Characteristics of LifeChapter 1

Organization and Cells

All living things are made up of one (unicellular) or more cells (multicellular). › Cell- smallest unit capable of performing

all life’s processes.

Organization and Cells Living organisms have organization.

› Organization- high degree of order within an organism’s internal and external parts and its interaction with the living world. Highest level of organization- organism is

made up of organ systems that carry out specific functions within the organism (Ex: digestive system).

Organization and Cells

Response to Stimuli (Responsiveness)

Living things respond to a stimulus. › Stimulus- physical or chemical changes in an

organism’s internal or external environment.› This is essential to survival.

Homeostasis Homeostasis- maintenance of a

stable internal environment despite the constant changing of an organisms external environment.

Organisms have built in system that maintains stable internal conditions, such as:› Temperature› Water content› Nutrient uptake by cell

Homeostasis

Metabolism Energy is required to power ALL life’s

processes, such as› Growth and development› Movement› Repair

Metabolism- sum of all the chemical reactions that take in and transform energy and materials from the environment.

Metabolism

Photosynthesis › Plants, algae, phytoplankton, and some

bacteria capture and use the sun’s energy to make sugar molecules.

Organisms that cannot make their own food must get their food from other organisms.

Growth and Development

Nonliving things (Ex: icicles) grow by accumulating more of the same material (Ex: ice) of which they are made.

LIVING things grow through division and enlargement of cells. › Living multicellular organisms mature

through cell division, cell enlargement, and development.

Growth and Development Development- process by which

organisms become more adult. › Involves: cell division, cell differentiation,

or specialization. › Your body contains trillions of specialized

cells (Ex: nerve cells, blood cells, skin cells..), all of which originated from a single cell, the fertilized egg.

Reproduction Reproduction- Organisms produce

more organisms like themselves. › NOT needed for individual’s survival.

However, reproduction is ESSENTIAL to survival of a species.

Hereditary information is passed from parent to offspring through DNA. Short segments of DNA make up individual genes.

Reproduction

Two major types of reproduction:› Sexual reproduction- hereditary

information recombines from TWO organisms. Offspring are similar but not identical to either parent. Ex: Frogs

› Asexual reproduction- herditary information comes from a single parent organism. Offspring are identical to parent. Ex: bacteria

Evolution The basic GENETIC characteristics of

an individual organism do not change over their lifetime.

Populations of organisms DO change through time, or evolve.› This is critical to survival in a changing

world.› Explains the diversity of life-forms we see

on Earth today.

Themes in Biology

Diversity and Unity of Life

Living things come in many varieties (huge diversity).

Diversity and Unity of Life

Although diverse, living things are characterized by unity, or things they have in common.› Genetic code- rules governing how cells

use hereditary information.› Organelles that carry out life’s functions.

Diversity and Unity of Life “Tree of Life”- a model of the

relationships by ancestry among organisms. › Living things share certain genes, yet no

two types of organisms share all the same genes.

› Three main lineages, called domains. Organisms found on closer branches (lineages) have more similar sets of genes.1. Bacteria2. Archaea3. Eukarya - complex cells containing a

nucleus.

Less complex cells

Diversity and Unity of Life

Another system of grouping organisms divides life into six categories called kingdoms.› 4 kingdoms within domain Eukarya

Kingdoms Animalia, plantae, fungi, protista› 1 kingdom within domain Archaea

Kingdom Archaea› 1 kindom within domain Bacteria

Kingdom Bacteria

Tree of Life

Interdependence of Organisms

Ecology- study of how organisms interact with each other and the environment.› Study single species as well as

ecosystems. Ecosystems- communities of species and

their physical environment. Studies have shown that species depend on

each other and their physical environment for survival.

Evolution of Life Evolution- (decent with modification)

process in which inherited characteristics within POPULATIONS change over generations.› Can lead to genetically distinct populations

and development of new species.

Evolution of Life Theory of Evolution by Natural

Selection› Natural Selection- organisms with

certain favorable traits survive and reproduce more than those without them. Those traits that increase an organism’s

ability to survive and reproduce are called adaptations.