1. Phylum
    2. 1. Classification of Animals
    2. Protozoa
    3. Porifera
    4. Coelenterata
    5. Platyhelminthes
    6. Nemathelminthes
    7. Annelida
    8. Earthworm
    9. Arthropoda
    10. Cockroach
    11. Mosquito
    12. Honey bee and Silk moth
    13. Mollusca
    14. Echinodermata
    15. Hemichordata
    16. Chordata
    17. Pisces
    18. Amphibia
    19. Frog
    20. Reptile
    21. Aves
    22. Mammalia
    23. Rabbit bone
  2. Animal Behaviour and Adaptation
    3. 24. Animal behaviour
    25. Animal adaptation
    26. Migration
  3. Developmental Biology
    4. 27. Development of Animals
    28. Development of Frog
  4. Human Biology
    5. 29. Tissues
    30. Sense organs
    31. Digestive system
    32. Circulatory system
    33. Respiratory system
    34. Nervous system
    35. Endocrine system
    36. Reproductive system
    37. Excretory system
    38. Skeletal system
    39. Basic concept of Immunology
    40. Human diseases
  5. Evolutionary Biology
    6. 41. Origin of Life
    42. Organic Evolution
    43. Theories of Evolution
    44. Evolution of Human beings
    45. Horse Evolution
Phylum
2. Protozoa
PROTOZOA
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    ◈ url: https://www.youtube.com/embed/THAKO7_z6Jg?si=K76ekn89wUu3LGE9
▢ General features:
Image 1
Fig. Well labelled diagram of Amoeba
Credit. Vecteezy
❖ Science of Protozoa: Protozoology
❖ Cell structure of protozoa:
  1. Microscopic
  2. Unicellular or Acellular with one or more nuclei
❖ Grade or organization: Protoplasmic level of body organization/ Acellular/ Molecular level of body organization.
❖ Symmetry:
◉ Usually asymmetrical
◉ Exception:
  1. Giardia lamblia is bilaterally symmetrical.
  2. Volvox is spherical symmetrical.
▢ Classification of Protozoa:
Characters
Sarcodina
Ciliata
Mastigophora
Sporozoa
Mode of Locomotion
Pseudopodia (Amoeboid movement)
Cilia (Coordinated, hair-like structures)
Flagella (Whip-like structures)
No locomotory organelles (Gliding or bending movements)
Habitat
Mostly freeliving found freshwater and marine environments, few parasitic and pathogenic
Mostly freeliving found freshwater and marine environments, few parasitic and pathogenic
Both free-living and parasitic, found in various aquatic habitats
Entirely parasitic, found inside host organisms
Reproduction
Asexual (Binary fission, sporulation), Some sexual (Syngamy)
Asexual (Binary fission), Sexual (Conjugation)
Asexual (Binary fission), Some sexual
Asexual (Sporogony), Sexual (Gamogony)
Nucleus
Usually one nucleus, though multinucleate forms exist
Two types of nuclei (Macronucleus and Micronucleus)
Usually one or two nuclei, can be multinucleate
Single nucleus in most species
Feeding Mechanism
Phagocytosis (Engulfing food particles)
Cytostome (Cell mouth) with food vacuoles
Absorption through general body surface or cytostome
Absorption directly from the host cells
Examples
  1. Amoeba
  2. Entamoeba
  1. Paramecium
  2. Balantidium
  3. Vorticella
  1. Euglena
  2. Trypanosoma
  3. Giardia
  4. Leishmania
  1. Plasmodium
  2. Monocystis
  3. Toxoplasma
1.
▢ Mode of life:
❖ Free living or Parasitic
❖ Free-living protozoans:
  1. Amoeba
  2. Paramecium
  3. Euglena
  4. Volvox
❖ Parasitic protozoans:
◉ Entamoeba: Colonize on Large intestine mucosa.
◉ Giardia lamblia: Inhabits in crypts of Duodenum and Upper part of jejunum of man.
◉ Balantidium: Resides in the Large intestine, similar to Entamoeba histolytica.
◉ Plasmodium: Resides in Liver and Blood.
◉ Leishmania donovani: Resides in Reticulo-endothelial system.
◉ Trypansoma: Resides in Blood lymph, spleen, CNS and Cerebrospinal fluid.
◉ Trichomonas: Resides in Genital tract and causes Vaginitis.
▢ Colonization:
❖ Majority of protozoans are solitary.
❖ Exceptions: Volvox and Proterospongia are colonial.
▢ Body covering:
❖ Shelled protozoans:
  1. Arcella
  2. Difflugia
  3. Elphidium
  4. Foraminiferans
❖ Radiolarians: Continuous internal skeleton between ectoplasm and endoplasm is found.
▢ Locomotion:
❖ Protozoan class that does not carry its name after locomotory organ is Sporozoa.
❖ Types of locomotory organs:
Locomotory organelle
Protozoans
Pseudopodia (Lobopodia)
Amoeba
Flagella
  1. Euglena
  2. Trypanosoma
  3. Giardia
Cillia
Paramecium
▢ Nuclear dimorphism:
  1. Nuclear dimorphism means nucleus varies from one to several.
  2. Paramecium shows nuclear dimorphism.
▢ Digestion:
❖ Nutrition:
  1. Holozoic
  2. Holophytic
  3. Saprozoic
  4. Parasitic
  5. Mixotropic: Euglena
❖ Digestion is always intracellular.
▢ Osmoregulation:
  • •
    Osmoregulation takes place in fresh water protozoan with the help of one or two contractile vacuoles which is absent in marine and parasitic protozoans.
  • •
    When a fresh water Amoeba is kept in sea water, it loses its contractile vacuole but when a marine Amoeba is kept in fresh water, it develops contractile vacuole.
▢ Respiration:
  • •
    Gaseous exchange takes place by diffusion through general body surface.
▢ Excretion:
  1. Excretion takes place through general body surface.
  2. They are ammonotelic. (NH3)
▢ Reproduction:
Reproduction in protozoa may be asexual or sexual.
❖ Asexual reproduction:
◉ Binary fission:
Types of Binary Fission
Protozoans
Simple Binary Fission
Paramecium
Longitudinal Binary Fission
  1. Trypanosoma
  2. Euglena
Oblique Binary Fission
Ceratium
Note
Binary fission of a multinucleated protozoa into two or more smaller multinucleate daughter individuals is termed as Plasmotomy.
◉ Budding:
Budding is a modified binary fission resulting in a single or many daughter individuals in addition to the parent.
◈ Examples:
  1. Vorticella
  2. Ephelota
❖ Sexual reproduction:
◉ Syngamy: Syngamy is fusion of two sex cells.
◉ Conjugation: Conjugation is temporary contact of two individuals with nuclear exchange.
Note
  1. In most protozoa, sexually mature individual is haploid.
  2. Many protozoans form cyst which help them in overcoming unfavourable conditions and cause dispersal.
Note
▢ Trichonympha:
  1. Trichonympha is symbiotic protozoan found in gut of the termite helping in cellulose digestion.
  2. Trichonympha secrete Cellulose digesting enzymes.
▢ Monocystis: Monocystis is parasite in the seminal vesicle of Earthworm.
▢ Opalina: Opalina is found in Rectum (Small intestine) of Frog.
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AMOEBA
Image 1
Fig. Well labelled diagram of Amoeba
Credit. Vecteezy
▢ General features:
❖ The comost common species of Amoeba is proteus.
❖ History: Amoeba was discovered by Rossel von Rosenhoff.
❖ Shape: Amoeba has no fixed shape.
❖ Habitat:
◉ Amoeba lives in:
  1. Freshwater
  2. Moist soil or
  3. Sea
❖ Culture: Amoeba is cultured in laboratory by Hay infusion method.
❖ Cellular structure:
◉ Plasmalemma:
◈ Structure of Plasmalemma:
  1. Plasmalemma is trilaminar and selectively permeable membrane.
  2. Outer layer of plasmalemma is made up of fibre like molecules of adhesive mucoprotein called microvilli.
    3. Note
    Microvilli project outside the surface and keeps the body dry; so Amoeba is never wet inside the water.
◈ Function of Plasmalemma:
  1. Body of Amoeba is covered by plasmalemma.
  2. Plasmalemma covers the body so in general protective in function.
  3. Plasmalemma is also respiratory, diffusion of oxygen and carbon dioxide takes place through it.
  4. Plasmalemma is excretory and protective in function, ammonia diffuses out through it.
◉ Uroid: Posterior end of Amoeba is marked by wrinkled plasma membrane - the Uroid.
◉ Cytoplasm:
Cytoplasm of Amoeba is differentiated into Outer ectoplasm and inner endoplasm.
◈ Ectoplasm: Ectoplasm is the outer tough plasmagel.
◈ Endoplasm:
  1. Endoplasm is central more fluid like plasmasol state of colloid cytoplasm.
  2. Endoplasm shows brownian movement.
◉ Nucleus:
  1. Nucleus of Amoeba is solid and biconcave.
  2. Just below the nuclear membrane, there is the presence of a network of protein fibre called honey comb lattice which gives shape to the nuclei.
◉ Vacuole:
◈ Food vacuole:
  1. Food vacuole of Amoeba is analogous to the Alimentary canal of an animal or Gastrovascular cavity of Hydra.
  2. The contents of food vacuole in Amoeba first becomes acidic then alkaline.
◈ Contractile vacuole:
  1. Endoplasm of Amoeba in the posterior part contains a single clear rounded and pulsating contractile vacuole.
  2. Contractile vacuole in Amoeba is concerned with osmoregulation, i.e. removal of water.
  3. Contractile vacuole is found only in freshwater forms; absent in marine and parasitic forms.
    1. If an amoeba is placed in distilled water, its contractile vacuole works faster.
    2. If an Amoeba is placed in sea water/ salt water, its contractile vacuole will disappear.
    3. When a fresh water Amoeba is kept in sea water, it loses its contractile vacuole but when a marine Amoeba is kept in fresh water, it develops contractile vacuole.
  4. Contractile vacuole of Amoeba is analogous (similar in function) to Uriniferous tubules(nephron) of frog.
  5. Due to filling of water, contractile vacuole enlarges and called Diastole.
  6. Difference between Amoeba and Entamoeba is in contractile vacuole.
    1. Entamoeba lacks contractile vacuole.
❖ Locomotory organ:
◉ Pseudopodia:
  1. Locomotory organ in Amoeba is Pseudopodia.
  2. Pseudopodia in Amoeba is composed of both ectoplasm and endoplasm.
  3. Pseudopodia is a temporary locomotory structure.
  4. Pseudopodia at its forward end gets its firm consistency by hyaline cap which is made of ectoplasm.
  5. Pseudopodia in Amoeba are meant for feeding and locomotion.
◉ Amoeboidal movement:
◈ Locomotion in Amoeba is known as 'amoeboid movement'.
◈ Sol-gel theory of amoeboid movement:
  1. Sol-gel theory of amoeboid movement is most widely accepted for locomotion in Amoeba.
  2. Sol-gel theory of amoeboid movement was given by Hyman.
  3. According to sol-gel theory, amoeboid movement is due to change in the viscosity of cytoplasm.
  4. The conversion of plasmasol into gel and vice versa is a physio-chemical phenomenon.
  5. Sol-gel conditions are due to contraction and relaxation of long chains of proteins.
◉ Skeletal: Amoeba has no skeleton.
◉ Nutrition:
◈ General:
  1. Mode of nutrition in Amoeba is holozoic i.e. Amoeba is heterotrophic.
  2. Amoeba is omnivorous.
  3. The process of ingesting solid food is phagocytosis.
  4. Digestion is intracellular.
  5. Amoeba is not able to digest fat.
    6. Note
    Hydra is not able to digest starch.
◈ Ingestion of food:
■ Import:
  1. Amoeba = inactive; Prey = inactive
  2. Import involves passive sinking of food into body by rupture of plasmalemma.
  3. E.g. ingestion of algae
■ Circumfluence:
  1. Amoeba = active; Prey = inactive
  2. Circumfluence is the ingestion of less active or motionless organisms like bacteria.
■ Circumvallation:
  1. Amoeba = active; Prey = active
  2. Circumvallation is the engulfment of active prey like ciliate or flagellate.
  3. On contact with a solid food particle, plasmalemma and ectoplasm suddenly invaginate forming a tube.
■ Invagination:
  1. Amoeba = active; Prey = inactive/active
  2. Invagination is the process of paralyzing the prey and engulf it.
◈ Digestion process:
  1. Food vacuole of Amoeba is analogous to the Alimentary canal of an animal or Gastrovascular cavity of Hydra.
  2. The contents of food vacuole in Amoeba first becomes acidic then alkaline.
  3. Egestion of undigested food in Amoeba takes place through a temporary rupture of the surface membrane.
❖ External stimulus:
◉ Amoeba responds to external stimulus.
◉ Taxis:
◈ Response to the stimuli is called taxis (movement), positive - towards stimulus and negative - away from the stimulus.
◈ Types of taxes:
■ Thermotaxis (temperature): Optimum temperature is 25oC.
■ Phototaxis (light): Positive to moderate light and negative to strong light and darkness.
■ Geotaxis (Gravity): Positive behaviour as it lives always at the bottom.
■ Thigmotaxis (touch): Positive if reaches a solid object slowly, negative if solid object comes abruptly.
■ Rheotaxis (water current):
  1. Positive behaviour + as it moves away from the origin of water current.
  2. Paramecium shows negative⛔ response and moves against water 💦 current.
■ Galvanotaxis (electric current): Negative to strong electric current. In weak electric current, it move to cathode or negative pole(-).
❖ Reproduction:
◉ Reproduction takes place by Asexual methods.
◉ Asexual methods:
◈ Binary fission:
  1. Binary fission takes place when food is abundant and temperature is suitable and is completed in 30 minutes.
  2. Interesting feature of mitosis during binary fission in Amoeba is that multiple nuclear spindle is formed which is reduced to unipolar nuclear spindle.
◈ Multiple fission:
◈ Sporulation:
  1. Multiple fission and sporulation takes place during unfavourable condition after encystment.
  2. Encystment/ Sporulation helps in dispersal.
  3. There are three layers of cysts.
  4. Lack of oxygen and food induces encystment.
  5. Products of multiple fission are called Amoebulae.
Note
  1. Amoeba undergo rejuvenation for regaining energy.
  2. Amoeba regenerates from nuclear bits.
ENTAMOEBA
▢ General features:
❖ The genus Entamoeba is usually found in the intestine of vertebrates and invertebrates.
❖ Characteristics: Entamoeba is characterized by a Vesicular nucleus containing an Endosome (Nucleolus).
❖ Vesicular nuclei:
◉ Contain a large amount of nucleoplasm and a small amount of chromatin material.
◉ Structure:
  1. Vesicular nuclei consist of a nuclear membrane which binds the nucleoplasm in which the endosome (Karyoasome) or nucleolus is located centrally.
  2. The endosome is devoid of DNA whereas the nucleolus possesses it (DNA).
❖ Common species of Entamoeba found in humans:
  1. Entamoeba histolytica
  2. Entamoeba coli
  3. Entamoeba gingivalis
▢ Entamoeba histolytica:
Image 1
Fig. Entamoeba histolytica
❖ Entamoeba histolytica is commonly called a tissue-dissolving parasite.
❖ Habitat (Location in the Human body):
  1. Entamoeba histolytica is an Endoparasite, a pathogenic intestinal parasite found in:
  2. The lower part of the Ileum of humans.
  3. The upper part of the colon.
❖ Host: Entamoeba histolytica has only one host and is thus monogenetic.
❖ Pathogenicity:
  1. Entamoeba histolytica causes Amoebiasis/Amoebic dysentery and Liver abscess in chronic conditions.
  2. Stool of a person suffering from amoebiasis is acidic.
❖ Cellular structure:
◉ Forms:
  1. Entamoeba histolytica has two forms: Magna and Minuta.
    2. ■ Comparison between Magna and Minuta:
    ● Magna (Trophozoite):
    1. Pathogenic form.
    2. Found in the mucosa and submucosa of the intestine forming ulcers.
    3. Feeding form.
    4. No fixed shape, larger in size, motile, and active.
    ● Minuta (Precyst and Cyst):
    1. Non-pathogenic form.
    2. Found in the lumen of the intestine.
    3. Non-feeding form.
    4. Spherical, small in size, non-motile, and inactive.
◉ Structural Characteristics:
  1. Entamoeba histolytica is trimorphic: Trophozoite (Magna), Cyst, and Precyst (Minuta).
  2. The most pathogenic, motile, and active feeding stage of Entamoeba histolytica is the Trophozoite, which is typically monopodial, producing one large, finger-like pseudopodium at a time.
  3. Entamoeba has no contractile vacuole, differentiating it from Amoeba.
❖ Life cycle:
Image 1
Fig. Life cycle of Entamoeba histolytica
◉ Reproduction:
  1. Trophozoites of Entamoeba reproduce mitotically (binary fission) within the host's gut.
  2. Minuta forms undergo encystation in the lumen of the intestine.
  3. Minuta forms of Entamoeba form 'Precystic amoeba'.
  4. Encystment takes place by the action of Trypsin.
◉ Cyst:
  1. A mature cyst is called a Quadrinucleate cyst.
  2. It has four nuclei and two chromatoidal bodies or bars.
    3. Note
    Chromatoidal bodies
    Aggregations of ribosomes found in cysts of some amoebae including Entamoeba histolytica and Entamoeba coli. They exist in the cytoplasm and are dark-staining.
  3. The reserve food material in the cyst of Entamoeba histolytica is Glycogen.
  4. The Quadrinucleated cyst is the infective stage.
  5. Each cyst of Entamoeba gives rise to 8 individuals.
  6. Cysts are highly resistant to desiccation and certain chemicals (e.g., chlorinated compounds).
❖ Mode of Transmission:
  1. Contaminated food and water with cysts.
  2. Entamoeba histolytica is mainly transmitted by houseflies.
❖ Treatment:
◉ Effective drugs:
  1. Metronidazole
  2. Tinidazole
  3. Ornidazole
▢ Entamoeba coli:
❖ Entamoeba coli is more common than E. histolytica.
❖ Habitat: Entamoeba coli inhabits the human colon.
❖ Parasitic nature: Entamoeba coli is a commensal parasite, generally considered non-pathogenic in humans.
❖ Life cycle:
  1. The trophozoite of Entamoeba coli does not ingest or invade host tissues.
  2. The mature cyst is Octanucleate, i.e., it characteristically contains eight visceral nuclei but usually produces four amoebulae.
  3. Entamoeba coli is monogenetic, and infection is oral through contaminated food and water.
❖ Treatment: Because Entamoeba coli is a commensal, no treatment is required.
▢ Entamoeba gingivalis:
❖ Entamoeba gingivalis lives on the surface of the teeth and gums and also in the gingival pockets near the base of the teeth.
❖ Parasitic nature: Entamoeba gingivalis, like Entamoeba coli, is a commensal and non-pathogenic.
❖ Habitat: Entamoeba gingivalis is found in people with unhygienic oral conditions (i.e., gingivitis or periodontitis).
❖ Life cycle:
◉ Adult form: The adult form is called a trophozoite and has 2-3 pseudopodia.
◉ Cyst: A cyst is not formed in E. gingivalis and it is transmitted either directly (kissing) or indirectly via trophozoite-contaminated food, sharing eating utensils, toothpicks, etc.
❖ Associated condition: Pyorrhoea is aggravated by Entamoeba gingivalis but caused by Trichomonas buccalis.
PARAMECIUM
Image 1
Fig. Paramecium caudatum
▢ General Information:
❖ Common Species: Paramecium caudatum
❖ Common Name: Slipper animalcule
❖ Discoverer: John Hill
❖ Habitat: Free-living and aquatic, found in fresh stagnant water with abundant organic matter.
❖ Culture Method: Hay-infusion method in laboratory
▢ Classification:
❖ Phylum: Protozoa
❖ Subphylum: Ciliophora
❖ Class: Ciliata
❖ Subclass: Holotrichia
❖ Genus: Paramecium
❖ Species: caudatum
Note
Paramecium is Holotrichous ciliate protozoan.
▢ Cellular Structure:
❖ Shape: Slipper shaped
❖ Size: 0.05 to 0.32 mm
❖ Body Surface:
◉ Oral Surface: Ventral surface
◉ Aboral Surface: Dorsal surface
❖ Pellicle:
Image 1
Fig. Pellicle of Paramecium caudatum
Thin, firm, and flexible membrane covering the body.
◉ Structure:
  1. Uniform appearance.
  2. Composed of a lattice of hexagonally shaped pits, each centrally perforated by a single cilium.
  3. The margins of hexagonal depressions are slightly raised up as ridges. Trichocysts open in the ridges.
◉ Ultrastructure:
◈ 3 membranes:
  1. Outer plasma membrane
  2. Outer alveolar membrane
  3. Inner alveolar membrane
◉ Function:
  1. Maintains definite shape of the animal.
  2. Serves as a skeletal structure.
❖ Cilia:
Image 1
Fig. Ultrastructure of Cilia
Numerous cilia covering the entire body surface, acting as locomotory organelles.
◉ Arrangement:
  1. Longitudinal rows
  2. Almost parallel on the dorsal surface and slightly oblique on the ventral surface.
  3. Uniform length throught the body except few longer at the posterior end of body called Caudal tuft.
◉ Ultrastructure:
3 major parts
◈ Outer Plasma membrane:
◈ Interposed cytoplasmic matrix:
◈ A central axoneme:
  1. Typical 9 + 2 arrangement of microtubules
◉ Movement:
◈ Longitudinal Row: Moves simultaneously one by one (Metachronous rhythm)
◈ Transverse Row: Moves in Synchronous rhythm
◉ Role of ATP: ATP plays a crucial role in the movement of cilia
❖ Trichocysts:
Image 1
Fig. Trichocyst of
Paramecium caudatum
◉ Description: Peculiar bottle-shaped organelles in the ectoplasm
◉ Function: Organs of attachment, previously thought to be organs of offence and defence
◉ Structure:
◈ Spike: Conical outer membrane
◈ Cap: A cap over the spike
◈ Shaft: Anterior end becomes very long when discharged
◈ Length: Discharged trichocyst is ten times longer than undischarged one
❖ Oral Apparatus:
◉ Oral groove/ Peristome:
◉ Vestibule:
◉ Buccal cavity/ Gullet:
◉ Cytostome/ Mouth:
◉ Cytopharynx/ Oesophagus:
◉ Buccal ciliature:
Image 1
Fig. Buccal ciliature
◈ Endoral membrane/ Undulating membrane:
■ Location: At the junction of vestibule and the buccal cavity.
■ Shape: Crescentic
■ Formation: Due to sticking together of the cilia of a single row.
◈ Penniculi:
■ Dorsal peniculus:
■ Ventral peniculus:
◈ Quadrulus:
❖ Anus/ Cytopyge/ Cytoproct:
  1. Undigested food is egested through it by active vacuolar activity called exocytosis.
❖ Contractile Vacuoles:
◉ Number: Two, permanently open on the dorsal surface
◉ Structure: Each vacuole has 6-10 radiating canals/accessory vacuoles
◉ Function: Helps in osmoregulation
❖ Food Vacuoles:
◉ Description: Numerous vacuoles containing food particles
◉ Movement: Food vacuole moves along a definite course (Cyclosis) within the streaming endoplasm
◉ Alternative Name: Gastrioles
❖ Nucleus:
◉ Type: Heterokaryotic (dimorphic nuclei)
◉ Macronucleus:
◈ Description:
■ Shape: Kidney-shaped, large, polypoid
■ Function: Regulates daily metabolic activities
◈ Component: Trophochromatin
◉ Micronucleus:
◈ Paramecium caudatum: 1
◈ Paramecium aurelia: 2
◈ Paramecium multi-micronucleatum: Many
◈ Function:
■ Description: Genetic reserve of the cell, controls reproductive activities
■ Component: Idiochromatin
▢ Nutrition:
❖ Type: Holozoic
❖ Feeding Mechanism: Filter feeder
❖ Favorite Food:
◉ Name: Tetrahymena
◉ Description: Another ciliate protozoa, used in biological research
❖ Oral Groove: Takes food through oral groove/peristomal groove at the left side of the anterior end of the body
❖ Cyclosis: Ensures uniform distribution of digested food material
❖ Digestion:
◉ Type: Intracellular
◉ Medium: Acidic to alkaline
◉ Color:
◈ Acidic: Blue-green
◈ Basic: Yellow
❖ Cytopyge or Cytoproct:
◉ Function: Egestion of undigested food
◉ Description: Temporary anus, situated on the ventral surface of the oral groove
◉ Alternative Name: Cell anal spot
▢ Excretion:
❖ Mechanism:
  1. General body surface
  2. Contractile vacuoles
▢ Osmoregulation:
❖ Mechanism: By contractile vacuole only
▢ Respiration:
❖ Mechanism: Through general body surface
▢ Taxes:
❖ Response: Shows negative response and moves against water current
❖ Reaction: Contact with a foreign body induces avoiding reaction
❖ Electrotaxis: Moves towards the cathode (negative charge) under weak current
▢ Reproduction:
❖ Asexual:
Image 1
Fig. Binary fission of Paramecium caudatum
◉ Method: Binary fission (Transverse fission)
◉ Process:
  1. Paramecium stops feeding and oral groove disappears
  2. Macronucleus divides amitotically, micronucleus divides mitotically
  3. Division occurs at a right angle to the body axis
  4. Two daughter Paramecia are produced: Proter (anterior) and Opisthe (posterior)
  5. Binary fission occurs during favorable conditions
  6. Time": "Half an hour to 2 hours, 2-3 times a day
❖ Sexual:
◉ Method: Conjugation
Image 1
Fig. Conjugation in Paramecium caudatum
◉ Description: Temporary union of two individuals of different mating types for the exchange of micronuclear material
◉ Functions:
  1. Overcomes ageing or senescence
  2. Brings about nuclear reorganization and rejuvenation
◉ Process:
  1. Two Paramecia of different mating types unite ventrally by their oral grooves (Conjugants)
  2. Macronucleus disintegrates and is absorbed by cytoplasm
  3. Micronucleus divides twice, one division being reductional
  4. Functional nucleus divides into female and male pronucleus
  5. Male pronuclei are exchanged and fusion occurs, forming a diploid zygote nucleus (Synkaryon)
  6. Conjugants separate and become ex-conjugants
  7. Zygote nucleus divides, producing macronuclei and micronuclei
  8. Binary fission occurs, resulting in 8 daughter Paramecia
❖ Autogamy:
◉ Description: Self-fertilization
◉ Occurs in: Paramecium aurelia
◉ Result: Two daughter Paramecia from each individual
❖ Cytogamy:
◉ Description: Two individuals come in contact without cell membrane breakdown or nuclear exchange
◉ Occurs in: Paramecium caudatum
❖ Endomixis:
◉ Type: Parthenogenesis
◉ Description: Asexual reproduction where macronucleus disappears, and micronucleus divides without fusion
◉ Occurs in: Paramecium aurelia
◉ Result: Four daughter Paramecia from each individual
❖ Hemixis:
◉ Description: Purification act; reconstitution of macronucleus without any changes in micronucleus
▢ Particles:
❖ Types:
  1. Kappa (Κ)
  2. Lambda (λ)
  3. Mu (μ)
  4. Pi (π)
❖ Kappa Particle:
◉ Description: Special particle in cytoplasm, present in some Paramecia
◉ Function: Secretes toxic substance called Paramecin
◉ Strain: Paramecia with Kappa particles are called killer strain
◉ Features:
  1. Very minute
  2. Capable of self-replicating
  3. Contain nucleic acids
  4. Concerned with cytoplasmic inheritance
◉ Effect: Sensitive strain Paramecia die when conjugating with killer strain Paramecia
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BALANTIDIUM
Image 1
Fig. Balantidium coli
▢ Description: Balantidium coli is the largest protozoan parasite of humans.
▢ Type: Ciliate
▢ Location in Human body:
  1. Caecum
  2. Colon
▢ Life cycle:
Image 1
Fig. Life cycle of Balantidium coli
❖ Type: Monogenetic
❖ Host: Has only one host
❖ Encystment: Encystment takes place in this parasite.
▢ Pathology:
❖ Disease caused:
  1. Balantidial dysentery
  2. Balantidiasis
❖ Prevalence: This is a common disease in the Philippines.
❖ Mode of Transmission: Food and water
▢ Treatment:
❖ Medicines:
  1. Carbarsone
  2. Di-iodohydroxyquin
  3. Tetracycline
EUGLENA
▢ General features:
Image 1
Fig. Euglena
❖ Euglena forms a link between animals and plants.
❖ Nutrition:
◉ In Euglena, the mode of nutrition is mixotropic.
❖ Plant or Animal:
◉ Resemblance with animals:
  1. Presence of gullet.
  2. Presence of contractile vacuole.
  3. Holozoic mode of nutrition.
  4. Sometimes absence of chlorophyll pigments.
◉ Resemblance with plants:
  1. Presence of chlorophyll pigment.
❖ Habitat: Euglena lives in ponds and lakes rich in organic matter.
❖ Habit: Euglena is always solitary (never forming a colony).
▢ Cellular structure:
❖ Pellicle: Euglena has a hard yet flexible covering beneath its plasma membrane called the Pellicle.
❖ Eyespot and Photoreceptor: Two organelles, an eyespot and photoreceptor, help Euglena stay near the light. (The name Euglena means 'True eye'.)
▢ Nutrition:
❖ Euglena ingests solid food.
▢ Reproduction:
❖ Euglena is haploid and reproduces by longitudinal binary fission.
❖ Sexual reproduction: Sexual reproduction in Euglena is unknown.
TRYPANOSOMA
▢ Hi: Me too
Image 1
Fig. Trypanosoma
▢ Location in Human Body:
❖ Blood lymph: So called Blood parasite, endoparasite, extracellular parasite.
❖ Other locations:
  1. Spleen
  2. Central Nervous System
  3. Cerebrospinal fluid
▢ Cellular structure:
❖ Nucleus: 1 (Uninucleate)
❖ Flagellum:
◉ Description: Uniflagellate parasite
◉ Origin: Flagellum arises from basal granula.
❖ Basal granule: Blepharoplast
❖ Kinetoplast:
❖ Undulating membrane:
◉ Description: Body is covered with a cytoplasmic sheath called Undulating membrane.
◉ Functions:
  1. Gives parasitic adaptation.
  2. Helps in locomotion in viscous fluid.
❖ Cytoplasm: Cytoplasm is homogenous.
▢ Nutrition:
❖ Reserve food material: Volutin granules (Also in diatoms).
▢ Different forms:
Form
Description
Crithidial stage/Epimastigote stage
With flagella
Leptomonas stage/Promastigote stage
With flagella
Leishmanial stage/Amastigote stage
Without flagella
Metacyclic stage/Trypanosomal stage
With flagella (Infective stage)
▢ Life cycle:
Image 1
Fig. Life cycle of Entamoeba histolytica
❖ General Information: Digenetic
❖ Hosts:
◉ Primary/Definitive host: Man
◉ Secondary/Intermediate host/Vector: Tse-tse fly (Glossina palpalis)
▢ Different species of Trypanosoma:
❖ Trypanosoma brucei complex:
◉ Vector: Tse-tse fly (Glossina palpalis)
◉ Species:
◈ Trypanosoma brucei brucei: Nagana disease (Parasite of African ruminants)
◈ Trypanosoma brucei gambiense: African sleeping sickness/Gambian trypanosomiasis
◈ Trypanosoma brucei rhodesiense: East African trypanosomiasis/Rhodesian trypanosomiasis
❖ Trypanosoma cruzi:
◉ Disease: American sleeping sickness/American trypanosomiasis/Chagas' disease
◉ Vector:
  1. Kissing bugs
  2. Water bugs
◉ Vector Species:
  1. Triatoma infestans
  2. Rhodnius prolixus
  3. Panstrogylus megistus
GIARDIA
▢ Common name: "Grand old man of Intestine"
▢ Species: Giardia lamblia
▢ Pathogenicity: Pathogenic endoparasite
▢ Location:
❖ Small intestine:
  1. Duodenum (very common)
  2. Jejunum (sometimes)
  3. Ileum (rare)
▢ Symmetry:
❖ Body: Bilaterally symmetrical
▢ Cellular structure:
Image 1
Fig. Giardia lamblia
❖ Flagella:
◉ Number: 8 flagella (4 on each side)
◉ Origin: Flagella arises from rod-like axostyle
❖ Structure:
Form
Description
Trophozoite form
  1. Body resembles Tennis/badminton racket.
  2. Binucleated.
  3. Feeding stage.
  4. Trophozoites attach to intestinal mucosa and cause poor absorption.
Cystic form
  1. Oval shaped body.
  2. Quadrinucleated.
  3. Infective stage.
  4. Each Cyst hatches out two trophozoites.
▢ Life cycle:
Image 1
Fig. Life cycle of Giardia lamblia
❖ Type: Monogenetic
❖ Host: Life cycle is completed in a single host (Man)
❖ Reproduction: Trophozoite forms and Cysts are passed through stool. In the Trophozoite stage, the parasite multiplies in the intestine of man by binary fission.
▢ Nutrition:
❖ Reserve food material: Parabasal body
LEISHMANIA
▢ Leishmania donovani:
Image 1
Fig. Leishmania donovani
❖ Location in Human body:
  1. Reticulo-endothelial system of Viscera i.e.,
  2. Liver
  3. Spleen
  4. Bone marrow
  5. Blood
  6. Lymph
  7. Lymph nodes
  8. Pathogenic endoparasite and may be found in:
  9. Cerebrospinal fluid (CSF)
  10. Meninges
  11. Renal capsule
❖ Diseases:
  1. Visceral Leishmaniasis
  2. Kala-azar
  3. Black fever
  4. Death fever
  5. Dum-dum fever
❖ Vector: Its vector is Sand-fly (Phlebotomus argentipus).
❖ Life cycle:
Image 1
Fig. Life cycle of Leishmania donovani
◉ General Information: Leishmania donovani is Uniflagellate and has two forms, i.e., dimorphic.
Promastigote form/Leptomonad form
Amastigote form/Leishmanial form
i. Cylindrical and
i. Oval or Round and
ii. Flagellate (Uniflagellate)
ii. Non-flagellate
Contains Axonema and Kinetoplast.
Axonema and Kinetoplast are absent.
Promastigote form is Infective stage as it enters the human body.
Amastigote form is Feeding stage.
Promastigote form is found in Salivary glands and Guts of Sandfly.
Amastigote form is found in Reticulo-endothelial system of man.
Promastigote changes into amastigote form in man.
Amastigote changes into promastigote form in Sandfly (Phlebotomus argentipus).
◉ Additional Information:
  1. Leishmania donovani is Digenetic.
  2. Primary/ Definitive host: Man
  3. Secondary/ Intermediate host: Sand fly (Phlebotomus argentipus)
  4. Infected sand fly bites a normal man and inoculates promastigote stage into the bloodstream.
  5. From the bloodstream, the promastigote form enters the viscera, loses flagella, becomes round, and changes into the amastigote form.
  6. Amastigote stage can multiply until the cell is packed with the parasite.
  7. Amastigote attacks macrophages and disseminates to the Reticulo-endothelial system (blood, lymph, lymph nodes, bone marrow, liver, spleen).
❖ Lab diagnosis:
  1. K39 test
  2. Leishmania donovani body test (L.D. body test)
❖ Post Kala-azar Dermal Leishmaniasis (PKDL): Sometimes Leishmania donovani also causes Post Kala-azar Dermal Leishmaniasis (PKDL).
❖ Treatment:
  1. Antimony compound
  2. Recent drugs: Multifossine
▢ Leishmania tropica:
❖ Location:
  1. Skin (face and neck)
❖ Disease causes:
  1. Dermal Leishmaniasis/Cutaneous Leishmaniasis
  2. Skin ulcers
  3. Oriental sore
  4. Delhi boils
  5. Baghdad boils
▢ Leishmania braziliensis:
❖ Location: Naso-oral cavity
❖ Disease causes:
  1. Naso-oral Leishmaniasis
  2. Muco-cutaneous Leishmaniasis
  3. Espundia
PLASMODIUM
▢ General Information:
❖ Plasmodium is the causative agent of Malaria.
❖ Malaria: Malaria means 'Bad night air'. Malaria is a communicable disease.
❖ Malarial parasite: As Plasmodium is the causative agent of Malaria, Plasmodium is known as 'Malarial parasite'.
▢ Characteristics:
❖ Parasite Type:
  1. Endoparasite
  2. Blood parasite
  3. Intracellular parasite
  4. Pathogenic parasite
❖ Digenetic:
◉ Primary host/ Definitive host: Female Anopheles Mosquito (FAM)
◉ Secondary host/ Intermediate host: Man
▢ History:
❖ Laveron:
  1. Laveron discovered that 'Plasmodium is the causative agent of Malaria'.
  2. The term 'Plasmodium' was coined by Laveron.
❖ Ross:
  1. Ross discovered 'Oocyst stage of Plasmodium on the gut wall of Female Anopheles Mosquito (FAM)'.
  2. Ross won the 1st Nobel Prize for his work on Malaria.
❖ Grassi: Grassi discovered the life history of Plasmodium in FAM.
▢ Species of Plasmodium:
S.N.
Parasite name
Disease (Types of Malaria)
Dots/ Granules
Pre-patent period
Incubation period
a.
Plasmodium vivax
  1. Benign Tertian Malaria
  2. Tertian Ague
Schuffner's dots/ Schuffner's granules
8-10 days
14 days
b.
Plasmodium falciparum
  1. Sub-tertian Malaria
  2. Malignant tertian Malaria
  3. Cerebral Malaria
  4. Black water 💦 Fever
  5. Estivoautumnal Malaria
Maurer's dots
5-10 days
12 days
c.
Plasmodium ovale
  1. Benign Tertian Malaria
  2. Mild Tertian Malaria
Jame's dots/ Schuffner's dots
9 days
14 days
d.
Plasmodium malariae
  1. Benign Quartan Malaria
  2. Longest incubation period
Ziemann's dots
14-15 days
28 days
Note
  1. All Plasmodium species cause Benign Malaria except P. falciparum.
  2. Cerebral Malaria is drug-resistant and fatal.
  3. All Plasmodium species cause Tertian Malaria except P. malariae.
  4. Quotodian malaria results from mixed infection
  5. Plasmodium falciparum is the most fatal species.
  6. Exo-Erythrocytic cycle is absent in Plasmodium falciparum
  7. Pre-patent period is the duration between the initial sporozoite infection and the first appearance of the parasites in blood.
  8. Incubation period is the duration between the initial sporozoite infection and the first appearance of malarial symptoms.
▢ Granules:
❖ Schuffner's granules: Numerous yellowish eosinophilic granules appear in the cytoplasm of Host corpuscle, known as Schuffner's granules. These dots are believed to be antigens produced by Parasites.
▢ Life Cycle:
❖ Asexual Cycle / Schizogony - Human (Secondary host):
◉ Pre-Erythrocytic Cycle 🚴 (1st liver schizogony):
◈ Sporozoite(n):
■ Sporozoites feed upon the glycogen of liver cells, and this feeding stage is called Cryptozoite.
Image 1
Fig. Sporozoite of Plasmodium vivax
■ Infection: When an infected Female Anopheles Mosquito bites a person, thousands of Sporozoites are inoculated into the bloodstream of the person along with saliva.
■ Infective stage: The Infective stage of Plasmodium is Sporozoite.
■ Structure of Sporozoite:
  1. Sporozoite is Sickle-shaped.
  2. Pellicle acts as an outer boundary to Sporozoite.
  3. Proteolytic enzyme is produced by Paired Organelles and secreted by the Apical cap 🧢 to break down the cell membrane of liver cells.
■ Cycle start: Sporozoites directly go to Parenchyma cells of the liver within half an hour for multiplication. They start their life-cycle from liver cells to get protection against WBCs and utilize the liver's rich source of Glycogen.
◈ Cryptozoite(n): Cryptozoite increases in size and becomes Schizont.
◈ Schizont(n): The nucleus of Schizont divides and forms numerous nuclei, each surrounded by little cytoplasm, forming Cryptomerozoites.
◈ Cryptomerozoites(n): Cryptomerozoites are liberated into Liver Sinusoids.
◉ Exo-Erythrocytic Cycle 🚴 (2nd liver schizogony):
◈ Cryptomerozoite (n): Each Cryptomerozoite again enters liver cells, and Second liver schizogony occurs.
◈ Metacryptozoite (n):
◈ Schizont (n):
◈ Metacryptomerozoite (n):
■ Types:
● Micrometacryptomerozoites:
  1. Small
  2. Attack RBCs to start the Erythrocytic cycle.
● Macrometacryptomerozoites:
  1. Larger
  2. Attack Liver cells.
◉ Erythrocytic Cycle 🚴 (Golgi Cycle):
◈ Micrometacryptomerozoite (n): Micrometacryptomerozoite starts feeding and changes into Trophozoite.
◈ Trophozoite (n): Trophozoite form is called the feeding stage.
Image 1
Fig. Trophozoite of Plasmodium vivax
◈ Signet Ring Stage 💍 (n):
  1. During feeding, trophozoite creates a vacuole in the middle of the cytoplasm of RBC, pushing the nucleus towards the periphery. This gives the appearance of a ring with a signet, called the Signet ring stage.
  2. The Signet ring trophozoite throws out pseudopodial processes and assumes an Amoeba-like shape, known as Amoeboid trophozoite.
◈ Amoeboid/ Amoeboid Trophozoite.(n): Amoeboid trophozoite becomes large and spherical and is now called Schizont.
◈ Schizont(n):
  1. Schizont contains Haemozoin and Schuffner's dots (in P. vivax).
  2. Haemozoin causes chills and fever.
◈ Rosette/ Rosette stage 🏵 (n): The Schizont stage gives rise to the Rosette stage, which gives a petal-like appearance.
◈ Merozoites/ RBC merozoite(n):
  1. Schizonts give RBC merozoites, which are released along with haemozoin with the bursting of RBCs.
  2. This causes high fever, chills, and shivering.
  3. Ruptured RBCs and schizonts are called Ghost cells, which are destroyed by the spleen.
◈ Gametocyte(n):
After repeated schizogony, numerous RBC merozoites are formed, losing their power of asexual multiplication, so they undergo a sexual cycle. RBC merozoites become rounded and are known as Gametocytes.
■ Types:
  1. Microgamonts (Micro-gametocytes, male)
  2. Macrogamonts (Macro-gametocytes, female)
◉ Post-Erythrocytic Cycle 🚴 /Post-Erythrocytic Schizogony (Ross Cycle): Some of the RBC merozoites invade liver cells and continue a cycle called Post-Erythrocytic schizogony.
❖ Sexual Cycle/ Gamogony and Sporogony - Mosquito (Primary host):
◉ Gametocytes(n): When an Anopheles mosquito bites an infected person, along with all stages, gametocytes are ingested into the mosquito's gut. All stages except Gametocytes are digested in the mosquito's gut.
◉ Gametes(n):
Gametocytes develop into Gametes. There are two types of gametes:
◈ Types:
  1. Microgametes (Male 👨 gametes): Micro-gametocyte gives rise to 6-8 haploid microgametes after meiotic division. The formation of whip-like micro-gametes or sperms is known as Ex-flagellation.
  2. Macrogametes (Female 🚺 gametes): Macro-gametocytes give rise to one haploid macrogamete after meiotic division. It has a cone receptor.
◉ Zygote (Synkaryon)(2n): Micro and Macrogametes fuse to form Zygote (Synkaryon).
◉ Ookinete(2n):
  1. Zygote transforms into Ookinete, which is motile 🚶.
  2. Ookinete penetrates the Peritrophic membrane of the gut wall and forms an encysted zygote called Oocyst.
◉ Oocyst(2n):
Oocyst undergoes Sporogony, which is meiosis followed by mitosis. Sporogony occurs in the Stomach wall of the mosquito, producing about 10,000 sporozoites from each oocyst.
◉ Sporoblast (n):
◉ Sporozoite(n): Sporozoites migrate to the salivary gland.
▢ Treatment of Malaria:
❖ Drugs:
◉ Quinine:
Quinine is an important alkaloid in the treatment of malaria.
◈ Source: Quinine is extracted from the bark of the Cinchona tree.
◉ brin:
  1. Atebrin
  2. Melubrin
◉ quin:
  1. Basoquin
  2. Camoquin
  3. Chloroquin
  4. Emquin
◉ quine:
  1. Plasmoquine
  2. Primaquine
  3. Nivaquine
◉ Others:
  1. Daraprim
  2. Paludrine
  3. Mepacrine
  4. Resochin
◉ Mefloquine: Mefloquine is used to treat multidrug-resistant Plasmodium falciparum.
❖ Biological treatment:
◉ Gambusia affinis (mosquito fish): Gambusia affinis feeds on larvae and pupae of mosquitoes.
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Multiple Choice Questions

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[MOE 2063]

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[IOM 2004]

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[IOM 2069]

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[IOM 2016]

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[KU 2012]

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