sb5 Flashcards
What is the difference between a communicable and non communicable disease?
A communicable disease can be spread from person to person while a non communicable one can’t
Describe cholera
- spread by a bacteria
- causes diarrhoea
- spread in water
Describe tuberculosis
- spread by bacteria
- causes lung damage
- it is airborne
Describe chalara ash dieback
- caused by fungi
- causes lead loss and bark lesions
- airborne
Describe malaria
- caused by protists
- causes damage to blood/liver
- spread by a mosquito vector
Describe HIV
- caused by a virus
- destroys white blood cells which leads to AIDS
- spread by body fluids
Describe stomach ulcers
- caused by bacteria
- internal bleeding
- oral transmission
Describe ebola
- caused by virus
- causes fever with severe bleeding
- spread by body fluids
Describe the lytic pathway of viruses
- Virus binds to host cells
- Inserts genetic material into host cells
- Uses the cell machinery to produce viral proteins
- Viruses exit the cell through host cell membrane OR causes lysis of the host cell
- Virus particles leave the host
- Allows spread to another host and repeats
Describe the lysogenic pathway of a virus
- Uses restriction enzymes to insert its DNA into the host DNA
- Host cell replicates and viral DNA is also copied
- Lytic cycle begins at this point
What are some physical barriers of plants against pathogens?
- Thick cellulose cell wall:
—> impermeable to pathogens not allowing it to come inside - Thick waxy cuticles:
—> acts as a barrier to pathogens - Closes their stomata:
—> stops pathogens entering plant
What are some chemical barriers of plants against pathogens?
Releases compounds that attract larger insects to feed on pests
*** we can extract antimicrobal compounds from these plants to use in drugs such as antibiotics
How can plant diseases be detected in the field?
- chalara ash dieback causes browning of leaves
- aphids can cause structural damage
- bacterial canker causes loss of leaves
How can plant diseases be detected in the lab?
- Cuttings taken from diseased plant
- Virus/bacteria causing disease is grown on agar plate
- Pathogen tested and identified using monoclonal antibody testing kit
What are some physical barriers human have?
- Mucus
—> traps bacteria before they reach the lungs - Cilia
—> wafts away mucus that has trapped pathogens to be killed by stomach acid - Skin
—> provides a physical barrier from pathogens
What are some chemical barriers humans have?
- Lysozymes
—> used by white blood cells to kill and digest bacteria - Hydrochloric acid
—> used to kill bacteria in stomach due to pH
How does the immune system defend the body against disease?
- Antigens are on the bacteria which get detected by phagocytes
- Antibodies are produced by lymphocytes
- Antibodies surround pathogens and kill them
- Memory lymphocytes are produced which remain in the blood
- If a secondary infection occurs, the memory lymphocytes will produce antibodies faster
- Pathogens destroyed faster next time
What are the advantages and disadvantages of immunisation?
Advantages —
- epidemics can be prevented through herd immunity
- eradicated many diseases such as smallpox
Disadvantages —
- not always effective in providing immunity
- bad reactions can occur in response to vaccines
Why can antibiotics only treat bacterial infections?
They inhibit cell processes in bacterium but not host organism
Why are Petri dishes sterilised using an autoclave?
- otherwise could be contaminated with unwanted microorganisms
- can potentially produce a new pathogen
Why are inoculating loops sterilised by passing them through a flame?
Kills unwanted organisms
Why should the lid of the Petri dish be sealed but not completely?
- stops airborne microorganisms from contaminating
- should not be sealed all the way as harmful anaerobic bacteria can grow
What is the independent variable in the sb5 core practical?
type of antibiotic used
What is the dependant variable in the sb5 core practical?
The zone of inhibition (cross-sectional area)
What is the control variable of the core practical in sb5?
time period bacteria were incubated for
control variables increase the validity of the experiment and allows it to be compared
What’s the control experiment for the core practical?
Disk containing only water and no antibiotic
How do you increase the reliability of results from the core practical?
- repeating experiments
- calculating a mean
- identifying anomalies
What are the processes of developing new medicines?
- Discovery
- Development
- Preclinical and clinical testing
How are monoclonal antibodies produced?
- Scientists obtain lymphocytes from a rodent
- Fused with myeloma cells
- hybridoma produced
- Hybridoma divides to produce antibody
What are some uses of monoclonal antibodies?
PREGNANCY TESTING —
- First section has mobile antibodies complimentary to hCG hormones —> attached to blue beads
- Second section has stationary antibodies complimentary to hCG hormones
- Person urinates on first section — hCG binds to mobile antibody to form hCG complex and is carried to the second section
- Stationary antibodies bind with hCG complex
- Both bound to blue beads which results in a straight blue line indicating you are pregnant
CANCER TREATMENT —
Three ways:
- Monoclonal antibodies bind to tumour markers to attack cell
- Monoclonal antibodies bind to receptor sites on cancer cells and stops cells from dividing
- Monoclonal antibodies can only bind to cancer cells
What are some advantages and disadvantages of monoclonal antibodies?
Advantages —
- Only bind to specific cells so healthy ones not affected
- Can treat many different conditions
Disadvantages —
- Expensive to develop
- Can trigger immune responses when used in humans
How can people be affected by both gonorrhoea and chlamydia?
- they are both STIs and spread in the same way
- when an individual doesn’t use contraception
how can fungus spread from plant to plant?
- leaves through spores
- spread from water droplets
- enters through stomata
how does a gastric band help a person to lose weight?
- reduces volume of stomach
- reduces food intake
