Studying LifeVodcast 1.3

Unit 1: Introduction to Biology

What is Biology?

Biology – the study of life

Biology is the science that seeks to understand the living world

What Characteristics Do All Living Things Share?

Living things are made up of cellsCells are the basic unit of lifeOrganisms are composed of one or more cells – the smallest units

considered aliveDespite their small size, cells are complex and highly organized

Living things are based on a universal genetic codeAll organisms store the complex information they need to live,

grow, and reproduce in a genetic code written in a molecule call DNA

That information is copied and passed from parent to offspring

Living things obtain and use materials and energyAll organisms must take in materials and energy to grow, develop,

and reproduceMetabolism – the combination of chemical reactions through

which an organism builds up or breaks down materials

Characteristics of Living Things Continued…

Living things grow and developEvery organism has a particular pattern of growth and

developmentDuring development, cells divide and differentiate

(they begin to look different from one another and perform different functions)

Living things reproduceAll organisms reproduce, which means that they

produce new similar organismsSexual reproduction – cells from two parents unite

to form the first cell of a new organismAsexual reproduction – a single organism produces

offspring identical to itself

Characteristics of Living Things Continued…

Living things respond to their environmentOrganism detect and respond to stimuli from their

environmentStimulus – a signal to which an organism responds

Living things maintain a stable internal environmentAll organisms need to keep their internal environment

relatively stable, even when external conditions change dramatically

Homeostasis – relatively constant internal physical and chemical conditions that an organism maintains

Taken as a group, living things evolveOver generations, evolution (change over time)

occurs to groups of organismsEvolutionary change links all forms of life to a common

origin more than 3.5 billion years ago

What Are the Central Themes of Biology?

The study of Biology revolves around several interlocking big ideas:

Cellular Basis of LifeLiving things are made up of cellsUnicellular – single-celledMulticellular – consisting of two or more cells

Information and HeredityLiving things are based on a universal genetic code – DNA

Matter and EnergyLiving things obtain and use materials and energyLife requires matter that serves as nutrients to build body

structures, and energy that fuels life’s processesThe need for matter and energy link all living things on Earth in

a web of interdependent relationships

Central Themes in Biology Continued…

Growth, Development, and ReproductionAll living things reproduceDuring growth and development, generalized cells

typically become more and more different and specialized for particular functions

HomeostasisLiving things maintain a relatively stable internal

environment, a process known as homeostasisFor most organisms, any breakdown of homeostasis

may have serious or even fatal consequences

EvolutionTaken as a group, living things evolveEvolutionary theory is the central organizing

principle of all biological and biomedical science

Central Themes in Biology Continued…

Structure and FunctionStructures have evolved in ways that make

particular functions possible

Unity and Diversity of LifeAlthough life takes an almost unbelievable variety of

forms, all living things are fundamentally similar at the molecular level

One great contribution of evolutionary theory is that it explains both the is unity of life and its diversity

Interdependence in NatureAll forms of life on Earth are connected into a

biosphere – “living planet”Within the biosphere, organisms are linked to one

another and to the land, water, and air around themRelationships between organism and their

environments depend on the cycling of matter and the flow of energy

Central Themes in Biology Continued…

Science as a Way of KnowingScience is not a list of facts, but “a way of knowing”The job of scientists is to use observations,

questions, and experiments to explain the natural world in terms of natural forces and events

Successful scientific research reveals rules and patterns that can explain and predict at least some events in nature

Science allows us to take actions that affects events in the world around us

What are the levels of biological organization?

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Levels of Biological Organization

Atoms – basic unit of matter (ex: C, H, N, O)

Molecules – a chemical structure consisting of two or more atoms (ex: DNA, water)

Organelles – the various functional components present in a cell (ex: mitochondria, chloroplast) Cells – basic

unit of life - the structural and functional unit of all living things (ex: plant cell, animal cell)

Levels of Biological Organization

Tissues – made up of a group of cells that work together, performing a specialized function (ex: epidermal tissue, nervous tissue)

Organs – a body part made up of a group of tissues that carries out a particular function in the body (ex: the brain, leaves)

Organ Systems – a team of organs that cooperate in a larger function (ex: nervous system, digestive system)

Levels of Biological Organization

Organism – individual living thing (ex: elephant, tree)

Population – all the individuals of a species living within the bounds of a specific area

Community – the entire array of organisms inhabiting a particular ecosystem

Levels of Biological Organization

Ecosystem – consists of all the living (biotic) things in a particular area along with all the nonliving (abiotic) components of the environment with which life interacts

Biosphere – consists of all life on Earth and all the places where life exists – all of Earth’s ecosystems combined

How Do Different Fields of Biology Differ in Their

Approach to Studying Life?

Biology includes many overlapping fields that use different tools to study life from the level of molecules to the entire planet