MI: 1.2 Quiz

What occurred when both strain 1 and strain 2 were mixed

The DNA gene coding for ampicillin was transferred to strain 1 using conjugation to ensure that both strands were resistant to both ampicillin and streptomycin

Nucleoid

The DNA-containing area of a bacterial cell

Sulfa antibiotics effect and destroy bacteria

binds and inhibits an enzyme involved in folic acid synthesis (required for cell growth)

mutation

change in the DNA that can cause a change in the gene product, which is the target of the antibiotic

What antibiotic worked best on B.cereus ?

chloramphenicol

Which antibiotic could be used for both of the bacteria?

chloramphenicol

penicillins effect and destroy bacteria

inhibits cell wall synthesis by inactivating an enzyme

tetracyclines effect and destroy bacteria

inhibits protein synthesis by binding to bacterial ribosomes

how do antibiotics work to kill bacterial cells without harming the surrounding human cells?

target structures not present in human cells (cell wall)

nucleoids

region in the prokaryotic cell that contains the main DNA material

endotoxins

released when a cell disintegrates; responsible for disease.

Flagella

used for motility; rotate

gram positive bacteria

- innermost plasma membrane - thick peptidoglycan cell wall - outer capsule - more easily treatable with antibiotics - stains purple/ violet * easier to treat because the cell wall is closer to the surface for the antibiotics to attack*

gram negative bacteria

- innermost plasma membrane - thin peptidoglycan cell wall - another plasma membrane - outer capsule - harder to treat with antibiotics - stain red/ pink *Gram-negative are harder to treat because the cell wall is harder to reach because of the extra plasma membrane*

Conjugation

The one-way transfer of DNA between bacteria in cellular contact

Transduction

The transfer of genetic material from one organism (such as a bacterium) to another by a genetic vector

Fluoroquinolones affect and destroy bacteria

effective against DNA synthesis by inhibiting enzymes

Capsule

Layer of polysaccharide protects the bacterial cell; barrier against phagocytosis.

Destruction or Inactivation

Many bacteria possess genes which produce enzymes that chemically degrade or deactivate the antimicrobial, rendering them ineffective against the bacterium.

Antibiotic Resistance

Resistance to one or more antibiotics, usually due to additional genetic information

Efflux

an efflux pump is a channel that exports antibiotics and other compounds out of the cell. *antibiotics enter the bacteria through a porin then is pumped back out of the bacterium (by doing this it makes it so that then antibiotic cant affect the cell)

How do antibiotics work without harming the surrounding human cells?

antibiotics target cell walls (peptidoglycan) and human cells do not have a cell wall, as a result the antibiotics do not effect the normal healthy human cells.

Plasma membrane

diffusion and transport of materials between cytoplasm and the environment.

What antibiotic was E Coli strain 1 resistant to ?

gene found in chromosomal DNA coding for streptomycin

What antibiotic was E Coli strain 2 resistant to ?

gene found on the plasmid DNA coding for ampicillin resistance

What cellular components do some bacterial cells have that make them powerful pathogens? Explain your answer.

have three layers to protect their DNA and a pili to attach to multiple types of surfaces

Pili

hollow; made of protein; allows bacteria to attach to other cells

ribosomes

protein synthesis occurs here; reads mRNA

plasmid

small circular DNA fragments found in cytoplasm, contain code responsible for antibiotic resistance and other characteristics

examples of gram positive bacteria

streptococcus

Transformation

(genes are transferred as "naked DNA") When cells die and break apart DNA is released into surrounding environment. Other bacteria in close proximity can scavenge the DNA and incorporate into its own. DNA may contain advantageous genes such as antibiotic resistance.

Cell Wall

A rigid structure that surrounds the cell membrane and provides support to the cell gram positive= layer of peptidoglycan Gram negative= between plasma and outer membrane

Plasmids

A small ring of DNA that carries accessory genes separate from those of the bacterial chromosome

Antibiotic

A substance produced by or derived from a microorganism and able in dilute solution to inhibit or kill another microorganism

What antibiotic worked the best on E coli ?

Ampicillin

Why are antibiotics NOT effective against viruses?

Antibiotics only target bacteria because viruses have a different structure than bacteria. Bacteria have a cell wall and this is what antibiotics target but Viruses do not contain a cell wall so antibiotics render ineffective.

Why are penicillins often more effective against Gram positive bacteria than Gram negative bacteria?

Gram-positive has a more superficial cell wall that is made of peptidoglycans, and penicillin works directly on peptidoglycans It is easier to reach the cell wall than in gram-negative bacteria where it is under a the strong layer of plasma membrane

What class of antibiotics would you prescribe for Sue? Explain your answer.

I would prescribe sulfonamides, tetracyclines, or fluoroquinolones - anything but beta-lactam antibiotics. Because the penicillins inhibit the cell wall but because neisseria meningitidis in gram negative the cell wall is under another membrane bilayer making it harder to reach the cell wall.

examples of gram negative bacteria

Neisseria meningitides influenza B virus mononucelosis

Transformation

The genetic modification of a bacterium by incorporation of free DNA from another ruptured bacterial cell

Transduction

bacterial DNA is transferred from one bacterium to another inside a virus that infects the bacteria/ virus is called a "phage" - When a phage infects a bacterium, it essentially takes over the bacterium genetic processes to produce more phage -During this process, bacterial DNA is incorporated into the new phage DNA. During bacterial death (lysis) the new phage go and infect other bacteria -this brings along genes from previously infected bacterium.

conjugation

when 2 cells are in close proximity a hollow bridge made by the pilli forms. this allows plasmid to be transferred from one to another, enabling bacteria to acquire resistance. STEPS 1. F+ (donor) cell produces the pilus, which is the structure that projects out of the cell and begins contact with F- (recipient) cell. 2. The pilus enables direct contact between the donor and the recipient cells. 3. Because the F-plasmid consists of a double-stranded DNA molecule forming a circular structure, i.e., it is attached on both ends, an enzyme (relaxase, or relaxosome when it forms a complex with other proteins) nicks one of the two DNA strands of the F-plasmid and this strand (also called T-strand) is transferred to the recipient cell. 4. In the last step, the donor cell and the recipient cell, both containing single-stranded DNA, replicate this DNA and thus end up forming a double-stranded F-plasmid identical to the original F-plasmid.