Mock exam Flashcards

Question

what is microbial enumeration test?

Answer 1

quantative test that determines the total aerobic microbial count and total yeast and mold count present in test product

Answer 2

* direct * indirect * viable * total cell count * **_RMM:_** * growth based * direct measurement * cell component analysis

Answer 3

1. spherical (cocci) 2. rod (bacilli) 3. spiral (spirilla) 4. coma (vibrois) 5. corkscrew (spirochaetes)

Answer 4

because it is essential for correct diagnosis and treatment and trace back of disease outbreaks

Answer 5

**traditionals:** * cultivation (growth requirement) * cultivation (selective agar) * biochemical profiling **New/rapid:** * serological testing * nucleic acid techniques * MALDI TOF

Answer 6

Spore is metabolically dormant structure produced during unfavorable condition by the process called sporulation. Sporulation occur during late log phase or early stationary phase. Under favorable condition spores germinate to give vegetative cell.

Answer 7

because they are highly dehydrated with no metabolic activity and their constituents of small acid soluble proteins dipicolinic acid and their multilayered structure

Answer 8

process that kills all microorganisms including spores

Answer 9

broad spectrum antibiotics like: cephalosporins/fluoroquinolones/ampicillin/amoxicillin/clindamycin

Answer 10

* they alternate between infectious extracellular elementary body and reticulate body * elementary bodies enter mucosal cells and differentiate to reticulate bodies in membrane bound compartment * replication occurs, reticulate bodies redifferentiate into elementary bodies and released from host cell to infect other cells

Answer 11

* hydrophobic cell wall, peptidoglycan linked to arabinogalactan esterfied to mycolic acid * lipids 25% of dry weight * mycolic acid, high molecular weight (3 hydroxy fatty acid) * cord factor, parallel alignment of rows of bacilli

Answer 12

* isoniazid * rifampicin * pyrazinamide * ethambutol

Answer 13

* direct contact * fomites * aerosols * oral * vector borne

Answer 14

microbes that are both helpful and potentially harmful occupying the a habitat (human)

Answer 15

microbial product that contributes to virulence

Answer 16

intensity of pathogenicity of an organism

Answer 17

substance of organisms that damage the host

Answer 18

organism that becomes pathogenic following a perturbation to a host / disruption of microflora

Answer 19

endotoxins are toxic at high doses whereas exotoxins are can be extremely toxic at low doses. endotoxins are released when bacterial cell dies exotoxins produced during growth/division

Answer 20

neurotoxins enterotoxins cytotoxins

Answer 21

lipopolysaccharide molecule (Lipid A)

Answer 22

* bacterial status (resistance/biofilm/susceptibility) * antimicrobial concentration and subinhibitory concentration * host factors (serum effect/gut impact)

Answer 23

infections caused by fungus invading tissues and causing, superficial/subcutaneuous/systemic infections

Answer 24

mouth skin intestine

Answer 25

budding, whereby mother cell grows a protrusion (bud) until it's the same size as the mother cell and splits from it

Answer 26

polyene: nyastatin + amphoterecin B azole: itraconazole + ketoconazole echinocandins: caspofungin/micafungin/anudiulafungin synthetic: flucytosine

Answer 27

fungal skin, hair, or nail infections by dermatophytes (ringworm)

Answer 28

fungal infection caused by aspergillus a common mold that lives both indoors and outdoors

Answer 29

long branched thread-like filaments of hyphae that form mycelium

Answer 30

molds reproduce sexually when they are starved, in which 4 haploid cells fuse into two and further into one (increase genetic diversity/survival) they reproduce asexually when there's plentiful food supply, producing 2 identical daughter diploid cells

Answer 31

direct contact → aids/hiv/hsv/hpv/leukemia/hepatitis b/c airborne → chickenpox/influenza/measles/mumps/rubella/corona food/water → gastroenteritis/norovirus/hepatitis A/poliomyelitis arthropod → yellow fever

Answer 32

nucleic acid covered by capsid forming the nucleocapsid, with an envelope covering it along with viral receptors

Answer 33

1. attachment and penetration 2. macromolecular synthesis 3. assembly of progeny virions and release from host cell

Answer 34

spherical with an outer lipid membrane (envelope) derived from host cell

Answer 35

hemagglutinin (HA) and neuraminidase (NA)

Answer 36

antigenic drift: two virus strains infect the same cell and mix during assembly of new viruses e.g. h3n2+h5n1=h5n2 antigenic drift: small changes in the virus over a period of time, producing new strains not recognized by immune system and are difficult to treat/vaccinate

Answer 37

influenza is a single stranded negative sense RNA virus, they have genomes which consist of more than 1 RNA viruses, transcription results in unique mRNA for each protein rather than a single polycistemic mRNA

Answer 38

process by which influenza viruses swap gene segments

Answer 39

herpes viruses are DNA containing viruses, which means they make mRNA using strategies similar to host cell replication, in which DNA is transcribed into mRNA in the host cell nucleus with host cell enzymes resulting in early and late transcripts that encode for structural proteins and those required for replication

Answer 40

**_productive infection:_** Following primary infection, the virus replicates productively within mucosal epithelial cells and enters sensory neurones via nerve termini **_latent infection:_** e virus is then transported to neuronal cell bodies where latency can be established (it can reactivate and generate new virus progeny when transported back to periphery)

Answer 41

* initiation of viral lytic gene expression * newly formed capsids are transported to axonal termini * infectious virus released from axon and infects epithelial cell resulting in recurrent infection and virus shedding

Answer 42

single stranded positive sense RNA

Answer 43

RNA dependent RNA polymerase

Answer 44

high intrinsic error rate, introducing multiple nucleotide changes, jump across templates

Answer 45

viral RNA exonuclease

Answer 46

the combination of RNA recombination due to high polymerase error and regulated replication fidelity favors the generation of recombinant and highly diverse viruses

Answer 47

close contact

Answer 48

release of virus progeny after assembly in host cell

Answer 49

it stands for severe acute respiratory syndrome (SARS) that is a viral respiratory disease caused by coronaviruses

Answer 50

enveloped, positive sense RNA virus

Answer 51

zidovudine, is a reverse transcriptase inhibitors, It inhibits the activity of HIV-1 reverse transcriptase (RT) via DNA chain termination after incorporation of the nucleotide analogue. It competes with the natural substrate dGTP and incorporates itself into viral DNA.

Answer 52

uses CD4+ cells to replicate, The retroviruses, such as HIV, contain single-stranded positive-sense RNA but employ a unique replicative strategy using a DNA intermediate. Viral positive-sense RNA serves as a template for a virion-associated RNA-dependent DNA polymerase (reverse transcriptase). The DNA is then integrated into host chromosomal DNA, where it resides for the life of the cell. Transcription of the integrated viral DNA, like transcription of host cell genes, is carried out by host cell DNA-dependent RNA polymerases

Answer 53

HIV is a retrovirus that primarily infects CD4+ cells, macrophages, and dendritic cells aids: acquired immunodeficiency syndrome that describes life threatening infections occurring due to damaged immune system caused by HIV

Answer 54

below 200 cells per microlitre

Answer 55

direct/indirect: isolation (immunofluoroescence)/ antigens/antibodies/PCR biological specimens: nasopharynx swab/throat swab/rectal swab/eye swab/ lesion swab

Answer 56

unicellular, eukaryotic, heterotrophic microorganism that are sometimes parasitic depending on the life stage found in aqueous environments and they are transmitted via arthropod vectors

Answer 57

parasitic worms such as flukes and tapeworm

Answer 58

schistosomiasis lymphatic filariasis cysticercosis onchocerciases

Answer 59

metabolism → biochemical pathway for non digestible foods (cellulose/gum/hemicellulose/pectins). synthesize vitamins k and b12 and develop caucum immune development: produce antimicrobials (fatty acids/peroxides) and compete for nutrient sites in sites of attachment in the gut preventing colonization gut-brain-axis → stress influences microbiota composition and integrity of gut epithelium

Answer 60

inflammatory bowel syndrome obesity/diabetes 2 atopic eczema and allergies

Answer 61

microorganisms believed to provide health benefits when consumed

Answer 62

* contaminated manure * irrigation water * soil * livestock/wildlife

Answer 63

water → chemical treatment NaCl/membrane filtration/UV irradiation 250nm/heating 80c operator → gloves/good hygiene/cover when sneezing buildings → good ventilation/disinfectant/filtration/floor cleaning/avoid drainage in manufactures/dusting packages → maintain integrity (shelf-life)/safe delivery equipment → sterilizaition/disinfection/disposable (single use) air → filtration (HEPA)/chemical disinfection/UV radiation

Answer 64

* transform heavy metals like mercury to non toxic form * petroleum biodegradation * xenobiotic degradation

Answer 65

* leuconostoc bacteria can produce dextran from sucrose which is an antithrombotic that improves tissue function * clostridium botilinum produces botilinum toxin that is used in minute amounts in the cosmetic industry to prevent wrinkles and to treat dystonia * bacillus sphaericus produce 51 & 42 kDA which are toxic to larvae and used in waters where larvae develop

Answer 66

Almost all amino acids contain a chiral centre on the alpha carbon. All naturally occurring amino acids have L-stereochemistry, i.e. they have the same configuration as the reference compound glyceraldehyde. D-amino acids are very rare, and are the product of biosynthesis

Answer 67

Glycine has no chiral centre and therefore cannot exist in L/D-forms. The alpha carbon does not have four non-identical groups attached, two are hydrogen (i.e. identical

Answer 68

Acidic conditions will protonate the basic side chain of Lys, becoming positively charged. Basic conditions will deprotonate the acidic carboxylic acid group, becoming negatively charged. (You could also, or might be asked, to draw the resulting structures

Answer 69

A small protein containing 50 or less amino acid residues

Answer 70

Peptides should be named, using three letter or single letter amino acid abbreviations starting from the N-terminal residue and listing sequentially to the C-terminal. Abbreviations separated by dashes.

Answer 71

a. Lysine b. Aspartic acid

Answer 72

Lys – basic Ala, Val, Leu and Ile – hydrophobic Ser – polar; Asp – Acidic

Answer 73

in an aqueous environment, hydrophobic residues e.g. Ala, Val etc would be folded away from water into the interior of the protein. Hydrophilic residues, e.g. Ser, would face the solvent. Charged side chains would form an interaction where possible.

Answer 74

Will have some water solubility, although mostly non-polar amino acids there are three polar aa’s, two of which form a salt. OR – will not be soluble in water as 7 non-polar aa’s versus 3 polar.

Answer 75

Compact (tightly folded), roughly spherical, structurally complex, comprised of many elements of secondary structure, e.g. alpha helix, beta sheet, often clearly defined active site / cleft, internal bonding to maintain structure, e.g. disulfide bridges

Answer 76

trypsin (all enzymes)

Answer 77

Hydrophobic interior, hydrophilic exterior, water soluble, often function as catalysts

Answer 78

ionic interactions, hydrogen bonding, hydrophobic interactions, covalent crosslinks

Answer 79

false The alpha helix is a single peptide backbone coiled around itself and stabilised by intra-strand H-bonds. [By contrast, DNA is an example of a double helix – two chains stabilised by inter-strand H-bonds]

Answer 80

true All proteins fold spontaneously into a conformation that is biological active

Answer 81

true Cis-amide bonds force unfavourable steric interactions between aa side chains and are not commonly found in proteins

Answer 82

false Anti-parallel beta sheets are more stable – the network of inter-strand H-bonds are better aligned and more stable in the anti-parallel type.

Answer 83

Proteins do not exist as a linear conformation of amino acids (the primary sequence) they fold very specifically into a specific conformation called the native conformations. This is generally the biologically active form of the protein

Answer 84

. Alpha helix important form of secondary protein structure. Single polypeptide strand coiled in a tight helix excluding water from the centre. + + Describe properties and H-bonding network etc. Some proteins composed exclusively of a-helix, usually as coils of coils, e.g. keratin, collagen. Also common in membrane spanning receptors

Answer 85

An amino acid that can be biosynthesized with the body and therefore is not essential in the diet. E.g. Ala, Gly, Pro, Ser etc. It requires energy and raw materials to synthesize aa’s so in practice these are obtained from diet whenever possible

Answer 86

A polypeptide joined via an amide (peptide) bond between the N and C terminal amino acids creating a continuous cyclic peptide backbone. Have pharmaceutical use. E.g. ciclosporin, a microbial cyclic peptide that contains non-coding biosynthesized amino acids. When non-amino acid groups are incorporated known as a pseudo-peptide

Answer 87

…by lowering the activation energy barrier to the reaction. Achieved by precise orientation of the substrate in the active site in a reactive conformation and provide missing functional groups or cofactors for the reaction. Enzymes provide the reaction ‘template’.

Answer 88

Two methods, trivial and systematic. Trivial – name associated with the function or substrate (or both) is suffixed with –ase. E.g. L-dopa decarboxylase or DNA polymerase. Systematic system (enzyme commission: EC) assigns a unique serial number comprised of 4 digits. First digit is one of the six classes (list them) followed by two sets of sub classes and finally the unique identifier, e.g. alcohol dehydrogenase = EC1.1.1.1.

Answer 89

The 20 amino acids that occur naturally in proteins have limited functional groups / chemistry in their side chains. Co-factors, which can be metal ions or organic molecules (co-enzymes) supply this chemistry. Alcohol dehydrogenase uses two co-factors, a zinc ion and a NAD+ coenzyme. The zinc aligns the substrate in the active site to the –OH group. The NAD+ contains a functional group that accepts a proton (i.e. dehydrogenation). Could also include a sketch? Another example could be L-Dopa decarboxylase. The enzyme uses a co-enzyme (pyridoxal phosphate/vitB6) to facilitate the removal of a carboxylic acid. The co-enzyme contains an aldehyde functional group – not found in amino acids – to form an intermediate (imine) with the substrate etc etc

Answer 90

Proteins containing metal ions are known as metalloproteins or metalloenzymes if they have a catalytic function. The 20 amino acids that occur naturally in proteins have limited functional groups / chemistry in their side chains. Co-factors, which can be metal ions or organic molecules (co-enzymes) supply this chemistry. Metals are important in transport proteins (e.g. haemoglobin, Fe required to bind, store then release O2, four Fe atoms held in 4 prosthetic haem groups etc etc). Alcohol dehydrogenase and Zn etc etc

Answer 91

glycolysis: 2 pyruvate + 2ATP +2 NADH pyruvate → acetyl coa: 2 NADH per glucose krebs: coa to co2+ 2GTP + 6NADH + 2 FADH2

Answer 92

occur as esters in natural fats and oils and FFA in blood

Answer 93

saturated: no double bonds in acyl chains, end in anoic e.g butyric acid unsaturated: 1 to several double bonds in acyl chain, end in enoic e.g. oleic acid

Answer 94

fats have more/all available bonding sites TAKEN UP by Hydrogen (saturated). whereas, oils have fewer hydrogens on the account of double bonds (unsaturated) they are also liquid at room temperature

Answer 95

a minute spherical sac of phospholipid molecules enclosing a water droplet, especially as formed artificially to carry drugs or other substances into the tissues.

Answer 96

ggregate of surfactant phospholipid molecules dispersed in a liquid, forming a colloidal suspension.

Answer 97

glycerol phosphate fatty acid side chain

Answer 98

cytoplasm → contains all cell organelles except nucleus cytosol → densely packed aqueous gel, protein synthesis mitochondria → cellular respiration/apoprosis/oxidative phosphorylation lysosomes → cellular digestion/enzyme function site peroxisomes → site of oxygen utilization nucleus → DNA/RNA synthesis ER → lipid synthesis/protein distribution Golgi → modification/sorting/packaging of proteins + delivery and secretion lysosomes → cellular digestion

Answer 99

Without oxygen, organisms can split glucose into just two molecules of pyruvate. This releases only enough energy to make two ATP molecules. **With oxygen, organisms can break down glucose all the way to carbon dioxide.** **This releases enough energy to produce up to 38 ATP molecules**