1. Scientists have identified a quality control mechanism in cells that ensures the proper production of ribosomal subunits and proteins. Ribosomal subunits undergo a translation-like test cycle using the same factors involved in normal protein production to check that they are functional before full maturation. 2. When cells encounter toxins like hydrogen peroxide, they modify transfer RNA to reprogram protein production away from normal activities and toward an emergency response. A specific tRNA modification directs ribosomes to preferentially produce proteins needed to respond to the toxin. 3. This research reveals insights into cells' general response to various stimuli and offers potential medical applications, such as understanding how drugs target ribosomes to control cell growth and the cell cycle.

1. 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

4. Introduction
• Cells have a system repair of its genome,
which can be damaged by external agents
such as substances, accidents of
metabolism, etc... The repair process,
prevents the cell from replicating the
wrong way.
• The ribosome is the organelle responsible
for the assembly of proteins, and for
this reason, they are responsible for cell
growth and cycle control

5. Scientists Identify Critical 'Quality Control' for Cell Growth
ScienceDaily (July 5, 2012)
• Scientists from the Florida campus of The
Scripps Research Institute have identified
a series of intricate biochemical steps
that lead to the successful production of
proteins, the basic working units of any
cell.

6. Scientists Identify Critical 'Quality Control' for Cell
Growth
ScienceDaily (July 5, 2012)
Trial Run
3. In the
cytoplasm, these pre-
mature ribosomal
2. To produce mature, subunits encounter
functioning ribosomal large pools of mature
RNAs, the body first subunits, messenger
makes precursor RNA, and numerous
rRNAs that can be assembly factors and
the ribosome decodes processed into mature translation factors
information carried in ones. that help complete
messenger RNA the process.
(mRNA) to produce a
protein -- a chain of
amino acids

7. Scientists Identify Critical 'Quality Control' for Cell Growth
ScienceDaily (July 5, 2012)
During the final their presence raises another
maturation important question, Karbstein
process, various said -- Does the conversion of
assembly factors inactive assembly
prevent the translation intermediates into mature
process from acting on ribosomes require checkpoints
the subunits to assure that subunits are
prematurely functional?
during this translation-like cycle
This large ribosome the newly made ribosome subunit
complex contains no initially joins with its
messenger RNA, which complementary preexisting
is blocked by assembly subunit to form a much larger
factors, and thus complex through the influence of
produces no protein a single translation factor

8. Scientists Identify Critical 'Quality Control' for Cell Growth
ScienceDaily (July 5, 2012)
• "What is important here is that the test
cycle involves the same translational
factors that are involved in normal
translation," Karbstein said. "It's the most
elegant and efficient way to produce
perfect ribosomes."
• Interestingly, the study noted, the majority
of assembly factors involved in this
translation-like test cycle are conserved in
creatures ranging from one-celled
organisms to humans, suggesting that this
evolutionary mechanism is common to all.

9. Growth
ScienceDaily (July 5, 2012)
continue a sequence to ensure
• PERSONAL
a correct transcription, followed by
OBSERVATION a perfect translation, some factors
Ribosomes are the principal want to damage the RNA's
factory of proteins, they have the sequence, and turn aside it.
control of cell cycle, and around So, if the science can control this
them many antibiotics have the factors, and can to ensure a correct
objective for avoid diseases, also, production of proteins, may be the
is very important to recognize that cell growth and the proteins are
ribosomes are responsible for cell good and promote a good health
growth, and that the RNA has to

10. Genetic 911: Cells' Emergency Systems
Revealed
Oxic
The study
chemicals This response
reveals how a
wreak havoc helps it survive
molecular
on such attacks by
emergency-
cells, damag rapidly producing
response system
ing DNA and proteins that
shifts the cell
other counteract the
into damage-
critical harm
control mode
molecules

11. 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
The researchers found that modifications
toxic stresses reprogram help cells
the tRNA modifications to survive.
turn on a system that
diverts the cell's protein-
building machinery away
from its routine activities
to emergency action

12. Genetic 911: Cells' Emergency Systems
THE FINDINGS
Revealed
any time there's a A NEW ROLE FOR RNA
stimulus, you're going to
The findings offer have a reprogramming
The primary job of
insight into not only [of tRNA] that causes
tRNA is to bring amino
cells' response to selective translation of
acids to the ribosomes,
toxins, but also their proteins you need for
which string them
reactions to all kinds of the next step in
together to make
stimuli, such as nutrients whatever you're going to
proteins.
or hormones do
They first discovered that
the researchers focused on a this modification occurs
particular tRNA predominantly in one of the
modification, known as m5C, which tRNAs that carry the amino
occurs when cells encounter acid leucine
hydrogen peroxide

13. Genetic 911: Cells' Emergency Systems
Revealed
The researchers found that m5C
modifications attach to the first
The researchers focused on a pair
letter of the leucine tRNA
of ribosomal proteins known as
sequence that pairs with the TTG
RPL22A and RPL22B, which can
codon, which makes that tRNA bind substitute for each other, slightly
more strongly to ribosomes. They altering the ribosome's activity
then scoured the yeast genome for
genes in which most of the leucine
codons consist of TTG.
when the ribosome have
the RPL22A protein,
The research also offers preferentially assembles RPL22A has 100
insight into how cells have the proteins needed to percent of its
successfully exploited the respond to hydrogen leucines coded by
redundancy of the genetic peroxide damage. "You TTG, while RPL22B
code need this sort of has 40 percent
emergency ribosome coded by TTG
response to make the
critical proteins.

14. Genetic 911: Cells' Emergency Systems
Revealed
PERSONAL OBSERVATION
know that the cell is attentive to substances that can attack and
threaten its vital structure, to control and thus generate a chain of
responses against this, it is of vital importance for the development
of genetic studies. The exposure to harmful factors for the
cell, instead of causing cell death, cause the cell to become strong
and able to use these factors to the production of proteins that may
abolish the damage. this is really important to try to potentiate this
emergency response of the cells, and to allow the cell growth and
therefore health

15. MEDICAL UTILITY
Is quite important that progress in science for
health, because so much morbidity can be
avoided.

16. MEDICAL UTILITY
• the cause of many medical failures is the
ignorance of certain diseases or on cell
behavior.

17. MEDICAL UTILITY
• to describe that ribosomes are responsible
for cell growth and production and assembly
of proteins, these may be the site of action
of multiple drugs, which can be started to
study after this discovery.

18. MEDICAL UTILITY
• Also acting on ribosomes, the cell cycle is
controlled, preventing replication and avoid
the incorrect start or perhaps the
continuation of major diseases

19. BIBLIOGRAPHY
• Martinez S, Lina Maria. Biología Molecular. 5
ed Medellín: UPB. Fac Medicina
• Scientists Identify Critical 'Quality Control'
for Cell Growth. Science Daily , July 5, 2012
• Genetic 911: Cells' Emergency Systems
Revealed. Science Daily July 3, 2012

20. thanks