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what are the 3 major shapes of bacteria?
coccus (round)
bacillus (rods)
spirilla (coils)
Bacteria are classified as gram-________ or gram-________
gram-positive or gram-negative
what is the diff between gram+ & gram- ?
gram+ has a thicker cell wall & stains purple while gram- stains pink.
Bacterial Cell walls are made of _____________>
peptidoglycan
what is peptiodglycan made up of?
2 glycan chains:
N-acetyl glucosamine (NAG)
N-acetyl muramic acid (NAM)
what gives peptidoglycan a strong & rigid 3D structure?
cross-linking between AAs achieved by the enzyme DD-transpeptidase.
whats an antibiotic?
medicine used to treat or prevent bacterial infection.
___________ are antibiotics that interfere with bacterial cell wall synthesis.
penicillins
how does penicillin interefere with cell wall synthesis?
it binds to transpeptidase enzymes to inhibit cross linking
what are porins & what to they do?
Outer membrane proteins that block the entrace of harmful chemical & antibiotics
why is gram- bacteria more diff to treat than gram+?
porins are more abundant in gram- bacteria.
define lipopolysaccharide (LPS)
a polysaccharide attached to a lipid which acts as an endotoxin
why does LPS act as an endotoxin?
it induces fever & shock in the human host
define pilus
hair like appendage required for bacterial conjugation (transfer of genetic material)
define capsule
Polysaccharide layer, contains water to prevent the cell from dying out, protects the cell from phagocytosis, helps adhere to surfaces
define plasmid
circular DNA with genes for bacterial virulence (ability of an organism to infect the host and cause a disease)
define flagellum
hair like appendage that enables movement & chemotaxis
define cytoplasm
fluid that fills the whole cell, house and maintain an optimal environment for the organlles
describe the cell membrane in 3 points
double phospholipid layer
embedded with proteins & other lipidss
plasma membrane controls passage of materials in & out of the cell
describe the nucleus in 3 points
largest organelle in the cell
DNA in nucleolus attached to histones to form chromat in
ribosomal RNA (rRNA) is made in the nucleolus
describe the mitochondria in 3 points
double membrane: outer membrane + folded inner membrane
matrix contains enzyme & some DNA
they produce ATP
what are the folds in the inner membrane of mitochondria called?
cristae
define lysosome
vesicle containing enzymes that break down proteins, lipids & nucleic acids
define peroxisome
vesicles that produce & decompose hydrogen peroxide
define centriole
A structure made of microtubules found in pairs near the nucleus
define centrosome
2 centrioles oriented at right angles to each other
define golgi apparatus
A series of flattened sacs that receive vesicles from the endoplasmic reticulum, modify, sort and package their contents and secrete it to other organelles.
define plasma membrane
a phospholipid bilayer that acts as a semi-permeable barrier in which proteins are embedded and act as receptors, pumps & channels.
