1. Define heterotroph, autotroph, photosynthesis, and cellular respiration.
To survive living beings must perform a basic and inherent function, nutrition. In this
sense, living beings can be classified into two major branches according to how they perform
this process of nutrition, autotrophs and heterotrophs.
a) Autotrophs, sometimes called producers, are able to synthesize all essential substances
for their mutualisms from inorganic substances, so that for their nutrition they do not
need other living things. The term autograph comes from the greek and means "that it
feeds by itself".
Autotrophic organisms produce their cell mass and organic matter, from carbon
dioxide, which is inorganic, as the only source of carbon, using light or chemicals as a
source of energy. Plants and other organisms that use photosynthesis are
photoautotrophic. Bacteria that use the oxidation of inorganic compounds like sulfur
dioxide or ferrous compounds as energy production are called chemolithotrophic.
b) Heterotrophs, in contrast to autotrophs, are those that must be fed with the organic
substances synthesized by other organisms, either autotrophic or heterotrophic in turn.
Among heterotrophs is a multitude of bacteria and predominantly animals.
Heterotrophic nutrition is performed when the cell is consuming already formed
organic matter. In this type of nutrition there is no transformation of inorganic matter
into organic matter. However, heterotrophic nutrition allows the transformation of food
into its own cellular matter. They have this type of nutrition some bacteria, protozoa,
fungi and animals.
c) Photosynthesis is the process of processing food by plants. Trees and plants use
photosynthesis to feed, grow and develop. To perform photosynthesis, plants need
chlorophyll, which is a green substance they have in the leaves. It is responsible for
absorbing adequate light to perform this process. In turn, chlorophyll is responsible for
the characteristic green color of plants.
d) Cellular respiration is the process by which cells degrade food molecules for energy.
Cell respiration is an exergonic reaction, where part of the energy contained in the food
molecules is used by the cell to synthesize ATP, part of the energy because not
everything is used, but a part is lost.
It can be considered as a series of oxide-reduction reactions in which the fuel molecules
are gradually oxidized and degraded releasing energy. Protons lost by food are picked
up by coenzymes.
Describe the structures and processes in the heterotroph (from consumption
through digestion) related to cellular respiration, including, at a minimum: digestive organs,
absorption, glycolysis, Krebs cycle (citric acid cycle, tricarboxylic acid cycle), the electron
transport chain (oxidative phosphorylation), cell membranes, cytosol, and mitochondrion.
The heterotrophic nutrition process of a cell can be divided into seven stages:
Capture: the cell attracts food particles by creating vortices through its cilia or
flagella, or by emitting pseudopodia, which encompasses the food.
Ingestion: the cell introduces the food into a food vacuole or phagosome. Some
ciliated cells, such as paramecia, have a kind of mouth, called a cytostome, by which
they phagocyte the food.
Digestion: the lysosomes pour their digestive enzymes into the phagosome, which
will thus transform into a digestive vacuole. Enzymes break down foods into the small
molecules that make them up.
Membrane passage: the small molecules released in the digestion pass through the
membrane of the vacuole and diffuse through the cytoplasm.
Defecation or management: the cell expels to the outside the molecules that are not
useful to him.
Metabolism: it is the set of chemical reactions that take place inside the cells of living
organisms and that allow the realization of vital functions.
Excretion: excretion is the elimination of the products that are generated during the
metabolism. These products are usually carbon dioxide (CO2), water (H2O) and
Cell respiration occurs in different cellular structures. The first of these is the glycolysis
that occurs in the cytoplasm. The second stage will depend on the presence or absence of O2
in the medium, determining in the first case aerobic respiration (occurs in mitochondria), and
in the second case anaerobic respiration or fermentation (occurs in the cytoplasm).
Glycolysis: occurs in a series of nine reactions, each one catalyzed by a specific
enzyme, to form two molecules of pyruvic acid, with the concomitant production of
ATP. The net gain is two molecules of ATP, and two of NADH per molecule of
The reactions of the glycolysis are realized in the cytoplasm, as already anticipated
and can occur in anaerobic conditions; i.e., in the absence of oxygen.
The first four steps of glycolysis serve to phosphorylate (incorporate phosphates) into
glucose and convert it into two molecules of the 3-carbon glyceraldehyde phosphate
compound. In these reactions two molecules of ATP are inverted in order to activate
the glucose molecule and prepare it for its rupture.
In the presence of oxygen, the next step in the degradation of glucose is respiration,
i.e. the stepwise oxidation of pyruvic acid to carbon dioxide and water.
Aerobic respiration is accomplished in two stages: the Krebs cycle and the electron
transport and the oxidative phosphorylation (these last two processes go hand in hand). In
eukaryotic cells these reactions take place within the mitochondria; In prokaryotes are carried
out in respiratory structures of the plasma membrane. It is important to note that the Krebs
cycle is carried out in the mitochondrial matrix; while electron transport and oxidative
phosphorylation occur at the cristae.
Mitochondria structure: Mitochondria are surrounded by two membranes, one
external that is smooth and one internal that folds inwards forming crests. Within the
inner space of the mitochondria around the ridges, there is a dense solution (matrix or
stroma) containing enzymes, coenzymes, water, phosphates, and other molecules
involved in respiration. The outer membrane is permeable to most small molecules,
but the internal membrane only allows passage of certain molecules such as pyruvic
acid and ATP and restricts the passage of others. This selective permeability of the
inner membrane is critically important because it enables the mitochondria to destine
the energy of the breath to produce ATP.
Most of the Krebs cycle enzymes are found in the mitochondrial matrix. The enzymes
that act in the transport of electrons are in the membranes of the peaks.
Krebs cycle: known as the citric acid cycle, is the final common route of oxidation of
pyruvic acid, fatty acids and carbon chains of amino acids.
The first reaction of the cycle occurs when coenzyme A transfers its acetyl group (2
carbons) to the 4-carbon compound (oxaloacetic acid) to produce a 6-carbon
compound (citric acid). Citric acid initiates a series of steps during which the original
molecule reorders and continues to oxidize, consequently reducing other molecules:
from NAD + to NADH and from FAD + to FADH2. In addition, two carboxylations
occur and because of this series of reactions an initial molecule of 4 carbons is
obtained oxaloacetic acid.
The entire process can be described as a cycle of oxaloacetic to oxaloacetic, where
two carbon atoms are added as acetyl and two carbon atoms are lost as CO2.
Electron transport chain: At this stage, the reduced coenzymes are oxidized, the
NADH is converted to NAD + and the FADH2 is FAD +. When this reaction occurs,
the hydrogen atoms (or equivalent electrons) are carried through the respiratory chain
by a group of electron carriers, called cytochromes. Cytochromes undergo successive
oxidations and reductions (reactions in which electrons are transferred from an
electron donor to an acceptor).
Consequently, in this final stage of respiration, these electrons of high energy level
descend step by step to the low energy level of the oxygen (last acceptor of the chain),
thus forming water.
It should be noted that the first three acceptors receive H + and the electron together.
In contrast, from the fourth acceptor, only electrons are transported, and the H +
remain in solution.
Oxidative phosphorylation: the electron flow is intimately coupled to the
phosphorylation process, and does not occur unless the latter can also be verified.
This, in a sense, prevents waste because the electrons do not flow unless there is the
possibility of formation of energy rich phosphates. If the electron flow were not
coupled to phosphorylation, there would be no formation of ATP and the energy of
the electrons would degrade as heat. Since the phosphorylation of ADP to form ATP
is coupled to the oxidation of the components of the electron transport chain, this
process is called oxidative phosphorylation. At three transitions in the electron
transport chain, significant drops occur in the amount of potential energy retained by
the electrons, so that a relatively large amount of free energy is released at each of
these three steps, ATP being formed.
Describe the structures and processes in the autotroph related to photosynthesis,
including at a minimum: the chlorophyll, carotenoids, chloroplast, stroma, grana, and
Consumers depend on other living things for energy. Virtually all that energy comes
from plants and algae. These producers convert solar energy into chemical energy, through
a process called photosynthesis. The chemical energy derived from photosynthesis is stored
in the cells of these producers in the form of carbohydrates and other organic molecules
necessary to sustain all life forms on the planet.
Several types of electromagnetic radiation come to the surface of the earth. Light is an
electromagnetic radiation in a specific band of wavelength. The visible light comprises a
specific region of the electromagnetic spectrum from 400 nm. At 700 nm. of wavelength.
Within this spectrum, violet has the shortest wavelength, while the red light has the longest.
Light is made up of particles of energy called photons. The energy of a photon is
different for the light...