Diversity of microbes, Fungi and protists

Question 1

What are the 3 domains of life?

Answer 1

Bacteria, Archaea, and Eukarya

Question 2

What is extremophiles?

Answer 2

They are prokaryotes that can grow under extreme conditions that would kill other lifeforms due to their extremities.

• Found in extreme environments such as deep oceans, hot springs, arctic/antartic, harsh chemical/high radiation environment

Question 3

What is biofilm?

Answer 3

They are a microbial community held together in gummy- textured matric. They are a community of interactive prokaryotes. They are present almost everywhere and cause large- scale contamination outbreaks of food, colonize kitchen/bathroom household surfaces

Question 4

What is the difference between phototrophs and chemotrophs

Answer 4

PHOTOTROPHS: Obtain energy from sunlight

CHEMOTROPHS: Obtain energy from chemical compounds

Question 5

What are the three categories phototrophs and chemotrophs fall into?

Answer 5

• Cocci (spherical)
• Bacilli (rod-shaped)
• Spirilla (spiral shaped)

Question 6

What is the difference between Bacteria and Archaea?

Answer 6

Similarities:

Both are types of
prokaryotic cell
* Have same basic
structures, but built
from different chemical
components showing
an ancient separation of
lineages

Both have cell walls and
membranes but are different in
structure

DIFFERENCES:
Differ in the lipid
composition of their cell
membranes and in cell
wall characteristics
* E.g. Archaea: lipid
monolayer plasma
membrane
* E.g. Bacteria:
phospholipid bilayer plasma membrane

Question 7

What are the cells walls like in Bacteria?

Answer 7

• Their cell walls contain peptidoglycan ( made of sugar chains linked to peptides)
• Gram positive vs Gram negative

Question 8

What is the difference between gram - positive and gram negative? (BACTERIA)

Answer 8

GRAM - POSITIVE: have thick wall with many layers of peptidoglycan

GRAM - NEGATIVE: have thinner cell wall composed of layers of peptidoglycan and additional structures surrounded by an outer membrane

Question 9

What are the cell walls like in archaea?

Answer 9

• their walls do not contain peptidoglycan
  FOUR TYPES OF CELL WALLS:
• One composed of pseudopeptidoglycan
• Other three types contain polysaccharides, glycoproteins and surface layer proteins known as S- layers

Question 10

What are other differences in Archaea and bacteria cell walls?

Answer 10

ARCHAEA:
More likely to live in extreme environments with high level of chemical and radiation
* Many are anaerobic and
live in low-oxygen
environments
* Reproduce by budding,
fission, and fragmentation

BACTERIA:
Less likely to live in
extreme environments
* Most are aerobic
* Reproduce by binary
fission, budding, and fragmentation

Question 11

Eukaryotic origins

Answer 11

• Evolved from ancestral prokaryotes by a process that involved the spread of membranes, cell wall loss, development of a cytoskeleton and organelle evolution
• Evolved from both bacteria and archaea
• genes in nucleus of eukaryote came from Archaea
• Energy machinery of eukaryotic cells came from Bacteria
  -Mitochondria and plastids originated from endosymbiotic events
• ancestral cells engulfed an anaerobic bacterium and a photosynthetic bacterium

Question 12

Protists

Answer 12

• organisms that didn’t fit the criteria of the kingdom elsewhere were historically classified as protists
• other protists live in many other environment
• huge diversity in habitats and characteristics
• most are microscopic and single - celled, some are large and multi cellular
• Almost all protists live in some type aquatic environement, including freshwater/marine environments

Question 13

What is parasite?

Answer 13

Adapt/feed on another organism without killing it. Protist parasites causes malaria, african sleeping sickness, and waterborne gastroenteritis in humans

Question 14

what are the characteristics of protists?

Answer 14

wide variety of feeding habits
- some have chloroplasts and are photosynthetic
- some are heterotrophs and consume organic materials for nutrition
- may be aerobic or anaerobic
- wide variety in cell structure
- some have cell walls, others cell membrane,
- some live as colonies, others as single cells,
- most are mobile and use flagella or cillia to move around in their environment
- show that they are a very diverse group

Question 15

Fungi

Answer 15

• Fungal cells are eukaryotes and contain a true nucleus and many membrane - bound organelles
• contain mitochondria and other membrane- bound organelles and does not contain chloroplasts
• have thick cell walls made of chitin
• Unlike plants, not capable of photosynthesis
  they need plants/ animals to be present in order to sustain their nourishment
• they use complex- organic compounds as sources of energy and carbon. They obtain carbon and nitrogen from their diet not the atmosphere

Question 16

What are Saprobes (FUNGI)

Answer 16

• obtain nutrients from decaying organic matter

Question 17

What are the characteristics of Fungi?

Answer 17

• they are decomposers and participate in the cycling of nutrients by breaking down organic materials into simple molecules
• can multiply either asexually or sexually
• most fungi produce a large number of spores that are disseminated by the wind to send the spores to a geographic new area
• often enjoys moist, acidic environments
• can grow with or without light
• most are aerbic but some are anerobic( no oxygen)
• often interact with other organisms, forming mutually beneficial associations

Question 18

Fungi infections

Answer 18

• fungal infection are hard to treat in humans because they are eukaryotic and does not respond to antibiotics
• these infections can be deadly for people (HIV/AIDS)