CH.9-Decomposers Flashcards
What is detritus?
Non-living organic matter
What is a decomposer?
Organism that breaks down organic nutrients in detritus by secreting exoenzymes
How does the breakdown go back to the producers?
Breakdown products absorbed for energy –> Inorganic nutrients are returned to the physical environment –> Available for producers to reuse
Decomposer are essential nutrient ___ of all ecosystems
recyclers
What happens if we don’t recycle nutrients by decomposers?
Nutrients would remain trapped withing dead organisms –> Unavailable for producers to use
Name the eukaryotic decomposers?
Fungi & certain protists (slime, water molds)
Can bacteria be a decomposer?
Yes
FUNGI: What kingdom?
Eukaryotic
FUNGI: General characteristics
- Unicellular or multicellular?
- Are cells surrounded by walls? If yes, what?
- They usually make up most/least mass of decomposers in their environment?
- Asexual or sexual reproduction
- Uni and multicellular (most are multi)
- Cell walls = chitin
- Most of the mass of decomposers
- Asexual and sexual
True or false: Fungi and animals, when compared molecularly, are the least similar than other eukaryotic kingdoms
False - They are more similar
FUNGI: Cells join together forming filaments called ___
hyphae
FUNGI: Networks of hyphae are called ___
Mycelium
What makes up majority of fungal organism?
Subterranean mycelium
What does hyphae do?
Maximize absorptive surface area to take nutrients in from organic matter being decomposed
Are fungi heterotrophic or autotrophic? Why?
Heterotrophic - They get E from detritus
What enzymes do fungi excrete?
Exoenzymes
Yeast is an example of what type of reproduction in fungi?
Simple asexual reproduction
Multicellular fungi: What is produced that are dispersed into the environment?
Spores
Each spore can grow into a new organism: T or F
True
What do fruiting bodies on fungi aid in?
Dispersal of spores
Is yeast a unicellular or multicellular fungi?
Unicellular
Yeast lives in what type of environment?
Rich in simple sugars, fruits surfaces…
Are molds multicellular or unicellular?
Multicellular
Where does mold grow (environment)?
Moist organic matter
Aspergillus is an example of a highly toxic __
mold
Club fungi produce large ___
fruiting bodies
Why are fungi used for bioremediation?
- They secrete exoenzymes to breakdown pollutants
- Can breakdown petroleum fuels
Can protists be decomposers? If so, which ones?
Yes, certain ones - Slime molds and water molds
Protists that are decomposers are often mistaken for fungi due to what?
Their ability to produce fruiting bodies for reproduction
Slimes molds are a type of ___
amoeba
How are slime molds formed?
Solitary amoebas are gathered to form macroscopic aggregates that breakdown detritus
Where are slime molds found?
Damp forest floors, fallen logs
How do slime molds reproduce?
Producing fruiting bodies that disperse spores
Water molds: Its cells arrange into ___
hyphae
Where are water molds found?
Decomposers of dead algae and animals in freshwater
Bacteria as decomposers are ___trophic
chemohetero - acquire E and carbon by breaking down large organic molecules in waste products from living organisms
Bacteria in soil as decomposers and have different cell shapes, what are the names for: rod and spherical
bacillus - cocci
Actinomycetes are what?
Fungi like bacteria, specialized decomposer bacteria
Why are actinomycetes mistaken for fungus orginally?
Cell arrangement
What characteristics do actinomycetes share with fungi?
1) Rod shape cells that form hyphae
2) Hyphae join to form mycelium
3) Very important decomposers in soil
4) Gives soil earth smell
Do bacteria have organelles?
No
Inside bacterial cells:
1) Main circular chromosome in nucleoid region
2) Plasmids:
- Small circular DNA molecules in cytoplasm
- Can be exchanged between bacterial cells during conjugation
3) Ribosomes
- Required to make proteins
- Smaller and less dense than euk cell ribosomes
External bacterial cell features and functions:
1) Cell wall w/ substance called peptidoglycan (sugar+protein) –> Maintain shape + Protect from external enviroment
2) Capsule exterior with sticky texture –> Adhere to substrate or to each other
What are the 2 groups bacteria can be placed based on structure of their cells walls?
Gram+ or Gram-
What is Gram+ cell wall?
Composed of thick layer of peptidoglycan
What is Gram- cell wall?
Thin peptidoglycan layer with outer membrane composed of lipopolysaccharides LPL
What does fimbriae help with? What is it?
Adhere to surfaces - hairlike appendages
What does flagella help with?
Locomotion
What does pili help with?
Cell movement and DNA transfer between cells
What are sex pili used for?
Pull 2 bacterial cells closer to transfer plasmids during conjugation (sexual reproduction)
Bacterial asexual reproduction: Binary fission procedure
1) Chromosome and plasmids are replicated
2) Cell stretches
3) 1 copy of chromosome and plasmids are placed at opposite sides of cell
4) Cell divides into 2 daughters (genetically identical)
How can bacteria adapt quickly?
Rapid reproduction + Mutation
Is bacteria replication horizontal gene transfer (one species to another)? How?
Yes
1) Transduction: Virus
2) Transformation: Pick up pieces of DNA from surroundings
3) Conjugation: Transfers plasmids between cells temporarily joined
Are plasmids essential to survival? Why?
NO - they’re an extra pool of genes (only useful in special situations)
When antibiotic is given it kills ___ bacteria and the resistant ones survive and multiply
Sensitive
The selective pressure is greater/lower when antibiotics are used?
Greater
Do antibiotics cause resistance?
No they create an environment which favors the growth of resistant variants. When resistance, multiply quickly
How do some bacteria survive hostile conditions?
By producing endospores - tough dormant structures that contains the genome of the cell
Metabolic capabilities of bacteria:
1) Obligate aerobes: Need O to produce __
2) Facultative anaerobes: Can produce E in presence/absence of ___
3) Obligate anaerobes: Are poisoned by __. Anaerobic production of E only
Energy - oxygen - oxygen
