has one cell it is
known as a unicellular organism; and when it has more than one it is known as
amulticellular organism. Most unicellular organisms are of microscopic size and are
thus classified as microorganisms. Humans are multicellular organisms composed of
many trillions of cells grouped into specialized tissues and organs.
An organism may be either a prokaryote or a eukaryote. Prokaryotes are
represented by two separate domains, the Bacteria andArchaea. Eukaryotic organisms
are characterized by the presence of a membrane-bound cell nucleus and contain
additional membrane-bound compartments called organelles (such as mitochondria in
animals and plants and plastids in plants and algae, all generally considered to be
derived from endosymbiotic bacteria). Fungi, animals and plants are examples of
kingdoms of organisms within the eukaryotes.
Estimates on the number of Earth’s current species range from 10 million to 14
million, of which only about 1.2 million have been documented. More than
99% of all species, amounting to over five billion species, that ever lived on Earth
are estimated to beextinct. In July 2016, scientists reported identifying a set of
355 genes from the Last Universal Common Ancestor (LUCA) of all organisms
living on Earth.
Diversity in Living Organisms
1) Every living organism is unique and this uniqueness is the basis of the vast
diversity displayed by the organisms in our world.
2) This huge diversity is the result of evolution, which has occurred over
millions of years.
3) The massive biological diversity can only be studied by classification i.e.
arranging organisms into groups based on their similarities and differences.
4) Different characteristics are used to determine thehierarchy of classification.
5) The primary characteristics that determine the broadest divisions in
classification are independent of any other characteristics. The secondary
characteristics depend on the primary ones.
6) Prokaryotic or eukaryotic cell organization is the primary characteristic of
classification, since this feature influences every detail of cell design and capacity to
undertake specialized functions.
7) Being a unicellular or multicellular organism formsthe next basic feature of
classification and causes huge differences in the body design of organisms.
8) The next level of classification depends on whether the organism is
autotrophic or heterotrophic. Further classification depends on the various levels of
organization of the bodies of these organisms.
9) The evolution of organisms greatly determines theirclassification.
10) The organisms who evolved much earlier have simple and ancient body
designs whereas the recently evolved younger organisms have complexbody designs.
11) Older organisms are also referred to as primitive or lower organisms
whereas the younger organisms are also referred to as advanced or higher organisms.
12) The diversity of life forms found in a region is biodiversity.
13) The region of mega-diversity is found in the warm and humid tropical
regions of the Earth.
14) Aristotle classified organisms depending on their habitat.
15) Robert Whittaker proposed the five-kingdom scheme of classification,
based on the cell structure, nutrition and body organization of the organisms.
16) The main characteristics considered in the five-kingdom scheme of
i) Presence of prokaryotic or eukaryotic cells.
ii) If eukaryote, whether the organism is unicellular or multicellular.
“Monophyletic tree of organisms”. Ernst Haeckel: Generelle Morphologie der
Organismen, etc. Berlin, 1866. (Photo credit: Wikipedia)