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PY5 > REDS > Flashcards

REDS Flashcards

1
Q

Briefly describe the differences between the structures of bacterial gram-positive and gram-negative cell walls. (4 marks)

A
  • Gram negative cells have an outer membrane, not present in gram positive cells (1 mk).
  • Gram negative cells contain LPS, not present in gram positive cell walls (1 mk)
  • Gram positive cell walls contain teichoic acid, not present in gram negative cells (1 mk).
  • The tetrapeptide chains
    connected to NAM units are linked by pentaglycine cross-bridges in gram positive cell walls but are directly cross-linked in gram negative
    cell walls (1 mk)
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2
Q

Name TWO environmental factors which can affect bacterial growth and
for each, explain your rationale. (4 marks)

A
  • Solute - osmotolerant (able to grow at wide range of osmotic conc), halophile (requries
    high salt conc for growth),
  • Water - water used in many ways e.g. to dissolve food and uptake pH - acidophile (optimum growth at 0-5.5), neutrophile (optimum growth at 5.5 to 8.0),
    alkalophile (optimum growth at 8.0-11.5)
  • Carbon - key for all molecules
  • Oxygen – obligate aerobe (oxygen essential for growth), facultative anaerobe (grows best
    with but also without oxygen), aerotolerant anaerobe (grows equally well with/without O2),
    obligate anaerobe (cannot grow in the presence of O2), microaerophile (requires low level
    of oxygen)
  • Temperature - psychrophile (optimum growth in cold temps), psychrotroph (cold tolerant
    bacteria), mesophile (optimum growth at moderate temperatures), thermophiles (grow optimally in high temps), hyperthermophiles (optimally grow at very high temps).Mark also
    given if they specify temperature ranges (but this is not required)
  • Pressure – barotolerant bacteria (can grow at high pressures), barophilic (require high
    pressure to grow)
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3
Q

Briefly explain how the baroceptor reflex restores normal blood pressure after an initial increase in blood pressure. (4 marks)

A
  • Increased signalling from the baroceptors (or cells in aortic arch carotid artery) (1 mark; could say baroceptor would be stimulated)
  • would reduce sympathetic nerve stimulation form the central nervous system (1 mark; accept reduced sympathetic outflow)
  • meaning less noradrenaline being released (1 mark; adrenaline NOT accepted)
  • thereby reducing cardiac output and peripheral resistance
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4
Q

Describe four conditions that arise due to dysfunction of platelets (4)

A
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5
Q

What is ‘haematocrit’?

A

Percentage of red blood cells

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6
Q
A

Calcium

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7
Q
A

Sodium

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8
Q
A
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9
Q

Differnce in both bacterias structures - detailed

A
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10
Q

Why is gram negative naturally more resistant to some Abx?

A

Due to its outter membrane which acts as a barrier
It also has LPS which regulates entry of molecules

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11
Q

Major mechanisms of antibiotic action

A

Give examples of each

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12
Q

Major mechanisms of anti viral drugs

A
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13
Q

What anti viral drugs were used in management of covid?

A
  • Nirmatrelvir plus ritonavir, molnupiravir and remdesivir
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14
Q

How do anti fungal drugs work

A
  • Inhibit ergosterol synthesis (membrane component)
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15
Q

Anti-protozoal drugs

A
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16
Q

Define antimicrobrial stewardship

A

“An overarching program to change and direct antimicrobial use at a health care institution”

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17
Q

Reasons for AB stewardship

A

Lack of new antimicrobials coming onto market
Strains developing resistance to existing antimicrobials
CRE
Pandrug resistance (e.g. Acinetobacter spp.)
“Post-antibiotic era”

18
Q

Define disinfectant and give ideal features of it

A
  • Disinfectant: kills/inhibits microorganism on Inanimate objective, non-selective
  • Ideally would be: sterilizing, fast-acting, non-toxic to other life, non-irritating, non-corrosive, broad spectrum of activity, stable, easy to use, cheap but usually are not all of these
19
Q

Define antispetic and give ideal features of it

A
  • Kills/inhibits microorganisms on living surfaces, non-selective
  • Non toxic to other life, fast acting, non irratiting for skin, dont stain, good smell, active for long periods of time
20
Q

Cells and molecules of immune system

A
21
Q

Name some classes of disinfectant and antiseptics

A
22
Q

Describe how the recombinant Hepatitis B vaccine is produced
(4 marks)

A
  • Plasmid DNA from bacteria is cut and Hb antigen gene is inserted into plasmid
  • This recombinant DNA is introduced into a yeast cell
  • Yeast cells placed in fermentation tank to multiply and produce HB antigen
  • Extraction and purification of the Hb vaccine
23
Q

Describe any FOUR features about dimorphism of fungi. (4 marks)

A
  • Many fungi species have the capacity to change their forms (1 mark)
  • This change occurs based on the environment where they live (1 mark)
  • Animal pathogens are normally filamentous when they are in saprophytic phase (1 mark)
  • Animal pathogens change their shape into yeast-like structure during pathogenic phase within an animal (1 mark)
24
Q

Describe TWO similarities and TWO differences between bacterial and fungal cells. (4 marks)

A
25
Q

The first two steps of endosporulation are DNA replication and membrane formation around the DNA. Briefly describe the next FOUR steps of endosporulation (4 marks)

A
  • A second layer of cytoplasmic membrane then forms around the DNA to form a forespore (1 mark)
  • Both of these membrane layers then synthesize peptidoglycan in the space between them to form the first protective coat, the cortex (1 mark)
  • A spore coat composed of a keratin-like protein then forms around the cortex (1 mark)
  • Finally, the remainder of the bacterium is degraded and the endospore is released (1 mark)
26
Q

Describe the structure of a virus (4 marks)

A
  • Viruses consist of a nucleic acid (either RNA or DNA) (1 mark)
  • The nucleic acid (genome) is surrounded by a protein coat called a capsid (1 mark)
  • As well as the genome, the capsid contains a few enzymes to direct the synthesis of new virions (1 mark)
  • Each capsid composed of protein subunits called capsomeres - made of one/more different types of proteins (1 mark)
27
Q

Steps of binary fission

A
  • Genome attached to membrane
    ➢Chromosome replicates

➢Septum formation
➢2 daughter cells separate/ diplococci/ chains
➢Chromosome replication and cell division tightly regulated
➢Daughter cells are identical to the parent

28
Q

Define lung vital capacity

A

Maximum amount of air that can be exalted after a maximum inspiratory effort

29
Q

General problems with gene therapy

A
  • Short-lived nature of gene therapy patients will have to undergo multiple rounds of gene therapy.
  • Immune response - risk of stimulating the immune system in a way that reduces gene therapy effectiveness
  • Problems with viral vectors-viruses, the carrier of choice, present potential problems to the patient, like toxicity, immune and inflammatory responses, and gene control and targeting.
  • Multi-gene disorders - most common disorders, such as heart disease, high blood pressure, Alzheimer’s disease, arthritis and diabetes, are caused by the combined effects of variations in many genes.
30
Q

Where is cholecytoskinin secreted from and whats its functions? (five major functions)

A
  • A hormone which is secreted by cells in the duodenum
  • Stimulates the release if bile into the intestine and the secretion of enzymes into the pancreas
  • Its five major actions
    • contraction of gallbladder and ejection of bile
    • Secretion of pancreatic enzymes
    • Secretion of bicarbonate
    • Trophic effects on exocrine pancreas and gallbladder
    • Inhibition of gastric emptying
31
Q

Adult stem cells: advantage

A
  • Present in nearly all tissue and organs
  • No ethical issues
  • Could be used in personalised setup
  • No tumour risk
32
Q

Adult stem cells limitations

A
  • Adult stem cell can only differentiate limited - they are multipotent not pluri like ES
  • Adult stem cells aren’t immortal, many injections may be needed
33
Q

What properties make up the ‘ideal stem cell’

A
  • Safety - has high stability, no tumour formation
  • High regenerative potential (regeneration of more than one cell type)
  • Potential autologous application (personalised regenerative medicine)
  • Easy accessibility (minimally-invasive isolation)
  • Ethical acceptance
  • Affordable
34
Q

Define antiseptic, sterlisation and disinfectant

A
  • Antiseptic: kills/inhibits microorganisms on living surfaces, non-selective
  • Disinfectant kills/inhibits microorganisms on inanimate objects, non-selective
  • Sterilisation: removal/killing of all microorganisms (including spores) – Gold Standard
35
Q

Mechanism of action of antiseptics, sterilisation and disinfectants

A
  • Oxidation - oxidising agent including halogens
  • Denaturing proteins which disrupt membrane
  • Increased permeability
36
Q

Name three ways water is regulated

A
  1. Osmotic gradient across renal medulla/ascending and descending limb
  2. Counter current
  3. ADH regulation of the collecting duct
37
Q

Describe the molecular basis of chemotherapy

A
  • Class I: reactions that utilise glucose and other carbon sources are used to produce ATP and simple carbon compound
  • Class II: pathways utilising energy and class I compounds to make small molecules (e.g. amino acids and nucleotides)
  • Class III: pathways that convert small molecules into macromolecules such as proteins, nucleic acids and peptidoglycan
38
Q

Name the six stages of an infectious disease

A
  1. Acquisition
  2. Colonisation
  3. Penetration
  4. Spread
  5. Damage
  6. Resolution
39
Q

What happens when decrease in blood pressure is detected

A
40
Q

Two way process of proprioception

A
  1. Proprioceptors signal to the spinal cord/CNS (afferent)
    The two major proprioceptors are:
    (i) Muscle spindles (within muscle; respond to stretch)
    (ii) Golgi tendon organs (within tendons; respond to tension)
  2. Motor neurons signal to skeletal muscle (efferent)
41
Q

Function of non-neuronal cells

A

(i) Astrocytes: supportive function for CNS neurones, contribute to the protective blood brain barrier (BBB)
(ii) Oligodendrocytes: form the myelin sheath around axons in the CNS
(iii) Microglial: phagocytotic action in the CNS
(iv) Ependymal cells: epithelial cells in the fluid-filled spaces of the brain and central canal of the spinal cord. Possess microvilli which help circulate CSF around the CNS

PY5 (16 decks)

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