Chapter 1 - An Introduction to Biology

BIOL 190A 1004

What is biology?

The study of life

Principles 1-6 define

the basic features of life

Principle 1

Cells are the simplest units of life

What is cell theory?

All organisms are composed of one or more cells, cells are the smallest units of life, new cells come from pre-existing cells be cell division

Principle 2

Living organisms use energy

The two major strategies to gain energy:

photosynthesis and consumption

Principle 3

Living organisms interact with their environment (e.g. predators (living), light (non-living))

Principle 4

Living organisms maintain homeostasis

Principle 5

The genetic material (DNA) provides a blueprint that allows organisms to grow, develop, and reproduce

Principle 6

Populations of organisms evolve from one generation to the next and are related by an evolutionary history

All organisms contain genetic material composed of

DNA, deoxyribonucleic acid (dee-OK-see-RY-boh-noo-KLAY-ik A-sid)

The genetic information of a ___ can change over time

population

Principle 7

Structure determines function

Principle 8

New properties of life emerge from complex interactions

Principle 9

Biology is an experimental science

Principle 10

Biology is a quantitative science

Principle 11

Biologists use models and simulations to test experimental predictions and convey their ideas

A model is…

a conceptual, mathematical, or physical depiction of a real-world phenomenon

Principle 12

Biology affects our society

The organization of living organisms can be analyzed at different levels of complexity. Rank from least to most complex (11):

Atoms, molecules, cells, tissues, organs, organ systems, organism, population, community, ecosystem, biosphere

Terms often used to describe life:

Unity and diversity

Unity…

refers to the common characteristics displayed by all forms of life (Principles 1-6)

Diversity…

refers to the many different forms of unicellular and multicellular life

The underlying factor that explains both the unity and diversity of modern species is…

evolution

Evolution

the changing genetic composition of a population over time

bya

billion years ago

Evolutionary history helps us…

understand the structure and function of an organism

Evolutionary change occurs by 2 mechanisms:

vertical descent with mutation and horizontal gene transfer

Vertical descent with mutation involves…

transfer of genetic information form parents to offspring

New species evolve from pre-existing species by the accumulation of…

mutations

Better…

stronger… faster…

Natural selection…

drives an increased frequency of beneficial mutations in a population over time

Horizontal gene transfer is

a distinct process of exchanging genetic information that is relatively rare

“Evolution happens…

now.”

In horizontal gene transfer, an organism…

incorporates genetic material from another organism without being offspring (e.g. bacteria becoming antibiotic resistant, humans undergoing gene-replacement therapy)

Adaptation

a characteristic in a species that is the result of natural selection; affect survival and reproduction

Artificial selection

a human driven form of selection (e.g. tuskless elephants appear to be increasing die to poaching (which is an exclusively female trait)… address me…)

The tuskless condition is

an adaption that may lessen poaching

Taxonomy

the grouping of species based on common ancestry

The largest groups in taxonomy are the three domains of life:

Bacteria, Archaea, and Eukarya

Prokaryote

single-celled organisms that do not have a distinct nucleus or other membrane-bound internal structures

Bacteria

unicellular prokaryotes

Archaea

unicellular prokaryotes

Eukarya

unicellular and multicellular eukaryotes

The smallest group in taxonomy is the

species; each has a unique scientific name

Science

the observation, identification, experimental investigation, and theoretical explanation of natural phenomena

Many scientists utilize ___ ___ in their research and use a ___ ___ to test hypotheses

model organisms; scientific method

Hypothesis

a proposed explanation for a natural phenomenon

Hypotheses must

yield predictions that are testable and falsifiable

Theory

a broad explanation of some aspect of the natural world that is substantiated by a large body of evidence

Theories are viewed as

knowledge

Researchers typically utilize 2 general approaches:

discovery-based science and hypothesis testing

Discovery-based science involves

the collection and analysis of data without a preconceived hypothesis

The scientific method of hypothesis testing is

designed to be an objective was to gather knowledge

Data are often collected in parallel ___ and ____ groups, which differ by a single factor

control; experimental

Biologists engage in a variety of

interpersonal interactions and communication practices

Biodiversity

the variation in life; encompasses genetic, species, and ecosystem diversity

Importance of biodiversity: food security

many foods are derived from wild species, so decreased biodiversity limits development of new agricultural crops

Importance of biodiversity: medicines for humans and domesticated species

over 50% of commercially available drugs (including 75% of cancer drugs) are compounds extracted or derived from wild species

cleaner water and air

wild species cycle water and nutrients and filter pollutants

ecosystem resilience

diverse communities are more resistant to disease and disturbances

Biodiversity in the past several decades

steadily decreasing, however there are many approaches for restoration