2 Cell Structure

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.