Featured Posts

[it][feat1] [science][feat1]

Nadra Technologies Limited NTL Islamabad Job Interview 2022

10:02 PM
NADRA National Database & Registration Authority nadra.gov.pk Jobs

Date Posted / Updated:
02 December, 2022
Category / Sector:
Vacancy Location:
Islamabad, Punjab, Pakistan
Job Industry:
Job Type:
Full Time
Expected Last Date:
20 December, 2022
or as per paper ad

Nadra Technologies Limited NTL Islamabad, Islamabad Islamabad Pakistan invites applications from eligible candidates for the post of security guard and data entry executive as per advertisement of December 2, 2022 published in daily Ausaf Newspaper. Candidates with Bachelor, Intermediate and Middle etc. educational background will be preferred.

Latest Government jobs in Nadra Technologies Limited NTL in Management and others can be applied till NaN undefined NaN or as per closing date in newspaper ad. Read complete ad online to know how to apply on latest Nadra Technologies Limited NTL job opportunities

Nadra latest Government Management jobs and others can be applied till December 20, 2022 or as per closing date in newspaper ad. Read complete ad online to know how to apply on latest District Council job opportunities.
For more jobs register with YourLearningPoint.

👉General Information :

Job Posted Date: 02 December, 2022

City/Location: Rawalpindi, Islamabad, Rawalakot, Gilgit, Skardu, Azad Kashmir

Job Category: Full Time

Job Type: Government

Vacancies Title:
  • Data Entry Executive
  • Security Guard
Total Vacancies: 85

Last Date To Apply: 20 December, 2022

👉Eligibility Criteria :

Education Required: Primary | Middle | Matric | Bachelor

Experience Required: N/A

Age Limit: 18-35 Years

👉Company / Department Information :

Organization: District Council

Website: https://nadra.gov.pk/careers

Email: N/A

Telephone: N/A

👉How To Apply ? :

APPLY ONLINE: https://nadra.gov.pk/careers

How to Apply for this job: Mentioned in image below

👉WhatsApp Job Alerts :

Join our WhatsApp group and every day we will send you the best job links, curated by our team of jobs alert.

Join Our WhatsApp Group:
Click Here!

👉Job Description :

Latest Government jobs in Nadra Technologies Limited in Management and others can be applied till 20 December 2022 or as per closing date in newspaper ad. Read complete ad online to know how to apply on latest NADRA Nadra Technologies Limited job opportunities.
Nadra Technologies Limited Job 2022

Original Source: https://www.dailyausaf.com/epaper/page?station_id=7&date=2022-12-02&page_id=174541

Nadra Technologies Limited NTL Islamabad Job Interview 2022 Nadra Technologies Limited NTL Islamabad Job Interview 2022 Reviewed by SaQLaiN HaShMi on 10:02 PM Rating: 5

District Council Rawalpindi Job 2022

10:31 PM
Latest District Council Management Posts Rawalpindi 2022

Date Posted / Updated:
15 November, 2022
Category / Sector:
Vacancy Location:
Rawalpindi, Punjab, Pakistan
Job Industry:
Job Type:
Full Time
Expected Last Date:
10 December, 2022
or as per paper ad

District Council Rawalpindi, Rawalpindi Punjab Pakistan invites applications from eligible candidates for the post of Mali, Chowkidar, Sanitary Worker and Naib Qasid as per advertisement of November 15, 2022 published in daily Nawaiwaqt Newspaper. Primary and Middle etc. educational qualification will be preferred.

District Council latest Government Management jobs and others can be applied till December 10, 2022 or as per closing date in newspaper ad. Read complete ad online to know how to apply on latest District Council job opportunities.
For more jobs register with YourLearningPoint.

👉General Information :

Job Posted Date: 15 November, 2022

City/Location: Rawalpindi

Job Category: Full Time

Job Type: Government

Vacancies Title:
  • Chowkidar
  • Naib Qasid
  • Sanitary Worker
  • Mali
Total Vacancies: 25

Last Date To Apply: 10 December, 2022

👉Eligibility Criteria :

Education Required: Primary | Middle | Matric

Experience Required: N/A

Age Limit: 18-25 Years

👉Company / Department Information :

Organization: District Council

Website: https://lgcd.punjab.gov.pk/district-rawalpindi

Email: N/A

Telephone: N/A

👉How To Apply ? :

APPLY ONLINE: https://lgcd.punjab.gov.pk/district-rawalpindi

How to Apply for this job: Mentioned in image below

👉WhatsApp Job Alerts :

Join our WhatsApp group and every day we will send you the best job links, curated by our team of jobs alert.

Join Our WhatsApp Group:
Click Here!

👉Job Description :

Latest Government jobs in District Council in Management and others can be applied till 10 December 2022 or as per closing date in newspaper ad. Read complete ad online to know how to apply on latest District Council job opportunities.

District Council Rawalpindi Job 2022

Original Source: https://www.nawaiwaqt.com.pk/E-Paper/multan/2022-11-15/page-10

District Council Rawalpindi Job 2022 District Council Rawalpindi Job 2022 Reviewed by SaQLaiN HaShMi on 10:31 PM Rating: 5

What is Z-Scheme Explain?

2:20 AM


"The reaction which depends upon light are called light reactions or Z-Scheme."

It is also called an "ENERGY CONVERSION PHASE".

That phase is completed by following the steps.

(1) Photosystems:

Photosynthetic pigments are organized into clusters called photosystems in the thylakoid membrane. The photosystems absorb and utilize solar energy.

There are the following parts of photosystems.

(a) Antenna Complex:

In the photosystem, the part which absorbs light energy is called the antenna complex.

The antenna complex contains carotenoid chlorophyll b and chlorophyll a.

(b) Reaction Centre:

The area which takes electrons (energy)k from the antenna complex and starts the light reaction is called the reaction center. The reaction center contains.

(i) One or more molecules of chlorophyll a.

(ii) Primary electron acceptor.

(iii) Electron-associated protein.

(c) Electron Transport Chain :

Photosystems contain a series of electron transport systems and chains such systems contain PQ, cytochrome, and PC.

There are two photo systems:

  • Photosystem I
  • Photosystem II

Reaction in Photosystem II:

PS II absorbs light of 680 nm wavelength it contains chlorophyll which is the best light absorber of 680 nm. PS II chlorophyll antenna complex transfer this energy to the reaction center and then from the reaction center to the primary electron acceptor.

This acceptor traps the high-energy electrons and then pushes these electrons to the series of electron carriers' electron transport chains.

During this flow of electrons following reactions take place.

Non-Cycle Phosphorylation:

That process is completed by following the steps.

(i) PS II absorbs light and an electron is excited.

(ii) P680 As Oxidizing Agent:

The excited electron is shifted to the reaction center and then to electron (primary) acceptors of PS II.

That chlorophyll is oxidizing and acts as a strong oxidizing agent. It has an electron "hole" that must be filled.

(iii) Photolysis:

The breakage of water during this light reaction is called photolysis.

This reaction breaks water into two Hᐩ, 2eー, and one oxygen atom. Oxygen atoms combine with another atom to form oxygen molecules O2  ─ to remove in the air.

(iv) Electron Transport Chain: (First):

Photoexcited electrons are shifted from PS II to PS I by the electron transport chain. This chain consists of :

(a) PQ          Plastoquinone

(b) Cyt         Cytochromes - two complex.

(c) PC           Plastocyanin - Copper-containing protein.

(v) Photophosphorylation:

The formation of ATP in the presence of light is called photophosphorylation.

Energy flow provides energy for the synthesis of ATP-ATP formation during non-cyclic electron flow is called non-cyclic photophosphorylation.

This ATP provides chemical energy for dark reactions as the electrons move down the chain their energy is decreased.

(vi) Reactions in Photosystem I:

The electrons reach the bottom of the electron transport chain and fill the electron hole in PS I.

PS I has chlorophyll a and absorb light of 700 nm. It is also called P700.

When PS I absorb light and its electrons move towards the primary acceptor of PS I. So the hole is produced which is filled by the electron of PS II.

(vii) Second Electron Transport Chain:

From the primary acceptor of PS I the electrons are shifted to a second electron transport chain. This chain consist of

(a) Fd - ferredoxin - ion-containing protein.

(b) NADP - nicotinamide adenine dinucleotide phosphate.

The electrons are from the primary acceptor to Fd and from Fd to NADP. In the presence of NADP reductase enzyme, the NADP changes into NADPH.

NADPH molecule provides reducing power for the formation of sugar during Calvin Cycle.

(viii) Cyclic Phosphorylation:

The process in PS-I is in which electrons are shifted from Fd to cytochrome, then to PC, and again to PS I. During this reaction, no NADPH and oxygen is produced. It does not take place by PS-II. It takes place by PS II. It takes place in PS I when the chloroplast produces low ATP for the Calvin Cycle. When more NADPH is collected in the chloroplast and the demand for ATP is fully supplied that cyclic phosphorylation is down.

The cyclic flow is a short circuit it is started due to the rise of NADPH. It is a temporary shifting of electrons from non-cyclic to cyclic electron flow.

What is Z-Scheme Explain? What is Z-Scheme Explain? Reviewed by SaQLaiN HaShMi on 2:20 AM Rating: 5

The Importance of Fungi

7:04 AM
Write a note on the importance of fungi?


Fungi are ecologically as well as economically very important.

Ecologically Importance:

Fungi have great ecological importance as decomposers, symbionts, and bioremediators.

1) Decomposers:

Fungi, along with saprobic bacteria, play a vital role in the recycling of inorganic nutrients in the ecosystem.

Without decomposition, all the essential nutrients would soon become locked up in the form of dead animals, plants, and the wastes of the animals and plants. Therefore, the essential nutrient would be unavailable to the organisms. As a result, the life would cease.

2) Symbionts:

(i) Mycorrhizae:

Mycorrhizae fungi improve the growth of plants with which they are associated.

About 95% of all kinds of vascular plants have this association.

(ii) Lichens:

lichens growing on the rock break them, setting a stage for other organisms during the course of ecological succession.

(iii) Bioremediation:

Some fungi are also used for bioremediation(degrading/removing) environmental poisons/ pollutants by organisms.

(iv) Bioindicators:

Lichens are very good bioindicators of air quality as they are very sensitive to pollution.

3) Commercial Importance:

Fungi cause economic gain as well as losses.

Economics gains due to fungi:

1) Edible Fungi:

Certain fungi are edible. About 200 species of mushroom,(e.g. Agaricus sp), morels (e.g. Morchella esculenta), truffles (underground fruiting bodies of some Ascomycetes, e.g. Tuber sp that people find with the help of trained dogs or pigs) are common edible fungi.

Reindeer moss (a lichen, not a moss) is used as food for reindeer and some other large animals in the arctic/subarctic/boreal region.

There are some poisonous mushrooms called the toadstools, such as death cap/death angle (Amanita) and jack-O lantern mushroom.

Edible fungi (a) A common morel (Morchella esculenta).

(2) Fermenting Agent:

Certain fungi are used in the food industry because of their fermenting ability.

Yeasts (Saccharomyces cerevisia) are used in the production of bread and liquor.

Penicillium species are used for giving flavour, aroma, and characteristics colour to some cheese.

Some species of Aspergillus are used for fermenting/producing soya sauce and soya paste from the soya bean.

Citric acid is also obtained from some Aspergillus species.

Antibiotics and Drugs:

(a) Some fungi are sources of antibiotics and some other drugs. Penicillin, the first antibiotic discovered (by A. Fleming-1928) is obtained from Penicillium notatum.

(b) Lovastatin is used for lowering the blood cholestrol.

(c) Cyclosporine obtained from a soil fungus is used in organ transplanation for preventing transplant rejection.

(d) Ergotine is used to relieve one kine of headache, migraine.

(e) Griseofulvin is used to inhibit fungal growth.

(4) Dyes:

Some natural dyes obtained from lichens are used in the textile industry.

(5) Biological Research:

(a) Yeasts are heavily used in genetic/molecular biological research because of their rapid generation and rapidly increasing pool of genetic and biochemical information.

(b) Yeasts were the first eukaryotes to be used by genetic engineers. In 1983, a functional artificial chromosomes was made in Saccharomyces cerevisiae.

The same yeasts was the first eukaryote whose genomic sequence was completely studied in 1996.

(c) Yeasts are also being investigated for the production of some hormones.

(d) Pink bread mold (Neurospora) has also been used for genetic research.

Economic Losses Due to Fungi:

Fungi are responsible for plant diseases, animal diseases, and food spoilage.

Plant Diseases:

Fungi are responsible for many serious plant diseases because they produce several enzymes that can break down cellulose, lignin, and cutin. All plants are susceptible to them. Some of the plant diseases are as follows.

(i) Rusts and Smuts:

Extensive damages due to rusts and smut diseases of wheat, corn, and rise prompted mass displacement, and starvation to death of many people.

(ii) Other Diseases:

Powdery mildew (on grapes, rose and wheat, etc.), ergot of rye, red rot of sugar cane, Potato wilt, cotton root rot, apple scab, and brown rot of peaches, plums, apricots, and cherries are some other common plant diseases caused by fungi.

(iii) Wood-rotting Fungi:

Wood-rotting fungi destroy not only living trees but also structural timber.

Bracket/shelf fungi (Fig. 816) cause a lot of damage to the stored cut lumber as well as stands of timber of living trees.

Animal Diseases:

Fungi also cause certain animal diseases. Some are as follows:

(i) Ringworm and Athlete's Foot:

Ringworm and athlete's foot are superficial fungal infections caused by certain imperfect fungi.

(ii) Candidiasis or Candidosis:

Candida albicans, a yeasts, causes oral and vaginal thrush (candidiasis or candidosis).

(iii) Histoplasmosis:

Histoplasmosis is a serious infection lungs caused by inhaling spores of a fungus which is common in soil contaminated with bird's feces.

If infection spreads into blood stream and then to other organs (which is very occasional), it can be serious or even fatal.

(iv) Aspergillosis:

Aspergillus fumigatus causes aspergillosis, but only in persons with the defective immune system such as AIDS and may cause death.

(v) Aflatoxins:

Some strains of Aspergillus flavus produce carcinogenic (cancer-causing) mycotoxins (toxins produced by fungi) called aflatoxins.

Aspergillus contaminates improperly stored grains such as peanuts and corn etc and they have aflatoxins.

Milk, eggs, and meat may also have small traces of aflatoxins.

Note: Any moldy human food or animal forage produce should be discarded.

(vi) Ergotism:

Ergotism is caused by eating bread made from purple ergot-contaminated rye flour.

The poisonous material in the ergot causes nervous spasm, convulsion, Psychotic delusion, and gangrene.

Food Spoilage:

Saprobic fungi are not only useful recyclers but also cause vast damage to the food, wood, fiber and leather by decomposing them.

About 15-50% of world's fruit is lost each year due to fungal attack.

Growth on Shower Curtains:

A pink yeast (Rhodotorula) grows on shower curtains and other moist surfaces.
The Importance of Fungi The Importance of Fungi Reviewed by SaQLaiN HaShMi on 7:04 AM Rating: 5

Role of Antibiosis and Immunization in Controlling Bacterial Disease

1:27 AM

Discuss the role of antibiosis and immunization in controlling bacterial disease?


Chemical methods for control of bacterial include antiseptics, disinfectants and chemotherapeutic agents controlling bacterial diseases.

(1) Antiseptics:

These are chemical substances used on living tissues to kill and inhibit the growth of microorganisms.

(2) Disinfectants:

These chemical agents are used to inhibit the growth of vegetative cells on the non-living materials.

These include oxidizing and reducing agents. For example halogens, phenols, hydrogen peroxide, Potassium permagnate, alcohol and formaldehyde etc.

(3) Chemotherapeutic:

Chemotherapeutic agents and antibiotics work with natural defense and stop the growth of bacteria and other microbes. They destroy or inhibit the growth of microorganisms in living tissues.

These are Sulfonamides, tetracycline, penicilin, etc.

Some other processes that kill/inhibit the microbial population are:

(i) Microbicidal Effect:

Microbicidal effect is one that kills the microbes immediately.

(ii) Microbistatic:

Microbistatic inhibits the reproductive capacities of the cells and maintain the microbial population at constant size.

Mode of Action:

Mode of action, of different physical and chemical agents, of control vary.

Damage can result malfunctions in cell wall, cell membranes, cytoplasm, enzymes, or nuclei acid.


To control and prevent microbial diseases following methods are used:

(i) Immunization (e.g. vaccination)

(ii) Antisepsis (used to eliminate or reduce infection)

(iii) Chemotherapy and

(iv) Public health measures (e.g. water purification, sewage disposal and food preservation)

Pasteur made many discoveries about the cause and prevention of infectious diseases. His work is very important in developing immunity by vaccines.

Pasteur's Work on Chicken Cholera:

In 1880's he isolated the bacterium that caused chicken cholera. He grew it in a pure culture.

To isolate the bacterium of this disease, Pasteur used the techniques of Koch. He also demonstrated this publically.

He inoculated healthy chicken with this pure cultures.

He waited for many days but chicken cholera did not develop in the chicken.

Error in his experiment:

Pasteur found that he had used the cultures several weeks old instead of fresh one.


He discovered that somehow bacteria had lost their ability to produce the disease (virulence) after standing and growing old.

These less virulent bacteria, could still stimulate the host (in this case the chicken) to produce antibodies.

Antibodies are substances that protect the host against infection from virulent organism.

(i) Pasteur's Work on Anthrax:

Pasteur applied the above mentioned principle for the prevention of anthrax.

This culture of the less virulent germs was called vaccine (in Latin vacca means cow).

Similarly immunization with less virulent germs was called vaccination.

(ii) Pasteur's Work on Rabies:

Then Pasteur also developed a vaccine for hydrophobia, or rabies.

It is a disease transmitted to people by bites from rabid dogs, cats, and other animals.

(iii) Pasteur Honouring Edward Jenner:

Pasteur honoured Edward Jenner (1749 - 1823).

Jenner successfully vaccinated a boy against small pox in 1796.

He observed that milkmaids who contracted cowpox from the cows, never developed small pox.

He tested his hypothesis by inoculating a bot (James Phipps) first with cowpox causing material and later with small pox causing material. The boy did not get small pox.

Role of Antibiosis and Immunization in Controlling Bacterial Disease Role of Antibiosis and Immunization in Controlling Bacterial Disease Reviewed by SaQLaiN HaShMi on 1:27 AM Rating: 5

The Body of Fungus

5:42 AM
Explain the body of fungus?


The body of a fungus is called mycelium. (except yeasts which is non-hyphal unicellular fungi).


Mycelium is composed of long slender, branched, tubular, thread like flaments called the hyphae (single hypha). Hyphae spread extensively over the surface of substratum. Their walls are composed of chitin, so their wall is more resistant to decay than are cellulose and lignin which is present in plant cell wall. Hyphae may be septate or non-septate.

Septate Hyphae:

Septate hyphae are divided by cross walls called septa (singular septum) into individual cells containing one or more nuclei. Septa of many septate fungi have pores through which ribosomes, mitochondria and even nuclei flow from cell to cell. Thus materials are carried to growing tips and enabling the hyphae to grow rapidly when food and water are abundant and temperature is favourable. Septate hyphae may be monokaryotic having one nucleus per cell or dikaryotic having two nuclei per cell.

Non-Septate Hyphae :

Non-septate hyphae lack septa and are not divided into individual cells. These are in the form of an elongated multinucleated large cells. Such hyphae are called coenocytic hyphae which consists of a continuous cytoplasmic mass with hundreds or thousands of nuclei. The coenocytic condition results from the repeated division of nuclei without cytoplasmic division.

Functions of Hyphae:

(i) Extensive spreading system of hyphae provides large surface area for absorption of nutrition, Parastitic fungi usually have some of their hyphae modified as haustoria, nutrient-absorbing hyphal tips that penetrate the tissue of the host.

(ii) Hyphae may be packed together and organized to form complex reproductive structures such as mushrooms, puff ball, morels etc., which can be expand rapidly. All fungal nuclei are haploid except for transient diploid zygote that forms during sexual reproduction.

A single mycelium may produce up to a kilometer of new hyphae in only one day. A circular clone of Armillaria, growing out from a central focus, has been measured up to 15 hectare (1 hectare = 10000m²) Armillaria is a pathogenic fungus afflicting conifers.
The Body of Fungus The Body of Fungus Reviewed by SaQLaiN HaShMi on 5:42 AM Rating: 5

Organisms In Kingdom Fungi & Its Taxonomy

6:32 AM
What type of organisms are included in kingdom Fungi? Also describe their taxonomic status.


Approximately 100,000 species of organisms called "fungi" are known and thousands are thought to be present. This group includes

(i) Pathogens such as rusts, smuts of wheat and corn and molds found growing on important crops and foodstuff.

(ii) Delicate species such as mushrooms, truffles and morels.

(iii) Organisms of commercial use such as Penicillium. It is also source of antibiotic penicillin.

(iv) Yeast it is used in bakeries and breweries.

Ecological role of fungi as decomposers is paralleled only by bacterial.

Taxonomic Status of Fungi:

Taxonomic status of fungi has changed from that of a group of plant kingdom. Now they are placed in a separate kingdom "Fungi".

Plant - Like Characters:

They resemble plants in some respects:

(i) They have cell wall.

(ii) They lack centrioles.

(iii) They are non-motile.

Animal - Like Characters:

Fungi resemble, more animals than plants. They show following animal-like characters:

(i) Fungi are heterotrophs.

(ii) They lack cellulose in their cell wall and contain chitin-a nitrogen containing polysaccharide also found in exoskeleton of arthropods. For this reason, some mycologists (scientists who study fungi) think that fungi and animals probably arose from a commom ancestor.

Differences between Fungi and Animals:

Fungi are different from animals in following ways:

(i) Fungi have cell wall.

(ii) They are absorptive heterotrophs.

(iii) They are non-motile.

So fungi are neither plants nor animals.

Fungi Different from all Organisms:

(i) DNA Studies:

Their DNA studies also confirms that they are different from all other organisms.

(ii) Nuclear Mitosis:

They show a characteristic type of mitosis, called 'nuclear mitosis'. During nuclear mitosis, nuclear envelope does not break; instead the mitotic spindle forms within the nucleus and the nuclear membrane constricts between the two clusters of daughter chromsomes. (In some fungi nuclear envelop dismantles late).


As fungi are distinct from plants, animals and protists in many ways, they are assigned to a separate kingdom 'Fungi'.

Organisms In Kingdom Fungi & Its Taxonomy Organisms In Kingdom Fungi & Its Taxonomy Reviewed by SaQLaiN HaShMi on 6:32 AM Rating: 5

Two to Five Kingdom Classification

7:02 AM

Explain the Two to Five kingdom classification.


Two to Five Kingdom Classification Systems:

Different classification systems recognize Two to five kingdoms

For centuries, the living organisms have been classified into Two kingdoms, plants and animals.

(1) Kingdom (Plante):

Plant can prepare their own food from simple inorganic material and store energy (autotroph), while.

(2) Kingdom (Animalia):

Animals cannot synthesize their own food from simple inorganic material and depend for their food either on autotrophs or on decaying organic matter (heterotrophs).

Objection in Old Classification:

Bacteria were included in plants.

Many biologist found this system satisfactory, while other found it unworkable for many unicellular organisms like.

Euglena that have both plant like (presence of chlorophyll) and animal like (lack of cell wall) characters and also because it.

Ignores the differences between Prokaryotic and Eukaryotic cells.

(3) Kingdom (Protista):

In 1866, Ernst Hackel proposed a third kingdom PROTISTA to accommodate Euglena like organisms and bacterial.

In 1937, E-Chatton suggested differentiating terms:

Procariotique (from Greek pro, meaning before, and karyon, meaning nucleus) used to describe bacterial and blue-green algae, and Eu-caritique (from Greek eu, mean true) to describe animal and plant cells.

(4) Kingdom (Fungi):

Some biologists also disagree about the classification of FUNGI, such as bread mold, yeast and mushrooms, which, Resemble plants in many ways but are not autotrophs.

Fungi are special forms of heterotrophs that obtain energy and structural material by breaking down (decomposing) and absorbing food substances from the surroundings, and possess chitin as a major structural component in their cell walls.

(5) Kingdom (Monera):

Robert Whittaker (1969):

A relatively recent system of classification, the five kingdom system, was proposed by Robert Whittaker (1969).

This system of classification is based on three different levels of cellular organization associated with three principal modes of nutrition.

(i) Photosynthesis.

(ii) Absorption and

(iii) Ingestion.

The Five Kingdoms Proposed:

(i) (MONERA) the prokaryotic unicellular organisms such as bacterial,

(ii) (PROTISTA) the Eukaryotic predominantly unicellular organisms such as Euglena and Amoeba

(iii) (PLANTAE) the Eukaryotic multicellular Autotrophs

(iv) (FUNGI) the Eukaryotic multicellular Reducers: (mushrooms)

(v) (ANIMALIA) the Eukaryotic multicellular Consumers

PLANTS are autotrophic in nutritional mode, making their own food by photosynthesis such as mosses, ferns, flowering plants.

FUNGI are heterotrophic organisms that are absorptive in their nutritional mode.

Most fungi are decomposers that live on organic material.

Secrete digestive enzymes and absorb small organic molecules which are produced by digestion.

ANIMALS live mostly by ingesting food and digesting it within specialized cavities.

They lack cellulose and show movements for example birds, reptile.

In five kingdom classification all eukaryotes that did not fit the definition of plants, fungi, or animalia were included in Protista.

Most Protists are Unicellular forms, but this kingdom also includes relatively simple multicellular organisms that are believed to be direct descendants of unicellular protists.

Modification of 5 Kingdom System:

Lynn Margulis and Karlene Schwartz (1988) modified five kingdom classification of Whittaker by considering

(a) Cellular organization

(b) Mode of nutrition

(c) Cytology, Genetics &

(d) Organelles of Symbiotic origin (Beneficial relationship Mitochondria, Chloroplast)

These five kingdom are in modified forms:

(i) Prokaryotae (Monera),

(ii) Protoctistsa (Protists),

(iii) Plantae,

(iv) Animalia and

(v) Fungi
Two to Five Kingdom Classification Two to Five Kingdom Classification Reviewed by SaQLaiN HaShMi on 7:02 AM Rating: 5

Structure and Life Cycle of Bacteriophage

9:36 AM

Write structure and life cycle of Bacteriophage?


The structure under an electron microscope looks like a tadpole and consists of a head and tail.

(1) Head:

(i) The head is elongated having:

      (a) Pyramidal (having two triangular structures with a common base).

      (b) Hexagonal or

      (c) Prism-shaped structure.

(ii) To it straight tail is attached.

(iii) Head contains double-stranded DNA.

(2) Tail:

The structure of the tail is more complex than the head.

(i) Tail has a core of protein which is surrounded by a sheath of another protein.

(ii) On one side of the sheath is the collar and on the other side is the end plate (Base plate).

(iii) Six tail fibers are attached to the end plate. These fibers are for attachment.

Volume of Phage:

It is about 1/1000 of the host.

Life Cycle of Bacteriophages:

The bacteriophage replicates only inside the bacterial cell. There are many steps in replication.

(1) Attachment (Adsorption) of Phage to the Host Cell:

(i) First of all the bacteriophage attaches to the bacterial cell at the receptor site. The receptor sites are present on the cell wall of the bacterium.

(ii) During attachment, weak chemical union occurs between virion and receptor site.

(2) Penetration:

In this step, the tail releases the enzyme lysozyme. This enzyme dissolves a portion of the bacterial cell wall.

The tail sheath contracts and the tail core is forced into the cell through the cell wall and cell membrane.

The virus injects its DNA into the cell (just as the syringe is used to inject the vaccine).

The protein coat, consisting of head and tail, remains outside the cell.

Many animal viruses enter the host cell as a whole.

A Phage Injecting its DNA in to host

After penetration one of the following cycles take place:

(1) Lytic cycle.

(2) Lysogenic cycle.

(1) Lytic Cycle:

During the lytic cycle following steps occur.

(i) Multiplication:

Soon after entering the bacterium, the viral DNA takes the control of the biosynthetic machinery of the host.

The host is forced to synthesize viral DNA and proteins. As a result, viruses begin to multiply.

Within 25 minutes about 200 new Bacteriophages are formed.

(ii) Lysis

After the formation of bacteriophages, the bacterial cell bursts (lysis occurs).

Newly formed bacteriophages are released to infect other bacteria. A new lytic cycle may start.

The phage that causes the lysis of the host cell is called lytic or virulent phage.

(2) Lysogenic Cycle:

In some cases instead of the lytic cycle, the lysogenic cycle takes place. It occurs as follows:

(i) Formation of Prophage:

The viral DNA does not take over the control of the host's machinery.

The DNA is incorporated into the bacterial chromosome. Phage at this stage is called prophage and this process is known as lysogeny.

The phage which causes lysogeny is called temperate (lysogenic) phage. 

Lysogenic bacteria are resistant to infection by the same or related phages.

(ii) Replication:

During lysogeny, the bacterium lives and reproduces normally.

Viral DNA is the part of a bacterial chromosome and passes to each daughter cell generation after generation.

(iii) Induction:

Some times the viral DNA detaches from the chromosomes of the host and the lytic cycle starts. This process is called induction is spontaneous or environmentally induced excision of the prophage from the bacterial chromosome. 

Structure and Life Cycle of Bacteriophage Structure and Life Cycle of Bacteriophage Reviewed by SaQLaiN HaShMi on 9:36 AM Rating: 5
Theme images by lucato. Powered by Blogger.