Prokaryotic and Eukaryotic Cells

In general microbes or microorganisms may be either prokaryotic bacteria or eukaryotic protists, fungi, and some animals.. Appendages are basically involved in movement or adhesion Flage

Prokaryotic and Eukaryotic Cells

Structure and Function

In general microbes or microorganisms may be either prokaryotic (bacteria) or eukaryotic (protists, fungi,

and some animals)

However, there are some microbial organisms that appear to be intermediates between prokaryotes and eukaryotes (they possess a nucleus but do not have

mitochondria or chloroplasts, an example is Giardia

intestinalis

Prokaryotes differ from eukaryotes in several ways including but not limited to:

Characteristics Prokaryotic Eukaryotic

protists)

PROKARYOTIC

CELLS

Key Functions of Cells

A boundary that keeps the cellular contents

separate from the external environment but allows for the transfer of some substances into and out of the cell.

Replication of DNA

Synthesis of cellular components

The ability to obtain energy through metabolic

processes

Appendages are basically involved in

movement or adhesion

Flagella (singular flagellum)

are cellular appendages that

consist of three parts:

•a filament that rotates for

movement

•a hook where the filament

attaches

•a basal body that anchors the

hook to the cell

•the arrangement of the

hook/basal body articulation

allows the hook with its

filament to rotate 360 o

Arrangements of Flagella

polar - flagella are attached at

one or both ends of the cell

monotrichous - a single flagellum at one end lophotrichous -

multiple flagella arising

from one or both ends

amphitrichous – a single flagellum arises

from each end

peritrichous - flagella are

randomly dispersed over the

cell surface

Axial filaments

are modified flagella that

occur in spirochetes

Non-locomotor appendages

Pili are longer and sparser

than fimbriae

fimbriae are involved in

adhesion and pili (found

only in Gram - bacteria)

are involved in

conjugation ( a “mating”

process)

Cell envelopes differ between taxa but they basically consist of three

layers:

The capsule or slime layer

(outermost layer) differs greatly in

thickness, organization and chemical

composition depending on the

bacterial species T

Beneath the outer layer lies the cell

wall

The cell membrane is a thin flexible

sheet that surrounds the contents of

the bacterial cell Its functions

include: transport, energy extraction,

nutrient processing, and synthesis

The Gram Stain

An important tool in the

identification of bacteria is the

Gram stain Some bacteria are

Gram + while others are Gram -

(some however, do not show a

Gram reaction) Gram + bacteria

stain purple (the color of the

primary dye) and Gram - bacteria

stain pink (the color of the

counterstain or second dye) The

Gram stain is a differential

staining technique because

different species of bacteria stain

differently The difference is a

result of the composition of the

cell wall.

The protoplasm or cytoplasm

is the dense gelatinous

solution within the cell

membrane that is the

primary site for the cell’s

biochemical and synthetic

processes The following

are found within the

protoplasm of the

prokaryotic cell:

chromatin body or the

bacterial chromosome

nucleoid or nuclear region

of the cell that is

associated with the

chromatin body

plasmids are tiny circular extrachromosomal

strands of DNA

ribosomes are small

structures consisting of RNA and proteins that are involved in protein

synthesis

inclusions or granules are areas where nutrients are concentrated

Endospores are dormant structures produced by

some species of Bacillus and Clostridium

Shapes and arrangements of bacteria

There are six common

shapes of bacteria: coccus,

bacillus, coccobacillus,

vibrio, spirochete, and

spirullum and there are

Eukaryotic Cell

Recognition (e.g., self vs non-self)

Reception (for protein hormones)

Adhesion

Structure and Function

– membrane similar to cell