life! - dvusd

LIFE! (A BRIEF snapshot)

HTTP://WWW.PBS.ORG/WGBH/NOVA/EVOLUTION/ORIGINS-LIFE.HTML

Atmospheric Stuff of Life-

Coacervates

When exactly (what criteria) do we

obtain a living cell?

Cellular

Reproduction

Growth/Development

Metabolize

Respond

Evolve

Prokaryotes-life’s first fully

independent creatures

See hand out, or better yet, the colored version on the ppt!

So, what are some basic

environmental conditions cells had

to evolve to overcome? (In order

to exsist and thrive?)

So what drove complexity?

In no small part, the cyanobacteria

Evolutionary flow chart for cellular

achievement Coacervate (empty cell) formation-anaerobic

prokaryotes- aerobic prokaryotes aerobic

eukaryotes & anaerobic eukaryotes (individual cells)

multicellular aerobic and anaerobic organisms

First mass extinction-End of the

archaea-bacteria reign!

Darn the cyanobacteria!

Favored heterotrophic chemosynthetic bacterium

Increase complexity of DNA

Who is LUCA? (Traits)

Who is still around?

Who is more ancestral?

Revisit diagram (hand out)

So the environment is the spark to

cellular evolution.

Today’s relationship?

Endosymbiosis http://highered.mheducation.com/sites/9834092339/student_view0/

chapter4/animation_-_endosymbiosis.html

Cell size and function!

Why do cells remain small?

SA:V ratio

How do we compensate for small size?

Why does evo favor all this

additional boundary complexity?

HOMEOSTASIS (Mr Prey!)

The Leftovers?

Viruses

Prion

Back to the idea of maintenance

of cellular life? How do we

maintain internal homeostasis?

Cellular structures

Chemical properties- Water potential

Enzyme reactions

Chemical reactions/Chemical presence (+/-)

What do ALL (cells) continue to

share? (Structurally)

Although ONLY eukaryotes have all the extras!

Must knows: phospholipid by-layer (orientation), 5 types of glycoproteins

(see next slide), cholesterol, carbohydrate chains/antenna

Critical components (extras) in

eukaryote membrane evolution

Phosphate (polar)-lipid (non-polar)molecule

(phospholipids)-all about passive movement

5 types of large glycol-proteins : Adhesion,

Communication, Identification, Transport, Receptor

Sugar molecule (carbohydrate) antenna

Sterols-support

Why need all these extras??

Outside the cell membrane-cell

walls

Peptidoglycan (Prokaryotes only…huge in medicine!)

Chitin-fungi

Cellulose-plants

NONE-animals

4 ways to communicate

Carbohydrate antenna

Ion concentration and exchange

Chemical close or far

Tactile

3 areas for communication

For chemical communication

There are three stages of cell signaling:

Reception – where the target cell detects

a signaling molecule present in the

exogenous environment.

Transduction – the conversion of the signal

to a form that can bring about a specific

cellular response, we can amplify here.

Response – the specific cellular effect

brought about by the signaling molecule.

Reception: a signal molecule (ligand) binds to a receptor protein (receptor), causing it to change shape. The interaction between a ligand and receptor is highly specific. A conformational change in a receptor is often the initial stage in the transduction of a signal. Receptors are found in two places; Intracellular proteins are found inside the plasma membrane in the cytoplasm or nucleus. The signalling molecule must cross the plasma membrane and therefore must be hydrophobic (for instance the steroid hormone testosterone), or very small (Nitric Oxide). Or Cell-surface proteins are embedded in the plasma membrane, and these receptors bind to water-soluble ligands.

Transduction: cascades of molecular interactions relay signals from receptors to target molecule in the cell. Enzymes called protein kinases . These proteins cause an amplification of the signal, thus exaggerating the

Response: cell signaling leads to the regulation of cellular activities.

Increase in cellular complexity=

increase in cellular

specificity=increase in # of

cells=increase in cell to cell

communications