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Flashcards by gurhanabdirahim, updated more than 1 year ago
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Created by gurhanabdirahim
almost 11 years ago
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| Question | Answer |
| What color does Gram positive and Gram negative bacteria stain? | Gram Positive= Purple/blue Gram Negative bacteria= Stain Pin/red |
| Explain the structure of Gram-positive bacteria. | Most gram positive bacteria have cell walls that are thick and composed primarily of Peptidogylcan. the cell wall contains secondary cell wall polymers. including teichoic acid. Teichoic acid--> are polymers of glycerol and ribitol joined by phosphate groups. Teichoic acid are covalently connected to peptidoglycan or to plasma membrane. if the teichoic acid is connected to plasma membrane its called lipoteichic acid. Teichoic acid extend to surface b/c they are negatively charged. |
| What is the function of Teichoic acids? | Create and maintain the structure of the cell envelope. Protects the cell from harmful substances in the environment. I.e Protect from anti-bodies and host defense molecules. Also binding pathogens. |
| Enzymes secreted by gram-positive bacteria are called? | Exo-enzymes- they often serve to degrade polymeric nutrients that would other-wise be too large for transport across the plasma membrane. |
| Explain the structure of the Gram- negative Bacteria? | The gram negative cell wall is more complex than the gram positive cell wall. It has three layers the plasma membrane in most layer then the peptidoglycan layer and finally the outer membrane. Braun's lipoprotein connects the peptidoglycan layer with the outer membrane. It is the most abundant protein in the outer membrane, it is covalently joined to the peptidoglycan layer and embedded in the outer membrane by its hydrophobic ends. LPS - Lipoplysachrides, are large complex molecules that contain both lipids and carbohydrates. They consist of three parts the first Lipid A is embeded in the outer membrane while the core polysachrides and o-antigen extend to the surface. The o-side chain elicits an immune response from the infected host. They recognize the o-side chain and produce anti-bodies against it. However many gram-negative bacteria can changed the o-side chain in order to ovoid an immune response. |
| What are some functions of LPs and what is Porin protein? | 1. Lps contributes to the negative charge on the bacterial surface b/c the core-polysacchride contains charged sugars and phosphates. 2. Lps contributes to bacterial attachment and biofilm formation. 3. Creates a permeability barrier it restricts the entrace of bile salt or anti-bodies that might harm the cell. 4. plays a role in protecting pathogenic gram negative bacteria from host defenses. porin protein--> most porin proteins cluster togather to from a trimer in the outer membrane. Allows small molecules such as glucose and other monsachrides to enter the cell. |
| What is plamolysis? what does lysozyme and penicillin do to peptidoglycan layer ? | Plasmolysis--> A cell in a hypertonic solution water floes out and the cytoplasm shrivels up. Lysozyme attacks peptidoglycan by hydrolyzing the glycosidic bond that connects Nam and NAG. While penicillin inhibits transpeptidase which is responsible for making the cross links between peptidoglycan chains. |
| protoplast Vs. Spheroplast? | Protoplast- when gram postive bacteria are treated with lysozyme or pennicillin it results in the lost of the cell wall, and become a protoplast. while when gram negative bacteria are treated with with either of the above they loose the peptidoglycan layer but the outer membrane reamins thus a spheroplast. |
| Capsules and slime layers | Capsules help pathogenic bacteria resist phagocytosis by host phagocytes. Slime layers are produced by gliding bacteria they facilitate motility. |
| Explain aracheal cell wall and difference bte mono layer and bilayer? | Archeal cell walls lack peptidoglycan they have a S-layer cell. The bilayer is known as C20 its more fluid while the mono layer C40 is much more rigid and found in exterme thermophiles thus expalining their need for a rigid and stable mono layer. |
| Nucleoid and plasmids explain the difference. | Nucleod--> Is an irregular shaped region that contains the cell chromosome. Plasmids--> are small double stranded DNA molecules that can exsist independently of the chromosme. They can also replicate independelty and contains less that gene. They are used in PCR to make clones of targeted Regions. |
| Episomes and curing | Plasmids that get integrated with the chromosome and replicate with it. Curing--> the loss of plasmids. it inhibts plasmid replication but not host cell replication. |
| Conjuctive plasmid, F factor, R plasmids? | Conjuctive plasmids--> they can transfer copies of themselves to other bacteria during conjugation. F-factor--> this is a type of conjuctive plasmid known as Fertility factor or F factor. R-plasmid--> these are resistant plasmid, they confer antibiotic resistance to the cells that contian them. |
| Bacteriocins, virulence and and metabolic PLasmids? | Bacteriocins--> Are a type of plasmid that give the cells harboring them a competitive advantage, by destroying other closely related bacteria. Bacteroicins are proteins. Virulence--> Virulence plasmids encode factors that make their hosts more pathogenic. Metabolic Plasmid--> Carry genes that degrade substances such as tolune, pesticides and sugars. |
| Fimbriae VS sex pili? | Fimbria --> are small short fine, hair like appendeges that are thinner than flagella. Sex pili--> are often larger than pili. they are genetically determined by conjucative plasmids and are required for conjugation. Some bacterial viruses attach specifically to receptors on sex pili at the start of their reproductive cycle. |
| Bacterial flagella 3 patterns ? | 1: Monotrichous--> they have only one flegella. 2: Amphitirochos--> Bacteria that have flagella on both sides. 3: Lophotrichous bacteria--> have flegalla as clusters. |
| Explain the structure of Flagellin? | The flagella has A filament, basal body and hook. The filament extends from the surface to the tip of the cell. While the basal body is embeded in the cell. The hook links the filament to the basal body? |
| Explain the structures of the basal body specifally the rings. ? | The basal body has 4 rings L ring, P ring, S ring and m ring. The s and m ring are now reffered to as the ms ring b/c they are different portions of the same protein. Know we also include C ring which is on the cytoplasmic side of the ms ring. |
| What is the motor of the fallegala made of? | The motors is located at the base of the fallagelum where it is associated with basal body. torque produced by |
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