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Microbio Comprehensive


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Brightfield microscopy
Requires staining and heat fixing

Darkfield Microscopy
Used to observe live and unstained objects
Phase-Contrast Microscopy
-Uses direct and indirect light
-Can observe live and unstained objects
Fluorescence Microscopy
Uses photoluminescence to observe objects
What are the basic requirements for cell growth?
Temperature/pH, macro/micro nutrients, and oxygen requirements
Obligate anaerobe
only grow in oxygen
facultative anaerobe
both aerobic and anaerobic growth but grow greater in oxygen
aerotolerant anaerobes
only anaerobic growth but grows throughout
oxygen required in low concentration, grows in middle of tube
Lowering microbial counts on eating/drinking utensils
kills microbes
destruction of pathogens
Genetic code
A set of rules that determines how nucleotide sequences are converted into amino acid sequences of proteins
complementary structure
allows precise copying of DNA during division
What is the energy source for DNA replication?
DNA--> RNA code
RNA--> AA sequences
Sense codon
3 nucleotide sequence that codes for an Amino Acid
complementary sequence to a codon
In Translation, what is the P-site?
The peptidyl site where the first tRNA sits
In translation, what is the A-site?
Acceptor site where the second codon of the mRNA pairs with a tRNA carrying the second amino acid.
What are the two stages where we can control gene expression?
Pre-Transcriptional Control
Post-Transcriptional Control- After the mRNA has been made, but before translation takes place.

What are the two types of pre-transcriptional control?
Mechanism that inhibits gene expression or decreases synthesis rate of mRNA from a gene
Mechanism that turns on the transcription gene
Set of operator and promoter sites and structural genes they control
What are the two types of base substitutions (point mutations)?
Missense mutation
Point mutation causes a change in the codon that changes the amino acid type
Nonsense mutation
point mutation changes codon to a "stop" codon
Frameshift mutation
Deletion or insertion of a few nucleotides
Genetic recombination
The exchange of genes between two DNA molecules
Transformation (Frederick Griffith)
To absorb and recombine "naked" DNA
Transfer of bacterial DNA via bacteriophage (virus)
What are the two methods of transduction?
Generalized transduction
an accidental packaging of bacterial DNA instead of phage DNA
Specialized transduction
phage DNA includes toxin genes that the bacteria can use
Conjugative plasma (F factor plasmid)
Carries genes for sex pili and transfer of the plasmid
What are the different types of plasmids?
1. Conjugative (F factor)
2. Dissimilation plasmid
3. Resistance factors (R factor)

Dissimilation plasmid
enzymes to break down unusual sugars or hydrocarbons
What dangers do R plasmids present to humans?
R plasmids can prevent antibiotics from working for humans which means humans can be resistant to antibiotics and become incapable of being cured with antibiotics
segments of DNA that can move from one region of DNA to another
Crossing over
process were foreign DNA is inserted into a chromosome by breaking and rejoining the chromosome
Polymerase Chain Reaction (PCR)
Used to make multiple copies of a piece of DNA enzymatically
Preparing cells to take up DNA (making them competent)
How are gene libraries made in prokaryotic and eukaryotic organisms?
-Genomic libraries are made from restriction enzyme digests of an organisms DNA that are packaged into “books”.
-“books” are stored as a bacterial or phase strain.

Small interfering RNA (siRNA)

therapeutic version of RNA that can bind to disease causing genes of viruses or cancer cells.

Toll-like receptors
Induce cytokine activity and attach to components found on PAMP pathogens
Function of basophils
release histamine that causes inflammation
Function of Eosinophils
Kills parasites with oxidative burst
Function of Neutrophil
Phagocytizes bacteria and fungi
Function of monocytes
cause inflammation and perform phagocytosis
Function of dendritic cells
Phagocytize bacteria and present antigens to Tcells
What three things can the activation of the complement system do?
1. Cytolysis (osmotic lysis)
2. Opsonization: promotes phagocytosis
3. Inflammation

MAC complex
Membrane Attack Complex→ creates a hole on a pathogen’s cell membrane and makes transmembrane channels for flow of extracellular fluid into pathogen and it bursts
How can bacteria evade the complement system?
-Capsule production – blocking C3b and C4b binding sites
-Sialic acid- discourages opsonization and MAC formation
- Inactivation of complement via bacterial produced enzymes.

What does IFN-α and IFN-β do?
interfere with viral multiplication by signaling neighboring cells of an ongoing viral infection
What is the bacterial equivalent of transferrins?
iron-binding blood plasma glycoproteins that control the level of free iron (Fe) in biological fluids
Who is the father of the theory of immunity?
Paul Ehrlich
A molecule, usually a protein, that stimulates an adaptive immune response.
A protein molecule secreted by B cells (plasma cells) that can bind to antigens.
What are the 2 arms of the adaptive immune system and what cell type is important for each?
Humoral ( B lymphocytes)
Cellular (T-cells)
What is a hapten and why does it need a carrier?

Hapten: low molecular weight compounds that need a carrier to elicit an immune response (antibodies)
How many polypeptide chains and binding sites does an antibody have?

What is the part of the antigen that binds to the antibody called?

i. 4 Polypeptide chains
ii. 2 binding sites- Variable and Constant
iii. Antigens bind in the Variable region

What is passive immunity?
the process of providing IgG antibodies to protect against infection
Which form of isotypes are in monomer form?
G, D and E
What form is the isotype IgM in?
What form is the isotype IgA in?
What is the function of isotype IgG?
Enhance phagocytosis, neutralize toxin/viruses
What is the function of isotype IgM?
Effective against microorganisms and agglutinating antigens

First antibodies produced in initial infection

What is the function of isotype IgA?
localized protection on mucosal surfaces
What is the function of isotype IgD?
unknown serum function, presence on B cell functions in initiation of immune response
What is the function of isotype IgE?
allergic reactions, lysis of parasitic worms
Where are IgG isotypes found?
Blood/lymph, intestine
Where are IgM isotypes found?
Blood/lymph, B cell surface
Where are IgA isotypes found?
Secretions (tears, saliva, mucus)
Where are IgD isotypes found?
Blood/lymph, B cell surface
Where are IgE isotypes found?
Blood, bound to mast and basophil cells throughout body
What 5 things can antibodies do?
1. Agglutination
2. Opsonization
3. Neutralization
4. Antibody-dependent cell mediated cytotoxicity
5. Activation of complement

antibodies cause antigens to clump together
the antigen is coated with antibodies that enhance its ingestion and lysis by phagocytic cells
IgG antibodies inactivate microbes by blocking their attachment to host cells
Antibody-dependent cell mediated cytotoxicity
The killing of antibody-coated cells by NK cells and leukocytes, occurs with organisms too large to phagocytize
activation of complement
inflammation and cell lysis
What negative effect can antibodies have on the host?
IgE antibodies can cause allergic reactions
Thymic selection
Weeding out process of T cells that won’t recognize MHC molecules of the host and T cells that will attack host cells.

-prevents the body from attacking its own cells

What are the basic T cell forms?
T helper cells
T cytotoxic cells
Function of Helper T cells
control the immune response through cytokines (chemical messengers)
Function of cytotoxic T cells
kill intracellularly infected cells

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