B3- Infection and Response Flashcards
Define pathogen
A microorganism that enters the body and causes harm
What type of disease do pathogens cause
Communicable
Can plants and animals be impacted by pathogens
Yes
How do bacteria make people feel ill
Producing toxins
Are viruses cells
No
Where do viruses live inside you
Inside body cells (the host cell)
What makes you feel ill with a virus
The damage of the host cell
What are protists
Single-celled eukaryotes
What are parasites
They live on or inside other organisms and can cause them damage. They are often transported by the vector which doesn’t get the disease itself
What is an example of a protist
A mosquito carrying malaria
What are the 4 types of pathogens
- Protists
- Bacteria
- Fungi
- Virus
What are the 3 ways in which pathogens can be spread
- Water
- Air
- Direct contact
What are the 3 viral diseases you need to know
- Measles
- HIV
- Tobacco mosaic virus (TMV)
What are symptoms of measles
- Red skin rash
- Fever
What are potential complications of measles
- Pneumonia
- Encephalitis
What is encephalitis
A brain infection
What is pneumonia
Lung inflammation caused by bacterial or viral infection, in which the air sacs fill with pus and may become solid. Inflammation may affect both lungs (double pneumonia) or only one (single pneumonia).
How is HIV transferred
Sexual contact by the exchange of body fluids
What are the initial symptoms of HIV
Flu like for the first few weeks
How long after the initial symptoms of HIV will it be until the person experiences them again
A few years
What is crucial about the time in between the first symptoms and the next ones (HIV)
It’s when HIV can be controlled by antiretroviral drugs
What does the HIV virus attack
The body’s immune system
When does HIV turn into AIDS
When the body’s immune system can’t cope with other infections or cancers
What does TMV infect
Plants
What are the symptoms of TMV
- A Mosaic pattern on the leaves
- Parts of the leaves become discoloured
What does the discolouration in leaves cause
Less cell growth because it can’t carry photosynthesis
What is rose black spot
A fungus
What are the symptoms of rose black spot
- Purple or black spots
- Leaves turn yellow and drop off
What plants can get rose black spot
Rose plants
How does rose black spot spreads through the environment
Water or wind
What is malaria caused by
A protist
Who is the vector for malaria
A mosquito
What are the symptoms of malaria
Repeating episodes of fever
What are the two bacteria diseases you need to know
- Salmonella
- Gonorrhea
Salmonella is a type of bacteria that causes _ _
Food poisoning
What are the symptoms of salmonella
- Fever
- Stomach cramps
- Vomiting
- Diarrhea
How is gonorrhea caught
Sex
STD
What type of pathogen is salmonella
Bacteria
What type of pathogen is gonorrhoea
Bacteria
What are the symptoms of gonorrhea
- Pain while urinating
- Thick yellow or green discharge
How is gonorrhea treated
Antibiotics
How can people prevent the spread of gonorrhoea
Use conodms
What are the 4 main things you can do to prevent the spread of diseases
- Be hygienic
- Destroying vectors
- Isolating infected people
- Vaccination
What are features of your body’s immune system
- Skin
- Mucus
- Hairs
- Hydrochloric acid
What is the most important part of the immune system
White blood cells
What do white blood cells do to foreign cells. What is this called
Engulf and digest them. Phagocytosis
What are the pros to vaccines
- Control diseases
- Epidemics prevented
What are the cons to vaccines
- Don’t always work
- Bad reaction
Define monoclonal antibodies
Produced in the lab using mouse lymphocytes
What are is the process of monoclonal antibodies using mice
Mouse (using the mouse spleen)
○ Inject antigens into the mouse
○ White blood cells/ lymphocytes produce antibodies specific to this antigen
○ Combine white blood cell / lymphocyte with a tumour cell and this is called a hybridoma
○ Hybridoma can rapidly divide making lots of antibodies
○ Antibodies are isolated, harvested and purified
What is a communicable disease
A disease caused by a pathogen which can
be passed between animals or plants eg. flu
What is a pathogen
A disease-causing microorganism e.g.
bacteria
How do bacteria cause disease?
Once inside the body, they divide rapidly by
binary fission. They kill cells and produce
harmful toxins
How do viruses cause disease
They invade and reproduce inside living
body cells, leading to cell damage
Give three ways in which pathogens can be
spread
● By air - flu, tuberculosis and the common cold are
spread by droplet infection.
● By water - fungal spores in water spread plant
diseases.
● By direct contact - common in plant diseases and
sexually transmitted infections
Give four ways in which the spread of pathogens
can be reduced
● Hygiene - handwashing, disinfectants, tissues.
● Reducing contact with infected individuals -
quarantine.
● Removing vectors - use of pesticides and
insecticides, removal of habitats.
● Vaccination.
Why is it especially important to prevent the spread
of viral diseases
Scientists have not yet developed cures for
many viral diseases
What is measles
Measles is a serious viral disease that can
cause blindness and brain damage. The
main symptoms are a fever and a red skin
rash.
How is measles spread
By air - through the inhalation of droplets
from coughs and sneezes
What is HIV/AIDS
HIV is a virus which attacks and damages the
immune system until it can no longer function
properly. AIDS is the condition resulting from a
long-term HIV infection. There is no cure or
vaccine for HIV/AIDS
How is HIV spread
Direct sexual contact and the exchange
of bodily fluids eg. blood, breastmilk
How can the spread of HIV/AIDS be prevented
● Use of condoms ● Screening of blood for transfusions ● Not sharing needles ● Bottle-feeding by HIV-positive mothers ● Use of antiretroviral drugs to prevent the development of AIDS
What is tobacco mosaic virus
A plant pathogen which causes leaf discolouration
when cells are damaged. Affected areas cannot
photosynthesise, reducing the crop yield. As there is
no treatment, farmers grow TMV-resistant crop
strains to avoid infection
How is tobacco mosaic virus spread
Contact between infected and healthy plants.
Insects may act as vectors which transfer the
virus between different plants
What is salmonella
A type of bacteria found in raw meat, poultry
and eggs. If they enter the body via food
poisoning, they can affect natural gut
bacteria
What are the symptoms of salmonella food poisoning
● Fever ● Abdominal cramping ● Vomiting ● Diarrhoea May be fatal in very young or elderly populations due the risk of dehydration
How can the spread of salmonella be limited?
● Vaccinating animals intended for consumption
● Keep raw meat away from cooked meat
● Disinfect hands and surfaces after contact with
raw meat
● Thoroughly cook meat
What is gonorrhoea
A sexually transmitted bacterial infection caused by
unprotected sex with an infected individual. Early symptoms
include yellow/green discharge from genitals and painful
urination, although it may be symptomless.
Its spread can be controlled through the use of antibiotics (no
longer penicillin as many strains are resistant) and using
condoms
What is rose black spot
A fungal disease which causes purple or black
spots to develop on rose leaves. It reduces the
area of the leaf which is available for
photosynthesis and causes leaves to turn yellow
and drop prematurely
How is the rose black spot fungus spread
Fungal spores are spread by the wind
and in water
How can the rose black spot fungus be treated?
● Using fungicides
● Destroying infected leaves
What is malaria
Malaria is a disease caused by protist pathogens.
The disease is carried from host to host by
mosquitoes, and the protists enter the human
bloodstream when they feed. Symptoms include
fever and shaking, and it may also be fatal in some
cases
How can the spread of malaria be reduced
● Using insecticides ● Using insect nets to avoid bites ● Prevent mosquito breeding by removing stagnant water ● Antimalarial drugs
How does the skin prevent pathogens from entering
the body?
● Acts as a physical barrier.
● Scab formation after skin is cut/wounded.
● Antimicrobial secretions which can kill pathogens.
● Healthy skin flora compete with pathogens and
act as an additional barrier
How does the respiratory system prevent pathogens
from entering the body
● Nose - has hairs and mucus which trap
pathogens.
● Trachea and bronchi - have mucus that traps
pathogens. Ciliated cells move mucus to the
mouth so it can be swallowed.
How does the stomach prevent pathogens infecting
the body
● Secretes hydrochloric acid - kills any pathogens
present
How does phagocytosis protect us against disease
White blood cells (phagocytes) ingest and destroy
pathogens so they cannot infect more cells
How does antibody production protect us against
disease?
White blood cells produce antibodies which are
complementary to a specific antigen on a pathogen. The binding of antibodies to antigens causes pathogens to
clump together, making them easier to destroy. In the case
of a second infection, the correct antibodies can be
produced rapidly, preventing the person getting the same disease again
How does antitoxin production protect us against
disease
Antitoxins bind to toxins released by pathogens and
neutralise them
What is a vaccination
Contains a dead or inactivated form of the pathogen
which stimulates white blood cells to produce
complementary antibodies to the pathogen. In the
case of a second infection, memory cells can rapidly
produce the correct antibodies and prevent illness
What is herd immunity
If a sufficiently high proportion of a population are
immune to a disease (especially through
vaccination), the spread of this disease will be
limited
What are the advantages of vaccinations
● They have eradicated many deadly diseases eg.
smallpox.
● Many epidemics can be prevented by
vaccinations.
● Herd immunity protects those who cannot have
vaccinations
What are the disadvantages of vaccinations?
● Not guaranteed to work - might not protect
against multiple strains of a pathogen.
● May be side effects or adverse reactions
What drugs are used to cure some bacterial diseases
Antibiotics - they can kill bacterial pathogens inside
the body
How do antibiotics work
Antibiotics eg. penicillin kill bacterial pathogens
inside the body, but do not kill human cells. Whilst
some antibiotics kill a wide range of bacteria, it is
important that the right antibiotic is used for specific
bacteria
Why can antibiotics not be used to treat viral
diseases
Antibiotics have no effect on viral pathogens as they
live inside the host’s (human) cells. Therefore, it is
difficult to design drugs that would kill the virus and
not destroy human cells at the same time.
What is antibiotic resistance
Antibiotic resistance occurs when mutations lead to
individual bacteria being resistant to an antibiotic. These
bacteria are able to survive, reproduce and pass on their
alleles, leading to a greater proportion of antibiotic-resistant
bacteria. This is concerning as some types of bacteria are
becoming resistant to all known antibiotics, so the diseases that they cause cannot be cured
How can we prevent antibiotic resistance
● Avoid overuse and unnecessary use of antibiotics
- eg. antibiotics are often used for viral infections.
● Finish antibiotic courses - to ensure all bacteria is
killed.
What effect do painkillers have on infectious
diseases?
Painkillers can only treat the symptoms but do not
kill pathogens
What plant is the heart drug digitalis extracted from?
Foxgloves
What painkiller originates from a compound
found in willow bark
Aspirin
What antibiotic was discovered by Alexander
Fleming from a type of mould?
Penicillin
What are the four qualities of a good medicine
● Effective
● Safe
● Stable
● Able to be taken in and removed easily
What three main factors are tested for when
developing new drugs
● Toxicity
● Efficacy
● Dose
How is preclinical testing carried out
In a laboratory - uses cells, tissues and live animals
How is clinical testing carried out?
Uses healthy volunteers and patients. Firstly, the
drug is tested at a low dose on healthy people - then
tested on patients and on a larger scale to find the
optimum dose. Often, one group receive a placebo
(not the test drug) and the other group receive the
actual drug, in order to assess its efficacy.
What is the difference between a single-blind and
a double-blind trial?
In a single-blind trial, only the doctor knows whether
the patient is receiving the drug or the placebo. In a
double-blind trial, neither the patient nor the doctor
knows. Double-blind trials help remove bias on the
part of the doctor
What is a peer review
Where the results of drug trials are checked over by
scientists knowledgeable in this field
What are monoclonal antibodies (mAbs)
● Antibodies that are clones from one
parent cell
● Specific to one type of antigen
Describe how monoclonal antibodies are produced
- Specific antigen injected into an animal (e.g. mouse).
- B-lymphocytes producing complementary antibodies extracted.
- B-lymphocytes fuse with myeloma cells to form hybridoma
cells - these cells can divide and produce antibody. - Hybridoma cells cultured.
- Monoclonal antibodies collected and purified
Outline the uses of monoclonal antibodies
● Detection of pathogens
● Location of cancer cells and blood clots
● Treatment of cancer
● Used in pregnancy test kits
What are myeloma cells
Type of tumour cell
Outline the uses of monoclonal antibodies
● Detection of pathogens
● Location of cancer cells and blood clots
● Treatment of cancer
● Used in pregnancy test kits
What do pregnancy kits test for
hCG in urine
What does a pregnancy test consist of
A stick containing monoclonal antibodies (mAbs) specific
to hCG:
● mAbs attached to a blue bead (free to move)
● mAbs fixed to the test stick
Describe what happens to the test stick if a woman
is pregnant
● hCG in urine binds to mAbs attached to a blue bead. ● mAbs with hCG diffuse up dipstick. ● mAbs fixed to the stick bind to hCG. ● Blue line forms
Describe what happens to the test stick if the
pathogen is not present
No hCG in urine so a blue line is not
formed.
What is the advantage of using monoclonal
antibodies to test for pathogens
● Specific to one particular antigen
● Very accurate
● Quick results
Why can monoclonal antibodies be used to target
cancer cells?
● Cancer cells have specific antigens called ‘tumour
markers’ on their membranes.
● mAbs are specific to one type of antigen so can be
targeted to ‘tumour markers’ without damaging other
cells
Describe how monoclonal antibodies can be used to
diagnose cancer
● mAbs tagged to a radioactive substance.
● mAbs injected into the patient’s bloodstream.
● mAbs bind to ‘tumour markers’ on cancer cells.
● Emitted radiation is detected using a specialised scanner
enabling doctors to determine the location of cancer cells.
How can monoclonal antibodies be used to target
drugs to cancer cells
● mAbs attached to an anti-cancer drug.
● mAbs injected into the patient’s bloodstream.
● mAbs bind to ‘tumour markers’ on cancer cells.
● Anti-cancer drug destroys cancer cells
Why are cancer treatments that use monoclonal
antibodies favoured over traditional treatments?
● Radiotherapy and chemotherapy target rapidly dividing cells.
● Healthy cells (e.g. hair follicle cells, bone marrow cells) are
damaged as a consequence, producing unpleasant side effects.
● mAbs only target cancer cells, reducing damage to normal cells.
How can monoclonal antibodies be used to locate
blood clots?
● mAbs tagged to a radioactive substance.
● mAbs target and bind to specific proteins in blood clots.
● Radiation emitted by mAbs is detected, enabling the
location of blood clots to be identified
How do aphids cause damage to plants?
They use their sharp mouthparts to extract sap from
the plant phloem, weakening the plant. They are also
vectors who can transfer pathogens from diseased
plants to healthy plants
How can we reduce the number of aphids
● Chemical pesticides
● Biological pest control - using ladybirds
Why do plants need a good supply of nitrate
ions?
Nitrate ions are required to convert sugars
into proteins which are required for the plant
to grow. As a result, the growth of the plant
will be stunted if there is not an adequate
supply of nitrates.
Why do plants need a good supply of magnesium
ions
Magnesium ions are required to synthesise
chlorophyll, which absorbs light energy during
photosynthesis. As a result, the leaves cannot
photosynthesise properly and they turn yellow
(chlorosis)
What are the symptoms of disease in plants
● Stunted growth (lack of nitrate ions) ● Spotted leaves (eg. rose black spot fungus) ● Decay/rotting ● Growths ● Malformation of stems/leaves ● Discolouration ● Presence of pests
What are three ways in which plant disease
can be identified
● Reference to a gardening website or manual
● Laboratory testing
● Monoclonal antibody test kits
Give examples of physical defence responses
used by plants
● Cellulose cell walls
● Tough waxy cuticle on leaves
● Outside layer on stems/bark on trees
● Leaf fall
Give examples of chemical defence responses used
by plants
● Antibacterial chemicals
● Poisons
Give examples of mechanical defence responses
used by plants
● Thorns and hairs to deter animals
● Leaves that droop/curl on contact
● Mimicry to trick animals
