BIOLOGY
The scientific study of life is known as biology.
Although it is a natural science with a large reach, it is tied together as a unified, cohesive discipline by a number of overarching concepts.
For instance, every creature consists of cells that process genetic information that may be passed on to future generations.
The explanation for the unity and variety of life is provided through evolution, which is a key subject.
Processing energy is essential to life since it enables movement, growth, and reproduction in living things.
And lastly, all living things have the capacity to control their own interior surroundings.
The molecular biology of a cell, the anatomy and physiology of plants and animals, as well as the evolution of populations are all topics that biologists might research[1].
As a result, there are several subdisciplines of biology, each of which is determined by the type of research issues it addresses and the methods it employs.
Similar to other scientists, biologists gather data about their surroundings by making observations, asking questions, coming up with theories, running experiments, and drawing conclusions.
The variety of life on Earth, which first appeared more than 3.7 billion years ago, is enormous.
The many kinds of life, from prokaryotic species like bacteria and archaea to eukaryotic organisms like protists, fungi, plants, and animals, have been the subject of study and classification by biologists.
These different creatures support an ecosystem's biodiversity by playing specialized roles in the movement of nutrients and energy through its biophysical environment.
Article focus: Biology's history
Fly diagram from Robert Hooke's trailblazing Micrographia, published in 1665.
The oldest known origins of science, which included medicine, date back to Mesopotamia and ancient Egypt between 3000 and 1200 BCE.
They influenced the development of ancient Greek scientific philosophy.
Aristotle, a Greek philosopher who lived from 384 to 322 BCE, was a major contributor to the growth of biological knowledge.
He looked at the variety of life and biological causality.
Theophrastus, his successor, started the formal study of plants.
With the spectacular advancement of the microscope by Anton van Leeuwenhoek, biology started to advance swiftly.
Researchers made the discoveries of spermatozoa, bacteria, infusoria, and the variety of microscopic life at that time.
Jan Swammerdam's investigations sparked a renewed interest in entomology and contributed to the development of microscopic dissection and staining methods.
The development of microscopy had a significant influence on biological reasoning.
Biologists emphasized the vital significance of the cell in the early 19th century.
Schleiden and Schwann started promoting the now-universal ideas that (1) cells are the fundamental building block of organisms and (2) each individual cell possesses all the characteristics of life in 1838, though they disagreed with the notion that (3) all cells originate from the division of other cells and continued to support spontaneous generation.
Natural historians began to concentrate on taxonomy and categorization during this time.
A rudimentary taxonomy of the natural world was established by Carl Linnaeus in 1735, and all of his species were given scientific names in the 1750s.
Georges-Louis Leclerc, Comte de Buffon, saw living things as changeable and considered species as artificial classifications, even speculating on the idea of shared ancestry.
Jean-Baptiste Lamarck's writings, which offered a cogent explanation of evolution, are credited with inspiring serious evolutionary thought.
Charles Darwin, a British naturalist, developed a more successful evolutionary theory based on natural selection by combining Humboldt's biogeographical approach, Lyell's uniformitarian geology, Malthus's writings on population growth, and his own morphological expertise and extensive fieldwork. Alfred Russel Wallace came to the same conclusions independently based on analogous reasoning and data.
Gregor Mendel's research in 1865 laid the groundwork for contemporary genetics.
The fundamentals of biological inheritance were described in .several
Yet it wasn't until the early 20th century, when Darwinian evolution and conventional genetics were finally reunited, that the significance of his work came to light.
Alfred Hershey and Martha Chase conducted severalnumber of tests in the 1940s and early 1950s that suggested DNA was the part of chromosomes that carried the trait-carrying units that were now known as genes.
The advent of molecular genetics in 1953 was ushered in by the discovery of the double-helical structure of DNA by James Watson and Francis Crick, as well as a focus on novel types of model organisms including viruses and bacteria.
From the 1950s, molecular biology has seen a significant expansion.
With the discovery that DNA contains codons, Robert W. Holley, and Marshall Warren Nirenberg succeeded in deciphering the genetic code.
To map the human genome, the Human Genome Project was started in 1990.
Basis in chemicals
molecules and atoms
Further details:
Chemistry Chemical elements make up all living things; oxygen, carbon, hydrogen, and nitrogen make up the majority (96%) of an organism's mass, while calcium, phosphorus, sulfur, sodium, chlorine, and magnesium make up the majority of the remaining components.
Compounds like the essential to life substance water may be created when several elements mix.
The study of chemical reactions that take place inside and around living things is known as biochemistry.
The study of molecular biology, which includes molecular synthesis, modification, processes, and interactions, aims to comprehend the molecular underpinnings of biological activity inside and between cells.
Water
Diagram showing hydrogen bonding between water molecules
See also: Water distribution on Earth, Circumstellar habitable zone, and Planetary Habitability
The Earth's first ocean, which formed some 3.8 billion years ago, gave rise to life.
Since that time, every creature has had the highest concentration of the molecule water.
Water is necessary for life because it is an efficient solvent that can dissolve tiny molecules or solutes like sodium and chloride ions to create an aqueous solution.
These solutes are more likely to interact with one another after being dissolved in water and participate in chemical processes that support life.
When it is a liquid, water is denser than when it is a solid (or ice).
Because of this special quality of water, ice may float on top of liquids like ponds, lakes, and seas, protecting the liquid below from the chilly air above.
Water has a larger specific heat capacity than other solvents like ethanol because of its ability to absorb energy.
As a result, to turn liquid water into water vapor, a significant amount of energy is required to break the hydrogen bonds between water molecules.
Water is not entirely stable as a molecule because it constantly splits into hydrogen and hydroxyl ions before reforming back into a water molecule.
The quantity of hydrogen ions in pure water equals (or balances) the number of oxygen ions.
Organisms need organic substances like glucose.
Organic molecules are those that have carbon bound to a different element, like hydrogen.
Almost all of the molecules that make up each organism—with the exception of water—contain carbon.
Carbon can create covalent connections with up to four other atoms, which allows it to create a wide range of massive, intricate compounds.
For instance, a single carbon atom can create three triple covalent bonds, two double covalent bonds, or four single covalent bonds, as in the case of methane, carbon dioxide, and carbon monoxide, respectively (CO).
Carbon may also form ring-shaped structures like glucose or extremely lengthy chains of interconnecting carbon-carbon bond Hydrocarbon
The hydrocarbon, a broad family of organic molecules made up of hydrogen atoms linked to a chain of carbon atoms, is the most basic type of organic molecule.
Other elements, such as oxygen (O), hydrogen (H), phosphorus (P), and sulfur (S), can replace a hydrocarbon backbone, altering the chemical behavior of the resulting molecule.
Functional groups are made up of these atoms (O-, H-, P-, and S-) and are joined to a core carbon atom or skeleton.
The amino group, carboxyl group, carbonyl group, hydroxyl group, phosphate group, and sulfhydryl group are six major functional groups that may be found in organisms.
Macromolecules
The main, secondary, tertiary, and quaternary structures of a hemoglobin protein are (a), (b), (c), and (d), respectively.
Large molecules called macromolecules are composed of single components or monomers that are smaller.
Nucleotides, amino acids, and sugars are examples of monomers.
polys
The only category of macromolecules that is entirely composed of lipids does not contain any polymers.
They mostly consist of nonpolar, hydrophobic (water-repelling), and polar-free compounds, such as steroids, phospholipids, and fats.
Among all the macromolecules, proteins have the most variety.
These comprise structural proteins, transport proteins, big signaling molecules, enzymes, and antibodies.
Amino acids are the fundamental building block (or monomer) of proteins.
Proteins include twenty different amino acids.
A polymer of nucleotides is a nucleic acid.
To transmit, express, and preserve genetic information is what they do.
Cells Article central: Cell (biology)
According to cell theory, cells are the basic building blocks of life, all living things are made up of one or more cells, and all cells divide to create new ones from preexisting ones.
Most cells can only be seen under a light or electron microscope due to their extremely tiny sizes, which range from 1 to 100 micrometers.
Cells may be divided into two categories: prokaryotic cells, which lack a nucleus, and eukaryotic cells, which have.
Eukaryotes can be single-celled or multicellular, whereas prokaryotes are single-celled creatures like bacteria.
Every cell in a multicellular organism's body eventually descends from a single cell in a fertilized egg.
cell architecture
Animal cell structure showing different organelles
Every cell is surrounded by a cell membrane, which keeps the external environment from entering the cytoplasm of the cell.
The lipid bilayer that makes up a cell membrane includes cholesterols that sit between phospholipids to keep them fluid at varying temperatures.
Small molecules like oxygen, carbon dioxide, and water may flow through cell membranes, which are semipermeable, but bigger molecules and charged particles like ions cannot.
Membrane proteins are also found in cell membranes. They include integral membrane proteins, which penetrate the membrane and operate as membrane transporters, and peripheral proteins, which cling slackly to the cell's outer membrane and function as cell-shaping enzy mes.
Many substances, including proteins and nucleic acids, are found in the cytoplasm of a cell.
Eukaryotic cells also feature specialized organelles, which can be spatial units or have their own lipid bilayers, in addition to biomolecules.
Among these organelles are the cell nucleus, which houses the majority of the DNA in the cell, and the mitochondria, which produce adenosine triphosphate (ATP) to fuel cellular functions.
In the production and packaging of proteins, respectively, other organelles like the endoplasmic reticulum and the Golgi apparatus are involved.
Lysosomes are another another specialized organelle that are capable of engulfing biomolecules like proteins.
A cell wall that serves as support for the plant cell, chloroplasts that use sunlight energy to make sugar, and other extra organelles that set plant cells apart from animal cells are just a few examples.
Microtubules, intermediate filaments, and microfilaments make up the cytoskeleton of eukaryotic cells, which aids in the movement of the cell and its organelles as well as supports the cell.
The intermediate filaments are made up of fibrous proteins, whereas the microtubules are composed of tubulin (such as -tubulin and -tubulin).
Actin molecules that connect with other protein strands make form microfilaments.
Metabolism
More details: Bioenergetics
Example of an exothermic reaction induced by an enzyme
Energy is needed by every cell to maintain cellular functions.
The collection of chemical processes in an organism known as metabolism.
The three major functions of metabolism are to break down food and fuel into building blocks for monomers, to perform cellular operations, and to get rid of metabolic waste.
Organisms may grow and reproduce, maintain their structures, and react to their surroundings thanks to these enzyme-catalyzed processes.
Catabolic metabolic processes involve the breakdown of substances (for instance, the conversion of glucose to pyruvate during cellular respiration), whereas anabolic metabolic processes involve the creation of substances (such as proteins, carbohydrates, lipids, and nucleic acids).
Typically, anabolism uses energy whereas catabolism releases it.
The chemical processes of metabolism are arranged into metabolic pathways, where one molecule is changed into another by a sequence of stages, each of which is aided by a different enzyme.
Since they couple desired energy-consuming events that organisms want to push to occur with energy-releasing spontaneous reactions, enzymes are essential to metabolism.
Enzymes work as catalysts by lowering the activation energy required to transform reactants into products, allowing a reaction to occur more quickly without consuming them.
Moreover, enzymes enable the control of a metabolic reaction's pace, for instance in response to environmental changes or messages from neighboring cells.
The respiration of cells
An eukaryotic cell breathes
The process of converting chemical energy from foods into adenosine triphosphate (ATP), which is subsequently used to discharge waste products, is known as cellular respiration. During catabolic processes, which divide big molecules into smaller ones and release energy, respiration takes place. One of the main mechanisms through which a cell produces chemical energy to power cellular activity is respiration.
A sequence of biological stages, some of which include redox reactions, lead to the total reaction.
Although cellular respiration is a combustion process in theory, the gradual, controlled release of energy from the chain of reactions clearly distinguishes it from one when it happens in a cell.
The primary nutrient needed by animal and plant cells in respiration is sugar, namely glucose.
Aerobic respiration, which contains four steps including glycolysis, citric acid cycle (also known as the Krebs cycle), electron transport chain, and oxidative phosphorylation, is the name given to cellular respiration that uses oxygen.
In the cytoplasm, a metabolic process known as glycolysis transforms one glucose molecule into two pyruvates while simultaneously producing two net molecules of ATP.
The pyruvate dehydrogenase complex subsequently converts each pyruvate into acetyl-CoA while also releasing NADH and carbon dioxide.
The citric acid cycle, which occurs within the mitochondrial matrix, is entered by acetyl Coa.
The entire production from 1 glucose (or 2 pyruvates) at the end of the cycle is 6 NADH, 2 FADH2, and
dioxide of carbon.
The citric acid cycle, which occurs within the mitochondrial matrix, is entered by acetyl-Coa.
The entire yield from 1 glucose (or 2 pyruvates) at the end of the cycle is 6 NADH, 2 FADH2, and 2 ATP molecules.
The final step is oxidative phosphorylation, which takes place in the mitochondrial cristae in eukaryotes.
The electron transport chain, which is made up of four protein complexes and is involved in oxidative phosphorylation, transfers electrons from one complex to the next, releasing energy from NADH and FADH2, which is then coupled with the pumping of protons (hydrogen ions) across the inner mitochondrial membrane through chemiosmosis to produce a proton motive force.
The enzyme ATP synthase is propelled by energy from the proton motive force to produce additional ATPs by phosphorylating ADPs.
Pyruvate would undergo fermentation rather than cellular respiration, which occurs when oxygen is present, to be processed.
Instead of being delivered into the mitochondrion, pyruvate stays in the cytoplasm, where it is changed into waste materials that may be expelled from the cell.
In addition to eliminating the extra pyruvate, thpurposeserves the purposes of oxidizing the electron carriers so they may resume glycolysis.
For the purpose of using it again in glycolysis, fermentation converts NADH to NAD+.
In the absence of oxygen, fermentation inhibits the cytoplasmic accumulation of NADH and supplies NAD+ for glycolysis.
The type of waste produced depends on the organism.
Lactic acid is the waste product of skeletal muscles.
Lactic acid fermentation is the name given to this kind of fermentation.
When energy needs during vigorous exercise exthe ceed energy supply, the respiratory chain is unable to break down all of the hydrogen atoms linked by NADH.
NAD+ is replenished during anaerobic glycolysis when pairs of hydrogen join with pyruvate to create lactate.
Lactate dehydrogenase catalyzes the reversible process that results in lactate production.
As an indirect precursor for liver glycogen, lactate can also be employed.
When oxygen is available during recovery, NAD+ binds to the hydrogen from lactate to create ATP.
Ethanol and carbon dioxide are waste products in yeast.
Alcoholic or ethanol fermentation is the term used to describe this process.
Substrate-level phosphorylation, which does not require oxygen, produces the ATP in this process.
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