BIODIVERSITY

Our story so far…

Life appeared early after the earth began to cool.

The earth formed from the condensation of stellar gases

As life evolved, it also altered major aspects of the earth’s surface, particularly

a. lithosphere ______________________________________

b. atmosphere _____________________________________________________________________

c. hydrosphere___________________________________________

d. biosphere ____________________________________________

And life equally depends on the continued dynamic geology to __________________________________________________

Biosphere – refers to the reality that the earth’s surface and life have evolved together and influenced each other, it is an complex, integrated and dynamic system

What on earth is life doing here?

Life has had a profound effect on the conditions on earth

Some people think it may have come literally from __________________

Today life exists as a diverse array of organisms, from small single-celled microbes to large multicellular creatures.

Where do these cells come from?

Where do these cells come from? _____________

Cells take in resources from the environment (____), transform those resources into themselves (____), and divide into replicate cells (________).

This transformation is achieved by a complex network of interrelated chemical reactions, or “_________________”, occurring within the cells.

All cells today are derived from previous cells, in an unbroken chain all the way back to …?

One possibility is that the biochemistry of earlier cell ancestors was simpler, and that the earliest ancestors may have been so simple as to not even be considered “alive”. That is, life __________________________________________.

How could this unbroken chain of being ever get started?

This is the notion driving much of the current research on __________________.

Is this even plausible?

To consider this, we need to review some basic chemistry

http://www.the-reelgillman.com/

AB + CD => AC + BD

Some molecules have a strong tendency to react together – they spontaneously react and release energy – called exergonic reactions

Other reactions won’t run unless energy is added, called endergonic reactions

Most molecules have a degree of stability and won’t interact even if the reaction is spontaneous, unless they reach a critical energy level, called the ________________.

Chemistry is the study of the interactions among elements and molecules. These interactions are generally formulated in terms of reaction equations

This graph illustrates the idea of ____________ (EA) in an exergonic reaction

The reacting molecules exist at a relatively high energy state, and must be ____________ before they can react to form the products and release their energy (their final energy state is ___________).

Certain substances have been found that promote reactions, ___________ their rate, but are ____________________________. These are called catalysts. Catalysts are crucial for reaction regulation in industrial chemistry.

Catalysts

Catalysts in the form of protein __________ are essential for biochemical regulation in all living cells. Every step of a biochemical pathway is controlled by a specific _________.

Catalysts increase reaction rate by reducing the ______________, often by ______________ the reactants.

Some enzymes work by _________ an endergonic reaction with an exergonic reaction, and this is crucial for biosynthesis (making organisms).

Autocatalysts

Of the many catalysts, some have a unique feature – the reaction that they promote actually ______________________________. These are called autocatalysts.

e.g., if A + B => AB is autocatalytic, what is the autocatalyst?

Science

In a sense, autocatalysts “___”, “____” and “____________”

They appear “spontaneously” in the right environment, and can rapidly increase in abundance.

Exponential Growth. In autocatalytic chemistry, we see the _________________________, an important feature of life – the capacity for exponential growth.

One begets another, and each of those can then beget another.

One becomes two, two become four, four become eight, etc.

0

200

400

600

800

1000

1200

0 2 4 6 8 10

It is hard to describe the awesome power of exponential growth.

1 x 2 = 21 = 22 x 2 = 22 = 44 x 2 = 2 x 2 x 2 = 23 = 88 x 2 = 24 = 1616 x 2 = 25 = 3232 x 2 = 26 = 6464 x 2 = 27 = 128 128 x 2 = 28 = 256 256 x 2 = 29 = 512512 x 2 = 210 = 1024

1024 x 2 = 211 = 20482048 x 2 = 212 = 40964096 x 2 = 213 = 81928192 x 2 = 214 = 16,38416,384 x 2 = 215 = 32,768216 = 65,536217 = 131,072218 = 262,144219 = 524,288220 = 1,048,576230 = 1,073,741,824

50 folds get you to the ___60 the diameter of the _______100 the width of the ___________

Think of folding a piece of paper over and over. It keeps doubling with every fold.

If the paper is .1mm thick,

after 30 folds how thick is it? (107km)

After 40 folds? (109,951 km)1/3 to the _____

FIRE is another process with similar kind of expansive power. Actually, fire is not really exponential since it is space limited

It has that same start slow, imperceptible increase, explosive growth pattern characteristic of exponential growth.

0

200

400

600

800

1000

1200

0 2 4 6 8 10

Fig. 9-13/10-14

Exponential growth is a kind of positive feedback

____________ is another example

With exponential potential, it is clear how an autocatalyst can transform a system – from a small start it can become ______________________.

Autocatalysts often emerge in complex chemical systems, they might even be thought of as “inevitable”. The early earth was certainly chemically ____________.

Are they “alive”? ___________.

Can they evolve? _________.

It is easy to imagine changes in the early autocatalysts as 1. More efficient types replaced less efficient types (“__________”) 2. Autocatalysts themselves became substrate for still other, newer autocatalysts, a chemical “___________” interaction, chemical “__________” 3.  Use of new substrates would be favored including______ for energy

These changes would reflect a simple kind of “evolution by _______________” – those types that most efficiently transform reactants will increase to the highest frequency and exclude other competing autocatalysts.

 The details of this evolution, even if true,are still unknown (a research goal)

_____________ can be considered a chemical, rather than strictly biological process, and probably broader than that.

The value of this perspective is that it provides a plausible framework by which chemical evolution could have, fairly quickly and naturally, produced increasingly complex self-replicating organisms

Conditions on early earth (one version):Energy – Solar (high UV), lightning, geothermalAtmosphere – Water, CO2, ammonia, methane,

hydrogen sulfideEarly earth had many sources of ______, and likely even complex, energy rich organic molecules. Experiments recreating these early conditions spontaneously produce _______________________________________________

Early forms of life may have used these “abiotically” generated molecules as “_____” for biosynthesis, as well as for materials

Major biochemical pathways and processes in life today

Photosynthesis – light energy stored in sugar

CO2 + H2O + light = sugar + O2

Respiration – energy in sugar used for metabolism

Sugar + O2 = Energy + CO2 + H2O

Each is a complex chemical pathway requiring _______________

Eventually, early life began to use sunlight as an energy source to build organic molecules that would provide this molecular energy - photosynthesis

http://www.expasy.org/cgi-bin/show_thumbnails.pl

Each is a complex chemical pathway requiring ________________

Gene Expression - protein (enzyme) production system - ____ stores information

- copied to ____ - _____ builds the protein

All of these complex pathways are wonderful and crucial, but NONE of them are, by themselves, ______________

In fact, they all depend on each other

Only _________________________ can truly be considered fully autocatalytic

________________

_______________________________

It is plausible that natural selection in early autocatalytic chemical systems ultimately produced CELLS with

- selective uptake of _________

- ability to _________ as a unit

eventually

___________ cells (w/o nucleus)

____________ cells (w/ nucleus)

Finally, _______________ organisms

 

Still fundamentally a chemical process – biology is incomprehensible without study of this chemistry

In a sense, organisms exist to serve their biochemistry

Evidence supports an early origin for life

- Earliest rocks about ____ BYA - Earliest fossil bacteria ____ BYA

________ – fossilized bacterial mats

Including fossilized ______ similar to extant photosynthesizers

BYA – Billion Years Ago

Early photosynthesis did not generate oxygen, but by

2.7 BYA, Oxygen generating photosynthesis has caused increasing oxygen in the atmosphere – ________ forms in rocks.

2 BYA, Oxygen up to ___% of current level

The Biosphere has a history

Relatively soon after the surface cooled, fossils similar to current bacterial organisms appear, including photosynthesizers.

The atmosphere begins to change – O2 up, CO2 down

Life evolves, and the biosphere changes more – our history is one of continuous interaction between the earth and life.