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Biology > Communicable Diseases 4.1 > Flashcards

Communicable Diseases 4.1 Flashcards

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1
Q

What are opsonins ?

A

-a type of antibody
-they are proteins that bind to the antigen on a pathogen to enhance the ability of phagocytic cells to bind and engulf the pathogen

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2
Q

What is a neutrophil ?

A

-the most common phagocyte
-they have a multi-lobed nucleus
-they are manufactured in the bone marrow
-they are shorted lived
-a large amount of them will be released as a result of infection

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3
Q

How do neutrophils act to destroy pathogens ?

A

-neutrophil binds to the opsonin attached to the antigen of the pathogen
-the pathogen is engulfed by endocytosis forming a phagosome
-lysosomes fuse to the phagosome and release lytic enzymes into it
-after digestion the harmless products can be absorbed into the cell

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4
Q

Define a neutrophil

A

A type of white blood cell that engulfs foreign matter and traps it in a large vacuole (phagosome) which fuses with lysosomes to digest the foreign matter

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5
Q

Define an antigen presenting cell ?

A

A cell that isolates the antigen from a pathogen and places it on the plasma membrane so that it can be recognised by other cells in the immune system

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6
Q

Define what a cytokine is

A

Hormone-like molecules used in cell signalling to stimulate the immune response

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7
Q

What are macrophages?

A

-larger than neutrophils
-manufactured in bone marrow and travel in the blood as monocytes before settling in the body tissue, many found in lymph nodes

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8
Q

What is the role of macrophages?

A

-play a role in initiating the specific response to invading pathogens
-when it engulfs a pathogen it does not fully digest it
-the antigen from the surface of the pathogen is saved and moved too a special protein complex on the surface of the cell (the cell becomes an antigen-presenting cell)
-through this other cells in the immune system can recognise the antigen
-special protein complex ensures the antigen-presenting cell is not mistaken as a foreign cell and attacked

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9
Q

What do antigen-presenting cells do?

A

They move around the body where it can come into contact with specific cells that can activate the full immune response
It increases the chances that an antigen will come into contact with them

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10
Q

What is clonal selection ?

A

Selection of a specific B or T cell that is specific to the antigen

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11
Q

What do T helper cells do?

A

They release cytokines (chemical messengers) that stimulate the B cells to develop and stimulate phagocytosis by the phagocytes

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12
Q

What do T killer cells do?

A

They attack and kill host-body cells that display the foreign antigen
They do this by making holes in the cell surface membrane using perforins

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13
Q

What do T memory cells do?

A

They provide long-term immunity

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14
Q

What do T regulator cells do?

A

They shut down the immune response after the pathogen has been successfully removed.They are also involved in preventing autoimmunity.

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15
Q

What are B and T lymphocytes?

A

-white blood cells that have a large nucleus and specialised receptors on their plasma membranes.
-both are made by bone marrow stem cells
-but B cells mature in the bone marrow
-and T cells mature in the thymus

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16
Q

What are the two types of cells that B lymphocytes develop into?

A

-plasma cells
-B memory cells

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17
Q

What are plasma cells?

A

-they circulate in the blood
-they manufacture and release antibodies
-they are responsible for immediate defence

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18
Q

What are B memory cells?

A

-don’t produce antibodies directly
-they remain in the body for a number of years and act as immunological memory

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19
Q

What are interleukins?

A

Signalling molecules that are used to communicate between different white blood cells

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20
Q

What is cell signalling ?

A

The communication between cells in the specific immune response.
The communication is achieved through the release of hormone-like chemicals called cytokines.
In order to detect a signal the target cell must have a cell surface receptor complementary in shape to the shape of the signalling molecule.

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21
Q

What are three examples of communication using cytokines?

A

-macrophages release monokines. Some monokines attract neutrophils (by chemotaxix-movement of cells towards a particular chemical.) Others stimulate B cells to differentiate and release antibodies

-T cells and macrophages release interleukins which can stimulate the clonal expansion(proliferation) and differentiation of B and T cells

-many cells can release interferon, which inhibits virus replication and stimulates the activity of T killer cells

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22
Q

What is clonal expansion?

A

An increase in the number of cells by mitotic cell division

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23
Q

What is an antigen?

A

-usually proteins or glycoproteins in the plasma membrane of the pathogen
-they will be recognised by the body as foreign by the immune system they are usually a marker on the surface of a cell
-this will stimulate the production of antibodies

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24
Q

What is an antibody?

A

-an immoglobulins- complex proteins produced by the plasma cells in the immune system
-they are released in response to an infection
- they have a region with a specific shape that is complementary to that of a particular antigen
-they attach to antigens and neutralise them making them harmless
-our immune system must manufacture one type of antibody for every antigen that is detected

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25
Q

What do opsonins do?

A

-they are a group of antibodies that bind to the antigens on a pathogen
-they act as binding sites for phagocytic cells so that these can more easily bind and destroy the pathogen

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26
Q

What do agglutinins do?

A

-as each antibody molecule has 2 identical binding sites it is able to ‘crosslink’ pathogens by binding an antigen on one pathogen with one binding site and then an antigen on another pathogen with its other binding site
-when many antibodies perform this function they clump together (agglutinate) pathogens

27
Q

What are advantages of agglutinating pathogens?

A

-the agglutinated pathogens are physically impeded from carrying out some functions e.g. entering host cells also the pathogens are readily engulfed by phagocytes. This is particularly effective against viruses

28
Q

What are anti-toxins?

A

-they bind to molecules released by the pathogenic cells
-these molecules may be toxic and anti-toxins render them harmless

29
Q

What is the primary immune response?

A

-when an infecting agent is first detected the immune system starts to produce antibodies
-it takes a few days before the number of antibodies in the blood rises to a level that can combat the infection successfully
-once the pathogens have been dealt with number of antibodies in the blood drops rapidly

30
Q

What is the secondary immune response?

A

-antibodies do not stay in the blood so if the body is infected a second time by the same pathogen the antibodies must be made again
-however as a result of the specific immune response there will be B memory cells and T memory cells circulating in the blood
-meaning these cells can recognise the specific antigens and the immune system can act more quickly
-so the production of antibodies starts sooner and is much more rapid , therefore the concentration of antibodies rises sooner and reaches a higher concentration
-the secondary immune response is normally quick enough to prevent any symptoms being detected by the host

31
Q

What are 3 examples of diseases caused by bacteria?

A

-tuberculosis (caused by M.bovis)
-bacterial meningitis (caused by neisseria meningitidis )
-ring rot (caused by Clavibacter michiganesis )

32
Q

What are 3 examples of diseases caused by viruses?

A

-HIV/ AIDS (caused by human immunodeficiency virus)
-influenza (virus from family Orthomyxoviridae)
-tobacco mosaic virus

33
Q

What are diseases caused by protoctista?

A

-malaria (caused by plasmodium falciparum)
-potato/tomato late blight (phytophthora infestans)

34
Q

What are 3 diseases caused by fungus?

A

-black Sigatoka (mycosphaerella fijiensis)
-athlete’s foot (trichophton rubrum)
-ringworm -cattle disease

35
Q

Define a pathogen

A

-a microorganism that causes disease

36
Q

What type of cell is bacteria?

A

-prokaryote

37
Q

How do bacteria damage cells?

A

-by releasing waste products and/or toxins

38
Q

What are some examples of direct transmission?

A

-direct physical contact e.g. touching a person who is infected or contaminated surfaces (including soil) , kissing, sexual contact
-faecal-oral transmission- eating or drinking contaminated food and water
-droplet infection- droplets from coughing or sneezing
-transmission by spores(made by fungi), that can be carried in the air or reside on surfaces or in soil

39
Q

What are some examples of direct transmission?

A

-direct physical contact e.g. touching a person who is infected or contaminated surfaces (including soil) , kissing, sexual contact
-faecal-oral transmission- eating or drinking contaminated food and water
-droplet infection- droplets from coughing or sneezing
-transmission by spores(made by fungi), that can be carried in the air or reside on surfaces or in soil

40
Q

What are some factors that can reduce direct transmission?

A

-hygiene- washing hands regularly (especially after toilet), cleaning and disinfecting cuts, using condoms
-treatment of waste water and drinking water, careful preparation and cooking of food
-catch it- bin it- kill it
-washing skin after contact with soil

41
Q

What are some living conditions that affect transmission?

A

-climate- hot climates can increase spread of pathogens as they may reproduce quicker
-social factors- overcrowding, poor ventilation, poor diet , poor immune system (if a person has HIV/AIDS), poor education about the spread of disease, an area where less vaccines or medicines are available

42
Q

What is indirect transmission?

A

-when a pathogen is passed from host to new host, via a VECTOR

43
Q

What are some methods of transmission for a plant?

A

-pathogens that are present in soil enter the roots of a plant and infect it
-spores of fungi may be carried by the wind (airborne transmission?)

44
Q

What is an example of indirect transmission in plants?

A

—insects may act as a vector

45
Q

What are some physical passive defences in a plant?

A

-cellulose cell wall- physical barrier, may contain a variety of chemical defences
-waxy cuticles-prevent water collecting on plant surfaces, pathogens collect on water and need it to survive.
-bark-normally contains chemical defences
-callose- polysaccharide that that is deposited around the sieve plates and blocks the flow in the sieve tube
-tylose- can act as a plug in xylem vessel -to prevent spread through water. Also have a high concentration of terpenes that are toxic to pathogens

46
Q

What is callose deposition?

A

-the deposition of callose between the plant cell wall and cell membrane near the invading pathogen
-Callose deposits are polysaccharide polymers that impede cellular penetration at the site of infection
-it strengthens the cell wall and blocks plasmodesmata
-it is an active defense

47
Q

What are some examples of active defences in a plant?

A

-cell walls become thickened with additional cellulose
-oxidative bursts that produce highly reactive oxygen molecules capable of damaging the cells of invading organisms
-increase in chemical production
-necrosis-deliberate cell suicide. A few cells surrounding the infection are sacrificed ,this can limits pathogens access to water and nutrients

48
Q

What are terpenoids?

A

-a chemical released in a plants active defence against pathogens
-they are a range of essential oils that have antibacterial and anti fungal properties
-they may also produce a scent

49
Q

What are phenols?

A

–a chemical released in a plants active defence against pathogens
-have antibiotic and anti fungal properties
-tannins found in bark inhibit attack by insects as insects that ingest a large amount may die

50
Q

What are alkaloids?

A

-a chemical released in a plants active defence against pathogens
-they contain nitrogen
-they give a bitter taste to inhibit herbivores feeding
-also act on a variety of metabolic reactions by inhibiting or activating enzyme action
-if a plant can avoid grazing by larger animals then it will suffer less damage that can allow pathogens to enter plant

51
Q

What are defensive proteins (defensins)?

A

-a chemical released in a plants active defence against pathogens
-small cysteine-rich proteins that have broad anti-microbial activity
-they act upon molecules in the plasma membrane of pathogens,possibly inhibiting the action of ion transport channels

52
Q

What are hydrolytic enzymes in the plant defences?

A

-chemicals released in a plants active defence against pathogens
-found in spaces between cells. They include:
.chitinases (which breaks down chitin in fungal cell walls)
-glucanases (which hydrolyse the glycosidic bonds in glucans)
-lysozymes (which are capable of degrading bacterial cell walls)

53
Q

What is active immunity ?

A

-where the immune system is activated (as a result of infection) and manufactures its own antibodies
-a person suffers from the disease once and is then immune

54
Q

What is passive immunity?

A

-immunity achieved when the antibodies are passed to the individual through breast feeding
-or through an injection (artificial)

55
Q

What is passive immunity?

A

-immunity achieved when the antibodies are passed to the individual through breast feeding
-or through an injection (artificial)

56
Q

What is natural immunity?

A

Immunity achieved through normal life processes (in the immune system as a result of infection)

57
Q

What is artificial immunity?

A

-immunity provided by antibodies made in the immune system as a result of vaccination

58
Q

What is an autoimmune disease?

A

-when antibodies start to attack our own antigens

59
Q

What is arthritis?

A

-an autoimmune disease
-it is a painful inflammation of a joint
-the cause is uncertain, but it starts with antibodies attacking the membranes around a joint

60
Q

What is personalised medicine?

A

-the potential development of designer medicines for individuals

61
Q

Describe the process of phagocytosis

A

• Damaged cells and pathogens release cell-signalling chemicals (cytokines) that attract the phagocytes (macrophages and neutrophils)to the site of infection.
•An opsonin protein can attach to pathogens to mark them and make it easier for neutrophils and macrophages to engulf them
• Phagocytes have receptors which can attach onto chemicals on the surface of pathogens.
• The phagocyte then engulfs the pathogen into a vesicle to create a phagosome.
• Within the phagocytes, there are lysosomes which contain hydrolytic lysozyme enzymes.
• The lysosome fuses with the phagsome to expose the pathogen to the lyzozyme. The lysozyme hydrolyses the pathogen and any soluble useful molecules are absorbed into the cytoplasm of the phagocyte
• The phagocytes will present the antigen of the digested pathogen on their surface - they are then called antigen-presenting cells.

62
Q

Define the term parasite
3marks

A

-lives in host
-gains nutrition from host
-at the harm of host

63
Q

Explain why the human body’s primary defences do not prevent the entry of plasmodium into the body
(2marks)

A

-mosquito feeds on blood
-breaks skin, skin cannot act as barrier

Biology (10 decks)

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