PROKARYOTIC STRUCTURE

matthias shcleiden and theodor schwann

CELL THEORY: suggested that all organism

Rudolph Virchow

CELL THOERY: suggest that cells come only from preexisting cells because cells are self reproducing.

1mm - 1um

CELL RANGES IN SIZE

true, surface-area-to-volume relationships

T OR F : The surface-are-to-volume ratio requires that cells be small

large cell

LARGE CELL OR SMALL CELL : surface area relative to volume decreases, which also decreases the efficiency of transporting materials in and out of the cell.

small cell

LARGE CELL OR SMALL CELL - larger surface-area-to-volume ratio is advantageous for enhancing molecules

Magnification

- is the ratio between the size of an image and its actual size

Resolution

is the minimum distance between two objects that allows them to be seen as two separate objects

eukaryotic

WHICH CELL TYPE
Have nucleus and other membrane-bound organelles 

• Are also much larger than prokaryotic cells

• Compartmentalized 

• Contains small structures called organelles which perform specific functions

• Isolate reactions from other reactions

prokaryotic

WHICH CELL TYPE:

• Lack a membrane-bound nucleus 

• Structurally smaller and simpler than eukaryotic cells (which have a nucleus)

bacteria

• cause disease but are also environmentally important as decomposers

Can be useful in manufacturing products and drugs

archaea

live in extreme habitats

spirillum

if rigid spiral shape

spirochete

if flexible spiral shape

bacillus

rod shaped

coccus

sphrecial shape

Plasma Membrane

Lipid bilayer with embedded and peripheral proteins 

Can form internal pouches (mesosomes), which increase surface area.

Cell Wall

Maintains the shape of the cell and is strengthened by peptidoglycan. Also helps determine if gram-positive or negative.

Glycocalyx

Layer of polysaccharides on the outside of the cell wall

monococcus

diplococcus

staphylococcus

tetracoccus

streptococcus

sarcina

bacillus

coocbacillus

palisades

diplobacillus

spore former

streptobacillus

bacilli

rods, the length to width ratio differ.

vibrio

comma shaped

Mycelium (Fungi)

network of long filaments (hyphae)

Pleomorphic

organism that are variable in shape

flagella

provide motility

fimbriae

small,bristle like fibers that sprout from cell surface

conjugation pili

rigid, tubular structures used to pass dna from cell to cell

Nucleoid

Region that contains a single, circular DNA molecule

Cytoplasm

• Semifluid solution

• Encased by plasma membrane

Contains water,inorganic and organic molecules, and enzymes.

Ribosomes

• Are tiny structures in the cytoplasm that synthesize proteins 

cell membrane

• A living boundary between the cell and the environment

• Made up of phospholipids, and integrated proteins and carbohydrates.

plasmids

• Are small accessory (extrachromosomal) rings of DNA ( can be circular or linear) 

capsules

• well-organized layers made of polysaccharides. A thick layer secreted by the cell over the cell wall that serves a protective (desiccation, chemicals) as well as an attachment function.

slime layers

polysaccharide layers that are unorganized.

glycocalyx

polysaccharide extension that aids in attachment to solid surfaces

s-layres

geometric pattern made of protein that aid in protecting from ion and pH fluctuations.

peptiodglycan

, components are referred to as NAG and NAM, has peptide cross-links

simple stain

• Does not specifically stain an organelle

Used to determine cell size, shape, and arrangement

iodine, methylene blue

example of simple stain

differential stain

• More complex- gives specific information about the cell

Used to compare cell structures and different cells

gram stain

example of differential stain

primary stain (1)

GRAM STAIN STEP: Crystal Violet 

• Stains both gram-postive & gram negative bacteria

mordant: gram’s iodine (2)

GRAM STAIN STEP: Enters bacterial cell & forms iodine crystal violet complexes

decolorizer: acetone or alcohol (3)

GRAM STAIN STEP:
Gram-positive bacteria; iodine crystal violet dye complex is trapped in cells → gram-positive remains purple

Disrupts thin cell wall of gram-negative bacteria; iodine-crystal violet dye complex escapes cells → wgram-negative cells become clear

Counterstain: Safranin

GRAM STAIN STEP: Strain cell wall of cells

• Purple of gram-positive cells masks pink color & remain purple

Unstained gram-negative cells become pink

gram postive bacteria

Have thick layer of peptidoglycan in their cell walls

gram negative bacteria

Bacteria have a small amount of peptidoglycan, but have an outer membrane much more complex than the cell wall

bacterial cytoplasm

Makes up the largest part of the inside of the cell

many metabolic reactions take place in cytoplasm

Intracytoplasmic Membranes

It is plasma membrane invaginations, created as a plasma membrane infoldings

ribosomes

• Composed of rRNA, non-membraned bound organelles found throughout the cytoplasm of bacteria

Consist of alarge subunit and a small subunit

nucleoid

• The are in the cytoplasm where the mostly DNA, some RNA and some proteins are located 

• NOT membrane bound 

• Circular

• Usually only 1 strand, but there may be exceptions

plasmids

• Small extrachromosomal DNA molecules

• Carry genes that are NOT essential for survival

conjugation

• The process by which one bacterium transfers genetic material to another through direct contact using sex pili 

flagella

• Long, thin helical appendage used for mobility

• Arrangement of flagella can be used to classify bacteria

atrichous

monotrichous

amphitrichous

cephalotrichous

peritrichous

lophotrichous

Filament

extends from cell surface to the tip

Basal Body

embedded in cell envelope 

hook

 short curve segment

swimming

flagellar movement: Flagellum rotates like a propeller

• Very rapid rotation up to 1100 revolutions/sec

swarming

flagellar movement: Occurs on when cells move in unison across a moist surface

Most swarmers have peritrichous flagella

spirochete motility

flagellar movement:

• Multiple flagella from axial fibril which winds around the cell

• Flagella remain in inside the cell wall

• Moves like snakes

Corkscrew shape exhibits flexing and spinning movements

Twitching and gliding motility

• Occurs on solid surface

• Does not involve flagella

Similar to a snail

Chemotaxis 

• Movement toward a chemical attractant or away from a chemical repellent. 

chemoreceptors

that transmit signals throughout the chemosensing system to signal movement.

pili

Tiny hollow projections that help the bacteria adhere(stick) to surfaces

and is not involved in movement

fimbriae

short attachment pili

sex pili

: long, modified for transfer of genes between cells in a process called conjugation

endospores

• A resting stage 

• A way of survival when conditions are not favorable