Plegable biología molecular

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DNA REPLICATION Carolina Zapata Ramírez

Transcript of Plegable biología molecular

DNA REPLICATIONCarolina Zapata Ramírez

• Ori recognition by helicases

• Fork formation

Step 1

•Maintenance of fork

•Action on each strand of SSDBP

Step 2 •synthesis primer , the gaps are filled by polymerase

•joined by DNA ligase

Step 3

• leading strand is copied continuously

• the lagging strand is copied Okazaki fragments subsequently joined by ligase

Step 4

• Relax of supercoiling by topoisomerases

Step 5 • Finish of replication

Step 6

Ribonucleotide reductase (RNR) catalyzes the reduction of

ribonucleotides to the corresponding

deoxyribonucleotides, which are used as building blocks for DNA

replication and repair. This process is tightly regulated via two

allosteric sites, the specificity site (s-site) and the overall activity site

(a-site).

This four-in-one machine takes on four different shapes depending on

whether the RNA nucleotide is A, G, C, or U. It sends out DNA's four, A,

G, C, and T with the appropriate sugar

deoxyribose instead of ribose (replacing an OH radical with a hydrogen

atom, a "reduction" reaction).

RNR is a multi-tool The effectors, the substrates

and the active sites are all closely matched to the

operation at hand, whether generating more

DNA building blocks or regulating their supply in

the cell.

An intricate interplay between gene activation,

enzyme inhibition, and protein degradation

regulates, together with the allosteric effects, enzyme activity and

provides the appropriate amount of

deoxynucleotides for DNA replication and repair.

Enzyme that Maintains DNA Building Blocks

A lot of new building blocks are needed for repair and replication.

I can see why this enzyme is essential for a cell when it divides

or suffers stress.

They showed that this enzyme acts as a switch then clamps down on the substrate and

"reduces" it by replacing the oxygen radical with a hydrogen.

When released, the DNA building block is ready for use, the

effector switches the machine off, and the enzyme is ready for the

next operation.

I UNDERSTOOD

• “Deoxyribonucleotides are generated from ribonucleotides, which are the building blocks for RNAs -- molecules that perform many important roles in gene expression. RNR, which catalyzes the conversion of ribonucleotides to deoxyribonucleotides, is an evolutionarily ancient enzyme that may have been responsible for the conversion of the earliest life forms, which were based on RNA, into DNA-based organisms”

Drennan says.

Student’s observation

It is shocking how science has advanced by creating an enzyme that carries out the reduction of ribonucleotides to deoxyribonucleotides to ensure proper DNA replication

Newswise — STONY BROOK, NY, February 10, 2016 — A team of scientists led by Stony Brook University

biochemist Huilin Li, PhD,

DNA is unwound by a type of “pump jack” mechanism, similar to the way one operates on an oil rig.

•That “Each rocking motion could nudge the DNA strands apart and move the helicase along the double helix in a linear fashion”

THEY CHECKED

•The scientists produced high-resolution images of the helicase using a technique known as cryo-electron microscopy (cryo-EM).

THROUGH

HELICASE

•They wanted to know the structure of the helicase and thereby realized that the helicase can still function even When the ATP hydrolysis activity of some, but not all , of the components is knocked out by mutation

Student’s observation

Nowdays is very important to know the mechanism of DNA replication because we can understand mutations and even stop them. They studied in this research helicase which is a key protein for initiation of replication.

MEDICAL UTILITY

Both investigations seeking to Understand the process of DNA replication to find solutions to

the Changes That Occur at this time of the formation of a new

cell

MEDICAL UTILITY

•DNA replication is essential for life , as it allows genetic information is passed from a mother cell to daughter cells . It is also important that the split may have mutations

MEDICAL UTILITY

knowing the process of DNA replication possibly we can do target therapy against cancer or other diseases.

MEDICAL UTILITY

BIBLIOGRAPHY

Martinez Sanchez, Lina Maria. Biologia molecular.7.ed.Medellin: UPB.Fac.Medicina.

-Newswise. February 10 2016. Mechanism That Unwinds DNA May Function Similar to an Oil Rig “Pumpjack”. Retrieved February 12 2016.http://www.newswise.com/articles/mechanism-that-unwinds-dna-may-function-similar-to-an-oil-rig-pumpjack

-Mit news. January 16 2016. An "Exquisitely Designed" Enzyme that Maintains DNA Building Blocks. Retrieved February 12 2016.http://www.evolutionnews.org/2016/01/an_exquisitely102401.html

-Gen news. February 9 2016. Structural Study Points to New DNA Replication Mechanism. Retrieved February 12 2016 .-http://www.genengnews.com/gen-news-highlights/structural-study-points-to-new-dna-replication-mechanism/81252345/

THANKS