Medical Interventions Midterm

1.1

*review serial dilution and the steps of DNA sequencing*

  • Hans Christian Gram:

    • discovered certain stains were preferentially taken up and retained by bacterial cells

    • Carlweigert added a final step of straining cells with safranin

ELISA (Enzyme-linked immunosorbent Assay)

  • 4 Substances (in order)

    • Antigens

    • Primary Antibody

    • Secondary antibody w/enzyme

    • enzyme-substrate

  • Direct ELISA

    1. The target antigen is immobilized on a plate, and a specific enzyme-linked antibody is added directly to bind to the antigen.

  • Indirect ELISA

    1. target antigen is immobilized on a plate

    2. followed by a primary antibody that binds to the antigen.

    3. A secondary enzyme-linked antibody is then added to bind to the primary antibody.

  • A Sandwich ELISA

    • plate is coated with a capture antibody specific to the target antigen

    • After the sample

    • a detection antibody (which also recognizes the antigen) is added, forming a "sandwich" with the antigen in the middle.

    • An enzyme-linked secondary antibody is then added.

1. 2

* review serial dilution and the steps of DNA sequencing

Frederick Griffith

  • the first evidence of bacterial transformation

  • injected with a heat-killed version of the bacterium along with a rough version of the bacterium

  • rats in the group died of a massive pneumococcal infection

Class of antibiotics

  • B-Lactums: irreversibly degrades the cross-bridge linkable between peptidoglycan molecules causing the cell wall to weaken and burst due to too much internal pressure

  • Fluoroquinolones: inhibit the supercoiling of the chromosomal DNA within the bacterial cells so DNA replication cannot take place

  • Tetracyclines: prevents the continuation of protein synthesis at the ribosomes

  • Sulfonamids: inhibits the folic acid synthesis pathway in bacterial cell

Bacteria cell structure functions:

  • capsule: provides protection and aids in attachment

  • cytoplasm: houses cellular components and facilitates metabolic processes

  • flagella: enables movement and motility

  • inner cell membrane: controls transport of substances in and out of the cell

  • nucleoid DNA: contains the cell’s genetic information

  • outer cell membrane: serves as a protective barrier and regulates entry/exit of substances

  • peptidoglycan layer: offers structural support and maintains cell shape

  • pili: facilitate attachment to surfaces and genetic material exchange

  • plasmic DNA: carries additional genetic traits and can confer advantages

  • ribosomes: synthesize proteins necessary for cell functions

The bacterium can defeat an antibiotic through…

  • Efflux Pumps: actively transport antibiotics out of the cell, reducing the intracellular concentration of the drug and thereby minimizing its effectiveness

  • Blocked Penetration: Some bacteria alter their outer membrane or cell wall structure to prevent antibiotics from penetrating the cell

  • Target Modification: Bacteria can modify the molecular targets of antibiotics to reduce the drugs' binding affinity.

    • can occur through mutations in genes encoding target proteins, such as ribosomal subunits or enzymes, allowing the bacteria to survive despite the presence of the antibiotic.

  • Inactivation of Enzymes: produce enzymes that chemically inactivate antibiotics

F+ Bacterium

  • Definition: F+ bacteria possess the F (fertility) plasmid, which contains genes necessary for the formation of a pilus and the transfer of genetic material during conjugation.

  • Role in Conjugation: They act as donors in the conjugation process, capable of transferring genetic material to F- F-bacteria through a conjugation bridge.

  • Characteristics: F+ bacteria can produce sex pili, allowing them to connect with F- bacteria for genetic exchange.

F- Bacterium

  • Definition: F- bacteria lack the F plasmid and do not have the genes required for pilus formation or conjugation.

  • Role in Conjugation: They act as recipients during conjugation, receiving genetic material from F+ bacteria.

  • Characteristics: F- bacteria do not possess the capability to initiate conjugation but can become F+ if they successfully receive the F plasmid during the process.

Types of Gene Transfer

  • transduction:

    • bacteria can acquire genetic material from a virus (bacteriophage)

    • The virus infects a bacterial cell, incorporates part of the bacterial DNA into its own genome, and then transfers that DNA to another bacterial cell when it infects it.

  • transformation:

    • incorporation of free DNA from the environment by a bacterial cell

    • often occurs when bacteria die and release their DNA, which neighboring bacteria can then take up

  • conjugation:

    • One bacterium transfers genetic material (usually in the form of a plasmid) to another through a structure called a pilus.

1.3

Sound vibrations

  • high amplitude: loud sound

  • low amplitude: quiet sound

  • high frequency: high-pitched sound

  • low frequency: low pitched sound

  • sensorineural hearing: damage to the inner ear (cochlea) or the auditory nerve pathways to the brain

  • conductive: sound waves cannot effectively travel through the outer ear, eardrum, or middle ear

Ear Parts

  • Ossicles: between the tympanic membrane and oval window these transmit sound to the inner ear

  • tympanic membrane: a membrane that focuses sound from the outer ear to the middle ear

  • cochlea: houses sensory hair cells, detects different frequencies & amplitudes

  • round window: allows for the movement of fluid in the cochlea when the Stapes pushes on it

  • oval window: The stapes push on this membrane to move fluid in the cochlea

  • ear canal: transmits sound from the outer ear to the middle ear

  • pinna: the cartilaginous structure funnels sound into the ear canal, collets sound, and funnels it into the middle ear

  • eustachian tube: helps equalize air pressure between the middle ear and the outside atmosphere

The Middle Ear

  • Made up of:

    • Tympanic membrane

    • Malleus

    • Incus

    • Stapes

  • Gating

    • decreases sound intensity to prevent cochlear damage

    • locks the ossicles in place which lowers intensity levels by 30-40 db

    • masks low-frequency sounds in loud environments - allows for conversation in loud environments

causes a 22x increase in pressure on the cochlear fluid

The Inner Ear

  • Overview:

    1. stapes pushes on the oval window with enough force to move the fluid in the cochlea

    2. fluid in the cochlea transmits energy to the basilar membrane

    3. basilar membrane and so do the hair cells on the hair cell

    4. Bend of the cell opens a flap covering a channel of the hair cell. K+ flows in causing the cell to depolarize

  • Process of Sound

    1. Sound waves arrive at the tympanic membrane

    2. movement of the tympanic membrane causes displacement of the ossicles

    3. movement of the stapes at the oval creates pressure waves in the perilymph of the vestibular duct

    4. the pressure waves distort the basilar membrane on its way to the round window at the end of the tympanic duct

    5. vibration at the basilar membrane causes vibration of hair cells against the tectorial membrane

*identify each structure on a photo