Introduction to Prokaryotic Cell

Question 1

State some examples for Prokaryotic Cells

Answer 1

• Bacteria
• Blue green Algae
• mycoplasma
• PPLO ( Pluero-Pnumeonia Like Organism.

Question 2

what are the Basic Properties of Prokaryotic Cells?

Answer 2

• They are small
• multiply rapidly
• vary greatly in size

Question 3

what are the basic Shapes of Bacterial Cell?

Answer 3

• Bacillus (Rod shaped)
• Vibrio (Comma shaped)
• Spirillium ( Spiral Shaped)
• Coccus (spherical Shaped)

Question 4

comment on the organization of prokaryotic Cell

Answer 4

The organisation of prokaryotic cell, is fundamentally similiar even if it exhibits wide variety of shapes and function.

Question 5

what are the outermost layers of a prokaryotic bacteria?

Answer 5

All prokaryotes have a cell wall being outermost layer and cell membrane within it, however mycoplasma is an exception.

Question 6

comment about the Cytoplasm in Prokaryotic Cell

Answer 6

The fluid matrix, filling the cell is know as cytoplasm, there is no well defined nucleus

Question 7

if prokaryotic cell doesnt have well defined nucleus does it mean it doesnt have any genetic material at all?

Answer 7

The genetic material in prokaryotic cell is usually naked , not enveloped by nuclear membrane

Question 8

do we know the nature of genetic material, if yes elaborate more on it

Answer 8

Yes, its a single chromosome and circular in shape known as a genomic DNA.

Question 9

What are Plasmids?

Answer 9

In addition to the genomic DNA there are small circular DNA outside the genomic DNA, known as Plasmid

Question 10

List out the Functions of Plasmid

Answer 10

• Confer certain type of phenotypical characterstics, such as
  Eg: resistance to antibiotics
• Plasmid DNA is used to monitor bacterial transformation with Foreign DNA

Question 11

Describe about the Special Inclusions in prokaryotic cell?

Answer 11

A specialised differentiated form of cell membrane, known as mesosomes. it has extensions of cell membrane, these extensions are in the form of vesicles, tubules and lamellae

Question 12

Functions of Mesosomes

Answer 12

they help in
-DNA replication
- DNA formation
-distribution of daughter cells
- respiration
- secretion
- increase the surface area of
~ plasma membrane
~ enzymatic content

Question 13

What is unique about Cyanobacteria?

Answer 13

In Cyanobacteria, their are membranous extensions into cytoplasm known as chromatophores which contain certain pigment

Question 14

comment on Cell Envelope and Modifications

Answer 14

most prokaryotic cells, most particularly bacterial cells have a chemically complexed, tightly bound three layered structure known as cell envelope.

Question 15

describe about the Layers

Answer 15

outermost is glycocalyx, followed by cell wall , followed by cell membrane

Question 16

what are the common Functions of the layers

Answer 16

although each layer of cell are distinct function but together they act as a single protective unit.

Question 17

Explain the Classification of Bacteria based on how they respond to the staining procedure developed by Gram Viz?

Answer 17

the cells which take up the stain are known as gram positive

the cells which do not take up the stain are known as gram negative

Question 18

What is the Difference in composition and thickness of Glycocalyx in bacterias?

Answer 18

• It could be loose sheath called slime layer
  -in some others it may be thick and tough known as capsule.

Question 19

comment on the role of Cell wall?

Answer 19

Cell wall it helps in
determining the shape of cell
provides strong structural support to cell preventing it from bursting or collapsing

Question 20

comment on the role of Plasma Membrane?

Answer 20

is selectively permeable in nature and acts with outside world

Question 21

can cells be Motile or non motile?

Answer 21

Bacterial cells may be motile or non motile

Question 22

What if they are motile?

Answer 22

if they are motile they have thin filamentous extensions from their cell wall called flagella

Question 23

what are the three parts of flagella?

Answer 23

Bacteria show a range in number and arrangement of flagella. Bacterium Flagellum is composed of three parts
- Filament
- Hook
- Basal Body

Question 24

what is a Filament? (in terms of flagella)

Answer 24

Filament is the longest portion of flagella, extends from cell surface to outside

Question 25

What are Pili and Fimbriae

Answer 25

Besides Flagellum, Pili and Fimbriae are surface structures however they do not take role in motility.

Question 26

What are Pili?

Answer 26

are long tubular structures made of special proteins

Question 27

What are fimbriae?

Answer 27

Fimbriae, are tiny bristle like fibres sprouting from cell surface

Question 28

what are the Functions of Fimbriae?

Answer 28

• they help the bacteria to attach to the rocks in steam
• to host tissues

Question 29

what are Ribosomes

Answer 29

Ribosomes are associated with plasma membrane

Question 30

What is the Size of Ribosomes?

Answer 30

15 nm by 20nm

Question 31

comment on its Sub units?

Answer 31

They are made of 50S and 30S units when present together 70S

Question 32

what is the Function of Ribosomes?

Answer 32

site of protein synthesis

Question 33

What do ribosomes?

Answer 33

several ribosomes attach to single M(RNA) molecule to become polyribosomes or polysomes, the ribosomes Polysomes translate the RNA into proteins.

Question 34

what are inclusion bodies?

Answer 34

Reserve material in prokaryotic cell are stored in cytoplasm in the form of inclusion bodies, these are not bound by membrane system and lie freely in cytoplasm

eg: phosphate granules
cyanophacean granules
glycogen granules

Question 35

where are the gas vacuoles found?

Answer 35

gas vacoules are found in blue green and purple and green photosynthetic bacteria