Lecture 1: Themes in Biology Bio Sci 93

Evolution

the process by which populations of organisms change over generations, driven by mechanisms like natural selection acting on heritable variation

Adaptation

an inherited trait that improves an organism’s ability to survive and reproduce in its specific environment, arising through the process of evolution

Ecosystem

all the living organisms in an area together with the nonliving (physical/chemical) components of their environment, such as soil, water, and air, that they interact with; all the organisms living in a particular area, togther with the nonliving components of the environment with which they interact

Gene

a discrete unit of hereditary information, made of a specific sequence of DNA, that is passed from parents to offspring

DNA (deoxyribonucleic acid)

the molecule that stores hereditary information in nearly all living organisms and is used as the basis for inheritance and protein synthesis

Emergent properties

new properties that arise at each successive level of biological organization (e.g., molecules → cells → tissues → organisms), due to the arrangement and interactions of components at the level below

Order (as a property of life)

the highly organized, structured arrangement characteristic of living things, seen at every level from molecules to organisms - one of the defining properties of life

Regulation (as a property of life)

an organism’s ability to control and adjust its internal environment (homeostasis) even as external conditions change

Energy processing (as a property of life)

the property of life by which organisms take in energy from their surroundings and transform it to fuel their life activities (metabolism)

Reproduction (as a property of life)

the property of life by which organisms produce new individuals of the same kind, passing on their genetic information

Cell (as the basic unit of life)

the smallest unit of organization capable of performing all the activites of life; all cells share the traits of being enclosed by a membrane and using DNA as genetic information

Structure fits function

the biological theme that an organism’s or structure’s physical form is closely tied to, and enables, the specific job it performs (e.g., a bird’s wing shape enabling flight). Seen at every level (tissue, cellular, subcellular)

Evolutionary adaptation (as a property of life)

the property of life in which an inherited trait that increased an organism’s ability to survive and reproduce in its environment, having arisen through natural selection over many generations

Growth and development (as a property of life)

the property of life in which an organism’s DNA-directed program leads to an orderly increase in size and increasing specialization of structures and functions over time

Response to environment (as a property of life)

the property of life in which organisms detect and react to stimuli from their surroundings, such as light, touch, chemicals, etc

Biosphere

the global ecosystem - the sum of all of Earth’s ecosystems and all the life they contain; the braodest level of biological organization

Community

all of the different species populations living together and interacting within a particular area (living)

Population

a group of individuals of the same species lviing in the same area at the same time

Organisms

an individual living thing, which may be made of one or many cells, capable of carrying out all the activities of life

Organ

a structure composed of multiple types of tissue that work together to carry out a specific function (e.g., the heart, made of muscle, nerve, and connective tissue)

Tissue

a group of siimlar cells that work together to perform a specific function (e,g., muscle tissue, nervous tissue)

Organelle

a specialized, membrane-bound structure within a cell that performs a specific function (e.g., the nucleus, mitochondria)

Molecule

two or more atoms, fo the same or different elements, held together by covalent bonds - the smallest level shown in the hierarchy of biological organization

Hierarchy of life (largest to smallest)

biosphere, ecosystems, communities, populations, organisms, organs, tissues, cells, organelles, molecules.

Properties of life

order, regulation, reproduction, growth and development, energy processing, response to the environment, evolutionary adaptation. Life is easier to recognize by what living things do than to define in a sentence or two.

Theme: expression and transmission of genetic information

all life is based on heritable information and all forms of life use the same genetic code. Flow: DNA (transcription) to mRNA (translation) to amino acid chain (folding) to protein.

Theme: organisms as open systems

life requires the transfer and transformation of energy and matter. Energy flows through (sunlight to chemical energy to heat lost); chemicals cycle (plants, consumers, decomposers).