Lec 3 Microbiology Review
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- Protein coat called capsid (the head)
- Nucleic acid 1-several hundred genes, inside of the capsid
- Most animal viruses, some plant virus and very few bacterial viruses have a lipid rich envelope-borrowed from host (gained from reverse endocytotic process)
How many sides do they have?
What distinct part does it have?
- Tail and tail fibers-tail fiber is attached to a protein receptor on the host cell
The 4 differences that make viruses a non-living cell
- 1. Viruses don't make ATP
- 2. Don't have a separate membrane that separate themselves from their outside environment
- 3. They either have DNA or RNA but NOT both
- 4. They can't reproduce without using the reproductive machinery of the host cell
Virus requirement of specific glycoprotein, explains
Viruses usually require a specific glycoprotein on their cell membrane in order to infect the cell, so you will be immune to a type of virus if you don't have this type of glycoprotein
Two possible life cycles of the virus
- 1. Lytic: Immediately commandeer the host machinery and create virion, cell swells and finally lyses, and releases the virus
- 2. The viral nucleic acid is incorporated into the host genome, but reproducing, the host reproduce the viral gene; at some point, the viral nucleic acid is activated to become lytic, usually during a time of stress that damages the DNA
How are animal vs. plant host cell infection different in virus?
1. What gets injected into the bacteria by the virus?
2. What about animal cells?
3. Does the capsid go into the cell membrane
- 1. Nucleic acid of the virus
- 2. In animal cells, the virus is taken into the cell by endocytosis
- 3. No. Once inside the animal cell, lysosome is attached to a phagosome and the capsid is release into the cytosol via exocytotic process before the lysome can digest the virusSo the Capsid never
An inactive form of virus, the nucleic acid and enzymes wrapped in its capsid, metabolic inactive, but ready to infect a host cell.
What is it called when a virus is incorporated into the host bacteria cell DNA ?
A provirus, or prophage (if the host is a bacteria)
1. What's a basic way to define different viruses by?
2. (+) strand and (-) strands exist in DNA or RNA?
- 1. Can be defined by the type of nucleic acid it possesses, single or double stranded DNA OR RNA
- -2. If RNA, it can be plus strand or negative strand RNA
- (+) strand: directly translated, includes retro virus
- (-) must be transcribed first
What kind of virus possess reverse-transcriptase?
Give an example of retro-virus
- The enzyme carried by Retro viruses, it reversely transcribe its RNA to DNA in order to be incorporated into the host's geneome
What is an infective piece of naked RNA that only infect plants?
What do you call a single protein molecule, capable of reproducing themselves without using nucleic acid in animals?
- Believe to cause mad cow disease
Some virus can spread from ducks to humans through feces, the point is even if this virus is irradicated from humans, this virus can still be carried by ducks and reinfect humans
1. What kingdom does it belong to?
3. what's distinct about its DNA
- 1. Monera
- 2. Prokaryotes, no membrane bound nucleus and membrane bound organelles
- 3. Ribosomes are made of 70s ribosomes made from 30s small subunits and 50 large subunits
- 3. Circular DNA, double stranded
What is a virulent virus?
A virus that follows a lytic cycle
What is a temperate virus?
Temperate: A virus in a lysogenic cycle
Two types of vaccine
Are vaccines against rapidly mutating viruses effective?
- 1. An injection of antibodies
- 2. Injection of a non-pathogenic virus with the same capsid or envelope
Two major shapes of bacteria
- Cocci (round)
- Bacilli (rod shaped)
What are the differences between spirilla and spirochetes?
Spirilla is rigid, and spirochetes are not
*Certain species of spirochetes may have given rise to eukaryotic flagella
What kind of cell membrane do prokaryotes have?
Phospholipid bilayer, similar to the phospholipid bilayer membrane of Euk.
Structure of phospholipid membrane:
Phosphate group+two fatty acid chains and a glycerol backbone
*Structure of fatty acid
- 3 carbon backbone with a polar phosphate group attached to an end carbon and two non-polar carbon chains attached to the other carbons via an ester-linkage
- This structure make amphipathic:
- *Structure of fatty acid:
- Carboxylic acid with a long carbonohydrate chain
2 types of Active Transport
ONLY ACTIVE TRANSPORT CAN MOVE MOLECULE AGAINST ITS ELECTROCHEMICAL GRADIENT
- Active transport because it uses ATP: Sodium potassium pump:
- The other type of active transport: Secondary active transport: epithelial cells of the intestine and the epithelial cell of proximal tubule of the kidney use this mechanism to transport glucose
- The phosophobilayer and the cytoplasm
- -Most protoplasts are encased in a peptidoglycan cell wall
- Peptidoglycans are made from disaccharide polymers that formed in chains, and each chain are cross linked by polypeptide crosslinks, forming the wall, the entire peptidoglycan walls is one giant molecule
Bacteria gram (+) or (-)
(+) stains dark purple, they have a thick peptidoglycan wall that absorbs the gram stain well
(-) stains pink, their peptidoglycan walls are much thinner, in addition, they have a second phospholipid bilayer on outside of the peptidoglycan cell wall
Either type may also have a capsule or a slide layer that surrounds the entire bacteria. The capsule may protect against phagocytosis, decication, etc
Hair on bacteria
Gram (-) have fimbrae, or pilli that help them attach to solid surfaces, these should not be confused with sex pillis in conjugation or with flagella or cilia
How do bacteria move?
They have flagella, they are made from a small globular protein called flagellin
These flagellin are polymerized to make a long slender helix, they rotate powered by a proton pump
- When rotate in one direction, they run straight, if rotate in the opposite direction, it causes the bacteria to tumble, tumbling allows bacteria to change directions
- Bacteria move by chemotaxis, they sense the concentration gradient and move accordingly
What is the process of bacteria reproduction?
Binary fission, there is no genetic recombination; No sex;
Three methods for recombining their genes
What the tiny ring of DNA that may or may not be incorporated into the circular DNA?
- If it can be incorporated into the circular DNA, it's called a episome
What is the form of gene recombination for bacteria when one bacteria with a f plus that make a sex pillus without the f plus plasmid; it may send a copy of plasmid or send the actual plasmid to the f minus bacterium, and become a f-minus itself.
*Upon receiving the f plasmid, the bacteria can now make its own sex pillus
What kind of gene recombination is it when the bacteria pick up naked DNA from its surrounding environment?
Transformation, the naked DNA can be a lysed bacteria or placed by a scientis
What kind of gene recombination when we talk about the transfer of genetic information through a vector (such as a virus)?
Are endospores and slime coat, or capsule the same thing?
No. Bacteria can produce endospores that have a high resistent to heat, and lethal agents; the production of endospores and ususally due to lack of nutrients
All organisms require carbon, energy, and electrons. Organisms can be classified by the source of their energy
1. Carbon source?
3.Electrons (come from organic or inorganic matter)
- 1. Carbon source: organic or inorganic
- Organisms who can fix CO2 (use CO2 as a carbon source) are called autotrophs
- Organisms who must rely on organic source for their carbons are called heterotrophs
- 2. Energy:
- Phototrophs: getting their energy from the sun
- Chemotrophs: getting their energy from chemicals
- 3. Electrons:
- From inorganic matter: Lithitrophs
- From organic matter: Organotrophs
Moneras have species of all type
What are the 3 divisions of fungi?
Fungi is a distinct kindom, like plants, fungi are separated by divisions not phylum
- Like plants, its
*Oomycota is now a slide mode, its' now in protista
All fungi are exodigestors, they spit on their food, and lay in it and digest their food
Many do not extinguish between living or dead organic matter; they can eat dead matter
- Most fungi have cell walls called septa, Made from a polysaccharide called Chitin, it's strongly resistent to microbio attack, in their growth state, fungi exist in a tangled mass structure called hyphae; Hyphae are made of haploid cells
- The tangled mass is called mycellium
Dominant life stage for fungi
- Haploid; only a brief time as a diploid
- Fungi do have sex, they are capable of sexually and asexually reproduction
Advantage of asexual reproduction: faster more efficient, doesn't require a partner; when you're perfectly suited for your environment
Advantage of sexual reproduction: Product genetic variation, so if the environment is no longer good, you want to produce children that are different from you
Spores produced by fungi are haploid or diploid?
1. Sexual or asexual reproduction? How to do each?
2. Aerobes or anaerabes?
- (Single celled fungi, but may have invovld from multicellular ancestors
- 1. Reproduce asexually by budding; Rarely produce sexually, when they do, they produce spores
- 2. Facultative anaerabe, produce ethanol in anaerobic environment; they can live in no oxygen, but can also use it for more efficient production
Are Protists prokaryotes?
No, they are eukaryotes
Fungi are ____karyotic, and ____trophics, and spend most their time in ___loid state
- eukaryotes, heterotrophs, haploid
- Can reproduce sexually and asexually
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