| Figure: Mechanism by which vaccines act in our body and protect us from disease encounter. Source: http://hcrc.missouri.edu/2015/08/05/im-kind-of-a-little-big-deal-public-health-ninjas/ |
| Source: https://www.testbig.com/ielts-writing-task-i-essays/graph-shows-impact-vaccination-incidence-whooping-cough-childhood-0 |
| Figure: Mechanism by which vaccines act in our body and protect us from disease encounter. Source: http://hcrc.missouri.edu/2015/08/05/im-kind-of-a-little-big-deal-public-health-ninjas/ |
Learning objective
After this topic, you should know:
Treating the symptoms
Antibiotics- drugs to cure bacterial diseases
Figure: In 1940s, a successful example of use of antibiotic was seen. The number of deaths because of the infections in the first days after giving birth was dropped significantly. Source: http://www.slate.com/articles/health_and_science/science_of_longevity/2013/09/death_in_childbirth_doctors_increased_maternal_mortality_in_the_20th_century.html |
How antibiotics work
Figure: Several different antibiotics are tested on agar plate. Source: https://en.wikipedia.org/wiki/Antibiotic_sensitivity |
Usages of antibiotics have some drawbacks also. They are not the complete solution to the problems created by infectious diseases.
Questions and answers:
Q1. Describe the main difference between drugs such as paracetamol and drugs such as penicillin.
And 1 Paracetamol is commonly taken as painkiller. Cold problems like fever, sore throat and headache can be treated by taking such medicines. Viruses are not get affected by these type of drugs. Medicines will not kill or destroy the pathogens but it will decrease the intensity of symptoms. Immune system will fight against them by own and activation of immune system will take some days. Thus it will take some days in getting well.
Penicillin is an antibiotic. Antibiotics will kill the disease causing bacteria. Example of antibiotic is penicillin. They will act specifically on bacterial cells not your body cells. They will damage the bacterial cells thus hinder the growth of bacteria.
Q2. Explain why it is more difficult to develop medicines against viruses than it has been to develop antibiotics.
Ans 2 Viral diseases cannot be cured by using antibiotics. Viruses multiply inside of host cell. Thus it is challenging to develop drugs which will kill only viruses but will not create any negative effect on cells.
Q3. Use figure 2 to answer the following.
And a In 1930= 700, in 1940= 400 and in 1950 around 100 women were died due to maternal septicaemia.
i 1930 and 1940
Ans i. There is fall in numbers of women death from 1930 to 1940. The number of deaths was in 1930=700 and in 1940=400. To calculate percentage fall the formula is as follows:
First: work out the difference (decrease) between the two numbers you are comparing.
Decrease = Original Number – New Number
Then: divide the decrease by the original number and multiply the answer by 100.
% Decrease = Decrease ÷ Original Number × 100
Decrease = 700-400= 300
Percentage decrease= 300/ 700*100= 42.8%
Thus percentage fall in death rates of mothers around the time of birth in 1930 and 1940 is 42.8%.
ii 1940 and 1950
Decrease= 400-100= 300
Percentage decrease= 300/400*100= 75%.
Thus percentage fall in death rates of mothers around the time of birth in 1940 and 1950 is 75%.
Ans c. The reason for these observations is: from 1940s antibiotics are widely available. They were also known as wonder drugs. A successful example of use of antibiotic was the number of deaths because of the infections in the first days after giving birth was dropped.
Ans d. As we all know that evolution is an ongoing process. Bacteria also evolve and become simultaneously and as a result they become resistant antibiotics. Thus the antibiotic which was developed earlier for a particular bacteria will no longer show effect on those bacteria. Antibiotic resistant strain of bacteria is a matter of concern for scientist. Thus new antibiotics should be developed time to time to overcome this challenge which is also a major problem.
Learning objectives
After this topic, you should know:
Drugs form plants
Figure: Beaver rat chew the willow bark. As a result of which their tail glands has pain-relieving properties. By chewing the tail of beaver relief in pain is observed. Source: http://www.wildernessclassroom.com/wilderness-library/beaver/
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Drugs from microorganisms-discovering penicillin
He tried to extract that compound but failed to do so.
Medicines for the future
Figure: Noni fruit potential source of antibiotics. Source: https://greenblender.com/smoothies/4432/health-benefits-of-noni-fruit |
Questions and answers:
Q1 Describe how Alexander Fleming discovered penicillin.
Ans 1 During early 20th century, scientists were doing intensive research for discovering chemicals that might cure bacterial diseases by killing them. Alexander Fleming was doing his studies on bacterial culture in 1928. During that time healthy and safety procedures were not so up to the mark. One day Fleming saw some moulds growing on his culture plates and around that moulds clear ring of jelly was observed. Those rings are formed because of some inhibitory substances was secreted by mould which inhibited the growth of bacteria. Fleming called that substance that inhibits the growth of bacteria as penicillin because it was produced by Penicillium mould.
Ans 2 Plant extracts are assumed to be safe but sometime they show poisonous effects. It is difficult to control the concentration and dose of drug in plant extraction. Where poisoning from medicinal plants has been reported, it usually has been due to misidentification of the plants in the form, in which they are sold, or incorrectly preparation and administration by inadequately trained personnel. Herbal drugs are considered less potent than prescribed medicines. While many drugs have originated from biologically active plant chemicals, and many plants’ medicinal uses can be attributed to various active chemicals found in them, there is a distinct difference between using a medicinal plant and a chemical drug. Drugs usually consist of a single chemical, whereas medicinal plants can contain 400 or more chemicals. It’s relatively easy to figure out the activity and side effects of a single chemical, but there is just no way scientists can map all the complex interactions and synergies that might be taking place between all the various chemicals found in a plant, or a traditionally prepared crude plant extract, containing all these chemicals. Thus it is recommended to use synthetic drugs rather than plant extracts directly.
Ans 3 It is not an easy task to discover new medicines. It a major challenge to discover such drugs or chemicals that will only kill the bacteria not the human cells. Pharmaceutical industries are using chemical banks and computer models to discover and synthesise more and more drugs. Plants and microorganisms are used as starting material in drug synthesis. Compounds having antibiotic properties are modified in order to make them more powerful molecules. These modified molecules can be synthesised easily and cheaply. In Costa Rica, noni fruit is widely used as traditional medicine to treat infections and non-communicable diseases. People have also being used this for food and drink from centuries. There are no side effects of this fruit. Recently antibiotic properties are reported in noni fruit. Research is being carried out to find whether this plant can be a source of antibiotics and other medicines.
Learning objective
After this topic, you should know:
Developing and testing a new drug
Figure: Figure showing the testing and trial stages for a drug before its release. An enormous number of chemicals start the selection process but few actually become a new useful drug.
Double blind trails
Publishing results
Question answers:
Ans 1 Efficacy: Efficacy is the maximum effect produced by drug regardless of the dose.
Toxicity: Toxicity refers to how poisonous or harmful a substance can be. In the context of pharmacology, drug toxicity occurs when a person has accumulated too much of a drug in his bloodstream, leading to adverse effects on the body.
Dosage: A dosage is the amount of a medicine or drug that someone takes or should take.
Ans 2 a. To release a new drug it takes a lot of money and time. The following stages are there in drug testing:
Figure: Figure showing the testing and trial stages for a drug before its release. An enormous number of chemicals start the selection process but few actually become a new useful drug.
Ans b. If there is already a drug which works reasonably well against a disease, it would be unethical not to give that to a patient. It also allows us to compare how good the new drug is compared to existing drugs. It can only be done if there is already an active drug available.
Ans 3 Thalidomide wasn’t developed as a drug for morning sickness, but it turned out to have a beneficial effect and it was assumed that it would be safe. Extensive testing on pregnant animals was not carried out. Thalidomide uses resulted in limb deformities in developing foetuses. There was a lower standard of testing in those days. Thus it is necessary to use new drugs after tests and trials.
Learning objective
After this topic, you should know:
Making monoclonal antibodies
Figure: Production of hybridomas and monoclonal antibodies. Source: https://www.researchgate.net/publication/221929573_Immunoaffinity_Chromatography_A_Review/figures?lo=1 |
Using monoclonal antibodies
Figure: Pregnancy test kit. Source: http://www.elisa-antibody.com/ELISA-applications/home-pregnancy-test |
Question answers:
Ans 1 a. Clone is a identical copy of cell.
Ans 1 b. Antibodies are proteins synthesised by the white blood cells in response to detected foreing particles or pathogens.
Ans c. Researchers combine mice lymphocytes with a tumour cell. The combined cell is called hybridoma cell. Thus the produced hybridoma cell is now able to divide like a tumour cell and produce antibodies like a lymphocyte. Antibodies produced from these type of cells collected and purified. This antibody is known as monoclonal antibody. Monoclonal antibodies are nothing but the antibodies produced by a single clone of cells.
Ans 2 a. Like vaccination monoclonal antibodies are also depend on the immune system. Monoclonal antibody is a type of antibody only. They are proteins that are produced to target a particular cell or chemical. Some of the White blood cells can make antibodies but cannot divide. Tumour cells have tendency to divide rapidly but do not produce antibodies. Researchers combine mice lymphocytes with a tumour cell. The combined cell is called hybridoma cell. Thus the produced hybridoma cell is now able to divide like a tumour cell and produce antibodies like a lymphocyte. Antibodies produced from these type of cells collected and purified. This antibody is known as monoclonal antibody. Monoclonal antibodies are nothing but the antibodies produced by a single clone of cells. Scientists have also combined a mice cell with a human cell in order to produce human antibodies which are less likely to be rejected by human cells.
Figure: Production of hybridomas and monoclonal antibodies. Source: https://www.researchgate.net/publication/221929573_Immunoaffinity_Chromatography_A_Review/figures?lo=1 |
Ans 2 b. Like vaccination monoclonal antibodies are also depend on the immune system. Monoclonal antibody is a type of antibody only. They are proteins that are produced to target a particular cell or chemical. Some of the White blood cells can make antibodies but cannot divide. Tumour cells have tendency to divide rapidly but do not produce antibodies. Researchers combine mice lymphocytes with a tumour cell. The combined cell is called hybridoma cell. Thus the produced hybridoma cell is now able to divide like a tumour cell and produce antibodies like a lymphocyte. Antibodies produced from these type of cells collected and purified. This antibody is known as monoclonal antibody. Monoclonal antibodies are nothing but the antibodies produced by a single clone of cells. Scientists have also combined a mice cell with a human cell in order to produce human antibodies which are less likely to be rejected by human cells.
Q3 Explain how monoclonal antibodies have revolutionised the diagnosis pf pregnancy.
Ans 3. Mmonoclonal antibodies have revolutionised the diagnosis of pregnancy. One commonly used example which is based on monoclonal antibody use is pregnancy test. In this antibodies are specific for the hormone human chorionic gonadotropin (HCG). HCG is the hormone produced in the early stages of pregnancy. This hormone in tiny amount is passed with urine thus can be detected with this test kit. Change in colour is observed if the urine sample contains the HCG hormone.
Figure: Pregnancy test kit.
Source: http://www.elisa-antibody.com/ELISA-applications/home-pregnancy-test
Learning objectives
After this topic, you should know:
Treatment of disease
Figure: Monoclonal antibody directly attack on cancer cells and destroy them. Source: http://www.cancerresearchuk.org/sites/default/files/styles/cruk_wide_resp_breakpoint_one/public/diagram-showing-a-monoclonal-antibody-attached-to-a-cancer-cell_1.jpg?itok=R7imAS1Y |
Figure: Monoclonal antibodies are linked with raditoactive substances or toxic chemical that will detect the cancer cell and destroy them. Source: https://usercontent2.hubstatic.com/6712809_f520.jpg |
Figure: Growth receptors of cancer cells are blocked by monoclonal antibodies thus the cancer cell cannot divide and grow after that. |
Advantages and disadvantages of monoclonal antibodies
Question answers:
Ans 1 Sceintist are looking to use monoclonal antibodies to treat very specific diseases. There are different types of cancer and treatment for some are still not known in science. So scientists are working in this direction to develop specific monoclonal antibodies against the specific type of cancer. The success is enormous.
Figure: Monoclonal antibody directly attack on cancer cells and destroy them. Source: http://www.cancerresearchuk.org/sites/default/files/styles/cruk_wide_resp_breakpoint_one/public/diagram-showing-a-monoclonal-antibody-attached-to-a-cancer-cell_1.jpg?itok=R7imAS1Y |
Figure: Monoclonal antibodies are linked with raditoactive substances or toxic chemical that will detect the cancer cell and destroy them. Source: https://usercontent2.hubstatic.com/6712809_f520.jpg |
Figure: Growth receptors of cancer cells are blocked by monoclonal antibodies thus the cancer cell cannot divide and grow after that. |
Ans 2
Advantages and disadvantages of monoclonal antibodies
Q1 Vaccination uses your body’s natural defence system to protect you against disease.
Ans a Vaccination is there to combat for serious diseases such as meningitis. These serious diseases show their effect quickly and result in death before your body can generate antibody against them. Process of vaccination is known as immunisation. Vaccines are nothing but dead or inactivated form of a disease causing microorganisms. Immunisation will evoke natural immune responses against invading pathogen. Vaccines will create memory to fight the pathogen and prevent us from getting ill because of the invading pathogen. Dead or inactivated part of pathogen introduced in the form of vaccines will stimulate the white blood cells and in this form create memory against that pathogen. In future those memory cells will make the right antibody just as if you had a previous exposure to that pathogen and protect you from the pathogen.Vaccines are used against bacterial diseases such as tetanus and diphtheria and viral disease such as polio, measles and mumps. MMR vaccine is an example of vaccine which is used against measles, mumps and rubella. Millions of lives are saved by using vaccines.
Figure: Mechanism by which vaccines act in our body and protect us from disease encounter. Source: http://hcrc.missouri.edu/2015/08/05/im-kind-of-a-little-big-deal-public-health-ninjas/ |
ii a vaccination.
Ans b. After taking natural vaccines and vaccination the immune system is triggered and responds in same way. But Natural infection might only induce a small rise in low-affinity antibodies, while vaccination would have to induce protective antibodies. This will result in development of active immunity. The flow chart is as follows:
Ans c. First, what we think of as a cold is actually caused by many different viruses. Even the most common among those, rhinovirus, has more than a hundred different strains. “Curing” a cold and tonsillitis would actually mean eradicating a long list of respiratory viruses that happen to cause similar symptoms. Those symptoms, incidentally, are mostly just your immune system kicking into high gear to fight off an infection, something that can manifest as inflammation in the throat and congestion in the nose. Second, while sniffling and coughing is no fun, a cold is pretty low down on the list of ailments that need curing. It can be a concern for infants, the elderly, or those with pre-existing respiratory conditions, but for the majority of us, a common cold is more annoyance than threat. Thus till now there is no vaccines which can treat the common cold and tonsillitis.
Q2 Meningitis B and meningitis C are infections that can cause inflammation of the membranes around the brain and infection throughout the body (septicaemia). They are particularly serous in young children and teenagers, and can kill rapidly. Use of Figure 1 to help you answer these questions below.
Ans a. Cases of type meningitis B in 1999= around 1400 and for meningitis C is around 1000.
Ans b. For Type C almost 0 patients were recorded whereas for Type B around 1300 patients were recorded.
Ans c. Meningitis C vaccines are alone responsible for the induction in meningitis cases in UK between 1998 and 2010. This is nothing but an example of herd immunity. Because by that the only best-established single- group vaccine is a conjugate for Meningitis C.
Ans d. There are no vaccines are for meningitis B, the simple reason is that the strategy used for the other meningococci doesn’t work for MenB. Vaccines for meningococcus groups A, C, W, and Y induce an immune response against the polysaccharide capsule around the bacterium. The capsular polysaccharide of MenB however, is structurally similar to certain abundant human glycoproteins like NCAM. It is therefore not a suitable immune target due to the risk of autoimmune damage through molecular mimicry. The barrier to developing a MenB vaccine thus has two faces: the difficulty in developing vaccines in general, and the specific challenge of creating a vaccine against a pathogen that mimics host molecules. The requirements for the development of an effective vaccine for MenB will be examined in three parts: first, an overview of the general characteristics of an effective vaccine; second, a discussion of current meningococcal vaccine strategies and their limitations with regard to MenB; and third, an examination of a promising new strategy for inoculation against MenB.
Q3. a. There are no medicines to cure measles, mumps or rubella. What does this tell you about the pathogens that cause these diseases?
Ans 3 a. These three diseases are caused by viruses thus there are no medicines to cure these diseases. Viruses multiply inside the host cell thus it is difficult to design the medicines which will only destroy the virus infected cells but not the host cells.
Ans Paracetamol and aspirin are commonly used medicines which are used to make people feel more comfortable.
Ans c. These diseases are highly transmissible thus to irridicate these diseases completely from a population high levels of vaccination should be achieved. If the vaccination goals are not achieved then the outbreak of disease will be huge. Thus by seeing the transmissible of the disease the level of vaccination is decided. Higher the transmissibility of a disease higher should be the vaccination level.
Q4 a. Explain why new medicines need to be tested and trialled before doctors can use them to treat their patients.
Ans 4 a. It is required to test and try the new medicines before it comes into market for sale. Trials and tests are required to decide the efficacy, toxicity and dosage level on the new medicine.
Ans b. Developmet of new medicines is so expensive and time consuming. Consider a few basic requirements of the process:
Thus all these phases and steps of drug testing demand not only a huge amount of money but also time also.
Ans My answer is no. Because without trials the dosage level, side effects of that drug are not known. It may cause harm to your body also. If it is not target specific then it can cause damage to other body cells also.
Q5
Ans a. There is increased demand of new medicines because in the process of evolution the pathogens are also evolving and becoming resistant to drugs.
Ans b. The natural world is a vast resource of chemical and genetic diversity which makes major contributions to medicine. Chemical compounds produced by plants, animals or microbes have been used as medicines for decades – centuries in some cases. Some of the best known examples are the penicillin antibiotics, originally discovered as natural products made by fungi, and the painkiller aspirin, developed by making chemical modifications to a substance in willow bark called salicin. The chemical structures produced in nature are relatively few when compared to all possible structures – an infinite number – but they have been honed through many millions of years of evolution. If lost, these biologically active structures may not be so easily accessible through computational or synthetic means. So we can say that beside nature new drugs can be synthesised in the laboratories also. Thus drug industries are not solely depend on nature. But we cannot ignore the conversation of biodiversity.
Ans 2 c. To release a new drug it takes a lot of money and time. The following stages are there in drug testing:
Figure: Figure showing the testing and trial stages for a drug before its release. An enormous number of chemicals start the selection process but few actually become a new useful drug
Q 6 Evaluate the use of monoclonal antibodies to treat diseases such as cancer.
Ans Sceintist are looking to use monoclonal antibodies to treat very specific diseases. There are different types of cancer and treatment for some are still not known in science. So scientists are working in this direction to develop specific monoclonal antibodies against the specific type of cancer. The success is enormous.
Figure: Monoclonal antibody directly attack on cancer cells and destroy them. Source: http://www.cancerresearchuk.org/sites/default/files/styles/cruk_wide_resp_breakpoint_one/public/diagram-showing-a-monoclonal-antibody-attached-to-a-cancer-cell_1.jpg?itok=R7imAS1Y |
Figure: Monoclonal antibodies are linked with raditoactive substances or toxic chemical that will detect the cancer cell and destroy them. Source: https://usercontent2.hubstatic.com/6712809_f520.jpg |
Figure: Growth receptors of cancer cells are blocked by monoclonal antibodies thus the cancer cell cannot divide and grow after that. |
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Q1 A scientist investigated how effective five different antibiotics were at killing two types of bacteria, E.coli and S. aureus.
A clear area around the paper disc means that the antibiotic has killed the bacteria there. The results are shown in Figure:
01.1 Give one variable the scientist controlled. Use the results shown in the diagram to help you to answer the following questions.
Ans Scientist controlled the growth temperature and maintained it at 25°C.
01.2 Which antibiotic, A, B, C, D, or E was the most effective at killing E.coli?
Ans: Antibiotic D is more effective in killing the E.coli.
01.3 Which antibiotic, A, B, C, D, or E did not kill either E.coli or S. aureus?
Ans. Antibiotic C did not killed either E.coli or S. aureus.
01.4 Which antibiotic, A, B, C, D, or E would be the best to use to kill both E.coli and S.aureus?
Ans. Antibiotic B would be best to use to kill both E.coli and S.aureus.
01.5 MRSA is a strain of S.aureus. MRSA cannot be killed by most antibiotics.
| Immune powerful resistant |
Use the correct word from the box to complete the sentence.
Bacteria that cannot be killed by antibiotics are………….
Ans Resistant
Q2 New drugs have to be tested before they can be sold. Figure 2 shows how much time the different stages of testing took for a new drug.
02.1 How much more time did the clinical trials take than the laboratory testing?
Ans. Laboratory testing takes total 4 years whereas three different phases’ clinical trials take total 9 years. Thus clinical trial took 5 more years than laboratory testing.
02.2 Apart from the time taken, what other difference is there between laboratory testing and clinical trials?
Ans It takes a lot of time and money to release some medicine for use. Before release of some medicine extensive trials are done.
Scientist make huge amount of possible drugs for a disease. These drugs are further tested in laboratory to find out their toxicity and efficacy. They are tested on cells, tissues and even on whole organs.
Only few of the chemicals will pass the previous tests, remaining will be further tested in laboratory on animals. This testing will provide information about the doses and side effects of that drug. By doing this type of testing behaviour of the drug can be predicted.
The above said testing steps are preclinical testing. This type of testing is limited to laboratory trials on animals only.
The later step of testing is clinical testing. For this testing healthy volunteers and patients are used. Very low amount of drug dose is given to healthy volunteer to find out the side effects of the drug. If the drug has no side effects then it is given to a small number of patients to see whether they feel improvement or not after taking the drug. If it proves to be safe and effective then bigger trials take place. By doing bigger trials scientist optimize the dose of the drug.
02.3 During Phase 1 clinical trials, the drug is tested on healthy volunteers using low doses.
Suggest why only healthy volunteers and only low doses are used at this stage of drug testing.
Ans For phase 1 clinical trials healthy volunteers and low doses of drug are used because to observe the effect of that drug. If the volunteer used for trials are not healthy then it will matter of concern that whether the effect which volunteer is showing is because of the drug or may be other reason. Low doses are used to avoid dosage effect.
02.4 In phase 2 and phase 3 clinical trials, a double blind trial is usually done. Explain what a double blind trial is and why a double blind trial is good practice.
Ans Double blind trial is used by scientist to see how effective the new medicine. A group of patient take part in this trail. Some patients are given placebo that does not contain drug and some are given the new drug. Patients are assigned to different groups. Neither the doctor nor the patient know whether they have been given placebo or the drug until the trial is completed. Patient health is monitored carefully on regular basis. In case of placebo previously used and approved drugs are included. This means the patient is not deprived of the treatment whilst taking part in the drug trials.
Q3 Monoclonal antibodies are antibodies that target particular cells or chemicals in the body. They are used in diagnostic tests and in the treatment of some disease.
Figure shows how monoclonal antibodies are produces.
Use this figure and your own knowledge to describe how monoclonal antibodies are produced.
Ans 3. Researchers combine mice lymphocytes with a tumour cell. The combined cell is called hybridoma cell. Thus the produced hybridoma cell is now able to divide like a tumour cell and produce antibodies like a lymphocyte. Antibodies produced from these type of cells collected and purified. This antibody is known as monoclonal antibody. Monoclonal antibodies are nothing but the antibodies produced by a single clone of cells.
Figure: Production of hybridomas and monoclonal antibodies. Source: https://www.researchgate.net/publication/221929573_Immunoaffinity_Chromatography_A_Review/figures?lo=1 |
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Disclaimer: I have tried by level best to provide the answers and video explanations to the best of my knowledge. All the answers and notes are written by me and if there is any similarity in the content then it is purely coincidental. But this is not an alternative to the textbook. You should cover the specification or the textbook thoroughly. This is the quick revision to help you cover the gist of everything. In case you spot any errors then do let us know and we will rectify it.
References:
BBC Bitesize
AQA GCSE Science Kerboodle textbook
Wikipedia
Wikimedia Commons
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