CORSO DI BIOLOGIA E GENETICA

UNIVERSITA’ DEGLI STUDI DI CATANIA

CdLM Medicina e Chirurgia

A.A. 2014-2015

Docente del corso:

Dott. Davide Barbagallo, Ph.D.

Lodish – Biologia molecolare della cellula

The The DiversityDiversity and and CommonalityCommonality ofof CellsCells

Cells come in an amazing variety of sizes and shapesCells come in an amazing variety of sizes and shapes

Life…andLife…and virusesviruses

At a molecular level, archaea seem to resemble eucaryotes more closely in their machinery for

handling genetic information (replication, transcription, and translation), but bacteria more

closely in their apparatus for metabolism and energy conversion.

The studies that led to the classification of the living world into the The studies that led to the classification of the living world into the

three domains of bacteria, three domains of bacteria, archaeaarchaea, and , and eucaryoteseucaryotes were based were based

chiefly on analysis of one of the two main RNA components of the chiefly on analysis of one of the two main RNA components of the

ribosomeribosome——the sothe so--called small subunit ribosomal RNA. Because called small subunit ribosomal RNA. Because

translation is fundamental to all living cells, this component of the translation is fundamental to all living cells, this component of the

ribosome has been well conserved since early in the history ribosome has been well conserved since early in the history ofof life on life on

EarthEarth

BetweenBetween 10*1010*1066 and 100*10and 100*1066 speciesspecies

All cells share certain structural All cells share certain structural features and carry out many features and carry out many

complicated processes in complicated processes in basically the samebasically the same

way.way.

1) All the cells contain DNA as genetic material

2) All the cells transcribe DNA into RNA

3) All the cells use proteins for catalysis

4) All the cells translate RNA into proteins in the same way

5) All the cells request free energy to survive

6) All the cells use the same basic molecules to function

7) All the cells have got a membrane that separate the “inside” from

the “outside”

Central dogma of molecular biologyCentral dogma of molecular biology

Human_emb_devHuman_emb_dev

Identical twins occur naturally when the

mass of cells composing an early embryo

divides into two parts, each of which

develops and grows into an individual

animal. Each cell in an eight-cell-stage

mouse embryo has the potential to give rise

to any part of the entire animal. Cells with

this capability are referred to as embryonic

stem (ES) cells. ES cells can be grown in the

laboratory (cultured) and will develop into

various types of differentiated cells under

appropriate conditions.

Stem Cells, Cloning, and Related Techniques Offer Exciting Stem Cells, Cloning, and Related Techniques Offer Exciting Possibilities but Raise Possibilities but Raise Some Some ConcernsConcerns

The ability to make and manipulate mammalian embryos

in the laboratory has led to new medical opportunities as

well as various social and ethical concerns. In vitro fertilization,

for instance, has allowed many otherwise infertile couples

to have children. A new technique involves extraction of

nuclei from defective sperm incapable of normally fertilizing

an egg, injection of the nuclei into eggs, and implantation

of the resulting fertilized eggs into the mother.

However, cloning of humans per se has very limited scientific

interest and is opposed by most scientists because of its high

risk. Of greater scientific and medical interestscientific and medical interest is the ability to

generate specific cell types starting from embryonic or adult

stem cells

In 2012 Shinya Yamanaka and John Gurdon were

awarded the Nobel Prize for Physiology or

Medicine for the discovery that mature cells can be converted to stem cells

The Nobel Prize in Physiology or Medicine 2013 was The Nobel Prize in Physiology or Medicine 2013 was awarded jointly to James E. Rothman, Randy W. awarded jointly to James E. Rothman, Randy W.

SchekmanSchekman and Thomas C. and Thomas C. SüdhofSüdhof "for their discoveries of "for their discoveries of machinery regulating vesicle traffic, a major transport machinery regulating vesicle traffic, a major transport

system in our cells"system in our cells"..

http://www.nobelprize.org/http://www.nobelprize.org/nobel_prizesnobel_prizes/medi/medicine/cine/laureateslaureates//

Photo: A. MahmoudJames E. Rothman

Prize share: 1/3

Photo: A. MahmoudRandy W. Schekman

Prize share: 1/3

Photo: A. MahmoudThomas C. Südhof

Prize share: 1/3

The Nobel Prize in Physiology or Medicine 2014 was The Nobel Prize in Physiology or Medicine 2014 was divided, one half awarded to John O'Keefe, the other divided, one half awarded to John O'Keefe, the other

half jointly to Mayhalf jointly to May--Britt Moser and Britt Moser and EdvardEdvard I. I. MoserMoser ""for their discoveries of cells that constitute a for their discoveries of cells that constitute a

positioning system in the brainpositioning system in the brain".".

http://www.nobelprize.org/http://www.nobelprize.org/nobel_prizesnobel_prizes/medi/medicine/cine/laureateslaureates//

Photo: A. MahmoudJohn O'KeefePrize share: 1/2

Photo: A. MahmoudMay-Britt MoserPrize share: 1/4

Photo: A. MahmoudEdvard I. MoserPrize share: 1/4

A Living Cell Can Exist with Fewer Than 500 GenesA Living Cell Can Exist with Fewer Than 500 Genes

Alberts – Biologia Molecolare della cellula

Also genomes evolve: the birth of gene familiesAlso genomes evolve: the birth of gene families

Too many data!Too many data!Help comes from…BioinformaticsHelp comes from…Bioinformatics

The Molecules of a CellThe Molecules of a Cell

Molecular cell biologists explore how all the remarkable

properties of the cell arise from underlying molecular events:

the assembly of large molecules, binding of large molecules

to each other, catalytic effects that promote particular chemical

reactions, and the deployment of information carried by

giant molecules.

Temperatura media di superfice 15°Temperatura minima in cui si sviluppano organismi viventi

-15°

Temperatura massima in cui si sviluppano organismi viventi

+113°

Massima profondità in cui si trovano batteri 3.200 metriMassima acidità in cui è possibile la vita pH 0,00Massima intensità basica ammissibile per la vita pH 11Livello di alcalinità media per la maggior parte degli organismi

pH 5÷8

Massimo livello di radiazioni ionizzanti sopportate da organismi (una dose di 1.000 rad è mortale per l'uomo)

5.000.000 rad/anno

Massimo di sopravvivenza osservata di batteri a bordo di satelliti nelle condizioni estreme dello spazio esterno

6 anni

Massima pressione sopportata da organismi viventi nelle profondità oceaniche (la pressione a livello del mare è di ~1,00 bar)

1.200 bar

Massima salinità sopportata (la salinità media del mare ed anche del sangue umano è del 3,5%)

30%

CONDIZIONI LIMITE DELLA VITA SULLA TERRACONDIZIONI LIMITE DELLA VITA SULLA TERRA

TheThe Miller and Urey experimentMiller and Urey experiment (or(or UreyUrey––Miller experimentMiller experiment))

Considered to be the classic experiment on the origin of origin of lifelife, it was conducted in 1952 and published in 1953

by Stanley MillerStanley Miller and Harold UreyHarold Urey at the University of University of ChicagoChicago

The RNA World And The Origins Of LifeThe RNA World And The Origins Of Life

PNAs probably preceded RNAsPNAs probably preceded RNAs

RNAs may form secondary and tertiary structuresRNAs may form secondary and tertiary structures

RNA as enzymes: RNA as enzymes: ribozimesribozimes

RNA into viroids

Making different kinds of cellsMaking different kinds of cells——muscle, skin, bone, muscle, skin, bone, neuron, blood cellsneuron, blood cells——is not enough to produce the is not enough to produce the

human body. The cells must be properly arranged and human body. The cells must be properly arranged and organized into tissues,organized into tissues, organsorgans, and , and appendagesappendages..

In 1827, German physician Karl von Baer discovered thatmammals grow from eggs that come from the mother’s

ovary.

TowardsTowards MolecularMolecular Medicine: the Medicine: the genomicgenomic andandpostpost--genomicgenomic eraera

http://www.youtube.com/watch?v=slRyGLmt3qc

Human Genome Announcement Human Genome Announcement at the White House (2000)at the White House (2000)

http://www.genome.gov/10001772

The The importanceimportance ofof modelmodel organismsorganisms

LIFE_MOV