Topic 6B: Bacterial And Viral Infections Flashcards

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1
Q

Give some structural differences between viruses and Bacteria (4)

A
  • Bacteria are much bigger in size
  • Viruses have no plasma membrane (capsid) wheras bacteria have polysaccharide cell wall
  • Viruses contain no cytoplasm
  • Viruses contain no ribosomes
  • viruses contain only one type of nucleic acid, Bacteria have 2
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2
Q

What is a pathogen?(2)

A
  • Any organism/microorganism that causes disease

- Diseases caused by pathogens are called infectious diseases

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3
Q

How does HIV affect the immune system?

A

-Infect and destroys t helper cells which act as a host cell for virus

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4
Q

How is HIV spread?

A

Through infected bodily fluid coming into contact with mucosal surfaces

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5
Q

Describe the process of HIV replication(6)

A

– Attachment protein attaches to receptor molecule on cell membrane post

– Capsid released into cells where it uncoats and releases genetic material (RNA) into cytoplasm

– Reverse transcriptase used to make complimentary strand of DNA from viral RNA template

– New double-stranded DNA inserted into human DNA

– Host cell enzymes used to make fibre proteins from viral DNA

– Fire proteins assembled into new viruses which live via exocytosis

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6
Q

People infected with HIV eventually developed AIDs

Describe and explain the likely sequence of symptoms found in a person infected with HIV virus (6)

A

– Initial infection may lead to severe flu like symptoms well HIV replicates rapidly

– Latency period follows in which HIV replication drops to lower level and infected person went to experience symptoms

– Passing with HIV classed as having AIDS when symptoms of feeling immune system start to appear all T-helper cell count drops below a certain level

– Initial symptoms of aids include minor infections of mucus membranes, recurring respiratory infection caused by low t helper cell count

– After AIDs progresses number of T-helper cells decrease further patient becomes susceptible to more serious infections I.E.chronic diarrhoea/ serious bacterial infection /TB

– during late stages of AIDS patient has very low number of T-helper cells and suffer from a range of serious infections could kill them such as toxoplasmosis

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7
Q

What is AIDS?

A

Condition where are immune system deteriorates and eventually fails

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8
Q

When are people with HIV classed as having aids?(2)

A

– when symptoms of feeling immune system start to appear

– T-helper cell count drops below certain level

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9
Q

what are opportunistic infections?

A

When Diseases and infections that wouldn’t cause serious normally in people with a healthy immune system cause problems

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10
Q

What causes the length of time that people survive aids to very?

A

– Age

– Existing infections

– Strain of HIV

– Access to health care

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11
Q

What type of Cell does HIV replicate in?

A

T helper cells

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12
Q

What bacteria causes tuberculosis?

A

Mycobacterium tuberculosis

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13
Q

What is the cause of infection with TB?

A

Tiny droplets containing bacteria are inhaled into lungs (TB is an airborne bacteria)

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14
Q

What happens when Mycobacterium tuberculosis enters the lungs?(2)

A
  • Bacteria taken up by phagocyte (able to evade digestion)

- Bacteria survive & replicate in phagocyte

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15
Q

Why don’t people infected with Mycobacterium tuberculosis develop TB straightaway?

A

Immune system seals of infected phagocytes in tubercles

-When sealed inside tubercle, bacteria becomes dormant and infected person show no obvious symptoms

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16
Q

When is the reactivation of dormant MycoB more likely?

A

In people with weakened immune systems

17
Q

Describe and explain the likely sequence of symptoms found in a person with TB

A
  • Initial symptoms of TB (fever, general weakness severe coughing)
  • Caused by inflammation of lungs
  • As TB progresses, lungs becomes damaged
  • If left untreated, can lead to respiratory failiure which can lead to death
  • Tb can spread to other parts of body (i.e. brain/kidney)
  • If left untreated, can cause organ failiure which can lead to death