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Infection, immunity and forensics > Microorganisms and disease > Flashcards

Microorganisms and disease Flashcards

1
Q

Difference between bacterial cell and human cell

A
  • 70s (smaller) ribosome, 80s (larger) ribosome
  • no membrane bound organelles, membrane bound organelles
  • no nucleus, nucleus present
  • circular DNA, linear DNA
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3
Q

How phagocytosis destroys bacteria

A
  • macrophage engulfs bacteria (endocytosis)
  • vesicle containing pathogen fuses with a lysosome
  • enzymes digest bacteria
  • antigens are separated off (antigen processing)
  • antigen combines with MHC complexes which move to outer cell membrane
  • macrophage becomes APC, activating cells in specific immune response
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4
Q

The role of T helper cells in the immune response

A
  • macrophage becomes an APC
  • T helper cell with complementary CD4 receptor binds to the antigen/MHC complex on the APC
  • T helper cell is activated and divides to form active T helper cells and T memory cells.
  • each T cell has same CD4 receptor, so are specific to original antigen
  • T cells stimulate immune response
  • T helper cell binds to B cell APC and produces cytokines that stimulate the B cell to divide and produce antibodies
  • stimulates specific immune response
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5
Q

Describe how counting the numbers of T helper cells can provide a measure of AIDS in a person with HIV

A
  • HIV infects T helper cells
  • T killer cells then kill T helper cells
  • as HIV progresses, T cell count will drop
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6
Q

Give two common symptoms of HIV and AIDS

A
  • karposi’s sarcoma
  • excessive sweating
  • chronic lung infections (TB)
  • pneumonia
  • opportunistic infection
  • weight loss
  • extreme tiredness
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7
Q

Bacteria structure that contains resistance genes that can be transferred to another bacteria

A

-plasmid

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8
Q

Bacteria structure where protein synthesis takes place

A
  • ribosome
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9
Q

Bacteria structure that contains enzymes for respiration

A
  • mesosome
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10
Q

How TB is caused

A
  • by droplet infection, inhalation of bacteria by droplet or dust
  • mycobacterium tuberculosis
  • formation of tubercles in the lungs
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11
Q

How TB avoid being destroyed by the immune system

A
  • present inside macrophages
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12
Q

Describe the role of B cells and T cells in preventing the development of the symptoms of TB in an infected person

A
  • antigen binds to B cell, B cell become APC
  • T helper cell binds to APC
  • T helper cell releases cytokines which stimulate B cell proliferation
  • B cell divide into B effector cells and B memory cells
  • B effector cells differentiate in plasma cells which secrete antibodies
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13
Q

Why a patient infected with TB is more likely to develop symptoms of the disease if they are also infected by HIV

A
  • HIV infects T helper cells, which are destroyed by T killer cells
  • T helper cells are required to stimulate proliferation of B cells to produce antibodies
  • bacterial cells not destroyed by the immune system
  • bacteria proliferate
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14
Q

Symptoms of TB

A
  • tubercles
  • fever
  • excessive coughing/coughing of blood
  • weight loss
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15
Q

Explain why the response of the immune system to the viral proteins is an example of active immunity

A
  • it is the response of immune system to antigen
  • producing antibodies
  • T killer cell
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16
Q

Explain how active immunity provides immunity against future infections by the virus

A
  • memory cells are produced
  • response more rapid to second infection, faster antibody production
  • prevents symptoms
  • high concentrations of antibody produced
  • antibodies produced for longer
  • secondary response
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17
Q

What determines the usefulness of a vaccine

A
  • how quickly the population can be protected, time to produce enough doses for effective protection of population
  • if it is possible to keep high levels of herd immunity
  • if distribution is more reliable, possible to remote areas
  • if it has to be refrigerated/special treatment during distribution
  • how fast they can develop a vaccine against a new strain of virus, rapid response to change in pathogens
18
Q

Suggest how the use of viral DNA might be more effective than viral protein in producing herd immunity to a virus

A
  • antibodies only destroy virus in blood
  • virus infects body cells
  • viral DNA method stimulates T killer cells
  • T killer cells destroy virally infected cells
  • virus cannot spread/hide inside cells
  • T memory cells produced
  • more lymphocytes to combat infection
19
Q

State how the genetic material in HIV differs from the genetic material to the Mycobacterium tuberculosis

A
  • RNA in HIV and DNA in bacterium
  • nucleic acid is circular in bacterium and linear in HIV
  • bacterium contains plasmids, no plasmids in HIV
20
Q

Explain the change in the numbers of CD4 T-lymphocytes during the first 6 weeks after infection with HIV

A
  • glycoprotein 120 on virus binds with CD4 receptors
  • on surface membrane of lymphocytes
  • viral RNA enters T cell/lymphocyte
  • viral RNA used to produce viral DNA in T cell
  • by action of reverse transcriptase
  • formation of new viruses
  • lymphocyte destroyed when new viruses bud out cell (and take cell membrane)
  • T killer cells destroy T helper cells
21
Q

Explain why unbroken skin is an effective barrier against HIV infection

A
  • keratin in skin surface/epidermis

- forms a hard impenetrable physical barrier

22
Q

Effect of fall in T count on one other component of the infected person’s blood

A
  • B cells not activates
  • so fewer antibodies produced
  • T killer cells increases
23
Q

Describe how viruses are recognised and destroyed by the immune system

A
  • activation of T cell, virus engulfed by macrophage
  • antigens presented on macrophage, APC
  • T helper cell with complementary CD4 receptor binds to antigen/MHC complex
  • to form clones of active T helper cell and T memory cells
  • leads to cell mediated/humeral response
  • cell mediated, T killer cell with complementary receptor binds to anitigen/MHC complex on APC
  • T helper cell releases cytokines that stimulate division
  • T killer cell releases chemicals that cause lysis of virus infected cells
  • humoral response/clonal selections, antigen binds to B cell
  • B cell becomes APC
  • T helper cell binds to MHC/antigen complex and stimulate division
  • B effector cells differentiate into plasma cells
  • plasma cells secrete antigen specific antibodies
  • antibodies label antigens for phagocytosis

Infection, immunity and forensics (3 decks)

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