General Microbiology

Difference Between Prokaryotic And Eukaryotic Cell

By Jamseel.M

CellThe cell  Latin cella, meaning "small room.Basic structural, functional and biological unit of all known living organisms. 

Cells are the smallest unit of life that can replicate independently, 

"building blocks of life“There are two types of cells, eukaryotes, which contain a nucleus, and prokaryotes, which do not. 

PROKARYOTIC CELLS

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:

1. A filament that rotates for movement2. A hook where the filament attaches3. A basal body that anchors the hook to

the cellThe arrangement of the hook/basal body

articulation allows the hook with its filament to rotate 360o

Arrangements of Flagella

Axial filaments

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.

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

The protoplasm or cytoplasm

o Dense gelatinous solution within the cell membrane 

o  Primary site for the cell’s biochemical and synthetic processes.  

Nuclear region

chromatin body or the bacterial chromosome 

Nucleoid or nuclear region of the cell that is associated with the chromatin body

Plasmids Plasmids are tiny circular extra chromosomal 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.

Inclusions or granules

Shapes and arrangements of bacteria

FUNGI

Fungi are eukaryotic protista; differ from bacteria and other prokaryotes.

1. Cell walls containing chitin (rigidity & support) ,other polysaccharides

2. Cytoplasmic membrane contains ergosterols

3. Possess true nuclei with nuclear membrane & paired chromosomes.

4. Divide asexually, sexually or by both5. Unicellular or multicellular

• Simplest fungus :- Unicellular budding yeast

• Hypha :- Elongation of apical cell

produces a tubular, thread like structure called hypha

• Mycelium :- Tangled mass of hyphae is

called mycelium. Fungi producing mycelia are called molds or filamentous fungi.

• Hyphae may be septate or non-septate

CLASSIFICATION

• Depending on cell morphology 1. Yeasts2. Yeast like fungi 3. Molds 4. Dimorphic fungi 

Eukaryotic Cell

CELL MEMBRANEStructureComponentsArrangement 

Functions

BarrierTransport (know diffusion, osmosis, facilitated diffusion and active transport)Recognition (e.g., self vs. non-self)Reception (for protein hormones)Adhesion

Nucleus

Structure and Function

– membrane similar to cell membrane (similar function)

– Nucleolus (formation of ribosomes)

– Chromosomes (gene expression)

– Nucleoplasm (matrix)

Ribosomes Structure

– rRNA–Proteins

Function– Site of protein formation (translation)

Found in both prokaryotes and eukaryotes (different structurally)

Endoplasmic Reticulum Structure membranous

system of tunnels and sacs– Rough – with

ribosomes on surface

– Smooth- no ribosomes on surface

Function– Rough – protein

synthesis– Smooth- lipid

synthesis

Golgi Apparatus

Structure also membranous, kind of like a stack of pancakes

Function processing of lipids and proteins

LYSOSOMES

Structure Membrane bound sac containing

hydrolytic enzymes Function Digestion

Mitochondria

Structure – cigar-shaped, double membrane-bound organelle

Function – Energy transfer by ATP synthesis

Chloroplast

Structure Also cigar or spindle shaped, double membrane-bound, green

Function photosynthesis

Other structure

• Cell walls, not in animal cells• Vacuoles• Cytoskeleton• Cytoplasm

Differences Between Prokaryotic and Eukaryotic cells

No

Features

1. Occurrence

Prokaryotic cells are the characteristic of bacteria and blue green algae

These are cells are found in all, animals and plants, except blue green algae and bacteria.

2.

 Size

 Mostly 1-10 μm

Mostly 10-100 μm

3. Multicellular forms

   RareCommon, with extensive tissue formation

4. Cell wall

Present in most but not in all cells. In Bacteria, cell wall is made up murein,polysaccharides, lipid and proteins.

The animal cells lack cell wall, but plants cell wall is made up of cellulose and chitinous cell wall is present in fungi.

5.Plasma membrane

Present

PPresentresent

Present

6

Nucleus

7.Nuclear Membranes

Absent Present

8. Chromatin with histone

Absent Present

9. Number ofchromosomes

Each cell Has only one chromosome

Number of chromosomes per cell depends upon the type of organism.

10 Chromosome The Chromose is circular ringlacking a centromere.

 Each chromosome is linear having a centromere  

11.

Genetic material Circular or linear, double stranded DNA: only exons are present

 Linear doublestranded DNA:genes frequentlyinterrupted byintron sequences, especially inhighereukaryotes(called as splitgenes).

 

12Nucleoli and Mitotic apparatus

Absent Present

13. Nucleolus Absent Present (for the synthesis and organization of ribosomes)

14. Plasmid Commonly present

Rare

15 Mesosomes Mesosomes perform the function of Golgi bodies and mitochondria, and also help in the separation of chromosomes during cell division.

Absent

Mitochondria Absent PresentEndoplasmic Reticulum

Vacuoles

Absent

Absent

Present

Present

16. Cell organelles

Lysosomes Absent Present

Chloroplast Absent Present

Centrioles Absent Present

Ribosomes Only 70S type of ribosomes are present which lie free in cytoplasm, or are engaged in protein synthesis.

The cytoplasm has 80S type of ribosomes; and plastid and mitochondria have 70 S

Microtubules Absent Present

Flagellae

 

Simple structureComposed of theprotein Flagellin. 

 

Complex 9+2 Structure of tubulin and other protein. 

 Respiration

 Many strict anaerobes

 All aerobic, but somefacultative Anaerobes By secondary modifications. 

17

18

 

Photosynthetic Enzymes

 Bound toplasmamembrane ascompositechromatophore

 

Enzymespackedin plastidsbound by membrane 

 

19  Metabolic Patterns

 

 Great Variations 

All share cytochromeelectron transportchains, Krebs cycleoxidation, glycolysis.

 

 

 

 

20

 

 

 

 Sexual System

 

Rare: If present oneway (and usuallyforming partial diploids ormerozygotes)

 

Both sexes involved in sexual participation and entire genomes transferred 

21

Cyclosis

There are nostreamingmovementsof cytoplasm

Cytoplasmshows streaming movements

22

Protein

Synthesis

Transcriptionand translationtake place incytoplasm.

Transcriptionoccurs innucleus and translationtakes place incytoplasm.

23

Durationof cellcycle

Cell cycle is short,takes 20-60minutesto complete.

Cell cycle islong, takes 12-24 hours tocomplete.

CONCLUSION

Cell are basic unit of organization or structure of all living matter

There are two types of cell,that are prokaryotic and eukaryotic cell

There are are so many difference in between them include occurance,size,cell wall,  nucleus ,nuclear  membrane, cell organelles respiration, sexual system ,protein synthesis.

REFERENCE Prescott LM Harley JP and Klein DA-MicrobiologyJohn Webster-Introduction to fungiVoet and voetTortora-Microbiology an introductionPelczar Jr.MJ Chan,Ecs and Kreig-MicrobiologyLehninger’s principle of biochemistry