The BRCA 1 and BRCA 2 genes are two genes that are sought in the genetic study of an individual in order to seek a predisposition to breast cancer (in women and also in men).
The genes of Tay-sachs, are researched in order to diagnose or eliminate Tay-sachs disease.
The first difference lies in the goal of the research: for the BRCA (screening) genes, a predisposition is sought and for the Tay-sachs genes, it is sought to confirm the disease.
The second lies in the technique used:
The first step in the study of these genes is to isolate and replicate them. The best technique for this is the PCR (polymerase chain reaction). By using primers we can amplify the gene we want. So the primers used in BRCA and Tay-Sachs research are necessarily different.
Aspartame can be used to replace sugars that are sweet. Sucralose also replaces our regular sugar, like for those who cannot eat sugar. <span>Maltitol is also used to give a sweet flavor, and used in toothpastes. </span>
Question is incomplete. Complete question is as follows:
You have decided to determine how many microbes are living on the lettuce in the salad bar at your favorite restaurant. You place 1 gram of lettuce and 99 mls of water in a blender and blend the mixture. This is sample A. You then transfer 1 ml of this dilution into to another that contains 9 mls of water. This becomes sample B. You next transfer 1 ml of sample B into a separate container that contains 9 mls of water. This is sample C. Next you transfer 1 ml each from samples B & C onto separate nutrient rich agar plates, swirl, let harden and incubate at 37C. When you examine the plates after 48 hours you find 110 colonies growing on plate C. How many microbes were living on that 1 gram of lettuce?
Answer:
1.1x10^6 microbes
Explanation:
When 1gm of lettuce is mixed with 99 ml of water, the microbe concentration is diluted 100 times (Sample A). 1 ml of sample A is mixed with 9ml of water to make sample B which further dilutes microbe concentration 10 times making the total dilution 1000 times. This process is repeated with sample B to make sample C increasing the dilution to 10000 times.
110 colonies are counted from this sample C. Each colony signifies a single microbe during plate counting method. So, 110 microbes were present on the plate. Original number of microbes = microbes counted * times of dilution =
110 * 10000 = 1100000 = 1.1x10^6 microbes
Answer:
The correct answer is: a. Maggots do not arise spontaneously, but from eggs laid by adult flies.
Explanation:
- The meat in the open jars can be directly accessed by the adult flies for consumption. While accessing the food, some of these adult flies can lay egg into the jars which hatch to give rise to new maggots.
- The meat in jars closed by a gauze is exposed to the air but cannot be accessed by the adult flies as the flies are prevented from entering into the jar due to the presence of the gauze. As a result of this the flies do not consume meat, nor do they lay eggs and so no maggots will appear in this jar.
