Biology: Cell Theory, Genetics, Evolution, and Scientific Methods

Biology

The scientific study of life.

Reductionism

An approach that reduces complex systems to simple components that are manageable to study.

Emergent properties

Result from the arrangement and interaction of parts as complexity increases. These characterize nonbiological entities as well.

Systems biology

An analysis of the interactions among the parts of a biological system. It complements reductionism to explore emergent properties.

Cell

The smallest unit of organization that can perform all activities required for life.

Cell theory

States that all living organisms are made from cells.

Prokaryotic cells

The cells of bacteria and archaea; they are simpler, usually smaller, and do not contain a nucleus or other membrane-enclosed organelles.

Eukaryotic cells

Composed of all other forms of life; they have membrane-enclosed organelles, the largest of which is usually the nucleus.

Chromosomes

Structures within cells that contain genetic material in the form of DNA (deoxyribonucleic acid).

DNA (deoxyribonucleic acid)

The form of genetic material contained within chromosomes. Each DNA molecule is made up of two long chains arranged in a double helix.

Genes

The units of inheritance. They encode information for building the molecules synthesized within the cell, and the genetic information encoded by DNA directs the development of an organism.

Nucleotides

Four kinds of chemical building blocks (abbreviated A, G, C, and T) that make up each chain of a DNA molecule.

Gene expression

The process of converting information from a gene to a cellular product.

Genome

An organism's entire 'library' of genetic instructions.

Genomics

The study of whole sets of genes in one or more species.

Proteomics

The study of whole sets of proteins and their properties.

Proteome

The entire set of proteins expressed by a given cell, tissue, or organ.

Bioinformatics

The use of computational tools to process a large volume of data very rapidly, on which the genomics approach depends.

Producers

Plants and other photosynthetic organisms that generate chemical energy.

Consumers

Organisms that feed on other organisms or their remains.

Feedback regulation

A mechanism through which many biological processes can self-regulate, where the output, or product of a process, regulates that very process.

Negative feedback

The most common form of regulation in living organisms, in which the response reduces the initial stimulus.

Positive feedback

A less common form of regulation in which an end product speeds up its own production.

Global warming

The resulting effect from the increased burning of fossil fuels and release of carbon dioxide (CO2) into the atmosphere over the past 150 years. It is one aspect of climate change.

Climate change

A phenomenon that includes global warming, shifting wind and precipitation patterns, and more frequent extreme weather events.

Evolution

The scientific explanation for both the unity and diversity of organisms, based on the concept that living organisms are modified descendants of common ancestors.

Species

A classification of organisms, with approximately 1.8 million identified and named to date. Each species is given a two-part name: the genus and a unique species name (e.g., Homo sapiens).

Domains

The three divisions into which organisms are currently divided: Bacteria, Archaea, and Eukarya.

Prokaryotes

Include the domains Bacteria and Archaea.

Eukaryotes

Include all eukaryotic organisms, comprising the domain Eukarya, which has four subgroups: Plants, Fungi, Animals, and Protists.

Protists

The most numerous and diverse eukaryotes, mostly single-celled organisms.

Descent with modification

One of Charles Darwin's main points, stating that species showed evidence of evolving from common ancestors.

Natural selection

The mechanism behind descent with modification, proposed by Charles Darwin. It describes how individuals with traits best suited to their environment are more likely to survive and reproduce, leading to the propagation of beneficial traits and adaptation over time.

Adaptation

The result of natural selection, where organisms develop traits suited to the circumstances of their way of life and their environment.

Inquiry

The search for information and explanations of natural phenomena.

Qualitative data

Often takes the form of recorded descriptions.

Quantitative data

Expressed as numerical measurement, often organized into tables and graphs.

Inductive reasoning

Derives generalizations from a large number of specific observations.

Deductive reasoning

Uses general premises to make specific predictions.

Controlled experiment

An experiment in which an experimental group is compared with a control group.

Experimental variables

Features or quantities that vary in an experiment.

Independent variable

The variable that is manipulated by the researchers.

Dependent variable

The variable that is predicted to be affected in response to the independent variable.