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Chapter 5
Eukaryotes
60
Microbiology
07/17/2011

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Term
How were eukaryotic cells evolved?
Definition

Through symbiosis

(large prokaryotic cell engulfed smaller bacterial cells that began to live and reproduce inside prokaryotic cell rather than being destroyed)

 

First primative cell was probably single-celled and independent. Eventually formed colonies that became specialized and evolved into multicellular organisms.

Term
Which eukaryotic organism is always unicellular?
Definition
protozoa
Term
Which eukaryotic organisms may be unicellular or multicellular?
Definition

Fungi

Algae

Term
Which eukaryotic organism is always multicellular?
Definition

Helminths

(have unicellular eggs or larval forms)

Term
How are eukaryotic flagella different from prokaryotic flagella?
Definition

10x thicker

Structurally more complex

Covered by an extension of the cell membrane

Term
What's the arrangement of microtubules in euk. flagella? How does it move?
Definition

9+2 arrangement (9 outside, 2 in middle)

 

Whip-like movement

(not runs and tumbles)

Term
What are cilia?
Definition

Shorter locomotor appendages that are more numerous.

 

Also function as feeding and filtering structures

Term
Describe the glycocalyx and its functions.
Definition

Appears as network of fibers, a slime layer, or a capsule.

 

They both function as protection, adhesion, and reception of signals.

Term
Identify the variations of the layer beneath the glycocalyx.
Definition

Fungi and most algae have a thick, rigid cell wall

 

Protozoa and animal cells do not have a cell wall

Term
What makes up the cell wall of fungi?
Definition

Thick inner layer of chitin or cellulose

 

Thin outer layer of mixed glycans

Term
What makes up the cell wall of algae?
Definition
Varies- may contain cellulose, pectin, mannans, and minerals
Term
What makes up the cytoplasmic membrane of a eukaryotic cell?
Definition
Phospholipid bilayer with embedded protein molecules. Also contains sterols, which gives it stability. Sterols are important in cells without a cell wall.
Term
What are three unique things about eukaryotic mitochondria?
Definition
  1. Divide independently of the cell
  2. Contain DNA
  3. Contain prokaryotic-sized 70S ribosomes
Term
What do chloroplasts do? What do they have that's unique?
Definition
  • Convert energy of sunlight into chemical energy through photosynthesis
  • Contain chlorophyll and have own DNA and 70S ribosomes
Term
What's the S count for eukaryotic ribosomes? Why is this important for medicine?
Definition

80S

 

We can use drugs to affect 70S ribosomes of prokaryotic cells without affecting 80S ribosomes of eukaryotic cells. The drugs would however affect the ribosomes of the mitochondria and the chloroplasts of eukaryotic cells.

Term
What are the two types of cytoskeleton elements?
Definition
Microfilaments and microtubules
Term
What two groups can Fungi (myceteae) be divided into? Give examples of each.
Definition
  1. Macroscopic (mushrooms, puffballs)
  2. Microscopic (molds, yeasts)
Term
What distinguishes a yeast cell?
Definition
Its round shape and its mode of asexual reproduction (buds)
Term
What makes up a mold? How are they classified?
Definition

Hyphae- long, threadlike cells

 

Septate (segmented surface) or nonseptate (smooth surface)

Term
What's a dimorphic fungi?
Definition
A fungi that can take either the form of yeast or the form of hyphae depending upon growth conditions, such as changing temperature.
Term
What is a mycelium?
Definition
The woven, intertwining mass of hyphae that makes up the body of colony of a mold
Term
What's a pseudohypha?
Definition
A chain of yeasts formed when buds remain attached in a row and look like hyphae but are not.
Term

All fungi are heterotrophic.

True or False?

Definition
True- they acquire nutrients from organic materials called substrates
Term

Few fungi are saprobes.

True or False?

Definition
False- most are saprobes. They obtain their substrates from the remnants of dead organisms in soil or aquatic habitats
Term

Few fungi are parasites.

True or False?

Definition
True- Parasites are on the bodies of living animals or plants.
Term
What's the useful yeast identified in class?
Definition
Saccharomyces (makes beer, wine)
Term
What are two pathogenic fungi identified in class?
Definition

Cryptococcus

Candida

Term
What's the name of fungal reproductive bodies?
Definition

Spores

Term
What are the two subtypes of asexual spores? Describe them.
Definition
  1. Sporangiospores: formed by successive cleavages within a saclike head called a sporangium. Spores are released when sporangium ruptures.
  2. Conidiospores (Conidia): free spores not enclosed by a sac. They develop either by pinching off a fertile hypha or by segmentation of a preexisting hypha
Term

Sexual spores are produced by most fungi at some point.

True or False?

Definition
True
Term
What's a protist? What two subkingdoms does it contain?
Definition
  • any unicellular or colonial organism that lacks true tissues
  • algae and protozoa
Term
Describe algae.
Definition
Photosynthetic protists that are unicelluar, colonial, and filamentous in forms. They also have larger forms that possess tissues and simple organs.
Term

Algae contain all eukaryotic organelles.

True or False?

Definition
True
Term

Algae are one of the main components of plankton.

True or false?

Definition
true
Term
Algae are rarely infectious but one of their primary medical threats includes...
Definition
Shellfish exposed to red tide (food poisoning)
Term
Which eukaryotic organelle do protozoa lack?
Definition
chloroplasts
Term
How is protozoal cytoplasm divided?
Definition
  1. Ectoplasm: clear outer layer involved in locomotion, feeding, and protection
  2. Endoplasm: granular inner region house the nucleus, mitochondria, and food/contractile vacuoles
Term

Some protozoa have organelles that work like a primitive nervous system.

True or false?

Definition
True- ciliates and flagellates
Term
Do protozoa have a cell wall?
Definition
No- This allows for some flexibility. Cell shape can remain constant or change constantly (such as amoebas)
Term
Protozoa are heterotrophic. What are some ways they get their nutrition?
Definition
  • Some have special feeing structures (oral grooves)
  • Some absorb food directly through cell membrane
  • Parasitic species live on the fluids of their host or can actively feed on tissue
Term
What are the predominant habitats of protozoa?
Definition

fresh and marine water

soil

plants

animals

 

**main limiting factor is the availability of water**

Term
What's the dormant stage of a protozoa called?
Definition
A cyst
Term
All protozoa but the Apicomplexa are motile. What three means do they move by?
Definition
  • Pseudopods (false foot)- amoeboid motion
  • Flagella- one to several; some attached along the length of the cell by the undulating membrane
  • Cilia- mostly distributed over entire surface of the cell
Term
What's the trophozoite stage of protozoa?
Definition
The vegetative stage- require ample food and moisture to stay active
Term
What determines the life cycle of a parasitic protozoan?
Definition
the mode of transmission to the host
Term

All protozoa reproduce by asexual methods.

True or False?

Definition
True- most also reproduce with sexual reproduction like through conjugation with their cilia
Term
What are the 4 classifications of medically important protozoa?
Definition
  1. Mastigophora (flagellated)
  2. Sarcodina (amoebas)
  3. Ciliophora (ciliated)
  4. Apicomplexa (sporozoa)
Term
Describe mastigophora (flagellated) protozoa.
Definition
  • motility primarily by flagella
  • single nucleus
  • parasitic forms tend to lack mitochondria and Gogli apparatus
  • Most form cysts and are free-living
Term
What are examples of Mastigophora (flagellated) and why are they important medically? (4)
Definition
  1. Trypanosoma: sleeping sickness (T. brucei) and Chagas disease (T. cruzi)
  2. Leishmania: blood pathogens carried by insect vectors
  3. Giardia: intestinal parasite spread in water contaminated with feces
  4. Trichomonas: parasite of the reproductive tract of humans spread by sexual contact
Term
Describe Sarcodina (amoebas) protozoa.
Definition
  • pseudopods
  • some have flagellated reproductive states
  • mostly uninucleate
  • usually encyst
  • most free-living and not infectious
Term
What's an example of a sarcodina (amoeba) protozoa that's medically important? Why? (1)
Definition

Entamoeba

  • Amoebiasis caused by Entamoeba histolytica
  • 4th most common protozoan infection in the world
  • AKA amoebic dysentery
Term
Describe Ciliophora (Ciliated) protozoa.
Definition
  • Trophozoites mobile by cilia
  • some have cilia in tufts for feeding and attachment
  • most develop cysts
  • most have definite mouth and feeding organelle
  • show relatively advanced behavior
  • majority are free-living and harmless
Term
Describe Apicomplexa (Sporozoa) protozoa.
Definition
  • Most not motile
  • Complex life cycles
  • Produce sporozoites following sexual reproduction
  • Most form oocysts
  • ***Entire group is parasitic***
Term
What are 2 diseases caused by Apicomplexa (Sporozoa) protozoa?
Definition
  • Plasmodium (malaria)
  • Toxoplasma gondii (toxoplasmosis)
Term
What are parasitic helminths? When do you need a microscope with them?
Definition

Tapeworms, flatworms, roundworms

 

Microscope is necessary to ID eggs and larvae

Term
Describe flatworms.
Definition

Thin and often segmented.

 

In the phylum Platyhelminthes

 

Asexual or sexual reproduction.

Term
What are the two subdivisions of flatworms? Give examples of each.
Definition
  • Cestodes (tapeworms)- long, ribbonlike
  • Trematodes (flukes)- flat, ovoid bodies
Term
Describe roundworms.
Definition

AKA nematodes

 

elongated and cylindrical

unsegmented

 

phylum Aschelminthes

Term
Describe general characteristics of helminths.
Definition

Most developed organ are those of the reproductive tract

 

Some degree of reduction in digestive, excretory, nervous, and muscular systems

 

Most have thick cuticles for protection and mouth glands for break down the host's tissue

Term
Describe the helminth cycle, as based upon the pinworm.
Definition
  1. Person swallows egg (direct contact or by touching articles touched by an infected person)
  2. Eggs hatch in intestine
  3. Release larvae that mature into adult worms (1 month)
  4. Male and female worms mate
  5. Female migrates out of anuse to deposit eggs (causes intense itching- scratching contaminates fingers which transfer the eggs)
  6. Eggs spread to others or the host reinfects himself