zchapter 1: exploring life. unifying themes in biology zevolution~ biology’s core theme;...

Chapter 1:

Exploring Life

Unifying Themes in Biology Evolution~ biology’s core theme;

differential reproductive success (sex!)

Emergent Properties~ hierarchy of life The Cell~ all organism’s basic

structure Heritable Information~ DNA Structure & Function~ form and

function Environmental Interaction~ organisms

are open systems Regulation~ feedback mechanisms Unity & Diversity~ universal genetic

code Scientific Inquiry~ observation;

testing; repeatability Science, Technology & Society~

functions of our world

Hierarchy of Organization

MoleculeOrganelleCellsTissuesOrganOrganism

Feedback Regulation: Negative

Accumulation of an end product of a process slows that process

Example: sugar breakdown generates ATP; excess ATP inhibits an enzyme near the beginning of the pathway

Feedback Regulation: Positive

An end product speeds up its production

Example: blood clotting in response to injury

The Process of Science

The Scientific MethodDeductive reasoning “If….then” LogicHypothesis vs.

Theory

Properties of Living things

Early Views of life

Vitalism: The insistence that there is some big, mysterious extra ingredient in all living things

Led to idea of spontaneous generation

Flies came from dead animalsMice came from Hay

Idea was challenged by scientist Francesco Redi in 1698.

Designed an experiment where 3 jars contained meat.

The Redi Experiment

Setup 1

One Jar contained meat and had an open top which would allow the passage of flies. (maggots would appear on the

meat)

Setup 2

The second jar was covered with an airtight lid not allowing the passage of flies. (no maggots would appear on the meat)

Setup 3

The third was covered by a screen allowing passage of eggs, but not flies. (few maggots would appear on

meat)

Conclusion

Since the third setup would theoretically allow the passage of “ethers”, but no maggots appeared, it was implied that flies were the source of the maggots. Led to the theory of Biogenesis

All life comes from preexisting life

PROPERTIES of LIFEBe made of Cells.The Cell is the basic unit of life

Is self contained and possesses a barrier (membrane) which separates itself from the environment.

Two types of organisms. Unicellular - One celled organism

(Uni=1) Multicellular - Many cells

(Multi=”many”)

PROPERTIES of LIFE

Living Things must Reproduce.Must be able to create more of it’s own

kindTwo types of reproduction:

Sexual - Two parent organisms combine genetic material to produce the offspring.

Asexual - When a single organism can divide or “bud” to create it’s offspring without another of it’s species.

PROPERTIES of LIFE

Living things must Have DNA. (Universal Genetic Code?)

PROPERTIES of LIFE

Living things must Grow & Develop.Growth refers to two processes.

Increase in the number of cells. Increase in the size of cells.

Development refers to changes in the organism which occur through it’s life-span. Includes cell differentiation. Includes organ development Includes aging & death.

PROPERTIES of LIFE

Living things obtain & use energy.Energy is used by all living things

for growth, development & reproduction. Life processes which result in

“building” the organism ia known as Anabolism.

Life process where energy is extracted by “breaking-down” substances is called Catabolism.

PROPERTIES of LIFE

Living things must Respond (or react) to their environment in some way.

Something which causes an organism to react is known as a Stimulus (stimuli).

The ability of an organism to react is called Irritability.

Most responses are geared for maintaining Homeostasis. Homeostasis is a process where an organism maintains a

stable internal environment so life can continue. Some examples include temperature, pH, and water

content of the cell.