scientists identify critical 'quality control' for cell growth and genetic 911:...

Scientists Identify Critical 'Quality Control' for Cell Growth and Genetic 911: Cells'

Emergency Systems Revealed

Marcela Osorio Santos

Medicine Student

III Semester

Teacher:

Lina María Martínez Sánchez

Molecular Biology

Introduction• Cells have a system repair of its genome,

which can be damaged by external agentssuch as substances, accidents ofmetabolism, etc... The repair process,prevents the cell from replicating thewrong way.

• The ribosome is the organelle responsiblefor the assembly of proteins, and forthis reason, they are responsible for cellgrowth and cycle control

Scientists Identify Critical 'Quality Control' for Cell GrowthScienceDaily (July 5, 2012)

• Scientists from the Florida campus of TheScripps Research Institute have identifieda series of intricate biochemical stepsthat lead to the successful production ofproteins, the basic working units of anycell.

Scientists Identify Critical 'Quality Control' for Cell Growth

ScienceDaily (July 5, 2012)

the ribosome decodesinformation carried inmessenger RNA(mRNA) to produce aprotein -- a chain ofamino acids

2. To produce mature,functioning ribosomalRNAs, the body firstmakes precursorrRNAs that can beprocessed into matureones.

3. In thecytoplasm, these pre-mature ribosomalsubunits encounterlarge pools of maturesubunits, messengerRNA, and numerousassembly factors andtranslation factorsthat help completethe process.

Trial Run


During the finalmaturationprocess, variousassembly factorsprevent the translationprocess from acting onthe subunitsprematurely

their presence raises another important question, Karbsteinsaid -- Does the conversion of

inactive assembly intermediates into mature

ribosomes require checkpoints to assure that subunits are

functional?

during this translation-like cycle the newly made ribosome subunit

initially joins with its complementary preexisting

subunit to form a much larger complex through the influence of

a single translation factor

This large ribosome complex contains no

messenger RNA, which is blocked by assembly

factors, and thus produces no protein


• "What is important here is that the testcycle involves the same translationalfactors that are involved in normaltranslation," Karbstein said. "It's the mostelegant and efficient way to produceperfect ribosomes."

• Interestingly, the study noted, the majorityof assembly factors involved in thistranslation-like test cycle are conserved increatures ranging from one-celledorganisms to humans, suggesting that thisevolutionary mechanism is common to all.

Scientists Identify Critical 'Quality Control' for Cell Growth

ScienceDaily (July 5, 2012)• PERSONAL

OBSERVATIONRibosomes are the principalfactory of proteins, they have thecontrol of cell cycle, and aroundthem many antibiotics have theobjective for avoid diseases, also,is very important to recognize thatribosomes are responsible for cellgrowth, and that the RNA has to

continue a sequence to ensure

a correct transcription, followed bya perfect translation, some factorswant to damage the RNA'ssequence, and turn aside it.

So, if the science can control thisfactors, and can to ensure a correctproduction of proteins, may be thecell growth and the proteins aregood and promote a good health

Oxicchemicals

wreak havoc on

cells, damaging DNA and

other critical

molecules

The studyreveals how a

molecular emergency-

response system shifts the cell into damage-control mode

This response helps it survive such attacks by rapidly producing

proteins that counteract the

harm

Genetic 911: Cells' Emergency Systems Revealed

Genetic 911: Cells' Emergency Systems Revealed previous studies showed

that cells treated with poisons such as arsenic alter their chemical

modification of molecules known as transfer RNA (tRNA), which deliver protein building blocks

within a cell

the research team delved into

how these modifications

help cells survive.

The researchers found that toxic stresses reprogram the tRNA modifications to

turn on a system that diverts the cell's protein-building machinery away

from its routine activities to emergency action


The findings offer insight into not only cells' response to

toxins, but also their reactions to all kinds of stimuli, such as nutrients

or hormones

any time there's a stimulus, you're going to have a reprogramming [of tRNA] that causes selective translation of proteins you need for

the next step in whatever you're going to

do

The primary job of tRNA is to bring amino acids to the ribosomes,

which string them together to make

proteins.

the researchers focused on a particular tRNA

modification, known as m5C, which occurs when cells encounter

hydrogen peroxide

They first discovered that this modification occurs

predominantly in one of the tRNAs that carry the amino

acid leucine

THE FINDINGS

A NEW ROLE FOR RNA


The researchers found that m5C modifications attach to the first

letter of the leucine tRNAsequence that pairs with the TTG

codon, which makes that tRNA bind more strongly to ribosomes. They

then scoured the yeast genome for genes in which most of the leucine

codons consist of TTG.

The researchers focused on a pair of ribosomal proteins known as RPL22A and RPL22B, which can

substitute for each other, slightly altering the ribosome's activity

The research also offers insight into how cells have successfully exploited the redundancy of the genetic

code

when the ribosome have the RPL22A protein,

preferentially assembles the proteins needed to respond to hydrogen

peroxide damage. "You need this sort of

emergency ribosome response to make the

critical proteins.

RPL22A has 100 percent of its

leucines coded by TTG, while RPL22B

has 40 percent coded by TTG


PERSONAL OBSERVATIONknow that the cell is attentive to substances that can attack andthreaten its vital structure, to control and thus generate a chain ofresponses against this, it is of vital importance for the developmentof genetic studies. The exposure to harmful factors for thecell, instead of causing cell death, cause the cell to become strongand able to use these factors to the production of proteins that mayabolish the damage. this is really important to try to potentiate thisemergency response of the cells, and to allow the cell growth andtherefore health

MEDICAL UTILITY

Is quite important that progress in science forhealth, because so much morbidity can beavoided.

MEDICAL UTILITY

• the cause of many medical failures is theignorance of certain diseases or on cellbehavior.

MEDICAL UTILITY

• to describe that ribosomes are responsiblefor cell growth and production and assemblyof proteins, these may be the site of actionof multiple drugs, which can be started tostudy after this discovery.

MEDICAL UTILITY

• Also acting on ribosomes, the cell cycle iscontrolled, preventing replication and avoidthe incorrect start or perhaps thecontinuation of major diseases

BIBLIOGRAPHY

• Martinez S, Lina Maria. Biología Molecular. 5ed Medellín: UPB. Fac Medicina

• Scientists Identify Critical 'Quality Control'for Cell Growth. Science Daily , July 5, 2012

• Genetic 911: Cells' Emergency SystemsRevealed. Science Daily July 3, 2012

thanks

scientists identify critical 'quality control' for cell growth and genetic 911:...

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