Structure of Prokaryotes Flashcards
cell wall
peptidoglycan, pollysaccharide+amino acids
or
murein
whihc part is analogous to lysosome
The space between cell wall and cell membrane is known as periplasmic space. This
space, is analogous (functionally same) to lysosome because in this space the
digestion of complex substance is done.
nucleus
In Prokaryotic cell, the nucleus is primitive. The nucleus of prokaryotes is also known
as incipient nucleus, genophore, nucleoid or fibrillar nucleus. Nuclear membrane is
absent around nucleus. It also lacks nucleolus.
chromosome
Prokaryotes also lack the true chromosome. Instead of it, a false chromosome is
present, which is made up of ds circular naked DNA and polyamines. This false
chromosome coils and forms the chromosomal region, which is known as nucleoid.
peritrichous meaning
surrounded with flagella
explain the 3 parts of flgaella
(i) basal body
It is the basal part of flagellum and rod shaped in structure.
It lies with in the cell wall and cell membrane
This proteinaceous rod shaped structure is surrounded by two pairs of
rings
(ii) hook
It connects the basal body to filament
It is the middle part of flagellum
(iii)
Longest portion and extends from the cell surface to the outside.
It is cylindrical hollow structure made up of protein monomers.
Each monomer is made up of Flagellin protein. Monomers are arranged
in spiral manner. Flagellin is a contractile protein.
what are types of pili
Longer pili are also known as ‘F’ pili or ‘sex’ pili. Longer pili occur in only donor
(F+ or male) bacteria and help in conjugation. These are absent in recipient
bacteria or female.
(c) The shorter pili take part in attachment to rocks in streams and to the host
tissue. These are also known as ‘infective’ pili or Fimbriae.
structure of pili
Every pilus is cylindrical hollow structure and composed of protein monomers.
Each monomer is made up of ‘pilin’ protein. Pilin is non-contractile protein.
Pili do not play role in motility.
structure and func of glycocalyx
made of polysacchardes and polypeptides
Glycocalyx protects the bacteria from W.B.C. and also helps in colony
formation.
types of plasmid
F-plasmid (fertility factor) – On the basis of presence or absence of ‘F’
plasmid, there are two types of bacteria.
(a) F – Cells, carrying ‘F’ plasmid, act as donor and are called F+ or male.
(b) F – Cells, lacking ‘F’ plasmid, act as recipient and are called F- or female.
When ‘F” plasmid is attached with main DNA, it is designated as Episome and
this type of cell is known as Hfr cell. (Hfr – Highly frequent recombinant) cell
R-factor - Resistance to certain antibiotics.
Ti plasmid- tumor inducing plasmid
what is photosynetheic structure
In bacterial cytoplasm many photosynthetic pigments are present.
In purple bacteria (sulphur & non-sulphur) : Bacteriochlorophyll a & b, bacteriopurpurin
In green sulphur bacteria : Bacteriochlorophyll a, Bacterioviridin
photoautotrophic bactera
These bacteria use light energy for food synthesis.
In bacterial photosynthesis H-donor is not water, so they do not release
oxygen during photosynthesis hence this is called Non-oxygenic
photosynthesis.
– Purple sulphur bacteria – e.g. Chromatium,gives s2 gas
– Green sulphur bacteria – e.g. Chlorobium, Thiothrix, gives s2
– Purple non sulphur bacteria – e.g. Rhodospirillum, Rhodopseudomonas,no s2
explain chemoautotrophic
Chemical energy is obtained by oxidation of chemical compounds
(Inorganic or organic)
e.g. - Nitrifying bacteria – They oxidise nitrogenous compounds and obtain
energy.
nitrogen –rhizobium—nh3—-nitrosomonas/nitrococcus—-no2—-nitrobacter—-no3
respiration
On the basis of respiration bacteria are of two types
Aerobic bacteria :-They use oxygen in respiration.
e.g. Azotobacter, Acetobacter aceti (it causes souring of wine), Clostridium tetani
Anaerobic bacteria :- They do not use oxygen in respiration.
e.g. Clostridium botulinum, Fermentation bacteria (Lactobacillus) except
Acetobacter aceti. Lactobacillus causes souring of milk.
who differentiate bacteria on the basis of staining
HC Gram differentiates into gram +ve and gram -ve bacteria
gram+ve bacteria retian crystal violet stain while gram -ve bacteria loose the crystal violet and take up saffranin when aceton/alcohol is added.