Molecular Design of Life-2014

8/11/2019 Molecular Design of Life-2014

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Visualization of Developingegg cells

MovingAmoeba
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What is Life ?

Life is complex and dynamic

All organisms are primarily composed oforganic (carbon-based) molecules thathave three dimensional shapes

Their methods for sustaining biological

processes are similar Living processes (growth and development)

involve thousands of chemical reactions.


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What is Life ?

Life is organized and self sustaining Living organisms are hierarchically

organized systems(each level is based onthe one below)

The molecules that make up livingorganisms, referred to as Biomolecules

In multicellular organisms levels oforganization: tissues, organs and organsystems

At each level of organization the whole is

greater than the sum of the parts


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Organized systems


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What is Life ?

Life is organized and self sustaining

Emergent properties(Hemoglobin)

Continuous acquisition of both energy andmatter and removal waste molecules.

These tasks are accomplished by hundreds

of biochemical reactionsthat are catalyzedby enzymes

The sum total of all reactions in a livingorganism is referred to as Metabolism


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What is Life ?

Life is cellular

Cells differ widely in structure and function

Each is surrounded by a membrane thatcontrols the transport of some chemicalsubstances into and out of the cell.

The membrane mediates the responseofthe cell to components of the extracellularenvirontment.

Cells arise only from the division of existing

cells.


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What is Life ?

Life is information-based

Organization requires information

Living organisms can be considered to beinformation-processing systems

Interacting molecules within cells, between

cells and generation of future cells Genetic informationspecifies the linear

sequence of amino acids in proteins andhow and when those proteins are

synthesized


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What is Life ?

Life adapts and evolvesAll life on earth has a common origin, with

new forms arising from other forms

DNA mutationscan be repaired or have noeffect on the functioning of the organism

On rare occasions mutations maycontribute to an increased ability of theorganism to survive, to adapt to newcircumstances and to reproduce

The interplay of environtmental change and

genetic variation can lead to favorabletraitsand different forms of life.


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Prokaryotes

Form and Function

Life is based on morphological units knownas cells (1838)

Two major classifications of cells: theEukaryotesand Prokaryotes

Prokaryotes (various types of bacteria)

have relatively simple structures andunicellular (they may form colonies)

Viruses, are not classified as livingbecause

they lack the metabolic apparatus toreproduced outside their host cells


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Prokaryotic cell


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Prokaryotes

Prokaryotic classification

Taxonomy are inaplicable to prokaryotesbecause the relatively simple structuresprovide little indication of their phylogeneticrelationships

Based on cell wall properties: 3 major

types: Mycoplasma, Gram-positive bacteriaand Gram-negative bacteria

Mycoplasmas are the smallest of all living

cellsand possess ~20% of the DNA of anE.coli


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Some prokaryotic cells


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Eukaryotes

Eukaryotes cellular architecture

Structural complexity allows sophisticatedregulation of living processes

They have internal membrane-enclosedorganelles.


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Structure of cells

Plasma

Membrane

Endoplasmic

Retikulum

Golgi Apparatus

Lysosome

Mitochondrion

Cytoplasm

Nucleus

membrane


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Eukaryotes

Eukaryotic phylogeny and differentiation

One of the most remarkable characteristicsof eukaryotes is their enormous

morphologial diversity, on both the cellularand organismal levels (an amoeba, an oaktree and a human being)

Taxonometric schemes based on gross

morphology as well as on protein andnucleic acid sequences: three kingdoms(Fungi, Plantae, Animalia, Protista)


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The origin of life

We cannot hope to determine exactlyhow life arose

The development of life occupied threestages:

Chemical evolution

The self organization

Biological evolution


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The origin of life

The unique properties of Carbon

Elements (C, H, O, N, P and S) formcovalent bonds, comprise ~92% of the dryweight of living things.

Carbon has the unique abilityto form avirtually infinite number of compounds as aresult of its capacity to make as many asfour highly stable covalent bonds combined

with its ability to form covalently linked C-Cchainsof unlimited extent

Over 17 millionchemical compounds,nearly 90% are organic (carbon containing)

substances.


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The origin of life

Chemical evolution

We are far from certain as to how lifearose .

Earths atmosphere contain significantquantities of O2, H2O, N2, CO2and smalleramounts of CO, CH4, NH3, SO2and possiblyH2.

UV radiation from the sun or lightningdischargescaused the molecules to react toform simple organic compoundssuch asamino acids, nucleic acids bases andsugars.


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The origin of life

The rise of living systems

Living systems have the ability to replicatethemselves

The inherent complexity of such a processis such that no manmade device has evenapproached having this capacity.

There is an infinitesimal probabilitythat acollection of molecules can simply gather atrandom to form a living entity.

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Molecular Design of Life-2014

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