The RNA world is proposed to have evolved into the DNA and protein world of today. DNA through its greater chemical stability, took over the role of d

RNA world hypothesis

The phrase “RNA World” was first used by Walter Gilbert in 1986. however, the idea of independent RNA life is older and can be found in Carl Woese’s The Genetic Code.

The RNA world hypothesis is a theory which proposes that a world filled with RNA based live existed before the current DNA based life. RNA, which can store information like DNA and catalyze reactions like proteins, may have supported cellular or pre-cellular life. Some theories as to the biogenetic origin of life state RNA based catalysis and information storage as the first step in the evolution of cellular life.

The RNA world is proposed to have evolved into the DNA and protein world of today. DNA through its greater chemical stability, took over the role of data storage and protein, which is more flexible in catalysis through the great variety of amino acids, became the specialized catalytic molecules. The RNA world hypothesis suggests that messenger RNA, the intermediate in protein production from a DNA sequence, is the evolutionary remnant of the RNA world.

The RNA world hypothesis is supported by RNA’s ability to store, transmit and duplicate genetic information, as DNA does. RNA can also act as a ribozyme. Because it can reproduce on its own, performing the tasks of both DNA and proteins, RNA is believed to have once been capable of independent life.

Haploid: A cell with a single set of chromosomes (23 in humans), in humans this is usually in gametes. This is commonly represented by n. Diploid: A c

• Haploid: A cell with a single set of chromosomes (23 in humans), in humans this is usually in gametes. This is commonly represented by n.
• Diploid: A cell with two sets of chromosomes (46 in humans). This is commonly represented by 2n.
• Autotroph : an organism which can make its own energy
• Cell : Fundamental structural unit of all living things
• Eukaryote : an Organism with a nucleus
• Exoenzyme : an enzyme used to break down Organic Molecules outside the body
• Heterotroph : an organism which can not make its own energy
• Hydrocarbon : an organic compound that contains Carbon and Hydrogen only.
• Lipid : Fatty acid esters which form the basis of cell membranes
• Nucleus : Membrane-bound Organelle which contains the Chromosomes.
• Prokaryote : an organism with no nucleus

Papillae : The upper surface of the tongue has four types of papillae Vallate Papillae Filiform Papillae Fungiform Papillae Foliate Papillae, Dyspha

Vestibule : It is a slit like space bounded externally by lips and cheeks and internally by the gums and teeth.

Papillae : The upper surface of the tongue has four types of papillae

1. Vallate Papillae
2. Filiform Papillae
3. Fungiform Papillae
4. Foliate Papillae

These papillae have taste buds which respond to different types of taste.

Cirrhosis of the liver : The liver appears orange. It is due to the accumulation of bilirubin in the liver.

Dysphagia : Difficulty in swallowing the food.

Halitosis : Bad smell from mouth and bad breath. It is usually due to cavities in the teeth infection of throat and nose.

Oxyntic Cells : Oxyntic Cells are large and are most numerous on the side walls of the gastric glands. They secrete HCl.

Crypts of Lieberkuh : Crypts of Lieberkuh are simple, tubular structures which occur throughout the small intestine between the villi. Thet secrete digestive enzymes and mucus.

Prions are proteinaceous infectious particles that lack nucleic acid and are a type of infectious agent made only of protein.

Prion

Prions are proteinaceous infectious particles that lack nucleic acid and are a type of infectious agent made only of protein. Prions are believed to infect and propagate by refulding abnormally into a structure which is able to convert normal molecules of the protein into the abnormally structured form, and they are generally quite resistant to denaturation by protease, heat, radiation, and formalin treatments although potency or infectivity can be reduced.

Diseases caused by prions are fatal familial insomnia, kuruscrapie chronic wasting disease, variant Creutzfeldt-Jakob disease and bovine spongiform encephalopathy. All of these diseases affect the structure of the brain or other neural tissue, and all are untreatable and fatal.

Antimatter is any substance that, when combined with an equal amount of matter, results in the complete and direct conversion of all substance to ener

Antimatter is any substance that, when combined with an equal amount of matter, results in the complete and direct conversion of all substance to energy. Antimatter is composed of antiparticles. Each particle of matter has a corresponding antiparticle of antimatter.

The antiparticle of an electron is know as a positron. It has the same mass as an electron, but opposite electric charge. The antiparticle of the proton is called an antiproton. It has the same mass as a proton, but opposite charge. The antiparticle of the neutron is an antineutron. It has the same mass as a neutron and like the neutron, has no electric charge.

Liquids and gases are also called fluids. A substance is described as a fluid when it can change its shape easily and flow freely.

Liquids and gases are also called fluids. A substance is described as a fluid when it can change its shape easily and flow freely.

Ormeloxifene (Centchroman) is a selective Estrogen Receptor Modulator (SERM). It causes ovulation to occur asynchronously with the formation of the u

Ormeloxifene

Ormeloxifene (Centchroman) is a selective Estrogen Receptor Modulator (SERM). It causes ovulation to occur asynchronously with the formation of the uterine lining. Preventing implantation of a zygote. It has been WIDELY available as a birth control method in India since the early 90s. Centchroman is legally available only in India.

When the vasectomy is complete, sperm can no longer exit the body through the penis. They are broken down and absorbed by the body. Much fluid content is absorbed by membranes in the epididymis, and much solid content is broken down by macrophages and re-absorbed via the blood dtream.

The most common active ingredient of spermicides is nonoxynol9. spermicides containing nonoxynol9 are available in many forms, such as jelly (gel), films and foams.

additional material Amenorrhea : Absence of menstruation in a female

• Amenorrhea : Absence of menstruation in a female
• Menorrhagia : Excessive menstruation
• Infertility : Infertility in women is the inability to become pregnant. It may be due to failure to ovulate or to some anatomical factor that prevents the union of egg. (ovum) and sperm.
• Artificial Insemination: It is a technique by which the semen of a good quality male is introduced artificially into the vagina of the female.
• Sometimes, due to pressure in the abdomen, the intestine bulges into the scrotum through the inguinal canal and causes the most common type of Hernia
• Semen is the mixture of sperms and secretions from seminal, prostate, Cowper’s and urethral glands. It is milky fluid. Its average amount is 2-3 ml in a single ejaculation.
• Siamese Twins: These are conjoined twins produced from one egg twins who failed to separate completely.

A bacteriophage undergoes two types of cycle inside a host bacterium.

A bacteriophage undergoes two types of cycle inside a host bacterium.

• Lytic Cycle : In this type, the bacteriophage undergoes the normal cycle of adsorption with the help of its tail piece, then injection of genetic material, replication, and assembly of new phage particles and lysis of the host cell to release numerous progeny viruses which are exact clones of each other. Such viruses which induce lytic cycle are called virulent phages.
• Lysogenic Cycle : After infection, the bacterial DNA is not destroyed; instead, the phage releases its DNA into host which then incorporates itself within the bacterial DNA. The phage DNA gets attached to the bacterial DNA in a specific manner and replicates along with the bacterial DNA. In this condition, it is transmitted to the progeny of bacteria. Such a virus is called provirus or prophage.
• Bacteria which carry prophage are termed Lysogenic bacteria and the virus whose chromosomes become prophages are called Lysogenic viruses. The Lysogenic viruss under certain circumstances may bring about lysis of the host.

• Rods are sensitive to dim light Cones are sensitive to bright ligh
• Contain rhodopsin pigment Contain iodopsin pigment
• Does not help in seeing colors Help in seeing colors

The third eyelid is vestigial and is called as nictitating membrane or Plica Semilunaris,

• Meibomian or tarsal glands are present along the edge of the eyelids. They produce an oily secretion which serves to lubricate the corneal surface and hold a thin layer of tears over the cornea.
• Meissners corpuscles are located in the papillary layer of skin dermis just below the epidermis which responds to touch
• In a movie, pictures are projected on a screen at the rate of about 24 pictures per second, but we cannot see the individual frames on account of the after-images in our eyes. The life-like continuous movement on the screen is an illusion.

• Flavour is a combination of taste and smell while eating or sipping. If you hold your nose, you will find that grated apple and grated onion taste alike-slightly sweet. Cold with blocked nose has the same effect and makes food taste/smell flavourless.
• Ottis media is the infection of the middle ear which is characterized by severe pain and pus discharge.

• Many Lizards can undergo tail autotomy; in other words, they can lose the tail to distract or escape from a predator, it will grow back, but without bone and will be slimmer, shorter and a different color, with small scales.
• Pigment filled cells, called chromatophores, are located in the skin of the chameleon. These cells expand and contract, in response to the color of the environment and the need for concealment, as well as to the animal’s psychological or physical state.
• Most marsupials are night creatures so their most important senses are their sense of smell and their hearing. Most marsupials have extra scent glands which tell their neighbors whether they are boys or girls, if they are a stranger to the group, or if they are frightened or angry.

Ormeloxifene

Ormeloxifene is a selective estrogen receptor modulator (SERM). It causes ovulation to occur asynchronously with the formation of the uterine lining, preventing implantation of a zygote. It has been WIDELY available as a birth control method in India since the early 90s.

When the vasectomy is complete, sperm can no longer exit the body through the penis. They are broken down and absorbed by the body. Much fluid content is absorbed by membranes in the epididymis, and much solid content is broken down by macrophages and re-absorbed via the blood stream.

The most common active ingredient of spermicides is nonoxynol-9. Spermicides containing nonoxynol-9 are available in many forms, such as jelly

9gel), films and foams.

The crystal imperfections are the angular spread of the mosaic blocks in the crystal, the size of the mosaic blocks and the variation in cell dimensions between blocks. The analysis has implications for improving crystal perfection, defining data-collection requirements and for data-processing procedures. Measurements on crystals of tetragonal lysozyme at room temperature and 100 K were made in order to illustrate how parameters describing the crystal imperfections can be obtained. At 100 K, the dominant imperfection appeared to be a variation in unit-cell dimensions in the crystal.

Ecological efficiency : The relationship between the amount of energy accumulated, and the amount of energy utilized within one trophic level of food chain has an important bearing on how much energy on trophic level passes to the next trophic level in the food chain. The ratio of output energy to input of energy is referred to a s ecological efficiency.

Food Web : The collection of connecting feeding patterns in a biotic community tends to look more like a web than a chin and is called a food web.

Standing Crop : Amount of living material present in an ecosystem at any time.

Defibrinated Blood

Defibrinated Blood

If fresh blood is stirred with a twig, the fibrin is formed quickly and collects on the twig instead of forming a solid clot.

The liquid left behind, contains serum and corpuscles only which will not clot.

This liquid is called defibrinated blood.

Blood Blister

Blood may clot even without coming in contact with air is a blood blister such blisters may be formed due to injury like a sharp pinch when the skin does not break.

Lymphedema

Lymphedema disease causes abnormal swelling, especially in the appendages, though the face neck and abdomen can also be affected. An estimated 170 millon suffer with the disorder.

Blood Bank

A place where supplies of blood or plasma for transfusion are stored Blood donation is a process by which a blood donor voluntarily has blood drawn for storage in a blood bank or for subsequent use in a blood transfusion.

• Centrifugation is a method for separating the suspended particles of a substance from a liquid in which the mixture is rotated at a high speed in a centrifuge.
• Milk is a suspension of tiny droplets of oil or cream in a watery liquid.
• The process of centrifugation is used in dairies to separate cream from milk.
• The milk is put in a closed container in big centrifuge machine. When the centrifuge machine is switched on, the milk is rotated at a very high speed in its container. Due to this milk separates into cream and skimmed milk.

Peroxyacetyl nitrate (PAN)

PAN – photochemical smog mainly consist of ozone, peroxyacetyl nitrate (PAN) and nitrogen oxides (NOx).

Photochemical smog

It is formed by the reaction of hydrocarbons and nitrogen oxides in the atmosphere in presence of sunlight. It is mainly formed in traffic congested areas in metro cities where warm conditions and intense solar radiation are present.

Greenhouse effect

Green house gases like CO₂, CH₄, N₂O of atmosphere form a blanket over the earth that controls the escape of heat from the surface of earth to outer space so as to keep it warm and cosy. This phenomenon is called greenhouse effect. The mean annual temperature of earth is about 15^oC. if there would have no greenhouse gases in the earth, mean temperature would go sharply down to about – 20^oC.

Brown Air

Nitrogen oxides cause reddish brown haze in traffic congested city air, called ‘brown air’.

Grey Air

In areas of lesser solar radiation, smog formation is incomplete and the air is referred to as ‘grey air’.

• Blood Pressure : It is the pressure which the blood flowing through the arteries exerts on their walls. There are two limits of this pressure - the upper limit (Systolic pressure) which is at the time when fresh blood is pushing through the artery as a result of ventricular contraction of the heart. The lower limit (diastolic pressure) is the one recorded when the wave has passed over. Normal blood pressure in adult is 120 mm Hg (Systolic) and 80 mm Hg (Diastolic).
• Pulse : A person’s pulse is the throbbing of their arteries as an effect of the heart beat. It can be felt at the neck (carotid artery), near the ankle joint (Posterior Tibial Artery), and a few other places. A normal pulse rate for a healthy adult, while resting, can range from 60 to 100 beats per minute (BPM). During sleep, this can drop to as low as 40 BPM, during strenuous exercise, it can rise as high as 200 – 220 BPM. Generally, pulse rates are higher in younger people. A resting heart rate for an infant is as high as or higher that an adult’s pulse rate during strenuous exercise.
• Pacemaker : The impulse or command which starts the heart beat arises in pacemaker, located in the walls of the right auricle, in patients whose heart is not working normally, an artificial pacemaker is inserted which takes the place of natural pacemaker.

Turgidity : When a cell reaches a state when it cannot accommodate any more water, i.e., it is fully distended, it is called turgid and the condition is called turgidity.

Plasmolysis : It is the phenomenon of the contraction of the cytoplasm from the cell wall caused due to withdrawal of water when placed in a strong (hypertonic) solution.

Flaccidity : It is the condition in which the cell content is shrunken and the cell is no more “tight”.

Root Pressure : I is the pressure developed in the roots due to inflow of water, which helps in pushing the plant sap upwards.

Soil texture : It is a physical structure of the soil which is due to size, proportion and arrangement of its constituents. Three main types of soil texture are sandy, clay and loam. They are based on the proportion of three types of mineral particle (sand, clay and silt)

Ecotone : The transition zone between two communities is called ecotone.

Soil Porosity : Soil porosity is the percentage of soil volume occupied by pore spaces.

Field capacity : The maximum amount of water that a Soil can hold after stoppage of gravitational flow is known as field capacity.

Color Code of Resistors :

Color Code of Resistors :

The value of a fixed resistor is encoded in three color bands. A fourth band shows the possible variation of resistance between individual resistors of the given type. Each color represents a number according to the following scheme.

The first band on a resistor is interpreted as the FIRST DIGIT of the resistor value. For the resistor shown, the first band is yellow so the first digit is 4.

The second band gives the SECOND DIGIT. This is a violet band, making the second digit 7. The third band is called the MULTIPLIER and is not interpreted in quite the same way.

The multiplier tells you how many zeroes you should write after the digits you already have. A red band tells you to add 2 zeroes.

The value of this resistor is therefore 4 7 0 0 ohms.

The fourth band is called the TOLERANCE band. This indicates the percentage accuracy of the resistor value. Most carbon film resistors have a gold-colored tolerance band, indicating that the actual resistance value is with + or – 5% of the nominal value.

Button Cell

Button Cell

Some dry cells look like buttons in shape and size and therefore, are popularly known as button cells. They are compact and have long life. Examples are mercury oxide and silver oxide cells. A mercury oxide cell has mercury oxide as the cathode and zinc as anode. In a silver oxide cell, silver oxide is the cathode and zinc is the anode. These cells are used in watches, calculators, hearing aids and many other devices.

Interview Questions

Interview Questions

What qualities do you think will be required for this job?

Their advertisement for the job may help you a little bit, but you should also think of the other qualities that may be required. These may include leadership ability, supervisory skills, communication skills, interpersonal skills, problem solving, analytical skills, etc.

What can you contribute?

This is your chance to shine. Tell them about your achievements in your previous position's) which are relevant to the new position you are applying for.

Why do you want to work for this company?

Emphasize the positive reasons why you want to join their company, but avoid aspects such as more money or shorter hours. These would not endear you to a prospective employer.

What do you know about this company?

This is your chance to impress the interviewer with your knowledge of their company. Give them a run down of their products/services, sales figures, news, company figures, customers, etc. Visit their web site. Collect information from India Info Online etc. Click on Google and type in Company name and download latest happenings.

What interests you about Thier product s(or services)?

Again, your research into the company should aid you in answering this question.

What can we (the new company) offer that your previous company cannot offer?

Tread carefully here! Again do not mention money. Stress opportunities for personal growth, new challenges, etc. Never Criticise your earlier employer or the boss.

How long do you think it would be before you were making a significant contribution to the team/company?

If you think that you could contribute from day one then say so. Then turn the question round on them and say how soon would they expect it. It would be a good idea to ask them on what parameters you shall be evaluated at the end of the year. Would the company be willing to put that as an annexure to your appointment letter. This will indicate that you are a result oriented individual.

How ambitious are you? Would you compete for my job?

Depending on the position you are applying for you may want to sound fairly ambitious, but do not look as if you are after the interviewer's position.

What do you like and dislike about the job we are discussing?

Likes: Stress things such as a new challenge or the opportunity to bring fresh experience to the company.

Dislikes: Imply there is nothing to dislike about the job, which is why you are so interested.

Why did you choose a career in …?

Be positive about your reasons. If you have changed careers make a logical argument as to why you did so.

Why are you changing careers?

This question will only be asked if you are making a radical change in your career. Always stress the positive aspects of the change rather than the negative aspects of your previous career - you do not want to come across as someone who is moving just because you hate your old career. Say why you think you will be good in the new career - this should come from your experience and achievements, stress the transferable skills you have, such as leadership ability, etc.

How much does your last job resemble the one you are applying for? What are the differences?

The interviewer is trying to see how well you would fit in to the position you are applying for. So you should stress the similarities rather than the differences. When it comes to discussing the differences it will help your case if you can show that either you have done something similar in the past or that you can quickly pick up the new skills.

What do you think of the last company you worked for?

You should stress the positive aspects of your last company saying that they were a good company to work for. Tell them about the training you received or the work related experience you gained.

Why did you join your previous company? Did they live up to your expectations? Why are you leaving now?

Always be positive about your reasons for joining and leaving a company. Be very careful that you do not say anything negative about your present employer. If you do, the new company will wonder what you will say about them when you leave. You might want to stress that you are looking for a new challenge and that you feel that the company who is interviewing you fits the bill!

Explain the organizational structure in your last company and how you fitted into it?

This sort of question may be used to find out whether your old job is at a comparable level to your new job. If the new job being discussed would be a step up the ladder you will need to show that you are ready for a more demanding position. You may be able to show that you have already had many of the responsibilities and the necessary skills which would be required for the next step.

Interview General Tips

Before your interview find out everything you can about the company (read their annual report which can be obtained by telephoning them). Re-read your application, thinking through your own career and the questions they might ask you. You should try to anticipate the general questions which they will ask and also prepare some questions to ask them.

To do well at the interview you will need to convince the interviewer you are technically qualified to do the job. You will also need to show that you are sufficiently motivated to get the job done well and that you will fit in with the company's organisational structure and the team in which you will work.

You should dress smartly for the interview and should leave home earlier than you need to on the day of the interview - you may be delayed by traffic or for other reasons. Be courteous to all employees of the company. At the interview itself you must be positive about yourself and your abilities - but do not waffle.

Reach the interview site at least fifteen minutes before the scheduled time. Carry an extra CV .

After the interview ask how long it would take for the company to decide.

Questions you must ask your interviewer?

The interview is a two-way process. The company interviewing you will want to find out whether you are suitable to the position and you will want to find out if the company and position are right for you. You should therefore ensure that you have enough information to make up your mind whether you want the job. For example:

• What will be my responsibilities?
• Where will I fit into the overall organizational structure?
• Who will I report to?
• Where does he/she fit in the structure?
• Who will report to me?
• How experienced are they?
• What do you expect me to do in the first 6 months?
• What level of performance do you expect from me?
• Who are your customers?
• Where is the company going? Upwards? Expansion plans?
• What are the chances of advancement/promotion in this position? When?
• What will be my salary, benefits and bonuses? [Do not bring this up too early in the interview - wait until they are sold on you.]
• Will travelling be required in this position?
• Will relocation be required now or in the future?
• What training do you provide?
• When will you decide on the appointment?
• What is the next step?

Bacterial cell wall

• Bacterial cell wall : The cell walls of all bacteria are not identical, in fact cell wall composition is one of the most important criteria to identify bacterial species and classify them. Bacteria are broadly classified as gram negative and gram positive bacteria.
• The cell wall of Gram positive bacteria consists many layers of a polysaccharide peptidoglycan, cross linked by amino acids. 90% of gram positive bacterial cell wall is composed of peptidoglycan, whereas only 20% of gram negative bacterial cell wall is made of peptidoglycan. So, gram positive bacteria have a very thick cell wall but gram negative have a thinner wll. Example of gram positive bacteria include bacillus and clostridium. Gram negative bacteria include E.Coli and Salmonella