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Studying Life

Section 1-3

pg. 16-23

Characteristics of Living Things

Living things are made up of units called cells.

Living things reproduce.

Living things are based on a universal genetic code.

Living things grow and develop.

Living things obtain and use materials and energy.

Living things respond to their environment.

Living things maintain a stable internal environment.

In general, living things change over time.










Made up of cells

• Cell - a collection of living matter enclosed by a barrier that separates the cell from its surroundings.

A cluster of neural cells derived from human embryonic stem cells in the lab of UW-Madison stem cell researcher and neurodevelopmental biologist Su-Chun Zhang.

Made up of cells

• The cell membrane is able to create an “inside” and an “outside” that is necessary for life to exist.

Made up of cells

• There are both unicellular (single-celled)

• and multicellular (many-celled) organisms.

Tetrahymena, a ciliate protozoan genus related to Paramecium










Reproduction

• Sexual reproduction – Cells from two different parents unite to form the first cell of a new organism.

Reproduction

• Asexual reproduction – the new organism has only one parent.










Based on a Genetic Code

• DNA provides the code for how organisms are constructed.










Growth and Development

• All living things grow during at least part of their lives.

Growth and Development

• Differentiation – the development of many types of cells with many different functions from a single original cell.










Need for Materials and Energy

• All living things need both energy to do work and materials for building blocks.

Need for Materials and Energy

• Metabolism – the combination of chemical reactions through which an organism builds up or breaks down materials.

• Energy is required to build up large molecules.

• Energy is released by breaking down large molecules.










Response to the Environment

• Organisms detect and respond to stimuli from their environment.

Response to the Environment

• Stimulus – A signal to which an organism responds.










Maintaining Internal Balance• Even though

external (environmental) conditions may vary widely, internal conditions of living things must be kept fairly constant in order to survive.

Maintaining Internal Balance

• Homeostasis – The process of maintaining constant internal conditions or balance.










Evolution

• Groups of organisms change over time.

Branches of Biology

Branches of Biology• One can study

biology on various levels of organization

– Molecules– Cells– Groups of cells– Organism– Population– Community– Ecosystem– Biosphere

These levels are hierarchical, that means that each level contains all the previous smaller levels.

Levels of Organization

Biosphere

Ecosystem

Community

Population

The part of Earththat contains allecosystems

Community and its nonliving surroundings

Populations thatlive together in a defined area

Group of organisms of onetype that live in the same area

Biosphere

Hawk, snake, bison, prairie dog, grass, stream, rocks, air

Hawk, snake, bison, prairie dog, grass

Bison herd

Largest, most inclusive

smallestleast inclusive

Levels of Organization

Organism

Groups ofCells

Cells

Molecules

Individual livingthing

Tissues, organs,and organ systems

Smallest functionalunit of life

Groups of atoms;smallest unit of most chemicalcompounds

Bison

Nervous tissue Nervous systemBrain

Nerve cell

Water DNA

Largest, most inclusive

Smallest least inclusive

End

End for the day

• You can drop a mouse down a thousand-yard mine shaft; and, on arriving at the bottom it gets a slight shock and walks away, provided that the ground is fairly soft. A rat is killed, a man is broken, a horse splashes.

• From On Being the Right Size

by J. B. S. Haldane

Education

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