| What are protoplasts and spheroplasts? | They are L formed bacteria that are capable of growing and dividing unequally/ unevenly and lost their cell wall for an unknown reason, which makes them hard to culture |
| How do we culture protoplasts and spheroplasts? | By treating them like eukaryotes (since they lost their cell walls and became more fluid). |
| Can protoplasts and spheroplasts be stained? | No (lost cell wall) |
| What kind of bacteria are protoplasts and spheroplasts? | Protoplasts: gram + and spheroplasts: gram - |
| Can protoplasts and spheroplasts retain their cell walls? | Yes they can |
| Is mycoplasma a protoplast or a spheroplast? | It was once considered as an L form. |
| Interpret this graph. | This is the graph of what happens to bacteria when facing rough conditions.
X axis is the time, Y axis is the number of cells.
First bacteria are in latency phase, they are still managing the conditions, then they enter the exponential phase, where they increase in number to stay alive, then they enter the stationary phase, where cells are still managing their life together, and finally if no spores are formed, they enter the D phase which is the death.
If spores are formed it stays on S phase |
| What is a spore? | Haploid, non-functional state of a bacteria which occurs on harsh conditions. When no more nutrients are present. |
| Which bacteria undergo sporulation? | Gram + like Bacillus and Clostridium. |
| What does germination mean? | Opposite of sporulation, when bacteria retains its functions when nutrients are present. |
| List the steps for sporulation. | 1-Cell Division
2-Axial filament formation (septum forming assymetrically)
3-Big cell engulfs the small one making the forespore (Small cell)
4-Nucleiod of big cell denatures, only forespore remains.
5-Formation of cortex between inner and outer membrane of forespore (outer coming from big cell)
6-Synthesis of caot from keratin which is very tough
7-Exosporium formation which is an outer layer of lipoprotein and carbs giving strength.
8-Cell intakes needed nutrients and calcium dipicolinate inside the forespore.
9-Spore is released. |
| List the layers of the formed spores of bacteria (inside to outside) | Inner membrane
Cell wall
Cortex
Outer membrane
Coat
Exosporium |
| Where do we find Clostridium Tetani spores? | They are presents as spores in rusty nails, soil and sometimes in animal bites
Tetani (كزاز - صدأ) |
| What are the different shapes spores present in? | Different shapes are according to the placement of the nucleiod.
May be central, terminal or subterminal |
| What is the shape of the Clostridium Tetani spore? | Looks like a tennis racket (drumsick appearance) |
| What does refractivity mean? | Ability for refraction (it increases due to the coat of spores) |
| What do we mean by culture medium? | It is a tube containing nutrients where we can witness bacterial growth and multiplication. |
| What kinds of culture media do we have? | Broth medium (tube containing liquid nutrients)
Agar medium (Petri dish with gelly texture - includes solidifying agent - called petri in response to the scientists name, his wife suggested it) |
| How to witness bacterial growth in petri dishes? | Adding one drop of bacteria and streak it, after adding nutrients and maybe red blood cells (streptococcus and staphylococcus)
After streaking, bacteria is less on loop of dish and more on the agar, and they start appearing as little dots: these are colonies of bacteria, that resulted from one microscopic one. |
| Why do we call bacteria colony forming unit? | Since one microscopic bacteria on agar may give us a colony of bacteria seen as a dot on the eye sight level. |
| What are the two categories of culture media? | Selective (for specific bacteria , like MacConkey agar which has bile salts stopping gram + growth thus making it gram - selective)
Non-Selective (Gives colonies of all kinds if bacteria, without distinguishing them) |
| What is the differential medium? | It is a medium where chemical reactions done by bacteria allow us to identify it.
Non-selective
Strep and staph |
| What is the enrichment medium? | Medium where we add nutrients for bacteria to grow fast |
| What is the specific culture? | Selective and specific for one kind of bacteria, works only on salmonella and shigella (SS culture) |
| Talk about coccus shape of bacteria. | Diplococcus (strep pneumonia)
Streptococcus (Streptococcus pyogene - causes pharyngitis (sore throat))
Tetrad (4 coccus)
Staphylococcus (many dimensions like grapes) |
| Talk about bacillus shape of bacteria. | Spore - former (clostridium botulinum)
Flagellate bacilla (flagellated rod - Salmonella typhi)
Streptobacilli (chain of bacilli) |
| Talk about spiral shapes of bacteria. | Vibrios (Coma , shaped appearance - vibrio cholera)
Spirilla (heliobacter - helicopter shape - flagella on one side)
Spirochetes (spiral appearance with narrow width - observed by dark microscope) |
| Do we consider different bacteria types associating as biofilms? | No, in biofilms we are talking about cities of bacteria (millions and billions) |
| How is the metabolism of bacteria mediated? | Through genetics, where enzymatic proteins mediate anabolism and catabolism of sugars, lipids...
using focal metabolites (like aa and sugars) bacteria metabolism occurs |
| Do focal metabolites follow the same pathway of metabolsim? | No, there are many pathways according to the needs of the bacteria. |
| What is serotyping? | It is a test designed to describe a way of grouping of the bacteria, it is forensic fingerprinting by using antigens and antibodies attaching to them. |
| How many serotypes does vibrio cholera have? | Over 300 serotypes, but only O1 and O139 are what cause endemics and epidemics. |
| What microorganisms can be serotyped? | Bacteria (have many O and H antigens) and viruses. |
| What is hybridoma technology? | Cancer cell + B cell merged together to make loads of antibodies (monoclonal) |
| What is quasispecies? | Core of antigen O in gram- is common for gram - but every strain has its own antigens
Bacteria with small oligosaccharides instead of polysaccharides (O1.1 1.2 1.3) |
| Give an example of problematic quasispecies. | Immune system cannot degrade Neisseria Gonorrhea since it keeps changing oligosaccharides O antigen (so it has different but predictable O antigens but shifting makes it unpredictable) |
| What are dichotomous keys? | They are ways of testing the help identify the type of bacteria being tested.
For example, use catalase , if catalase negative - streptococcus
if catalase + - staphylococcus.
Then if staphylococcus, use coagulase, if positive aureus, if negative, epidermis. |
| Talk about Avery mcleod.... | They just mixed all experiments together to conclude gene DNA transformation, by direct uptake (DNA) |
| What is transduction? | Integrating bacteriophage DNA into the genome. |
| What is transposition? | Jumping genes that may jump from nucleoid to plasmid and vice versa
It has 2 components, DNA portion (insertion site) and Gene (coding portion) |
| Give an example of transposon. | Penicilin resistance moves from nucleoid to plasmid, when in plasmid it can be conjugated to another bacteria by pilli, which thus becomes resistant, however its progeny are not resistant unless the resistance gene is transposed back into the nucleoid genome.
RK bacteria who undergo conjugation and lose their plasmid do not lose resistance properties since we have many plasmids |
| Do all bacteria have transposons? | No, treponema paletum causing siphilis DNA has no transposon, so it will always be suseptable to penicilin |
