The nature of life

1.1 theories of the origin of the universe

Along the last centuries, the size of the universe grew conceptually in the minds of astrophysics and astronomers.
Copernican revolution (late 16th century) à the universe was exclusively our solar system surrounded by a spherical
background without thickness of fixed stars.
19th centuryà neighborhood of suns located at different distances, giving form to our galaxy, the milky way.
20th centuryà Became a vast, wide, and deep space which contained many galaxies far from each other but similar to
ours.
Static universeà universe remained static; it appeared to be fixed, changeless, beyond mere conceptual growth.
Gravityà Force that constantly attracted the different bodies of the universe between themselves.
Albert Einstein (1879-1955)à Believed that the universe was static, which is why he introduced a term of expansion
called the cosmological constant in his equation of general relativity (one of his biggest mistakes) he documented this in
his general theory of relativity between 1915 and 1916.
Edwin Hubble (1889-1953)à discovered that the stillness of the universe was mere appearance, he also discovered that
there existed other galaxies others than the milky way and dedicated all his efforts to calculate the distance between some
of these and ours.
The doppler sound effect: Change in frequency that waves experience when the emitting source and the observer are in
relative motion to the medium. Frequency increases when the source and the receiver approach each other and decreases
when they move away.
Object that emits sonorous waves is closer to an observer the waves compress as they approximate.
That’s exactly what Hubble discovered about galaxies: that they are a collection of planets, cosmic dust, dark matter, and
energy that are moving away from each other. With this information Hubble deducted that the universe is in motion.
Theories about the origin of the universe

Theory Big bang or great explosion Oscillating or pulsating Stationary state Inflationary state
universe
Author George Lemaitre in 1927, Alexander Friedman in Fred Hoyle, Herman Alan Guth in 1981
George Gamow, Ralph 1922 Bondi and Thomas Gold
Alpher and Robert Herman in 1948
continued in 1948
Date 1927 1922 1948 1981
Hypothesis Proposes that the Proposes that at some Opposes the Big Bang addition to the Big Bang.
phenomenon that caused the moment the attraction of and the Big Crunch. In its It explains that in the
expansion was a great the force of gravity will be place, it proposes that the initial seconds of the
explosion that took place 14 greater than the impulse Universe is in constant explosion, matter
000 million years ago. Then, force resulting from the expansion due to the expanded in an
matter and light that exist explosion; therefore, the continuous creation of exponential or
today hadn't appeared yet. Universe will stop its new matter that fills the inflationary manner,
All particles that formed the expansion and will collapse gaps from the center of which agrees with the
atoms of the Universe have back to its starting point, the Universe, left by homogeneity observed
passed a process of that is, a grand implosion or matter that was previously from any direction and
transformation. The proofs of Big Crunch will occur. This displaced. In this manner also with the fact that the
this theory are cosmic will produce a pattern of it complies with the explosion overcame the
background radiation and the explosions and implosions requisite of showing an powerful initial force of
fact that the hydrogen/helium that will happen apparently calm Universe; gravity, when all matter
ratio that exists in the indefinitely or eternally. and homogeneous in was closer to the rest of
Universe is practically the content of galaxies from matter.
same as that calculated by all directions from which
the model. it is observed.
In 1967 Armo Penzias (1933) and Robert Wilson (1936) accidentally discovered the existence of cosmic background
radiation predicted by the adjustments that Gamow made to the Big Bang Model, the big bang model also predicts that the
hydrogen and helium proportion (Hi/He) that must have formed in the great explosion, which would be 76 and 24%
respectively.
1.1.1 The History of the universe

The Universe didn't always exist. It had a beginning, almost 14 thousand million years ago, when all matter and energy
that now comprise all large and majestic structures that we can see were united in a single point.

The density of the matter of this initial point was infinite, and so were its energy, temperature and curvature caused in
space.

It is thought that the tension due to the quantum interactions between infinite matter and energy at this described point
was of such a magnitude that, without being able to contain itself any more exploded violently, creating a kind of
spherical universe in self-impulsive expansion: the Big Bang happened. Originating from that explosion not only the
matter of the Universe arose, but time in the Universe also started.

The initial expansion of the Universe was of the inflationary or exponential type, that is, it expanded in an unlimited form
in a very short period of time.

The velocity of the expansion was, in orders of magnitude, faster than the distance that life currently travels, which is
almost 300 thousand kilometers per second.

Likewise, as the Universe expanded, the high temperature descended abruptly. In the first fractions of the first second, it
decreased some 10 million Kelvin degrees, but after one second after the explosion it had decreased to only one million,
and after 380 thousand terrestrial years, the temperature of the Universe was still some 3 000 Kelvin degrees.

the four fundamental forces that exist in nature:

 Gravity: force that unites the solar system

 strong nuclear forces: Unites the nucleus.
 weak nuclear forces: Radioactive disintegration
 electromagnetism: force that unites the atoms.

These forces were probably united or undifferentiated before the Big Bang.

It is highly likely that during the first fractions of the first second of the explosion gravity began functioning and opposing
the initial inflationary velocity of the expansion, managing to slow it down a little until reducing it to a current constant
velocity.

Before reaching the mentioned limit of 380 thousand years, the Universe was a kind of heated cosmic plasma, conformed
exclusively of elemental particles of matter and antimatter: quarks and antiquarks, electrons, and antielectrons (or
positrons), neutrinos and antineutrinos, as well as energy particles: photons and other bosons.

For each type of particle of matter discovered there is a type of particle of antimatter that has the same properties.

Plasma: Highly ionized gaseous matter with an equal number of free positive and negative electrical charges.

The main part of the immense amount of matter and antimatter particles with which the cosmos initiated were mutually
destroyed before that period ended.
Nevertheless, an unexplainable or perhaps fortuitous unbalance or quantum asymmetry in the initial proportions between
particles and antiparticles of the Universe favored the particles of matter in a proportion of one for every thousand
millions of antimatter particles that caused the hecatomb: the disappearance of all antimatter, leaving Universe full of
some light quanta (photons) and some matter.

Below 3 thousand degrees Kelvin, the other distinct forces of gravity were able to occupy their place and function in the
cosmos. Thus, the electric attraction between protons and electrons allowed for the formation of hydrogen atoms that
balance the charges. Also, the interaction of the strong nuclear forces permitted the union of pairs of photons and pairs of
neutrons which, when being electrically balanced with two electrons, produced helium. Also, the next element in the
periodic table could have been formed: beryllium, but not significantly.
the attraction of gravity began to slowly generate aggregations of particles and extensive clouds composed of these two
gases formed. In these clouds atoms coalesced and formed disks which began to rotate by the same effect of gravity. This
movement caused them to become spherical and to heat up again to thousands and later to millions of degrees, until they
began to have thermonuclear reactions in their interiors; in this manner the first stars were formed.

Coalescence: Is the possibility that two or more materials are joined in one single body.

Stars were born near each other in large clusters, which gave rise to the first galaxies. The Milky Way galaxy likely
formed around 10 billion years ago.

A type of very massive stars, several tens to thousands of times the size and material of our Sun, have a relatively short
lifespan and a very violent ending; they explode, and this explosion is called a supernova, which is a stellar explosion that
can be remarkably visible in space, even to the naked eye, in specific locations of the celestial sphere, their time active
was very productive, and in the potent oven of millions of degrees in their interior, strengthened by the great pressures of
its mass, the atoms of all the other elements that follow helium in the periodic table were formed.

when one of these stars explodes, it pours its valuable content through the cluster of galaxies that surrounds it, and now
the new stars that form from their ashes may also form planets composed of atoms of diverse elements around them.

The Sun is a star, a celestial body that shines with its own light, composed of hydrogen and helium at tremendous
temperatures in a state of plasma, it is the closest star to Earth and upon which all life on Earth depends, it was born about
5 billion years ago from the remnants of different supernovae in the galaxy, and around it, the eight planets and a dwarf
planet.

Earth formed approximately 4.5 billion years ago. It is a rocky planet rich in iron and nickel, but it also contains almost all
the elements from the periodic table.

It is calculated that the Sun could continue having thermonuclear reactions for a time similar to the amount of years of its
existence. Its end won’t be so violent: close to the end it will grow and notably increase its energy; it will become a red
giant that will obliterate the surface of the planets, of course, including the Earth. In the end, upon losing all its energy, it
will shrink to close to a million times its present diameter and will extinguish until it becomes a cold body without
brightness. This shall be the death of our star and the end of our Solar System.

Besides all visible matter that emits or reflects light, which we shall call regular there is an enormous amount of matter
that doesn't emit light and doesn't seem to interact with it. This lackluster matter is called dark matter, and it is believed to
exist between the stars and in the apparently empty space between the galaxies

1.2 Origin of life

Jean Baptiste de Lamark was the first naturalist who tried to explain the origin of life. reformulating the spontaneous
generation.

Lamark explained the origin of living beings in the microbes, the ancestors of plants and animals.

Louis Pasteur refuted spontaneous generation with an experiment in which he introduced sterilized soup in a
recipient isolated from the environment and it didn´t decompose (microbes didn´t appear).
Ivanovich Oparin proposed that life on Earth originated in a primary atmosphere oxygenated by
photosynthetic activity of the first microbes.

1.2.1 Chemical evolution

Proposed that the first living things were unicellular and anaerobic (lived without oxygen) and emerged from
inorganic matter, transformed by chemical evolution into organic molecules dissolved in the primitive seas
(molecule soup or primordial soup). The molecules formed chains of polymers that would eventually form the
first simple cells.

Stanley L. Miller designed an experiment with tubes and flasks isolated from the exterior to simulate the
hydrosphere and the atmosphere of a primitive Earth. Introduced water, methane (CH4), ammonia (NH4),
and hydrogen in contact with electrical sparks to simulate the energy of lighting and a evaporation-condensation
circulation system to simulate the rain.

In a matter of days, the components transform into complex organic molecules, mainly amino acids and acids
like urea, and with this, he proved one of the premises of the heterotroph theory: “inorganic matter gave place to
organic molecules”.

Some other natural phenomena confirmed the predictions of that theory; organic molecules have been identified
in the dust clouds between stars and some planets or their moons.

1.2.2 Biologic evolution

Organic molecules of primordial soup must have been polymerized until they formed long chains and rose to the
complexity of the first heterotrophic cells. The amino acids formed enzymes that accelerated the biological reactions in
living beings, but the storage of hereditary material is exclusive to DNA and, in some cases, RNA, so we can choose the
nucleic acids for the origin of life in favor of biologic evolution. They transformed into more complex molecules to adapt
to the environment due to individual variation (they can create copies of themselves).

DNA forms genes and chromosomes, a reservoir for hereditary information, but it doesn´t interact. RNA is a simpler
molecule that shows synthesis activity to give origin to proteins and enzymes.
Alexander Rich, Carl Woese, Leslie Orgel, and Francis Crick proposed independently the existence of a "first" world
based on RNA.

In which RNA stores information, catalyzes chemical reactions (ribozymes), and replicates itself.

At the same time, in this RNA world, the first phospholipid membranes were formed, and casually genetic material
molecules were introduced inside the membranes (primeval cells). At some point, RNA was replaced by DNA, and RNA
was directly related to protein production.

Eons Eras Periods Description Image

Hadean Origin of Earth,
(4450-4000) Solar System,
a.c. atmosphere and
seas, High
temperatures
Archean Conditions for
(4000-2500) primeval soup
a.c. and the world of
RNA, appeared
Carbon 13 and
the oldest fossils
of cyanobacteria.
Properozoic Paleoproterozoic Accumulation of
(2500-543) (2500-1600) a.c. oxygen, ozone
a.c. layer formed and
the first
breathing
organisms
appeared.

The “snowball”
glaciation takes
place and
eukaryote cells
and organelles.
 Mesoproterozoic Diversification
(1600-1000) a.c. of eukaryote and
multicellularity.
Neoproterozoic. Rise of animal
(En el libro and fungi
aparece kingdoms and
Mesoproteroic second
repetida) (1000- “snowball”
543) a.c. glaciation.

Phanerozoi Palezoic Cambric Explosion of

c (543- (543-251 a.c.) (543-505) a.c cambric ad
present diversification of
day) animals

Ordovician Invertebrate
(505-435 a.c.) marine animals,
Trilobites and
arthropods reign
the seas

Silurian (435- Fishes appear

410) a.c. and invertebrates
get in land
masses.

Devonian Amphibians
(410-370 a.c.) appear.

Carboniferous Retiles appear.

(370-290 a.c.)

Pérmico Supercontinent
(290-240 a.c.) Pangea is
formed, origin of
dinosours,
largest massive
extinction and
origin of
mammal
reptiles.
 Triassic (240- Large aquatic
205 a.c.) reptiles appear.

Dinosours and
crocodriles
diversify. Turtles
and sharks
appear.
Jurassic (205- Period
138 a.c.) dominated by
dinosours. Small
mammals
similar to
rodents appear

Mesozoic (251 –
65 a.c.)
Cretaceous Pangea
(138-65 a.c.) fragments. Rise
of plants with
flowers and
pollination.

At the end of the

period the
extinction of
dinosaurs

Cenozoic (65 Terniary (65 Continents reach

a.c. to present a.c.-1.8 d.c) a similar
day) configuration to
nowadays.

Diversification
of mammals;
lineage of
monkeys gives
arise to the
human family
 Quaternary Diversification
(1.8 d.c. – of the human
present day) family, Homo
sapiens appear
and distributes to
whole planet.

Last glaciation
occurs.

Humans
domesticate
plants and
animals and
great
civilizations
appear.

1.3 Evolution
The term evolution refers to living beings and a series of natural processes that contribute to changing the genetic
characteristics of species and lead them to adapt to variable environmental conditions or go extinct when they don´t
possess enough variation to respond.
Speciation is the separation of a species into two or more populations; their populations isolate, accumulate
modifications, and eventually consolidate as different species.

 1.3.1 History if evolutionary thinking

Until the 18th century naturalists thought species were permanent (they didn’t change). Species were fixed in time

Creationism → Religious belief. The universe and life originated from specific acts of divine creation.

Fixism→ Belief that maintains that existing species have remained essentially unchanged sice their creation.
They would be immutable as they were originally created.
Theory of speciation through hybridization: In the 18th century, Carolus Linnaeus accepted that a new species of
plants could appear by sexual crossing. The products maintained morphological traits from the ancestral
species. He called them hybrids.
First to abandon fixism → George Louis Leclerc, Count of Buffon → established three causes by which species
could be modified: diet, climate and customs.
  Lamark said the three causes proposed by Buffon were the causes that diverted the progressive process
of increase in the organic and structural complexity of living beings, he called it march of nature.
External influences as agents for a transforming process.

Buffon’s and Lamarck’s ideas lack the minimal scientific confirmation.

 1.3.2 Evidences of Evolution

Fossils → Remains of the hard and most resistant parts of some living beings from the past. On the other hand,
sometimes only their impressions or tracks over a sediment matrix which deposited over them in an aqueous
environment.
Petrification → Part of the fossilization process. Slow chemical substitution of the remaining organic matter by
minerals from the surroundings.
*Remains of living beings will only be considered as fossils if they are at least 10 thousand years old. If not,
they are called: organic remains.
Paleontology →discipline in charge of studying fossils. Establishes how the environments where they lived
were.
In the Origin of Species (1859), Darwin referred to three aspects of evolution: adaptation, transformation and
diversification of species. He presented complementary theories.
1. Evolution exists
2. All live and extinct species come from common ancestors
3. The process occurs guided by natural selection
4. As a result of the process of natural selection, species adapt to the changing environment.
5. That the continuous specialization of species to adapt to the modifications of the environment leads
them to change and new species appear.
6. This process occurs in a slow and gradual manner as generations go by.
7. The actions that humans perform in the process of breeding of animals and cultivation of plants presents
great similarities with what happens in the evolutive process in nature.
Only the theories numbered 3, 5 and 6 have been modified.
*Modern Biology began from these seven theories.
To demonstrate the occurrence of evolution through time, and that common ancestors exist, fossils are used. A
detailed anatomical comparison is carried out in search of similar characters.
Ontogeny → Set of changes which occur during embryonic development of the individuals of a species, and
those that continue taking place from birth until completing the adult stage.
Genomics → Biologic discipline that has permitted the deciphering of the sequence of DNA. Studies the
genome of an organism.
Phylogeny →Conceptual image of genealogical relationship between species of one or various groups of plants
or animals.
Sister species → species that originate from a same ancestor
Chance is also a factor of fixation of characters.
The theory of slowness and gradualism of the evolutive process isn’t true in all cases.
Evolution is about the origin, adaptation and diversification of the biological species (as well as their
extinction).
 1.3.3 Theory of Evolution by Natural Selection (Darwin and Wallace)
In 1831 Darwin, who was a creationist and fixist, travelled the world. During this 5-year voyage, he passed through
Argentina and the Galapagos Islands, an archipelago of recent volcanic origin.
In Argentina he identified a non-descript species of ostrich. He sent the skeleton to an expert who proved him right and
named the new species: Rhea darwiii. He also discovered three fossil specimens.
In Galapagos he obtained the best evidence in favor of evolution. This was a variety of species of birds called finches.
When he returned home in 1836, the specialist told him he had sent a total of 13 unidentified species of finches.
In 1838, the idea of natural selection came to him. The theory explained the adaptation of species to the environment.
Since 1855 he began to write a book to postulate the theory.
In the summer of 1858, Darwin received a letter from a young man named Alfred Wallace. He told him he hed lived
similar experiences, but in Brazil and Malaysia.
Wallace said the increase in the number of individuals and in mire modifications would cause the formation of a new
species that would compete with the mother species until it is eliminated.
Darwin published The Origin of Species in 1859

Artificial selection → method by which new races and varieties were established through controlled breeding
among individuals of one or more races.
Natural selection → Phenomenon of evolution. Suggests that the conditions of an environment favor or hinder
the survival of organisms, by which populations evolve. They become more adequate to live in their
environments with the passage of time.
1.4 Taxonomy
Taxonomy is the most ancient discipline of Biological Sciences. It comes from a discipline called Natural History

Taxonomy → Science that deals with the principles, methods and purposes of classification for the hierarchical
and systematized ordering of the groups of animals and vegetables.
 1.4.1 Purposes
The purpose of Taxonomy is to order and classify biologic species to form inclusive groups, based on the peculiarities of
their homologous characters.
Equally important is to know the variation of their characters.

 1.4.2 Systems of Classification

Aristotle created the first system of scientific classification in two large groups: enaimos (with red blood) anmd anaimos
(without red blood).

Classification systems → A form of organization used to categorize living organisms.

In the 18th century it was covened, by the naturalists, that Latin and Greek would become the official tongues os
the classification of species.
Linnaeus set the rules in his book Systema Naturae (1735). He determined species would be ordered in
hierarchical or classification taxonomic categories. They were the kingdom, the phylum, the class, order,
family, gender and the species.
He created a code of binomial nomenclature – a set of rules to designate binary names to species.
 1.4.3 The kingdoms of life
Haeckel created a system of three kingdoms for living organism in 1866. He designated the name “Protista” to encompass
all unicellular organisms. Within this group, those with a visible nucleus inside were assigned the name “true cells”; the
other type was known as bacteria.
He named bacteria: “cytodes”. He placed bacteria or cytodes in a subdivision of Protista called Monera.
In 1925, Edouard Chatton observed that the presence or absence of the nucleus was the most notorious characteristic of
any cell. Cells with a nucleus he called eukaryotes, which means true cell. Cells without nucleus were called prokaryotes.
In 1939, Herbert Copeland separated bacteria from the protista, creating for them the fourth kingdom of cells without
organelles: the Monera.
In 1959, Robert Whitaker formalized the fifth kingdom of life which he called Fungi.

Monera or Bacteria Protista or Protoctista Plantae Fungi Animalia

 Living beings  Mainly composed  Include all plants  Unicellular  Organisms
lacking nucleus of unicellular and green algae (yeasts), formed by
 Contains all microbes but  Nucleated pluricellular nucleated cells
bacteria – there are multicellular (mosses) and  Are consumers
unicellular living multicellular organisms multicellular  Are heterotrophs
beings forms of life too  Autotrophs (mushrooms and  Are multicellular
 Some are (red and brown  Their way of life fungi) species.  They are
multicellular algae). is sessile –  They’re all sensitive, irritable
 Can be autotroph  Size of their cells without nucleated and reactive, due
or heterotroph is ten thousand movement  Are heterotrophs to a nervous
 The reproduce times superior to  Mainly sexual  They are spore system
sexually bacteria reproduction but forming  Mostly sexual
 They synthesize  They present there are forms of  Macroscopic reproduction
compounds modes of asexual fungi are sessile;
 Some gases they locomotion by reproduction. the rest move by
synthesize pseudopods  Ontogenetic sliding on
transformed the  They are development surfaces.
atmosphere of autotroph or from a seed
primitive Earth heterotrophs.
 Cyanobacteria  They reproduce
hold the most sexually and
ancient fossil asexually
recorded in
history: 3500 to
3650 million
years

THREE DOMAINS: In 1977, Carl Woese studied the sequences of nucleotides of genes originating from a diversity of
species representing all kingdoms. Studied the genes of RNA.
Woese and Fox (1990) established the new classification scheme of three domains: Bacteria, Archea and Eucarya
(includes protists, plants, animals and fungi).
2.1 Chemical Energy and ATP
ATP: