gene therapy

Since we are currently doing presentations for each specific topics which relates to genetics, i'll upload some of the information about my topic which is gene therapy and genetic screening. this topic really attracts me and gets me to think deep about the science about it.

*Genetic screening

A genetic screen is the process of test to identify DNA samples to detect the presence of a gene or genes associated with an inherited disorder.

Early detection may help avoid the consequences of getting genetic diseases.

3 types of genetic screening :

-prenatal screening

-is a test for diseases or conditions in an embryo before it is born, to detect birth defects for some certain genetic diseases for babies

-prenatal screening tells you that which one of these diseases your baby might have and the chance of your baby to get the disease

-newborn screening

-Newborn screening is the practice of testing every newborn for certain harmful or potentially fatal disorders that aren't apparent at birth.

-carrier screening

-- Carrier screening is testing that's done to see if each partner carries a genetic change that could cause a serious inherited disorder in baby.

*Gene therapy

 The technique for scientists to alter a person's genetic material to fight or prevent diseases.

 The most common form of gene therapy involves the insertion of functional genes into an unspecified genomic location in order to replace a mutated gene.

A carrier molecule called a vector must be used to deliver the therapeutic gene to the patient's target cells. A new gene is inserted into the vector, which is used to introduce the modified DNA into a human cell. Then the new gene will start to make functional proteins.

the picture basically shows the steps of gene therapy

2 types of gene therapy

- somatic gene therapy

-sperm or eggs, are modified by the introduction of functional genes, therefore the change due to this therapy would be heritable and would pass on to the generation

-germ line gene therapy

-the therapeutic genes are transferred into the somatic cells of a patient, would be restricted to the person himself only

After all those researching, i have got so interested in this topic, it really has a lot of fun staff.

DNA replication

As we have learnt DNA replication in class this week, i'm gonna vreifly talk about it and also do it as a review for the upcoming quest.

So basically, DNA replication is not a a simple process, it needs lots of emzymes accompanied so that it would successfully done.

In the eukaryotes, the DNA is formed in two strands, each composed of units called Nucleotides. The two strands look like two chains that form the DNA Double Helix. The DNA Replication Process is capable of opening the Double Helix and separating the two strands. Then the two strands are copied. As a result two new DNA molecules are created. The next step is the cell division. After that a daughter cell is created. In its nucleus lies a copy of the parental DNA.

The picture above clearly shows how each enzymes work in order to succeed the repulication, and there is a list of each enzyme and how it works.

Helicase
DNA replication begins at places called origins, within the DNA molecule and the creation of replication forks. Helicase separates the two strands using the energy that is derived from ATP hydrolysis.

DNA Primase
One of the most crucial DNA replication enzymes is DNA Primase. After the DNA strands are separated, to begin the creation of new DNA molecules, through addition of complementary bases to the templates, a short RNA segment, called a 'primer' is required. These primers are synthesized by DNA primase enzymes, thus initiating the DNA replication process. That is why DNA Primase is one of the most important DNA replication enzyme.

DNA Polymerase
The most important DNA replication enzymes, that carry out the main task of aligning the complementary bases with template strands of 'unzipped' DNA, are the DNA polymerases. They are a large family of enzymes that carry out the task of adding complementary base nucleotides by reading the template strands. Besides the task of elongating the DNA molecule, they also carry out DNA proofreading and repair.

Exonuclease (DNA Polymerase I)
The main function of Exonucleases like DNA polymerase I is to remove the RNA primer segments from the template strand. It is always involved in the 'Search and Remove' operation of RNA primers.

DNA Ligase
While Helicase works to unwind the DNA molecule, DNA Ligase is the DNA replication enzyme that binds the DNA fragments together by addition of phosphates in the gaps that remain in the phophate-ribose sugar backbone.

DNA extraction lab

On friday, the whole class did a Dna extraction lab, it was so much fun!  i'm just going to briefly talk about that lab as well as show some pictures which have been taken during the class.

so firstly, we are divided into to parts, one part of students do labs based on the strawberrys, the the other half do the labs on kiwi fruits. i and patrick were doing the strawberry one. basically, we put a few strawberrys into the hot water to warm it up in order to break the cell walls, the temperature should be no more than 55 degrees, otherwise it is gonna damage the cell. later on, after warming up, we take out the strawberrys and grind them into liquid, then add some buffer into it in order for the reaction to occur. then the most important part comes, by adding the alcohol to the mixed solution gently(naking sure the alcohol flow on the top of the solution, not mixing them), we finally extract the white substance on the top of the solution after waiting for a while, which is the DNA of the strawberry.

                                        the white substance on the top is the DNA

                                         lol~~~