eukaryotic microbes - cell structure

Question 1

what is a eukaryote?

Answer 1

a eukaryote is any cell or organism that possesses a clearly defined nucleus.

Question 2

what are eukaryotic microbes?

Answer 2

eukaryotic microbes are largely unicellular organisms.
the cell structure has greater complexity compared to prokaryotes containing a defined membrane bound nucleus and a range of membrane bound cell organelles.

Question 3

examples of eukaryotic microorganisms.

Answer 3

1. fungi
2. algae
3. protozoans

Question 4

what are the characteristics of fungi?

Answer 4

fungi lack chlorophyll.
all fungi are heterotrophic, requiring organic food.
most fungi are aerobes, although some like the yeast are facultative anaerobes.

Question 5

examples of unicellular fungi.

Answer 5

yeasts are unicellular fungi.

Question 6

examples of multicellular fungi.

Answer 6

all other fungi, including moulds, and macroscopic filamentous fungi like mushrooms are multicellular fungi.

Question 7

examples of yeast.

Answer 7

saccharomyces cerevisiae
candida albicans.

Question 8

characteristics of yeast

Answer 8

yeast possess a single nucleus and reproduce either asexually by budding, or sexually by spore formation.
yeast have a bud scar on their cell surface.

Question 9

what is a bud scar?

Answer 9

a bud scar is a characteristic of asexual reproduction - this happens by budding off a smaller daughter cell.

Question 10

candida albicans

Answer 10

candida albicans is a common yeast that forms pseudohyphae (chains of cells).
C.albicans is associated with various infections in humans, including vaginal yeast infections oral thrush, and candidiasis of the skin.

Question 11

characteristics of moulds

Answer 11

moulds may be saprophytic or saprotrophic, this means they feed on dead or decaying organic substances.

Question 12

what are the cellular components of fungi that are the same as human cells?

Answer 12

• cell wall
• cell membrane
• nucleus
• mitochondria
• vacuoles
• rough & smooth endoplasmic reticulum
• peroxisomes
  these are all essential like in human cells.

Question 13

what is the function of peroxisomes in fungal cells?

Answer 13

involved in cellular lipid homeostasis
invovled in metabolising reactive oxygen
involved in the making of secondary metabolites.

Question 14

what are the cellular components of fungi that are unique to fungi?

Answer 14

• sporangium
• sexual spores
• hyphae
• wornoin bodies
• chitin

Question 15

what is sporangium?

Answer 15

sporangium are the asexual spore-producing / spore-bearing structure of the fungi cell.

Question 16

example of sexual spores.

Answer 16

fungi have sexual spores that are usually named after the organism.
e.g. zygospores which are sexual spores from the species of fungi called the zygomycetes fungi (black bread mould)

Question 17

zygomycetes fungi

Answer 17

black bread mould
these fungi thrive in soil and dead plant material. they also have an exquisite taste for dung.

Question 18

hyphae

Answer 18

individual microscopic filaments.
hyphae are used for obtaining food
hyphae are involved in growth at the top of the cell
hyphae branch to form a network of hyphae called a mycellium.

Question 19

classifications of hyphae

Answer 19

septate
aseptate (Coenocytic)

Question 20

septate hyphae

Answer 20

divided into cells by internal cell walls called septa

Question 21

aseptate hyphae (Coenocytic)

Answer 21

large multinucleated cells without a septum

Question 22

what is the function of woronin bodies?

Answer 22

woronin bodies block septal pores, following damage to hyphae.
woronin bodies protect the hyphae by preventing the extensive loss of cytoplasm.

Question 23

fungi: cell wall

Answer 23

cell (hypha) is surrounded by a rigid wall
composed primarily of chitin and glucans - these fibres exist in a gel-like matrix within the cell wall.

Question 24

what is chitin?

Answer 24

chitins are major polysaccharides
chitin is a polymer of N-acetylglucosamine (NAG)

Question 25

what is glucan?

Answer 25

glucan is a polymer of D-glucose

Question 26

what is the function of the fungal cell wall?

Answer 26

protection of the yeast cell or hypha
maintains the shape of the yeast cell or hypha
is the interface between the fungus and its environment
involved in communication
attachment to surfaces
acts as a binding site for some enzymes
possess antigenic properties (immune response)

Question 27

what are algae

Answer 27

algae are aquatic organisms that have the ability to conduct photosynthesis.
algae are photoautotrophic so require light for growth.
algae reproduce by the asexual process binary fission
algae are found in ponds, lakes and streams.

Question 28

examples of algae

Answer 28

seaweeds, pond scum, algal blooms.

Question 29

what are the components of an algal cell?

Answer 29

nucleus, nucleolus, golgi apparatus, ribosomes, cell membrane, cell wall, centrioles, cytoplasm, starch vacuole, mitochondrion, flagellum, chloroplast.

Question 30

what are protozoans?

Answer 30

protozoans are microscopic unicellular organisms existing singly or in colonies, without tissues and organs, having one or more nuclei.
protozoans are classified by their features for movement.

Question 31

what is trophozoite?

Answer 31

trophozoite is the stage of life where protozoans are feeding
with a macronucleus, a micronucleus, a contractile vacuole, an oral groove, a cytosome, a cytoproct, an anal pore, a food vacuole, and a secretory vacuole.

Question 32

what is the function of the contractile vacuole?

Answer 32

osmoregulation, found in freshwater protozoans where water regulation is a problem.

Question 33

what is the function of the secretory vacuole?

Answer 33

contains enzymes

Question 34

what is the function of the food vacuole?

Answer 34

phagocytic vacuoles used to ingest food by phagocytosis.

Question 35

protozoan classifications for movement.

Answer 35

• sarcomastigophora
  > sarcodina
  > mastigophora
• ciliophora
• microspora

Question 36

characteristics of sarcodina

Answer 36

form pseudopodia

Question 37

characteristics of mastigophora

Answer 37

move by flagella

Question 38

characteristic of ciliophora

Answer 38

move by cilia

Question 39

characteristics of microspora

Answer 39

are parasites
have no locomotory organelles.

Question 40

protozoan locomotory organelles

Answer 40

1. flagella > mastigophora
2. cilia > cilates
3. pseudopodia > sarcodina

Question 41

protozoan: locomotory organelles - flagella

Answer 41

e.g. trypanosoma
cells may have one or more flagella which are long, thread-like extensions from the cell.
flagella move by spinning, whipping or moving like tentacles.
flagella are embedded in the ectoplasm.

Question 42

protozoan: locomotory organelles - cilia

Answer 42

e.g. balantidium
short, hair-like structures in large numbers on the cell.
move the cell by an oar-like stroke with a high degree of coordination.
cilia are embedded in the ectoplasm.

Question 43

protozoan: locomotory organelles - pseudopodia

Answer 43

e.g. rhizopods, entamoeba
are produced by pinching of the cell and extending the cell membrane, which sticks to most surfaces, and the rest of the cell then ‘flows’ into the extension thus the cell moves to the new position.
act as tentacles in movement
used to engulf food in feeding.