Now let's look at some methodologies that are used for different purposes and have opened up new perspectives mainly in the fields of medicine and agronomy, but they have also created a lot of controversy and deserve to be thoroughly evaluated, because they represent a double edged sword. But first you must known what do the restriction enzimes are.
DNAPROFILING OR DNAFINGERPRINT DNAprofiling also known as DNAfingerprint is a methodology which is now widely used in paternity testing and in criminal investigations. It consist basically of comparing some sections of DNA that are unique to each person.
GENE TRANSFER
Gene transfer consists of inserting a specific gene from an organism into another organism, so that the modified organism (GMO or transgenic) is able to sinthesize a protein and therefore to express a characteristic that was not its own.
Homework: Go to BioNinja site, read the secction about GMO's debate and take note from their benefits and risk. Then explain what you think about it, giving reasons that support your opinion. You can also read page 51 from your study guide book.
NATURAL AND ARTIFICIAL CLONING
Clones are groups of genetically identical organisms derived from a single original parent cell.
Cloning multicellular organism requires the production of stem cells that can be artificially generated from adult tissue using a process known as somatic cell nuclear transfer (SCNT)
Now see page 52 from your study guide book and read the last section, "investigating factors afecting rooting in stem cuttings".
POLYMERASE CHAIN REACTION This is one of the techniques used in gene sequencing, it consists on making millions of copies of a gene or a section of a DNA molecule. It makes possible to obtain millions of copies of a gene from a very small sample in a short time so you will have enough sample for any analysis you need to do. For example to know if a plant tissue is infected whith a virus. In the next videos you´ll see how is it preformed.
Another technique is that of gel electrophoresis, in this case the technique is used to separate proteins or fragments of DNA based on their charge and their size
PCR and Gel electrophoresis techniques can be used for diferent purposes, one of them being DNA profiling or DNA fingerprint.
HOMEWORK: Do an investigation about the Human Genome Project, How was it carried out, and its results. Then discusse the ethical implications of the used that can be given to the knowledge generated by the project.
The writing must have an extension of at least 2 pages and will be delivered the last class before exams.
Hi guys, as you know I'll be your temporary Biology teacher for a while, until the school find and hire an English-speaking teacher. Eventhough I don’t mastered the language, I have the ability to design exercises, assignments and tests in English and also to evaluate them. I'll use videos in English which I have sought and chosen among several in order that you can learn scientific terminology in both, Spanish and English lenguages, so you will be able to present the IB exams in the language of your choice Mutations
Mutations
are random changes in the base sequence of a gene. Mutations can occur naturally, due to errors
in gene transcription or during DNA replication.
Although
most of these mutations are repaired, and when they don’t, often have negative
effects on the organisms, mutations are in fact a source of genetic variation for
the evolution, since the new alleles that are formed can represent eventualy an adaptive
advantage for the specie.
High energy radiation and mutagenic chemicals increase the rate of mutation, and can cause
changes in alleles that have been selected over millions of years, so that, these
changes are detrimental in most cases. In addition, mutations in genes that
control cell division can cause cancer, because the cell begins to divide
uncontrollably until it forms a tumor.
Look at the
videos I put down here, so you can understand how the different types of
mutations occur and how they affect or change the information contained in the
DNA.
HOMEWORK: Analize the information given on page 46 of your Biology book and:
Resume and comment the 5 points about the
effects caused by the nuclear accident at Chernobyl.
Discuss
whether the evidence from registered cases of people dying of cancer or
leukemia, and malformations observed in children who were fetuses when the atomic
bombs were detonated, is sufficient enough to confirm the hypothesis that the
radiation is directly related with the presence of these diseases on people who
were exposed to it.
The next excercise was taken from the thick book, your task is:
Analyze the following graph and answer: "When would you expect the cases of thyroid cancer in young adults to start to drop, based on the data in the graph?
Sickle-Cell anemia We will now
review the case of a disease caused by a point mutation, a change of a single
base in the sequence of a gene.
To understand this, we will review the concepts
of gene and allele. As we see before, gene is a particular base sequence that
codes for a specific characteristic. That gene will always be located on the
same chromosome and at the same site within that chromosome (locus).
From this
it follows that on each chromosome there are several genes, therefore there
are many more genes than chromosomes in any organism (see the data on page 47
of your study guide book) and there is a certain relationship between the
complexity of the organism and the number of genes, this is true for the case
of prokaryotes and animals, in plants this relationship is not, due to the
presence of other survival strategies, that can be reflected in a remarkable
increase in the number of genes, without it being related to its Complexity as
an organism.
Moreover, organisms have more alleles than genes, since the same gene has more than one allele. The alleles are then versions of a gene, that means, they code for the same feature and are in the same locus, but they code for a different mode of the same characteristic, for example the black or brown color of the mice.
Now, please read the information given about the Sickle-Cell anemia and its relationship with Malaria which is in page 47 of your student book. After that, look at the next two videos.
DNA sequencingis a set of techniques used to know base sequence of genes whithin the DNA. It is used for many purposes, both for basic research and practical issues.
Knowing the base sequence of genes, allows us for
example, to establish how close a species is to another, or if a
person has the gene of a disease that can inherit to their children, or to select a specific gene to inser it in another specie.
Now look at page 48 of your book, read it carefully an take note of the different databases that are available on the web and can be consulted at any time. Write down their names and the content they offer, because eventually we are going to use them.
