Microbiology Chapter 4 - Prokaryotes and Eukaryotes

What are diplococci?

Cocci that remain in pairs after dividing

What are streptococci

Cocci that divide and remain attached in chainlike patterns

What are tetrads?

Cocci that divide in two planes and remain in groups of four

What are sarcinae?

Cocci that divide in three planes and remain attahed in cubelike groups of eight

What are staphylococci?

Cocci that divide in multiple planes and form grapelike clusters or broad sheets

What does monomorphic mean?

Cocci maintain a single shape

What does pleomorphic mean?

Cocci have many shapes

What is glycocalyx?

A substance secreted by prokaryotes that surround a cell. It is a sticky polymer composed of polysaccharide, polypeptide or both

Made inside the cell and then secreted to the cell surface

Often described as a capsule or a slime layer

What is an extracellular polymeric substance (EPS)?

A glycocalyx that helps cells in a biofilm attach to their target environment and to each other

What are the general characteristics of a prokaryote?

One circular chromosome

No histones

No organelles

Bacteria with peptidoglycan cell walls

Archea with pseudomurein cell walls

Binary fission for reproduction

What are the general characteristics of a eukaryote?

Paired chromosomes in a nuclear membrane

Histones

Organelles

Polysaccharide cell walls

Mitotic spindle

Cocco-

Cluster

Strepto-

Strand

Diplo-

Paired

Vibrio

Slight curve, macaroni noodle

Spirillum

Thick spiral

Spirochete

Skinny spiral

When looking at the structure of a prokaryote, what is in between the capsule and the plasma membrane?

The cell wall

Capsule, cell wall, plasma membrane

What size ribosome is present in a prokaryote?

70s

What are the general characteristics of glycocalyx?

Outside of the cell wall

Sticky

Extracellular polysaccharide allows cell to attach

What is the difference between a capsule and a slime layer?

Capsule: protection from phagocytosis and usually neatly organized

Slime layer: unorganized and loose

How do cells move?

Utilize flagella to move toward or away from stimuli (taxis)

What are flagella proteins?

H antigens which are useful for distinguishing among variations in species

example: E. Coli 0157:H7

What are the flagella?

Long filamentous appendages that propel bacteria

What are atrichous?

Bacteria that lack flagella

What does peritrichous mean when referring to flagella?

It is distributed over the entire cell

What does polar mean when referring to flagella?

It is located at one or both ends of the cell

What does lophotrichous mean when referring to flagella?

A tuft of flagella coming from one pole

What does amphitrichous mean when referring to flagella?

Flagella at both poles of the cell

What is taxis?

The movement of a bacterium toward or a way from a particular stimulus

example: chemotaxis or phototaxis

What are general characteristics of fimbriae?

Present in many gram negative bacteria

Shorter, straighter and thinner than flagella

Can occur at the poles of the bacterial cell or can be evenly distributed over the entire surface of the cell

Involved in forming biofilms and other aggregations

Help bacteria adhere to epithelial surfaces

What are general characteristics of pili?

Usually longer than fimbriae and number only one or two per cell

Involved in motility and DNA transfer

What is twitching motility?

When a pilus extends by the addition of subunits of pilin, makes contact with the surface of another cell and then retracts (power stroke) as the pilin are disassembled

What is gliding motility?

The smooth gliding movement of myxobacteria

Provides a means for microbes to travel in environments with a low water content such as biofilms in soil

What is conjugation?

Bacterial sex

What is the cell wall of a bacterial cell?

Complex, semirigid, responsible for the shape of the cell. Keeps the cell from rupturing when the water pressure inside the cell is greater than that outside the cell

What is peptioglycan?

The macromolecule that makes up the bacterial cell wall

What are the general characteristics of a gram positive cell?

Purple

The cell wall consists of many layers of peptidoglycan, forming a thick structure

Plasmic space between the cell wall and plasma membrane

Teichoic acids

2 ring basal body

Disrupted by lysozome

Penicillin sensitive

What is the significance of teichoic acid?

Provides much of the wall's anigenic specificity and thus make it possible to identify gram positive bacteria

What are the general characteristics of a gram negative cell?

Pink

Thin peptidoglycan layer

Outer membrane

Periplasmic space between outer membrane and plasma membrane

4 ring basal body

Endotoxin

Tetracycline sensitive

What is the significance of the periplasmic space present in gram negative cells?

Contains a high concentration of dehydrative enzymes and transport proteins

What are porins?

Inermembranous proteins that create chanels to increase the permeability of the outer membrane

What is a lipopolysaccharide (LPS)

On the outer membrane, large molecule containing lipids and carbohydrates

lipid A

core polysaccharide

O polysaccharide

What is an atypical cell wall?

Acid-fast cell wall

similar to gram positive cell wall

waxy lipid bound to peptidoglycan

examples: mycobacterium and nocardia

What type of acid is present in acid fast cell walls?

Mycolic acid which prevents the uptake of dyes

What is a characteristic of the cell wall of mycoplasmas?

Lack cell walls

Sterols in plasma membrane

smallest known bacteria that can grow and reproduce outside the living host cells

What is a characteristic of the cell wall of an archaea?

Lack cell walls

Walls of pseudomurein

Typically unable to do gram staining but appear gram negative because lack peptidoglycan

How can a lysozyme be damaging to a cell wall?

Digest disaccharide in peptidoglycan

How can penicillin be damaging to a cell wall?

Inhibits peptide bridges in peptidoglycan

What is a protoplast?

A wall-less cell

What is a spheroplast?

A wall-less gram negative cell

What are protoplast and spheroplast susceptible to?

Osmotic lysis

What are L forms?

A wall-less cell that swell into irregular shapes

What is the plasma (cytoplasmic) membrane?

Thin structure lying inside the cell wall and enclosing the cytoplasm of the cell

What is the fluid mosaic model?

The dynamic arrangement of phospholipids and proteins

What is facilitated diffusion?

Solute combines with a transporter protein in the membrane

What is osmosis?

The movement of water across a selectively permeable membrane from an area of high water concentration to an area of lower water concentration

What is osmotic pressure?

The pressure needed to stop the movement of water across the membrane

What is simple diffusion?

The net overal movement of molecules or ions from an area of high concentration to an area of low concentration

What is an isotonic solution?

A medium in which the overall concentration of solutes equals that found inside a cell

Water leaves and enters the cell at the same rate; the cells contents are in equilibrium with the solution outside the cytoplasmic membrane

What is a hypotonic solution?

What is a hypotonic solution?

What is a hypertonic solution?

A medium having a higher concentration of solutes than that inside the cell

Cells shrink and collapse or plasmolyze because water leaves the cells by osmosis

What do the terms isotonic, hypotonic and hypertonic describe?

The concentration of solutions outside the cell relative to the concentration inside the cell

What is active transport?

Requires a transporter protein and ATP

What is a group tansolcation?

Requires a transporter protein and PEP

occurs exclusively in prokaryotes

What is a nucleoid?

Bacterial chromosome which is a single long continuous, circularly arranged thread of double stranded DNA

What is a plasmid?

Small, circular, double stranded DNA molecules also found in a bacteria

What are the general characteristics of a ribosome?

Protein synthesis

70s for bacteria

50s + 30s subunits (rRNA)

What is an inclusion?

Metachromatic granules (volutin) - phosphate reserves

Polysaccharide granules - energy reserves

Lipid inclusions - energy reserves, reserve deposits

Sulfur granules - energy reserves

Carboxysomes - ribulose 1, 5 diphosphate carboxylase for CO2 fixation

Gas vacuoles - protein covered cylinders

Magnetosomes - iron oxide (destroys H2O2)

Endospores

Resting cells

Resistant to desiccation, heat, chemicals

Bacillus, Clostridium

What is sporulation?

Endospore formation

What is germination?

Endospores return to vegetative state

What are the 6 steps in the formation of endosporses by sporulation?

1. Spore septum begins to isolate newly replicated DNA and a small portion of cytoplasm

2. Plasma membrane starts to surround DNA, cytoplasm and membrane isolated in step 1

3. Spore septum surrounds isolated portion forming forespore

4. Peptidogylcan layer forms between membranes

5. Spore coat forms

6. Endospore is freed form cell

What is the difference between the ribosomes found in prokaryotes vs eukaryotes?

Eukaryotes ribosomes deal with protein synthesis and are 80s, membrane bound when attached to ER but also free in cytoplasm

Prokaryotes ribosomes are in chloroplasts and mitochondria and 70s

What is the endosymbiotic theory?

The theory explaining the origin of eukaryotes from prokaryotes

Pioneered by Lynn Margulis

Larger bacterial cells lost their cell walls and engulfed smaller bacterial cells