microbes and the immune system

Question 1

what are the microorganisms
1-photoautotroph
2-chemoheterotroph
3-photoheteretroph
4-chemoautotroph

Answer 1

1- uses energy as sunlight to convert co2 to carbs
2- uses organic chemical substances as energy source and organic substances as carbon
3- use light for energy but cannot use co2 as carbon source
4-chemoautotroph- uses inorganic chemicals as energy source to convert to organic compounds

Question 2

name 5 temperature organisms to allow bacteria to survive in different environments ?
1) psychrophiles (unsaturated fat)
2) mesophile
3) thermophile
4) hyperthemophile (saturated fat)
5) extremophile

Answer 2

1) survive <15 degrees. good fat= liquid. increase in unsaturated fats to allow fluid
2) human pathogens at body temp of 37 degrees
3) used as biological indicator
4) hyperthermophile- survive >70 degrees. good fat = solid. increase saturated fat to maintain shape.
5) extremophile- survive in extreme cold temperatures

Question 3

how does cryoprotectants help bacteria survive at different temperatures?

Answer 3

cold/ heat shock proteins. prevents proteins unfolding/ denaturing to maintain correct structure and activity.

Question 4

describe the two ways to sequence bacteria for
-16S sequencing
-whole genome sequencing

Answer 4

16S- bacterial DNA that encoded rRNA molecule. can identify species and relative frequencies

WGS- total microbiome DNA sequencing can fnd mutations, SNPs and better understanding of population

Question 5

how do we obtain short chain fatty acids in colon and what is there function with an example?

Answer 5

produced by bacterial fermentation of dietary fibre from plants.
they are the main energy source for epithelial cells

Question 6

how was clostridium difficile infection treated?

Answer 6

faecal tranplant

Question 7

what is the bodies initial response to infection - acute inflammation

Answer 7

activation of local irate immune cells
increase permeability of local blood vessels
immune cells and plasma protein migrate into tissues

Question 8

how are PAMP (pathogen associated molecular patterns) on all pathogens recognised by immune system?

Answer 8

recognised by pattern recognition receptors (PRR) on cells on the immune system and epithelial cells
different PRR are found on different cells e.g. TLR recognise PAMP on cell membrane.
occurs in cytoplasm

Question 9

what type of pathogen can hide from PRR by reducing recognition of TLRs using TLR5

Answer 9

heliocobacter pylori

Question 10

how does PRR activation of TLR warn the immune response about the infection?

Answer 10

TLR activation activates NF-kB. this alters gene transcription, but allows cell to warn the immune system

Question 11

what damage signals does PAMP receive to identify hosts ?

Answer 11

DAMPs - released by dying cells due to damage of tissue from pathogen

Question 12

describe two causes of antibiotic resistance
1) overprescribing of antibiotics
2) over use and misuse of antibiotics in livestock and fish farming

Answer 12

1) 20% of antibiotics prescriptions in primary care are estimated to be unnecessary
2) 70% of antibiotics are consumed by animals.
how animals can pass on resistant bacteria=
direct contact from animals to farmers
consumption of meat from animals
through the environment

Question 13

describe how antibiotics work in each stage
-nucleic acid synthesis
-target ribosomal function
-target cell wall
-target cell membrane
-inihibition of cell metabolism and growth

Answer 13

• targets machinery that makes DNA and RNA
  -targets the machinery that produces proteins
  -target the synthesis of cell wall e.g. chop up or stop being made
  -outer membrane of gram negative and inner of gram positive.
  -inhibit folic acid biosynthesis and oxidative phosphorylation of ATP synthase.

Question 14

explain the B-Lactam antibiotic

Answer 14

binds to prenecillian binding proteins (PBP).
the function is to build structure of cell wall in bacteria, which prevents the cross-linking of peptidoglycan layer of bacterial cell wall.
the bacteria swells, reputures and dies due to osmotic gradient.

however bacteria can change their binding protein to prevent B-lactam working

Question 15

how does antibiotic resistance develop in bacteria.
-two types of resistance?

Answer 15

1) intrinsic : evolution by changing their structure or components. occured before antbiotic treatment began.
2) acquired: bacteria develop resistance to antibiotics. induced after therapy e.g. random mutation or acquired DNA that encodes for antibiotic resistance

Question 16

what are two mechanisms for intrinsic and acquired resistance?

Answer 16

1) reduced drug uptake

2) enzymatic degradation

3) target modification= bacteria changes antibiotic that reduces the binding affinity with therapeutic targets.

4) increased drug efflux

Question 17

how quickly does antibiotic resistance develop

Answer 17

depends on how much antibiotic being used. using too much or too little increases antibiotic restitence.
using correct amount the bacteria cannot win;
100x MIC after 11 days

Question 18

example of complement cascade system in innate immune system to control pathogens
-C3a and C5a
-C3b
C5-C9

Answer 18

C3a and C5a = released at site of infection to activate acute inflammatory response by increased immune cells

C3b= improved phagocytosis leads to faster clearance and killing of pathogen e.g. small pox inactivates this

C5-C9= forms membrane attack complex MAC. which kills pathogens

Question 19

examples of how host cells and pathogens evade complements
-CD46
-CD59
-C1 inhibitor
-express CRIT

Answer 19

• CD46= inactivates C3b e.g. small pox
  -CD59= stops MAC from forming

c1 inhibitor = stop immune response e.g. e.coli

express CRIT= blocks early steps in complement activation e.g. trypanosoma

Question 20

Which of the following microbes can be found in both the Stomach and the Small Bowel System

Answer 20

lactobacilli

Question 21

how are Lymphocyte antigen specific receptors best characterised

Answer 21

millions of different receptors are generated through gene rearrangement

Question 22

What makes plasmids particularly effective in enhancing bacterial virulence?

Answer 22

Their mobility and capacity to carry genes for toxins and antibiotic resistance.

Question 23

role of quorum sensing in biofilm formation

Answer 23

quorum sensing= cell to cell communication of bacteria to share information.
triggers production of signalling molecules that coordinate extracellular matrix production

Question 24

consequence of prolonged antibiotic use on the gut microbiota

Answer 24

colonisation of opportunistic pathogen