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| Question | Answer |
| What are the 5 stages of decomposition? | Fresh Bloat Active Advanced Dry/remains |
| What are the characteristics of putrefaction? | Blisters appear on the skin. Green discolouration of the abdomen. Gases produced. |
| What happens during autolysis? | A body's own enzymes from lysosomes break down body tissues. Loss of oxygen from tissues encourages growth of anaerobic bacteria. |
| List 4 factors which affect rate of decomposition | Temp. Body size . Conditions. Circumstances (e.g. submerged). Activity before death. |
| What is the order of types of orgs. attracted to a cadavar during decomposition? | 1. Anaerobic bacteria - colonisers 2. Blow flies and other flies 3. Parasitic wasps 4. Beetles 5. Carcass and ham beetles 6. Hair mites and moss larvae |
| Describe the stages of rigour | 1. Muscles starved of oxygen and O-dep. reactions stop. 2. Respiration continues anaerobically. 3. Lactic acid is produced and pH drops. 4. Enzymes producing ATP and inhibited. 5. The lack of ATP means bonds between myosin + actin become fixed meaning muscles cannot contract or relax. 6. The body stiffens. |
| Describe the role of microorgs. | Bacteria and fungi produce enzymes released onto dead organisms and absorb the product of their external digestion. It is broken down in microbial respiration and CO2 is released. This recycles the carbon, helping to maintain the carbon cycle. |
| What type of enzymes can be used in gel electrophoresis to produced fragments from a section of DNA? | Restriction endonucleases. |
| List 5 structures found on a virus | Receptors Nucleic acid Capsid Capsomere Envelope |
| List 9 structures found in a bacterium | Capsule Mesosome Ribosomes Cell surface membrane Pilus Circular DNA Cell wall Plasmids Flagella |
| Describe a gram -ve bacterial cell wall | Thin layer of peptidoglycan between 2 layers of plasma membrane. |
| Describe a gram +ve bacterial cell wall | A thick layer of peptidoglycan with teichoic acid and 1 plasma membrane on the inside. |
| What are the 3 stages of HIV? | Acute Phase Chronic Phase Disease Phase |
| In which phase of HIV does AIDS onset? | Disease phase |
| What are the symptoms of active TB? | Coughing Shortness of breath Loss of appetite Fever Extreme fatigue |
| What copies viral RNA into viral DNA? | Reverse transcriptase |
| What inserts viral DNA into host DNA? | Integrase |
| List 4 non-specific immune response mechanisms | Inflammation Lysozyme action Phagocytosis Interferons |
| What are 2 types of phagocytes? | Neutrophils + Macrophages |
| What do interferons prevent? | Viruses spreading to uninfected cells. |
| What does MHC stand for? | Major Histocompatibility (protein) |
| What do antibodies do? | Agglutinate pathogens (cause clumping). Block cell surface receptors of pathogens reducing their ability to bind to host cells. The anti-b/anti-g complex marks it up for digestion by phagocytes. Neutralises toxins. |
| Which type of the specific immune response are T killer cells involved in? | Cell mediated response |
| Which type of specific immune response are B cells involved in? | Humoral response |
| What does non-overlapping, degenerate triplet code mean? | It is read as a sequence of 3 bases where no base of one triplet forms part of the next. There are 64 possible triplet combinations and not as many AA's therefore it contains more info than needed and is redundant. |
| Which is the coding region: introns or exons? | Exons |
| By which process are introns removed? | mRNA splicing |
| What are 2 post-transcriptional changes other than mRNA splicing? | Addition of a poly A tail and a guanine cap. |
| List 6 ways pathogens can be transmitted | 1. Vectors 2. Formites (inanimate objects) 3. Direct contact 4. Inhalation 5. Ingestion 6. Inoculation |
| What are 4 barriers to pathogens on the human body? | Skin Mucous membranes Stomach acid Gut flora |
| Define: Active immunity | When your immune system makes its own antibodies after being stimulated by an antigen. |
| How do you gain active natural immunity? | By catching a disease and fighting it so that you become immune. |
| What type of immunity do vaccines give you? | Active artificial |
| Define: Passive immunity | The type you get from being given antibodies from a different organism. |
| Give an example of natural passive immunity | When pre-formed antibodies are passed on from mother to foetus during pregnancy and in breast milk. |
| Define: vaccine | The process by which you immunise people to produce immunity. |
| List 3 pros of vaccinations | The child is protected from potentially lethal diseases. Society benefits from a reduced pool of infection and helps to form herd immunity. Vaccines are cheap compared to cost of treating diseases. |
| List 4 cons of vaccinations | Some live viruses are cultured from eggs and can cause an allergic response. A small % of people have an extreme immune response and can die. Mass vaccination has been linked to a rise in childhood asthma and allergies. Some vaccines are given more for the benefit of society that for the benefit of the child. |
| What are 3 evasion mechanisms of HIV | 1. It replicates inside T cells so viral particles are enveloped in host cell surface receptors. 2. It has a high mutation rate in genes coding for antigen proteins causing antigen variation. 3. It disrupts antigen presentation in infected cells. |
| Which receptors are on the surface of HIV? | gp120 |
| How does TB evade the immune system? | It produces a thick waxy outer layer preventing lysosomes fusing with the phagocytic vesicle and allowing it to multiply undetected inside macrophages and remain dormant for years. |
| The 2 types of antibiotic are... | Bactericidal & Bacteriostatic |
| What is the difference between a broad spectrum and a narrow spectrum antibiotic? | Broad spectrum antibiotics destroy a wider range of bacteria which may be harmful or beneficial where as narrow spectrum antibiotics target 1 or 2 specific pathogens. |
| Changes in hospital codes of practice | Sparing antibiotic use which is more selective Completion of treatment necessary Better hygiene Isolation of patients Screening incoming patients Advising against ill visitors Monitoring levels of HAI's |
| What does HAI stand for? | Hospital Acquired Infection |
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