b6.3 - immunity/ bacteria

Question 1

vaccination

Answer 1

• given a little bit of of inactive or dead pathogen
  -correct lymphocytes produce antibodies and destroy pathogens
• some lymphocytes become memory cells
• when live pathogens of the same type infect you your immune system can protect you immediately due to memory cells

Question 2

how are vaccines given

Answer 2

injection
orally
nasal sprays

Question 3

vaccine (primary vs secondary response)

Answer 3

secondary
- fast
- many antibodies
as you ahve memory cells so start with more cells and antibodies can be made faster

Question 4

mass vaccination

Answer 4

if everyone is vaccinate they can destroy the pathogen fast and not get symptoms
if not enough vaccinated they can continue to carry and spread it

Question 5

why do you need boosters

Answer 5

memory cells sometimes don’t last so need a boost to make more memory cells

Question 6

bacteria growth over time

Answer 6

lag phase
- no reproduction
- copy dna and proteins within single cells
exponential growth
- due to correct conditions
stationary phase
- resources become scarce
- die at same rate as reproduction
death phase
- bacteria poisoned by build up of toxins in the culture

Question 7

binary fission

Answer 7

• circular dna strand replicates
• circular strands migrate to opposite ends of cells
• cytoplasm replicates and divides
• cells divide in two
• identical daughter cells made

Question 8

how to calculate no. of bacteria in a population

Answer 8

1calculate no. divisions in the asked hours
- eg if it asks how many in 6h and it gives you 3 in 1h it’ll be 18 divisions
2calculate no. bacteria
- everytime it reproduces it doubles
- bacteria at start x2^no. divisions
3how long it takes to reach a given no. bacteria
- log2 x given no. bacteria
- times this by the mean division time

Question 9

aseptic techniques to grow microorganisms

Answer 9

• sterilise, petri dish and agar
• Work close to a roaring flame
• heat the inoculating loop
• Let the loop cool, without putting the loop back on the table
• Open the tube of bacteria and flame the neck of the tube - Dip the loop in the tube
• Lift the petri dish lid a little - draw a line down the plate using the loop
• label the dish and seal it with tape

Question 10

why do you sterilise and heat and not leave on the table and work near to a bunsen

Answer 10

to kill any contaminating bacteria (clean it)
- create convection current lifting unwanted microbes away from working area

Question 11

why use an incubation temperature not above 25°?

Answer 11

so we don’t grow pathogenic bacteria that can cause harm to humans.
- We only grow bacteria denatures at 25° so can’t survive in the human body

Question 12

how do antibiotics kill bacteria

Answer 12

by interfering with bacterias metabolism, e.g. processes that make the bacteria cell wall

Question 13

if not cell wall in bacteria why can it die

Answer 13

if in hypotonic solution it could lyse

Question 14

antivirals

Answer 14

A drug that treats viruses
- it prevents reproduction.
- It only slows down, doesn’t kill it
- because of the virus is in the host cells to kill the virus you killed the host cells, so it’s difficult to not damage cells

Question 15

antiseptics

Answer 15

antimicrobial substances applied to human tissue or skin
- different antiseptic skill, different pathogens,
e.g. alcohol/iodine

Question 16

disenfectants

Answer 16

Solutions that destroy a micro organism on the surface of nonliving things

Question 17

how to investigate the strength of disenfectants

Answer 17

• wash hands/ wear gloves
• divide the sealed plate into six equal sections, using a pen,
• use the sterile, forceps, dip one paper disk into each disinfectant
• put the paper desk, intro respective section on the agar plate, container bacteria
• dip one disc into water this is a control
• make sure disks do not touch each other
• reseal the plate with tape and incubate it.

Question 18

preclinical testing (step 1)

Answer 18

• tested using computer models and human cells grown in the laboratory
• scientists check side-effects and efficacy of the drug.
• Many drugs fail because they damage cells or don’t work

Question 19

preclinical trials (step 2 )

Answer 19

drug tested on live animals
- Involves giving a know amount to animals and monitoring them for side effects

Question 20

clinical trials (phase 1)

Answer 20

• drug tested on a small number (20–80) of healthy volunteers
• very low doses of the drug in at the start and volunteers monitored for side-effects.
• If deemed safe further tests carried out to find the optimum dose

Question 21

clinical trials (phase 2)

Answer 21

• The drug is seher, my small sample (100–300) volunteers, who suffer from the condition
• To look for efficacy & side effects

Question 22

clinical trials (phase 3)

Answer 22

• drug tested on a large number of people (1000–5000) who suffer from the condition
• To monitor, drug, effectiveness, side-effects, safety and adverse reactions to long-term use
• trials reviews by medical professionals and then published

Question 23

drugs from plants/ microbes

Answer 23

• heart drug came from foxgloves
• Aspirin comes from Willow trees
• Penicillin discovered by Alexander Flemmjng

Question 24

double blind trial

Answer 24

volunteers and patient, randomly, allocated
so neither doctor or patient know if they take the drug or the placebo
- minimises, the placebo effect, ensured results cannot be influenced by people in the trial

Question 25

why is single blind not effective

Answer 25

The doctor who knows what drug is being taken, may give away, clues about what the patient taking without realising it
- this is the observer bias

Question 26

cost of developing drugs

Answer 26

• find this may take years to find the right, chemical
• the raw materials, maybe rare or difficult to make
• the volunteers need to be paid for time and risking health
• Many patients need to be tested for several years to check it works
• permission to sell the medicine is only given if there’s good enough evidence it’s safe and effective