Chapter 4: A Survey of Prokaryotic Cells and Microorganisms

what is life's unit of structure and function

the cell

the cell is the ___ level of organization

lowest

the cell performs what

all activities of life

what are characteristics of all cells

a plasma membrane that creates distinct internal and external environments, store and transmit information use DNA (RNA), and process energy obtained from the environment

how are eubacterial cells defined

by shape, arrangement, and size

what shapes are most common in eubacteria

cocci and rods

how is arrangement determined for eubacteria

plane of division and ability to separate

cocci

spheres

diplococci

pairs

streptococci

chains

staphylococci

grape like clusters

tetrads

4 cocci in a square

sarcinae

cubic configuration of 8 cocci

bacilli

rods

coccobacilli

very short rods

vibrios

resemble rids, comma shaped

spirilla

rigid helices

spirochetes

flexible helices

mycelium

network of long, multinucleate filaments

pleomorphic

organisms that are variable in shape

what is the smallest prokaryotic size

mycoplasma, 0.3 micrometer

what size is the average prokaryotic rod

E.coli 1.1 to 1.5 by 2 to 6 micrometer

how big is the biggest prokaryotic size

Epulopiscium fishelsoni, 600 by 80 micrometer

how is a prokaryotic cell organized

internal structures, cell envelope, layers outside the cell envelope, external appendage structures

what does the cell envelope contain

plasma membrane and cell wall

what do the layers outside the cell envelope contain

glycocalyx (capsule or slime layer) and s layers

what do the external appendage structures contain

pili, fimbriae, flagella

what do the bacterial external structures function in

protection, attachment to surfaces, horizontal gene transfer, cell movement

pili is mostly found in

gram negative bacteria

what are fimbriae

short, thin, hairlike, protein appendages (up to 1000 per cell)

what can fimbriae mediate

attachment to surface, motility, and DNA uptake

what are sex pili

longer, thicker, and less numerous that are 1 to 10 per cell

sex pili are used where

genes for formation on plasmids

sex pili are required for

conjugation

sex pili are rarely used in

motility

what is taxis

the ability to move toward or away from from a stimulus

what are bacteria flagella different from

structurally and functionally different from eukaryotic flagella

what is periplasmic flagella

internal flagella, enclosed in the space between the outer sheath and the cell wall peptidoglycan

what do periplasmic flagella produce

cellular motility by contracting and imparting twisting or flexing motion

what are s layers (surface layer)

regularly structured self assembling laters of protein or glycoprotein

where are s layers found

found in almost all archaea, found in some bacteria (mostly gram negative)

what are some functions of the s layer

important for growth and survival, protect from ion and pH fluctuations, osmotic stress, enzymes, and predation, maintains shape and rigidity, promotes adhesion to surfaces, protects from host defenses

what do glycocalyx contribute to

pathogenicity

what is the coating of molecules external to the cell wall in the glycocalyx made up of

sugars and or proteins

what does the coating of the glycocalyx do

protects from dehydration, nutrient loss, inhibits phagocytosis by white blood cells

what does glycocalyx aid in

attachment to solid surfaces - biofilm formation

how many types of glycocalyx are there

2

what are the two types of glycocalyx

slime layer which is loosely organized and attached, and capsule which is highly organized and tightly attached

what does the eubacterial cell wall maintain

shape

what does the eubacterial cell wall help

protect cell from osmotic lysis and toxic materials, a cell is happy when it is turgid

what does the eubacterial cell wall possibly contribute to

possible pathogenicity

domain bacteria is composed of

peptidoglycan

what are the two types of bacteria based on gram stain

gram positive and gram negative

what color do gram postive bacteria stain

stains purple

what type of peptidoglycan do gram positive bacteria have

thick peptidoglycan

what type of acids do gram positive bacteria have

teihoic acid and lipoteichoic acid

what kind of membrane do gram positive bacteria have

selectively permeable

what color do gram negative bacteria stain

pink or red

what type of peptidoglycan do gram negative bacteria have

thin peptidoglycan

what membranes are present in gram negative bacteria

an inner and outer membrane

what are lipopolysaccharides in gram negative bacteria known for

they may become toxic when released during infections due to endotoxin and can also function as receptors and block the immune system

what are porin channels in gram negative bacteria used for

they regulate molecules entering and leaving the cell

what type of proteins are found in gram negative bacteria

lipoproteins

why are gram negative bacteria harder to treat

because of two plasma membranes

what is horizontal gene transfer

when a fully functional vegetative adult gives genetic information to another fully functional vegetative adult and that adult expresses those genes immediately

what is vertical gene transfer

when a male and female come together and make a new generation

a cell wall that is specific to a pathogen is what

a target, anything unique is a target

NAM and NAG in peptidoglycan formation

both sugars, monomers bonded by glycosidic linkage

what is the formation of a peptidoglycan

pentapeptide linking NAM to NAM, strands are cross linked once glycosidic bonds are gone in order to make a stronger peptidoglycan through transpeptidase

what is peptidoglycan

a huge three dimensional latticework that supports the cell

what do peptidoglycan strands form

helical structures

why are peptidoglycan chain cross linked by pentaglycine

for strength

what do transpeptidase enzymes form

the peptide cross links between the rows and layers of peptidoglycan to make the wall strong

what do gram positive stains sometimes have

periplasmic space

why are internal organelles needed

to create an electron transport chain so that a proton gradient can be made

how do prokaryotes make a hydrogen ion gradient

since they lack a compartment to make a hydrogen ion gradient, they do it through periplasmic spaces

what do prokaryotes utilize

everything they have

gram negative bacteria has larger what

periplasmic spaces

how does a gram stain work

the sample is fixed and crystal violet is applied which makes loose associates, iodine treatment shrinks and tightens the cell and traps crystal violet

what happens to peptidoglycan in a gram stain

thick peptidoglycan gets trapped while thin peptidoglycan gets washed out

what does the counter stain in gram stain do

safranin attaches to lipids and thus the plasma membrane and all bacteria which provides a negative control

what is the summary of a gram positive stain

simple walls, large amounts of peptidoglycan, traps crystal violet

what is the summary of a gram negative stain

less peptidoglycan, crystal violet rinsed away, toxic outer membrane, and likely to be antibiotic resistant

domain archaea cell walls contain and lack what

contain polysaccharides and proteins but lack peptidoglycan

what do scientists use the gram stain for

to classify bacteria by cell wall composition

what is a plasma membrane

a phospholipid bilayer with embedded proteins

what does a plasma membrane encompass

cytoplasm

what kind of membrane does a plasma membrane have

selectively permeable

how do proteins in a plasma membrane interact

with environment

a plasma membrane must contain

hydrophobic and hydrophilic regions

a plasma membrane detects

environment

plasma membrane proteins transport solutes via

protein channels (tunnels)

what is metabolic process

using energy to actively transport molecules into or out of the cell

what is cell cytoplasm

dense, gelatinous solution of sugars, amino acids, and salts that is 70-80% water serving as a solvent for materials used in all cell function

what do prokaryotic cells lack

complex compartmentalization

what do some prokaryotes have

specialized membranes that perform metabolic functions

what does cytoskeleton do

participate in cell division, localize proteins, determine cell shape

what are intracytoplasmic membranes

plasma membrane infoldings

what are intracytoplasmic membranes important for

high respiratory or photosynthetic prokaryotes

what are inclusions

granules, crystals, or globules of organic or inorganic material stockpiled for future use