Attitude is Everything

The process of human change begins within us. We all have tremendous potential. We all desire good results from our efforts. Most of us are willing to work hard and to pay the price that success and happiness demand.
Each of us has the ability to put our unique human potential into action and to acquire a desired result. But the one thing that determines the level of our potential, that produces the intensity of our activity, and that predicts the quality of the result we receive is our attitude.
Attitude determines how much of the future we are allowed to see. It decides the size of our dreams and influences our determination when we are faced with new challenges. No other person on earth has dominion over our attitude. People can affect our attitude by teaching us poor thinking habits or unintentionally misinforming us or providing us with negative sources of influence, but no one can control our attitude unless we voluntarily surrender that control.
No one else "makes us angry." We make ourselves angry when we surrender control of our attitude. What someone else may have done is irrelevant. We choose, not they. They merely put our attitude to a test. If we select a volatile attitude by becoming hostile, angry, jealous or suspicious, then we have failed the test. If we condemn ourselves by believing that we are unworthy, then again, we have failed the test.
If we care at all about ourselves, then we must accept full responsibility for our own feelings. We must learn to guard against those feelings that have the capacity to lead our attitude down the wrong path and to strengthen those feelings that can lead us confidently into a better future.
If we want to receive the rewards the future holds in trust for us, then we must exercise the most important choice given to us as members of the human race by maintaining total dominion over our attitude. Our attitude is an asset, a treasure of great value, which must be protected accordingly. Beware of the vandals and thieves among us who would injure our positive attitude or seek to steal it away.
Having the right attitude is one of the basics that success requires. The combination of a sound personal philosophy and a positive attitude about ourselves and the world around us gives us an inner strength and a firm resolve that influences all the other areas of our existence.

Solutions to Assignment 3 - BEL204

Clue to the assignment no.3

1. In these studies always look for the supplement that is + for all the mutants. In this case G. So, G is the final metabolite. Then work backward, like supplement that gives ++ and so on.
Sequence is
5 4 2 1 3
E -------- A -------- C--------- B -------- D ---------- G

2. Here, either trpB or trp A is closer to cys
In the first case, recipient is cys+trpA-. So, it may be cys+ trpA- trpB+ or cys+trpB+ trpA- and incoming DNA fragment is cys- trpA+ trpB- or cys- trpB- trpA+. In either case a double crossover event will form prototroph (all +ve).
In the second case, recipient is cys-trpB-. Now, depending upon the order among cys, trpA and trpB, the donor fragment will be cys+trpA-trpB+or cys+trpB+trpA-. Corresponding recipients will be cys-trpA+trpB- or cys-trpB- trpA+. In the first case where trpA is closer to cys, 4 crossover events will be required to get the prototroph, while 2 crossover events will be needed if trpB is close to cys. So, the sequence is cys-trpB-trpA.

Practice problems.....Asignment 3

1. In a biosynthetic pathway, A to E are intermediate metabolites and final product is G. Several mutants are isolated that are defective in one or the other step in the pathway. The order in which these intermediates are formed is not known. Each intermediate is tested for its ability to support the growth to each mutant (1 to 5). In the following table, + indicates growth and – indicates no growth.

A)What is the order of A to E in the pathway?
B) At which point in the pathway is each mutant blocked?
[ hint: approach followed by Tatum and Beadle with Neurospora arg- auxotrophs]

2. Two mutants at the tryptophan locus, trpA- and trpB-, are known to be close to a cysteine locus (cys). A bacterial strain of genotype cys+trpA-is conjugated to a donor strain that transfers cys-trpB-. The reciprocal cross in which donor transfers cys+trpA-to the strain that is cys-trpB-. In both the cases, the numbers of prototrophic recombinants are comparable. Determine the order of tryptophan loci relative to cysteine locus.

Bacterial Conjugation

Bacterial conjugation is the often regarded as the bacterial equivalent of sexual reproduction or mating; however it is not actually sexual as it does not involve the fusing of gametes and the creation of a zygote, it is merely the exchange of genetic information. In order to perform conjugation, one of the bacteria has to carry an F-plasmid, the other one must not.
The F-plasmid (also called F-factor) is an episome (a plasmid that can integrate itself into the bacterial chromosome by genetic recombination) of about 100 kb (kilo base pairs) length. It carries its own origin of replication, called oriV. There can only be one copy of the F-plasmid in a bacterium (which is then called F-positive), either free or integrated.
Among other genetic information, the F-plasmid carries a tra and a trb locus, which together are about 33 kb long and consist of about 40 genes. The tra locus includes the pilin gene and controlling genes, which together form pili on the cell surface, polymeric proteins that can attach themselves to the surface of F-negative bacteria and initiate the mating. The pili themselves do not seem to be the structures through which the actual exchange of DNA takes place; rather, some proteins coded in the tra or trb loci seem to open a channel between the bacteria.