METABOLISM
MICROBIOLOGY
ANATOMY
100
Is the gluconeogenesis pathway just the reverse of glycolysis? Why or why not?
Gluconeogenesis is NOT just the reverse of glycolysis.
This is because there are steps in the glycolysis pathway which are irreversible.
100
How do we determine MIC & MBC?
BROTH DILUTION
MIC = Minimum Inhibitory Concentration
The lowest concentration of a particular antibiotic that prevents growth of the bacterium.
Measured visually by inspecting turbidity of broth.
BROTH DILUTION + INNOCULATION OF AGAR PLATE
MBC = Minimum Bactericidal Concentration
The MBC can be determined by subculture of broths that show no growth to determine the lowest concentration which has resulted in a 99.9% kill of the inoculum.
100
What muscles are innervated by the musculocutaneous nerve?
BBC!
Biceps brachii
Brachioradialis
Coracobrachialis
200
Which steps of glycolysis are irreversible?
Why are they irreversible?
Irreversible steps: Step 1, 3 and 10.
They are irreversible because of the ΔG values of these steps are too great to overcome (this amount of energy is not feasibly achievable in normal physiological conditions).
ΔG = 0 = equilibrium.
ΔG < 0 = spontaneous.
ΔG > 0 = not spontaneous.
200
In gram stains, gram positive bacteria shows up _____ and gram negative bacteria show up _____.
Why?
In gram stains, gram positive bacteria shows up purple and gram negative bacteria show up pink/red.
Why?
GRAM POSITIVE bacteria have a thick peptidoglycan layer. So once it absorbs the crystal violet stain, the ethanol rinse is ineffective in fully clearing the purple colour. So when the counter stain (safranin) is used, it cannot be taken up.
GRAM NEGATIVE bacteria have a thin peptidoglycan layer. So the alcohol rinse easily clears the crystal violet stain. So when the counter stain (safranin) is used, it turns the gram negative bacteria pink/red.
200
List 3-4 differences between a female and male pelvis.
1. Female pelvis is wider (oval-shaped); Male pelvis is narrower (heart-shaped).
2. Female pubic arch and subpubic angle is larger than males (>80-90 degrees vs <70 degrees).
3. Ischial spines in females are everted whereas males are facing inwards.
4. Pelvic outlet in females is comparatively larger than in males.
300
Which enzymes are involved in the irreversible steps of glycolysis?
Step 1: hexokinase
Step 3: phosphofructokinase-1 (PFK-1)
Step 10: pyruvate kinase
300
Gram positive or negative?
- Helicobacter pylori
- Staphylococcus aureus
- Streptococcus pyogenes
- Pseudomonas aeruginosa
- Clostridium difficile
- Bacillus cereus
- Escherichia coli
- Salmonella enterica
Gram positive or negative?
- Helicobacter pylori = negative
- Staphylococcus aureus = positive
- Streptococcus pyogenes = positive
- Pseudomonas aeruginosa = negative
- Clostridium difficile = positive
- Bacillus cereus = positive
- Escherichia coli = negative
- Salmonella enterica = negative
300
Describe the route of cranial nerve II.
Retina
-> optic nerve
-> optic canal
-> optic chiasm
-> left and right optic tracts
-> lateral geniculate body of the thalamus
-> optic radiation
-> visual cortex in occipital lobe.
400
For gluconeogenesis to occur, what alternative enzymes does the body use in place of the irreversible reactions of glycolysis?
Step 1: Glucose-6-phosphatase
Step 2: Fructose 1,6-bisphosphatase
Step 10: 2 separate enzymes:
Pyruvate carboxylase & PEP carboxykinase
400
What's the difference between permissive vs selective vs differential agars?
Give examples of each.
Permissive agar: Agar which contain no ingredients to prevent the growth of microorganisms.
They may or may not be sufficiently enriched to support the growth of fastidious organisms.
E.g.: Blood Agar and Chocolate Agar.
Selective agar: contain ingredients to suppress the growth of normal flora and unwanted bacteria, and grow target organisms.
Selective agars are used on non-sterile site specimens, or perhaps to separate antibiotic-resistant strains of a pathogen from antibiotic-sensitive strains.
E.g. MacConkey (MAC) and Mannitol Salt Agar (MSA)
Differential agars: are formulated to differentiate different organisms by giving them characteristic appearances on plates.
Differential media takes advantage of biochemical properties of target organisms, often leading to a visible change when growth of target organisms are present.
Differential media, unlike selective media, does not kill organisms. It indicates if a target organism is present.
E.g. MacConkey (MAC) and Mannitol Salt Agar (MSA)
400
List the muscles of the anterior forearm.
Superficial layer:
Pronator teres
Flexor carpi radialis
Palmaris longus
Flexor carpi ulnaris
Middle layer:
Flexor digitorum superficialis
Deep layer:
Flexor digitorum profundus
Flexor pollicis longus
Pronator quadratus
500
Where do the following metabolic processes occur?
1. glycolysis
2. TCA cycle
3. electron transport chain
4. gluconeogenesis
5. glycogenesis
6. glycogenolysis
1. glycolysis: cell cytoplasm
2. TCA cycle: mitochondrial matrix
3. electron transport chain: inner mitochondrial membrane
4. gluconeogenesis: liver (cytoplasm & mitochondria)
5. glycogenesis: liver & muscle cells (cytoplasm)
6. glycogenolysis: liver & muscle cells (cytoplasm)
500
Describe the pathogenesis of giardia lamblia
(8 steps based on mini quiz SAQ)
1. Cyst ingestion in contaminated water or food.
2. Excystation in stomach and duodenum in the presence of acid and pancreatic enzymes.
3. Trophozoite multiply in small bowel.
4. Trophozoite enters large bowel.
5. Encystation occurs in the presence of neutral PH and secondary bile salts.
6. Encystation is a continuous process, the trophozoite attaches to an enterocyte.
7. Secretory vesicles appear, cyst wall proteins secreted, new cysts made with new antigenic differences.
8. Epithelial injury is caused by the trophozoite which induces cell apoptosis
500
Describe the layers pierced when performing:
1. epidural anaesthesia
2. lumbar puncture
Which level are these procedures normally done?
Epidural Anaesthesia:
1. skin
2. subcutaneous fat
3. supraspinous ligament
4. interspinous ligament
5. ligamentum flavum
6. you are now in the epidural space
Lumbar Puncture:
1. skin
2. subcutaneous fat
3. supraspinous ligament
4. interspinous ligament
5. ligamentum flavum
6. pass through epidural space
7. dura mater
8. arachnoid mater
9. you are now in the subarachnoid space.
Spinal cord ends at L1. So these procedures are often done in L3-L4.