Protozoans

Question 1

Protozoan general morphology

Answer 1

•bound by cell membrane
•cytoskeleton forms pellicle (cell wall almost, but depends on whether they are flexible or rigid - not al have it)
•some have a test - hardened outer structure
-secreted by organism

Question 2

Movement

Answer 2

• flagella propel organisms in undulatory wave
• cilia - similar to flagella but move and act in a different way - beat in metachronal waves
• pseudopodia - temporary extensions of body, by changes of viscosity in cytoplasm

Question 3

Acquisition of food and oxygen

Answer 3

• pinocytosis - unspecific engulfing of things
• receptor mediated endocytosis (engulf into vesicle if recognise)
• phagocytosis - large food particles (simple process)
• O2 taken up by diffusion on cell surface

Question 4

Reproduction

Answer 4

• Some simple and only haploid - undergo fission = asexual
• Sexual reproduction and mainly haploid = produce gametes which join and form zygote, then split by meisosi
• Diploid cycle - meiosis produces gametes, fuse and form dilploid zygote then develops to adult
• Alteration of generations - halpodiploid cycle

Question 5

Amboeboid

Answer 5

• asexual reproduction by fission or sexual
• moves by pseudopodia, lobopodia (tube-like) or filopodia (more pointy)
• free-living forms - amoeba

Question 6

Spore-forming or Apicomplexans

Answer 6

•compacted sexual and asexual stages - often take place in different organisms
•uses other organisms for movement - parasitic and spread in infectious cells - sporozoites
•e.g. Plasodium
-halciparum worst form

Question 7

Plasmodium

Answer 7

1. Contains sporozoites in salivary glands of mosquito so transfers when bites human
2. Go to liver cells - undergo multiple divisions and form merozoites
3. Merozoites infect RBCs - asexual divisions - break out and infect other RBCs
4. Eventually merozoites develop gametocytes
5. Mosquito bites infected human - takes up gametocytes
6. 3 gametes develop from these
7. Fertilisation in mosquito gut - short diploid
8. Oocyst from zygote and sporozoites develop in oocyst and migrate to salivary gland - REPEAT

Question 8

Flagellates

Answer 8

• flagella for movement
• have both asexual and sexual reproduction - poorly understand though
• free-living (found in roaches gut for breaking down cellulose)
• parasitic Trypanosoma (sleeping sickness)

Question 9

Trypanosoma

Answer 9

• kinetoplast were mass of DNa is found in mitochondria
•variant surface glycoprotein (VSG)
•extra-cellular parasite transmitted by tsetse fly
Human involving form - makes way into brain via cerebrospinal fluid if not treated = death in 2-3yrs
Game form - if in human, death = 6 weeks

Question 10

Ciliates

Answer 10

• asexual reproduction - macronucleus, nucleus divides and produces more
• reproduces by conjugation by micronucleus - no new individual just genetic exchange
• cilia beat in metachronal waves
• free-living Paramecium
• attached ciliate - Stentor
• few parasites effect humans