Feeding Strategies
Symbiosis – the relationship between two populations or organisms that
live together.

Commensalism – One benefits, one isn’t affected
Examples -

Parasitism – One benefits at the expense of the other
Examples –

Mutualism – Both organisms benefit
Examples –
What is a biofilm?

Predator – Prey relationships

Dead Feeder or detrivore
Metabolism – the sum of all the chemical reactions within an organism.

Catabolic reactions release energy (catabolism, exergonic,
hydrolic, breakdown reactions)

Anabolic reactions require energy (anabolic, endergonic,
dehydration, building reactions)
Coupled reactions – anabolic or catabolic reactions are coupled with
ATPADP + P or ADP +P ATP
1
Enzyme – a protein that functions to speed up a chemical reaction.




Name ends in –ase
Grouped by function, p. 117
Coenzyme, cofactor often needed
Examples –

Enzymes are denatured by temperature, pH

Inhibition of enzymes (to slow/stop reactions, why???)
o Competitive inhibition
o
Non-competitive inhibition
o
Limit the substrate
o
Feedback Inhibition
2
Metabolic Pathways
Organisms store and release energy through a series of controlled
reactions. Organisms pass electrons from one compound to another
through a series of oxidation – reduction reactions to release/store
energy.

OIL RIG

Which is catabolic, anabolic?
Electron Transport Molecules – important because….
examples -
Cellular Respiration –provides energy to the cell by oxidation of
carbohydrates, oxygen is the final acceptor molecule

3 steps – Glycolysis, Kreb’s cycle, Electron Transport Cycle
C6H12O6 + 6 O2  6 CO2 + 6 H2O + 36 ATP + heat
3
1.
Glycolysis – one molecule of glucose is split into two 3-carbon
molecules called pyruvate





2 ATP molecules are used to start the reaction
Net gain of 2 ATP
2 NADH are produced
2 H2O are produced
Glycolysis takes place in the ______________________
2.
Kreb’s Cycle – breaks down each of the two pyruvates,
releasing CO2
 Each pyruvate produces 1 ATP, 4 NADH, 1 FADH2, 3 CO2
 Kreb’s cycle takes place in the _____________________
3.
Electron Transport Cycle – Converts electron carrier molecules
into ATP (NADH, FADH2)
 Oxygen is used
 Each NADH produces 3 ATP
 Each FADH2 produces 2 ATP
 ETC takes place in the ___________________________
Fermentation – an alternate pathway that produces energy from
glucose; does not require oxygen.



Each glucose produces 2 ATP
Glycolysis is the first step
Microbes can ferment different substrates and produce
different end-products
4
Proteins, Lipids are also a source of energy. These molecules can be
broken down and pass through the cellular respiration or fermentation
metabolic pathways.
Photosynthesis
Cconversion of light energy from the sun into chemical energy.
Synthesis of carbohydrates from CO2.



Carbon Fixation – synthesis of sugar from CO2
Anabolic
6 CO2 + 12 H2O + Light energy  C6H12O6 + 6 O2 + heat

Two reactions make up photosynthesis
1. Light dependent reactions
 In – water
 Out – O2, ATP
2. Light independent reactions
 In – CO2, ATP, NADPH
 Out – Glucose, ADP, NADP+
Microbes are unique because they can sustain
themselves by using pathways unavailable to plants and
animals.
 Can be categorized by Energy or carbon source




Energy source
Chemotrophs – energy from chemical
source
Phototrophs – energy from a light source
Carbon Source
Autotrophs – carbon from CO2
Heterotrophs – carbon from organic
molecules
5
Carbon Cycle
Why is carbon important?


Natural Reservoir – tissues of living or once living organisms
Carbon is cycled between photosynthesis and cellular
respiration

What does global warming have to do with the carbon cycle?

What roles do microbes play in the carbon cycle?
Nitrogen Cycle
Why is the nitrogen cycle important?
 Natural Reservoir – 80% of N is atmospheric and is inaccessible

Nitrogen fixation – plants must be able to fix N to use, only a
few microbes can fix N
o
Ammonification – protein from dead organisms is
decomposed, forming ammonia (deamination)
o
Nitrification – ammonium is converted to nitrate, which
moves more easily through soil
o
Denitrification – returns N to reservoir, economic loss
6