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Biology edexcel 9-1 > Topic 5 viruses and diseases > Flashcards

Topic 5 viruses and diseases Flashcards

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1
Q

Describe the lytic pathway?

A
  1. Virus attaches to specific host cell and injects genetic material
  2. Virus uses proteins and enzymes in host cells to replicate GM
  3. Components for new virus assemble
  4. Host cell splits open, releasing new viruses to infect more cells
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2
Q

Describe the lysogenic pathway?

A
  1. The injected GM is incorporated into genome of host cell
  2. Viral GM and host DNA replicate when host cell divides but virus remains inactive. (no new viruses being made)
  3. Trigger (chemical) causes GM to leave genome of the host cell and enter the lytic pathway
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3
Q

Why does the Chlamydia bacterium behave like a virus?

A

Because it can only reproduce inside host cells

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4
Q

How can the spread of Chlamydia be reduced?

A
  1. By wearing a condom during sex
  2. screening individuals so they can be treated
  3. or avoiding sexual contact
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5
Q

What is HIV?

A

A virus which kills white blood cells (these are needed to trigger an immune response, so it can make a person very vulnerable to infections by other pathogens)

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6
Q

How is HIV spread?

A

Through bodily fluids

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7
Q

How can HIV be prevented?

A
  1. Use a condom during sex
  2. Drug users should avoid sharing needles
  3. an infected person should be screened so they have receive proper treatment and medication.
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8
Q

How does the waxy leaf cuticle of a plant protect it from pests and pathogens?

A
  1. the waxy leaf cuticle provides a barrier to stop pathogens entering
  2. stops water collecting on leaf. (this reduces risk of infection from pathogens that enter plant through water)
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9
Q

How does the cell wall protect a plant from pests and pathogens?

A

they form a barrier against pathogens that make it past the waxy cuticle

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10
Q

How do plants protect themselves against pests and pathogens through chemicals?

A
  1. produce chemicals called antiseptics which kill bacteria and fungal pathogens
  2. also produce chemicals to deter pests from feeding on leaves
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11
Q

What are antigens?

A

they are molecules on a pathogens surface

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12
Q

How can detecting antigens be used to detect pathogens in plants?

A

they can be detected in a sample of plant tissue (using monoclonal antibodies) and as they are unique to a certain pathogen, the pathogens can be identified and the disease diagnosed

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13
Q

How can detecting DNA identify pathogens in infected plants?

A

A pathogens DNA would be present in the plants tissue, which can be detected through special techniques. This would allow for the particular pathogen present to be identified

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14
Q

How are plant diseases detected and identified in the field?

A
  1. Through observations. (looking at symptoms)
  2. Analysing distribution of affected plants (e.g random distribution may suggest airborne pathogen)
  3. Eliminating environmental causes
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15
Q

How do the physical barriers in the body protect us from pathogens?

A
  1. Skin - barrier to pathogens. (blood clots heal cuts to keep microorganisms out)
  2. Hair and Mucus (in nose, trachea and bronchi) trap particles that could contain pathogens
  3. Contains cilia to waft mucus back up throat and away from lungs
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16
Q

What are the chemical barriers that defend us against pathogens?

A
  1. Stomach has HCL that kills most pathogens swallowed

2. Eyes produce lysozyme in tears which kill bacteria on surface of the eye

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17
Q

What are B-lymphocytes?

A

a type of white blood cell that helps protect the body against pathogens

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18
Q

How do B-lymphocytes protect us from pathogens?

A

When they come across an antigen, they produce proteins called antibodies. These lock on to the antigens so they can be destroyed. antibodies are then produced rapidly and flow around the body to find other similar pathogens

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19
Q

What are memory lymphocytes?

A

Antigens trigger production of memory lymphocytes. they stay in the body and remember a specific antigen. Therefore, they make a person immune as their system is able to respond much quicker to transmitted pathogens.

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20
Q

How can a person be immunised through the use of an inactive form of a pathogen?

A
  1. Inject a dead or inactive pathogen into the body
  2. The body will make antibodies to destroy them even though they are inactive. (they have antigens)
  3. The antigens also trigger memory lymphocytes
  4. So if the pathogen enters the body again, the memory lymphocytes can cause a faster secondary immune response
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21
Q

What are the pros of immunisation?

A
  1. They prevent epidemics as even those who aren’t immunised are less likely to catch it as there as less people to pass it on. (Herd plImmunity)
  2. Some diseases, e.g smallpox, have been wiped out due to immunisation
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22
Q

What are the cons of immunisation?

A

It doesn’t always give you immunity and it may sometimes give allergic reactions (swelling, fever, seizures)

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23
Q

What can antibiotics only be used to treat?

A

Bacterial infections as antibiotics only inhibits processes in bacterial cells, and not in the host organism/cells

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24
Q

Explain some aseptic techniques used in culturing microorganisms in the lab.

A
  1. Petri dishes and growth mediums must be sterilised before use. Can be done by using an autoclave (uses steam at a high pressure and temp to kill and microorganisms present)
  2. Before being used to transfer bacteria, inoculating loop should be sterilised by putting it through hot flame
  3. Liquid bacterial cultures should be covered and kept in a vial with a lid. Keep closed unless transferring bacteria
  4. After transferring bacteria, Petri dish should be covered with tightly taped lid to stop micros from air getting in.
  5. Store dish upside down to stop condensation falling into agar
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25
Q

How can you grow bacteria in a lab?

A
  1. You grow them in a growth medium (solid agar jelly) in a petri dish.
  2. Should form visible colonies, as they have multiplied, on surface of agar jelly
  3. Keep micros at 25 as harmful pathogens are less likely to grow at this temp. (scientists are able to though to provide optimum conditions for growth.
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26
Q

What is the equation used to calculate cross-sectional areas of bacterial cultures and agar jelly?

A

Area = 3.14 * r *r

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27
Q

What is preclinical testing?

A

(after discovering the drug) Preclinical testing - Drugs are tested on human cells and tissues in the lab. (dont use human cells to test drugs that affect whole or multiple body systems. Then use on live animal to see if the drug works, how toxic it is and for best dosage

28
Q

What is clinical testing?

A
  1. Using healthy volunteers to make sure there are no harmful side effects when the body is working properly
  2. If this works, it can be tested on ill volunteers. Optimum dose is found.
  3. Patients are put into 2 groups. One is given the drug, other is given a placebo (fake drug to trick them into thinking they had it)
  4. Can be double-blind where the patients nor the dr know which drugs which group is getting. This is so the results aren’t subconsciously influenced by their knowledge
  5. If it passes all of these steps, must be approved by a medical agency before it can be given to patients
29
Q

What are monoclonal antibodies

A

Identical antibodies

30
Q

What is the use of lymphocytes in monoclonal antibodies?

A
  • Monoclonal antibodies are produced by lots of clones of a single B lymphocyte
  • As they dont divide easily, a mouse B-lymphocyte is fused with a tumour
    myeloma cell, which divide very easily, to make a hybridoma.
31
Q

what do hybridomas do?

A

Hybridomas can be cloned to get lots of identical cells. these can then divide quickly to produce monoclonal antibodies as they divide. They are then collected and purified

32
Q

Why are monoclonal antibodies useful?

A

You can make monoclonal antibodies that bind to anything you want. e.g an antigen that’s only found on the surface of one type of cell. They are useful as they will only bind to (target) this molecule. This means you can use them to target a specific cell or chemical in the body

33
Q

What hormone is found in the urine of women when they are pregnant?

A

HCG

34
Q

Briefly describe how pregnancy tests work?

A
  1. The bit of the stick contains blue beads, with antibodies attached onto them. (antibodies for the hormone)
  2. The test strip has more antibodies to the hormone stuck onto it. (to make sure the hormone cant move)
  3. When pregnant, the hormone in the urine binds onto the antibodies on the blue beads and it moves up the stick and attaches itself onto the test strip. (the hormone makes the blue beads stick onto the test strip)
  4. The blue beads make the test strip turn blue
35
Q

What happens if a women is not pregnant?

A

The urine will still move up the stick with the blue beads, but there is no hormone to make the blue beads stick onto the strip. Therefore, it wont turn blue

36
Q

How can you make monoclonal antibodies that target cancer cells?

A

Cancer cells have proteins on their cell membranes called tumour markers. In the lab, you can make monoclonal antibodies that will bind to these tumour markers

37
Q

How can monoclonal antibodies be used to diagnose cancer?

A
  1. They are labelled with a radioactive element
    2, These are given to a patients blood through a drip, so it can be carried around the body
  2. When they spot a cancer cell, they bind to the tumour markers
  3. A picture of the body is taken with a camera that detects radioactivity and cancer cells would show up as a bright spot
  4. We can see where the cancer is, the size of it, and if its spreading
38
Q

How can monoclonal antibodies target drugs to cancer cells?

A
  1. An anti-cancer drug is attached to monoclonal antibodies and given to a patient through a drip
  2. The antibodies target these specific cancer cells and bind to the tumour marker
  3. The drug kills the cancer cells but not the normal body cells near the tumour
39
Q

Why is it better to use monoclonal antibodies in treating cancer than other drugs and radiotherapy?

A

The alternatives can affect normal body cells as well as killing the cancer cells, giving the alternatives more side effects

40
Q

What happens when blood clots?

A

Proteins in the blood join together to form a solid mesh

41
Q

How can monoclonal antibodies be used to find blood clots?

A
  1. Monoclonal antibodies have been developed to bind to these proteins
  2. Attach a radioactive element to these antibodies and inject them into the body
  3. Take a picture using a camera that detects radioactivity
  4. The blood clots will appear on the picture as a bright spot
42
Q

What are risk factors?

A

Things that are linked to an increase in the likelihood that a person will develop a certain disease

43
Q

What is cardiovascular disease?

A

Any disease associated with the heart or blood vessels

44
Q

What major risk factor is associated with cardiovascular disease and why?

A

Smoking

  1. Nicotine in the smoke increases heart rate and blood pressure
  2. High blood pressure damages artery walls, which contributes to a build up of fatty deposits in the arteries. These restrict blood flow and increases the risk of a heart attack/stroke
  3. Increases the risk of blood clots forming in arteries which can restrict blood flow, causing a heart/stroke
45
Q

What other risk factors are associated with cardiovascular disease?

A
  1. Drinking too much
  2. Lack of exercise
  3. Obesity
  4. A diet in high saturated fat
46
Q

What risk factor affects the liver?

A

Drinking too much alcohol as alcohol is broken down by enzymes in the liver and some of the products are toxic. Persistent drinking can cause permanent liver damage

47
Q

Are non-communicable diseases usually caused by a number of factors, or just one?

A

They are caused by several different factors interacting with each other. Including diseases such as cancer, liver and lung diseases

48
Q

How can non-communicable diseases affect local areas?

A

In areas where there are high levels of obesity , smoking, or excessive alcohol consumption, there’s likely to be a high occurrence of certain non-communicable diseases. This can put pressure on hospital resources.

49
Q

How can non-communicable diseases have an effect on a national level?

A

The NHS provides the resources for the treatment of patients all over the UK. The people suffering from non-communicable diseases may not be able to work. This can affect a country’s economy

50
Q

How can non-communicable diseases have an effect on a global level?

A

They are very common. In developing countries, malnutrition is a big problem because people are not able to access food. The high cost and occurrence of these diseases can hold back the development of a country

51
Q

What is a body mass index?

A

it is something which is used as a guide to help decide whether someone is underweight, normal, overweight or obese

52
Q

How is BMI calculated?

A

Weight (kg) / Height (m) squared

53
Q

How does exercise and diet affect obesity and malnutrition?

A

If you eat a high fat, high sugar diet and you dont do enough exercise, you’re more likely to take in more energy than you use, storing this excess energy as fat. This can give you a higher BMI

54
Q

What is the waist-to-hip ratio equation and what does it mean?

A

Waist-to-hip ratio = Waist circumference / hip circumference

The higher your ratio, the more weight you’re likely to be carrying around your middle. A ratio above 1.0 for males and above 0.85 for women indicates that you’re carrying too much weight around your middle

55
Q

How can statins be used as a lifelong medication for cardiovascular disease?

A

Statins reduce the amount of cholesterol in the bloodstream. This slows down the rate at which fatty deposits form, and therefore reduces the risk of heart attacks and strokes.

56
Q

What are the negatives of using statins?

A

They can sometimes cause side effects e.g. aching muscles. Some of these side effects can be serious e.g. liver damage

57
Q

How can anticoagulants be used as a lifelong medication for cardiovascular disease?

A

They make blood clots less likely to form

58
Q

What are the negatives of using anticoagulants?

A

It can cause excessive bleeding if the person is hurt in an accident

59
Q

How can antihypertensives be used as a lifelong medication for cardiovascular disease?

A

They reduce blood pressure. This helps to prevent damage to blood vessels and so reduces the risk of fatty deposits forming

60
Q

What are the negatives of using antihypertensives?

A

They can cause side effects e.g. headaches and fainting

61
Q

How can stents be used in a surgical procedure to reduce the risk of cardiovascular disease?

A

Stents are rubs that are inserted in arteries. They keep them open, making sure blood can pass through to the heart muscles. This lowers the risk of a heart attack

62
Q

What are the negatives of using stents?

A

Over time, the artery can narrow again as stents can irritate the artery and make scar tissue grow. The patient also has to take drugs to stop clotting on the stent

63
Q

How can healthy vessels be used in a surgical procedure to reduce the risk of cardiovascular disease?

A

If part of a blood vessel is blocked, a piece of healthy vessel can be used to bypass the blocked section. This is coronary bypass surgery

64
Q

How can a donor heart be used in a surgical procedure to reduce the risk of cardiovascular disease?

A

The whole heart can be replaced with a donor heart

65
Q

What are the negatives of using a donor heart?

A
  1. The new heart does not always start pumping properly
  2. drugs have to be taken to stop the body rejecting it. These drugs can have side effects e.g. making you more vulnerable to infections
66
Q

How can lifestyle changes be used to treat cardiovascular disease?

A
  1. They can reduce the risk of getting CVD and helps to reduce the risk of having a further heart attack/stroke for those who do have CVD
  2. People may be encouraged to:
    - eat a healthy diet (low in saturated fat)
    - Exercise regularly
    - Lose weight if necessary
    - Stop smoking

Biology edexcel 9-1 (8 decks)

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