Chapter 1

Exploring Life

Biology Biology is the study of life. It is very important because many recent advances such as techniques in molecular biology, cell biology, and genetics are providing us with ways to improve crop growth and improvements in medicine.

These advances in medicine have allowed us to treat patients better.

Unifying Themes of Biology

The cell. These are every organism’s fundamental unit of structure and function.

There are two main types:

Prokaryotes-bacteria and archea.

Eukaryotes-plants, animals, etc.

Unifying Themes of Biology

Heritable information. The continuity of life is dependent upon the passage of biological information from one generation to the next.

The genetic information is encoded in the nucleotide sequences of DNA.

Unifying Themes of Biology

Emergent properties of biological systems. Everything in the living world is organized in hierarchical fashion.

With each step upward in the hierarchy, things become more complicated as they interact with lower levels.

Unifying Themes of Biology Regulation. Feedback mechanisms, both positive and negative, regulate biological systems.

Unifying Themes of Biology

Interaction with environment. Organisms are open systems.

They exchange materials and energy with their surroundings.

It includes both living and non-living components.

Unifying Themes of Biology

Energy and life. All organisms must perform work--this requires energy.

Energy flows from sunlight to producers to consumers.

Unifying Themes of Biology

Unity and diversity. The diversity of life is grouped into three domains: Archea, Bacteria, and Eukarya.

As diverse as these three domains are, there is unity--such as the universal genetic code.

Unifying Themes of Biology

Evolution. This is the core theme of biology.

It explains both the unity and diversity of life.

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

Unifying Themes of Biology

Structure and function. Form and function are correlated at all levels of biological organization.

Unifying Themes of Biology

Scientific inquiry. Scientific inquiry is based on the scientific method.

It is also known as hypothesis-based inquiry.

Scientific credibility depends on the repeatability of observations and experiments.

Unifying Themes of Biology

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.

Biology Biology is unique in that it allows us to look at things from two perspectives:

1. The microscopic view. 2. The global view.

Biology--The Microscopic View

Using a microscope, you can look at the makeup of a leaf and discover that there are green organelles called chloroplasts.

Biology--The Microscopic View Zoom in further still on chloroplasts and you can see the structures that make up the organelle (electron microscope).

Biology--The Microscopic View Zoom out a little and look at the leaf and you’ll see it’s green.

Biology--Global View

Zoom out further and you will notice that the view from high above the forest is a seemingly endless sea of green.

Biology--Global View There are many different stages in between the 3 listed here.

The main point is that depending on how you look at the picture, you can see something different.

That is, there are many different levels of biological organization.

Biology Depending on what you are looking at, be it a plant or an animal, careful examination will allow you to wee a structural organization that fits the function of the organism.

Biological Systems

The organisms, whether they are individual bacteria or animal/plant cells, or entire groups of organisms comprising an ecosystem, make up a biological system.

Careful examination reveals that the system itself is greater than the sum of its parts.

You have to look at and understand how each component of the system interacts with and is dependent upon the others.

Biological Systems

For example, just because you have all of the parts of a bicycle shoved into a box doesn’t mean that you have a useable bike.

The parts have to be arranged in such a way to allow it to function properly.

This is a simplified example and emergent properties of a biological system are much more complex.

Systems Biology

Systems biology aims to understand a particular part of an organism and how it relates to the whole.

There are various ways in which systems can be regulated.

Two common ones are positive and negative feedback.

Negative Feedback Negative feedback is feedback in which the accumulation of an end product slows a system down or counters a change.

An example would be the accumulation of a metabolic end product that shuts down an enzyme system so as to conserve energy.3

Positive Feedback Positive feedback is one in which an end product speeds up production of or amplifies a change.

An example from a non-biological system is feedback into a microphone. When the mic is poorly placed, it picks up sound from speakers, which gets amplified, and sent back to the speakers, etc. The sound gets louder and louder.

The 3 Main Domains of Life There are 3 main domains of life: Eubacteria and Archea--prokaryotes which contain no nucleus or cellular organelles. They are bacteria.

Eukaryotes contain nuclei and cellular organelles. They are plant and animal cells.

The 3 Main Domains of Life Although the three domains are very different and diverse, they also represent remarkable unity between them.

They all have DNA that the cell uses to perform many of its functions.

Much of the DNA is used to trace the tree of life and show the relatedness of the 3 domains.

The 3 Main Domains of Life The process of evolution accounts for and can explain both the unity an diversity of life.

This can be done with inductive and deductive reasoning.

Inductive Reasoning

Inductive reasoning involves making generalizations based on specific observations.

It is also called discovery science. In discovery based science, inductive reasoning is used to make generalizations about a large number of specific observations

This often leads to hypotheses and hypothesis based science--a way of testing.

Deductive Reasoning

Deductive reasoning involves taking a generalization and extrapolating to find specific results. It is an “if-then” type of logic.

It is hypothesis based science. In hypothesis based science, scientists form hypotheses as to what will happen next based on general observations that have been made.

Inductive and Deductive Reasoning These 2 types of reasoning are important because they form the basis of the 2 main types of science: Discovery based science and hypothesis based science.