Wednesday 9 December 2015

Indigenous Learning-A new way to teach the masses



Enhancing the curriculum through indigenous knowledge

Today there is a growing recognition of the value of indigenous knowledge for sustainable development. It would, therefore, be wise to sustain indigenous knowledge in traditional communities and integrate it into the school curriculum where culturally and educationally appropriate.
Five ways indigenous knowledge could help enhance the curriculum include:
Learning Attitudes and Values for a Sustainable Future
Indigenous communities have lived in harmony with the environment and have utilised resources without impairing nature’s capacity to regenerate them. Their ways of living were sustainable. Indigenous knowledge shaped their values and attitudes towards environment, and it is these attitudes and values, which have guided their actions and made then sustainable. Therefore, indigenous knowledge can help to develop sensitive and caring values and attitudes and, thereby, promote a vision of a sustainable future.
Learning Through Culture
Indigenous knowledge is stored in culture in various forms, such as traditions, customs, folk stories, folk songs, folk dramas, legends, proverbs, myths, etc. Use of these cultural items as resources in schools can be very effective in bringing indigenous knowledge alive for the students. It would allow them to conceptualise places and issues not only in the local area but also beyond their immediate experience. Students will already be familiar with some aspects of indigenous culture and, therefore, may find it interesting to learn more about it through these cultural forms. It would also enable active participation as teachers could involve students in collecting folk stories, folk songs, legends, proverbs, etc., that are retold in their community.
Learning Across Generations
In view of its potential value for sustainable development, it is necessary to preserve indigenous knowledge for the benefit of future generations. Perhaps the best way to preserve indigenous knowledge would be the integration of indigenous knowledge into the school curriculum. This would encourage students to learn from their parents, grandparents and other adults in the community, and to appreciate and respect their knowledge. Such a relationship between young and older generations could help to mitigate the generation gap and help develop intergenerational harmony. Indigenous people, for the first time perhaps, would also get an opportunity to participate in curriculum development. The integration of indigenous knowledge into school curriculum would thus enable schools to act as agencies for transferring the culture of the society from one generation to the next.
Starting Locally: From the ‘Known’ to the ‘Unknown’
The philosophy of ‘from the known to the unknown’ should be adopted if education is to be effective. Therefore, it is wise to start with the knowledge about the local area which students are familiar with, and then gradually move to the knowledge about regional, national and global environments. Indigenous knowledge can play a significant role in education about the local area. In most societies, indigenous people have developed enormous volumes of knowledge over the centuries by directly interacting with the environment: knowledge about the soil, climate, water, forest, wildlife, minerals etc. in the locality. This ready-made knowledge system could easily be used in education if appropriate measures are taken to tap the indigenous knowledge, which remains in the memory of local elderly people.
Learning Outside the Classroom
Students can learn much from fieldwork in the local area. This calls for some prior knowledge and understanding. For instance, to be able to understand the relationship between indigenous people, soils and plants, students need to identify the plants and soil types in the local area. One way to get a preliminary knowledge of plants and soil types in the local environment is to consult indigenous people and invite them to teach your students in the field.
Indigenous people may also be willing to show students collections of artifacts and certain ceremonies and explain their significance and, where appropriate, share with them particular sites of special significance.

Sunday 6 December 2015

Epistasis- An Overview


Epistasis is a dihybrid cross with a difference. Instead of each of the genes at different loci affecting separate characteristics, the action of one gene will inhibit or affect the expression of the other gene. The gene that has the effect on the other is called the epistatic gene, and the one that is being acted upon is called the hypostatic gene. Epistasis changes the typical phenotypic ratio observed, and also reduces phenotypic variation.

Dominant Epistasis
In dominant epistasis, the dominant allele at the epistasic locus affects the expression of the gene at the hypostatic locus. A recessive allele at the epistatic locus will have no effect. The example used to illustrate this is feather colour in chickens. The colour of a chickens feathers is determined by the interaction of two gene loci I/i and C/C.
  • I/i is the epistatic gene. Any chicken with a dominant I in their genome will have white feathers. Being homozygous recessive ii at this locus enables the expression of genes coded for at the hypostatic locus.
  • At the hypostatic locus C/c the dominant allele C codes for coloured feathers while the recessive c codes for no colour. Hence, a chicken that is homozygous recessive cc will also be white.
Crossing a pure-breeding White Leghorn chicken (homozygous dominant at both loci IICC) with a pure-breeding white Wyandotte chicken (homzygous recessive at both loci iicc) produces an F1 generation that all have the genotype IiCc. These are all white as they possess the dominant I allele. If you are not sure how this works think back to normal monohybrid and dihybrid crosses - each of these parents can only produce one sort of gamete as they are homozygous: (IC) and (ic) respectively.
Now, crossing two F1 chickens which are heterozygous at both loci will produce this result:

(IC)
(Ic)
(iC)
(ic)
(IC)
IICC
white
IICc
white
IiCC
white
IiCc
white
(Ic)
IICc
white
IIcc
white
IiCc
white
Iicc
white
(iC)
IiCC
white
IiCc
white
iiCC
coloured
iiCc
coloured
(ic)
IiCc
white
Iicc
white
iiCc
coloured
iicc
white
You can see that our usual Mendelian 9:3:3:1 dihybrid cross ratio has been change by epistasis to 13:3 (white:coloured). In practice, this may sometimes be 12:3:1 if the double recessive genotype (iicc or equivalent) produces a phenotype different to either of the other ones. It just so happens that in this example iicc chickens are also white. 12:3:1 or 13:3 are typical phenotypic ratios of dominant epistasis.

Recessive Epistasis
In recessive epistasis, the epistatic gene will only affect the hypostatic gene if the organism is homozygous recessive at the epistatic locus. An example of this is the control of flower colour in Salvia. Once again, the colour is controlled by two genes A/a and B/b.
  • A/a is the epistatic gene. Organisms homozygous recessive aa at this locus will be white. The presence of the dominant allele A enables the expression of the colour coded for at the hypostatic locus.
  • B/b is the hypostatic gene. The dominant allele B codes for purple flowers, while the recessive allele b codes for pink flowers. Organisms will only have pink flowers if homozygous recessive bb at this locus, and if the epistatic locus enables the expression of this gene (i.e. a dominant A must be present).
Crossing two flowers heterozygous at both loci AaBb (which have the phenotype purple) produces the following results:

(AB)
(Ab)
(aB)
(ab)
(AB)
AABB
purple
AABb
purple
AaBB
purple
AaBb
purple
(Ab)
AABb
purple
AAbb
pink
AaBb
purple
Aabb
pink
(aB)
AaBB
purple
AaBb
purple
aaBB
white
aaBb
white
(ab)
AaBb
purple
Aabb
pink
aaBb
white
aabb
white
Our usual Mendelian 9:3:3:1 dihybrid cross ratio has once again been modified by epistasis. The typical phenotypic ratio for recessive epistasis is 9:3:4 as showed by this diagram.
Modified dihybrid Mendelian ratios
Dominant ´ Recessive 9 :6: 1
Single Dominant 12 :3: 1
Duplicate Dominant 15: 1
Single Recessive 9: 3 :4
Duplicate Recessive 9: 7
No Epistasis 9: 3: 3: 1
A-B- A-bb aaB- aabb
Type of gene interaction
1. Duplicate Recessive (9:7)
 Recessive at one either locus masks the expression of the dominant phenotype at the other locus.
2. Single Recessive (9:3:4)
 Recessive Trait at one locus masks the effect of the second locus.
3. Duplicate Dominant (15:1)
The dominant trait at either locus will express one phenotype, the other phenotype is homozygous at both loci.
4. Single Dominant (12:3:1)
Dominant trait at one locus masks the expression of the second locus.
5. Dominant ´ Recessive (9:6:1)
w Duplicate effects from the two loci. The phenotypes are: Two dominant, One dominant, and None dominant.
Multiple Alleles: The ABO Blood Group

Among the variety of more complex situations, one of the most common is multiple alleles. Typically, we teach with genes for which only two alleles are known, but many genes have more than two different alleles--thus, "multiple" alleles.
One such gene which is of great interest to humans is the ABO blood group gene. This particular gene has three alleles, rather than two. Of course, each of us has only two sets of chromosomes, so any one individual has only two of these alleles at once. But the presence of three different alleles means that there are six possible genotypes, rather than the three possible for the more familiar two-allele situation.
For the ABO gene, the three alleles are the IA, IB and i alleles. We typically call these alleles "A," "B," and "O," but of course our rules for assigning symbols to alleles demand that all three be represented by some version of the same symbol. In this case, that common symbol is the letter "I," which stands for "immunoglobin."
By now, the concept of dominance should be familiar to you. Of course, things get a bit more complicated when there are three alleles instead of just two. As the symbols above should suggest, the i allele (the "O" allele) is recessive to both the IA and IB alleles (the "A" and "B" alleles). The IA and IB show co-dominance. This means that in an individual who is heterozygous for these two alleles, the phenotypes of both alleles are completely expressed, thus producing blood type AB.
Thus we have the following:
Genotype
Phenotype
ii
Type O
IAIA or IAi
Type A
IBIB or IBi
Type B
IAIB
Type AB
Clearly, the additional genotypes produced by having three alleles rather than just two make for much more fun when it comes to figuring out genetic interactions between two people :^)
Other Blood Groups:
The ABO blood group isn't the only aspect of our blood type chemistry. There are about a dozen known genes which affect "blood type" activity. Because the ABO blood type has been known the longest, and has such a powerful effect, it is the one we focus on. The genes for the others work in similar fashions, though certainly not all have three alleles.
The other aspect of blood type which is of most interest to us is the Rh factor. Genetically, this is much simpler than the ABo system. It has only two alleles, one dominant (Rh-positive) and one recessive (Rh-negative). However, this facet of our blood type has some serious implications when we reproduce, and so has come under pretty heavy scrutiny. You can explore more about this part of your blood type by reading the Rh Disease essay.
Just what is blood type, anyway?
Our blood type is part of the marvelous protective machinery in our bodies called the Immune System.
Our immune system's task is to identify and destroy biological materials which are foreign to our own bodies. In order to perform this task, of course, your immune system needs to know how to distinguish between what belongs to you and what is foreign. This isn't the easiest of tasks, as you are made out of precisely the same materials that would compose any living invader. So a vital part of your immune system is the tagging of your own cells and tissues, so your antibodies won't destroy your own cells.
Blood type is part of this much larger self-tagging system aspect of your immune system. "Blood Type A" actually means "blood cells tagged with antigen A." Antigen A is a specific protein marker found on the surfaces of all Type A blood cells. And the task of the IA allele is to cause the creation and attachment of this specific kind of antigen. The IB allele causes the creation and attachment of a different protein marker, the B antigen.
Knowing this about blood type can also explain to you why the IA and B alleles are co-dominant, and why the i allele is recessive. The IAIB genotype results in both A and B antigens on the cell surfaces. The i allele causes no antigen to be produced, and is thus a "silent" allele.