Fundamental Concepts of Biology: From Cells to Ecosystems
Characteristics of Living Organisms
- Sensitivity
- Organisms respond to diverse stimuli.
- Adaptation
- All living organisms exhibit a “fit” to their environment.
- Metabolism
- This refers to the chemical reactions that occur within living organisms to maintain life.
- Homeostasis
- The ability of an organism to maintain constant internal conditions.
- Organization / Order
- Organisms are highly organized structures. The cell is the basic unit of life.
Levels of Biological Organization
- Population
- A group of organisms of the same species.
- Community
- A group of organisms of different species.
- Chemical Level
- Refers to the organization of living matter from atoms and molecules that form biomolecules.
- Organic Level
- Tissues with differentiated structural and functional characteristics come together to form organs.
- Ecological Level
- Individuals interact with others of the same species and with their environment.
The Hierarchy of Living Matter
- Atom
- Molecule
- Organelle
- Cell
- Tissue
- Organ
- System
- Organism
- Population
- Community
- Ecosystem
- Biome
- Biosphere
Theories on the Origin of Life
- Alexander Oparin
- He was the precursor of the Chemosynthetic Theory in the 1920s.
- Chemosynthetic Theory (or Primordial Soup Theory)
- This theory suggests that life originated from a series of chemical reactions in the Earth’s early oceans, where simple inorganic molecules formed complex organic compounds.
- Monomers
- The first simple organic molecules that joined by polymerization to form polymers.
- Chemosynthesis
- The process by which food is made by bacteria or other living organisms using inorganic molecules and chemical reactions.
Auxiliary Sciences of Biology
- Mathematics
- Helps to express observed results in numerical expressions such as percentages, statistics, and applied probability.
- Logic
- Proposes the foundations of scientific thought and reasoning.
- History
- Concentrates and recapitulates events that have occurred; without its knowledge, discoveries could not be accumulated and analyzed.
- Cytology
- Specialized in the study of the structure and function of cells, beyond what is studied by molecular biology.
- Zoology
- A discipline derived from biology that studies animal life.
- Physiology
- Studies the functions of living beings, such as respiratory functions, blood circulation, and the nervous system.
- Mastology (or Mammalogy)
- A branch of biology that deals with the specific study of mammalian animals.
- Ecology
- Studies the relationship between living beings and their habitat.
- Developmental Biology
- Studies the development of living beings from the moment they are conceived until they are born.
- Geography
- Describes territories and regions that are favorable or not for the development of life or the adaptation of living beings.
- Palynology
- A branch of biology that deals with studying pollen and spores.
- Cladistics
- Classifies living things based on their evolutionary relationships, based on their derived similarities.
- Aerobiology
- Deals with studying the distribution and levels of pollen and fungi for the study and prevention of allergies, as well as other small airborne particles.
Biomolecules: The Building Blocks of Life
Biomolecules are the most essential organic molecules involved in the maintenance and metabolic processes of living organisms.
The Four Major Types of Biomolecules
- Carbohydrates
- Lipids
- Proteins
- Nucleic Acids
Essential Elements of Life
Living matter is composed mainly of six elements: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), and Sulfur (S).
Carbohydrates
Carbohydrates are macronutrients and one of the three main ways by which our body obtains energy.
General Classification of Carbohydrates
- Monosaccharides (simple sugars)
- Disaccharides (two simple sugars joined)
- Polysaccharides (long chains of sugars)
Examples of Carbohydrates
- Hexoses (6-carbon sugars)
- Glucose, Fructose, Galactose
- Pentoses (5-carbon sugars)
- Ribose, Deoxyribose
- Maltose
- Glucose + Glucose
- Sucrose
- Glucose + Fructose
- Lactose
- Glucose + Galactose
- Starch
- The way plants store glucose.
- Glycogen
- Important for animals to store energy. It is found in the liver and muscles.
- Cellulose
- Found in the cell wall of plants. It is the most abundant carbohydrate in nature.
Lipids
Lipids are organic compounds that contain hydrogen, carbon, and oxygen atoms, which form the framework for the structure and function of living cells. In a lesser proportion, they contain Nitrogen, Phosphorus, and Sulfur.
- Fatty Acids
- A monomer or basic unit of many lipids.
- Saponifiable Lipids
- Lipids that contain fatty acids.
- Non-saponifiable Lipids
- Lipids that do not contain fatty acids.
Proteins
Proteins are very large molecules composed of basic units called amino acids.
- Essential Amino Acids
- Those amino acids that the human body does not produce by itself, such as valine, methionine, and lysine.
- Non-essential Amino Acids
- Those amino acids that the human body produces.
- Simple Proteins (Holoproteins)
- Proteins made up of only amino acids.
- Conjugated Proteins (Heteroproteins)
- Proteins made up of amino acids and other elements such as Chromium (Cr), Phosphorus (P), sugars, lipids, and nitrogenous bases.
Nucleic Acids
Nucleic acids are long-chain polymeric molecules. The monomer (the repeating unit) is known as the nucleotide.
- Ribose
- An important monosaccharide that is part of RNA and is involved in transforming and transporting proteins.
- Deoxyribose
- An important monosaccharide that is part of DNA and stores genetic information.
- Thymine
- A pyrimidine base that is found only in DNA.
- Uracil
- A pyrimidine base that is found only in RNA.
The Scientific Method
- Scientific Method
- A method of research with defined steps that include experiments and careful observations, establishing facts through testing and experimentation.
- Hypothesis
- A statement that can be tested by scientific investigation.