Introduction: Ten Themes in the Study of Life Chapter 1

Introduction: Ten Themes in the Study of Life

Chapter 1

Theme #1: Emergent Properties

The living world has a hierarchal organization, extending from molecules to the biosphere. With each step upward in organizational level,

novel properties emerge as a result of interactions among components at the lower levels.

Theme #2: The Cell

Cells are every organism’s basic units of structure and function. The two main types of cells are:

1. PROKARYOTIC in bacteria & archaea no nucleus, no membrane bound organelles

2. EUKARYOTIC in protists, fungi, plants, and animals

Larger & more complex w/ nucleus & membrane bound organelles

Prokaryotes v/s Eukaryotes

Theme #3: Heritable Information

The continuity of life depends on the inheritance of biological information in the form of DNA molecules. The genetic information is encoded in the nucleotide sequences of the DNA.

DNA DOUBLE HELIX

Structure & Function

Form and function are correlated at all levels of biological organization. Bird’s build makes flight possible Honeycombed construction of bones provides

lightweight skeleton of great strength Form of a cell fits its specialized function – nerve cells

have long extensions that transmit nerve impulses Mitochondria has inner membrane that is extensively

folded – able to pack large amount of membrane into very small container

Form Fits Function

Theme 5 – Interaction with the Environment Organisms are open systems that

exchange materials and energy with their surroundings.

An organism’s environment includes other organisms (biotic) as well as nonliving (abiotic) factors.

Energy Flow & Transformation in an Ecosystem

Regulation

Feedback mechanisms regulate biological systems.

In some cases, the regulation maintains homeostasis, a relatively steady state for internal factors such as body temperature.

Positive & Negative Feedbackhttp://bcs.whfreeman.com/thelifewire/content/chp41/41020.html

Feedback Inhibition – mechanism of homeostasis whereby a change in a physiological variable (D) that is being monitored triggers a response that counteracts the initial fluctuation (A). Final product (D) inhibits first enzyme in sequence (A) and shuts reaction down.

Positive Feedback – a physiological control mechanism in which a change in some variable (Z) triggers mechanisms that amplify the change. In this example, the product of the reaction (Z) enhances the reaction of one of the enzymes (black arrow), increasing the rate of production of the product.

Theme 7 - Unity and Diversity

The diversity of life is grouped into 3 domains: Bacteria, Archaea, and Eukarya.

Life is diverse, but we can find unity in the genetic code – the more closely related two species are, the more characteristics they share.

Classifying Life

Theme 8 - Evolution

Evolution is biology’s core theme. It explains both the unity and diversity of life.

The theory of natural selection accounts for adaptation of populations to their environment through the differential reproductive success of varying individuals.

Natural Selection

Theme 9 – Scientific Inquiry

The process of science includes observation-based discovery and the testing of explanations through the hypothetic-deductive method.

Scientific credibility depends on the repeatability of observations and experiments.

Idealized Version of Scientific Method

Theme 10 – Science, Technology, and Society Many technologies are goal-oriented

applications of science. The relationships of science and

technology to society are now more crucial to understand than ever before.