Lectures 17 & 18 Flashcards
All organisms contain which 6 primary atoms which are the building blocks of macromolecules?
Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Sulfur
Lipids
C, H, O, P
Proteins
C, H, O, N, S
Carbohydrates
C, H, O
DNA, RNA
C, H, O, P, N
Since CHONPS is limited, _____
each element cycles in and out of living systems in different ways
primary reservoir (PR) definition
where the element is when it’s not part of an organism
3 primary reservoirs
- atmosphere
- water
- sediment
water
PR for Oxygen: H2O molecules
PR for Hydrogen: H2O molecules
atmosphere
PR for Carbon: CO2 in the atmosphere
PR for Nitrogen: N2 in the atmosphere
sediment
PR for Phosphorus: soil and ocean beds
PR for Sulfur: soil and ocean beds
cycling pattern for CHONPS
Elements cycle between reservoirs and organisms
* look at pic
What connects photosynthesis and cellular respiration
cycling of C, H, and O
* look at pic
What 2 things are nitrogen needed for?
proteins and nucleic acids
What is the problem with N2?
atmospheric N2 is not usable by most organisms b/c it’s very stable with 3 bonds
The atmosphere is 80% __.
N2
What is step 1 of the solution to the nitrogen problem?
Step 1: Nitrogen Fixation
From its reservoir in the atmosphere, nitrogen enters ecosystems through nitrogen fixation
* Nitrogen-fixing bacteria (NFB) convert unusable inert N2 into reactive, usable ammonia and nitrate
* NFB live in soil and on the roots of some plants
What is step 2 of the solution to the nitrogen problem?
Step 2: Nitrogen Recycling
1. Plants incorporate the NH3 and NO3 into macromolecules (MMs)
2. N containing MMs are taken up by consumers and decomposers
3. Decomposers in the soil convert the nitrogen in MMs back into NH3 and NO3 (soil)
Nitrogen fixation provides __% of the N needed for living things
Nitrogen recycling provides __% of the N needed for living things
5
95
denitrification
NO3- is returned to the air as N2, carried out by bacteria
What 3 things are phosphorus important for?
Nucleotides (ex. ATP)
Nucleic acid polymers (RNA/DNA)
Phospholipids (plasma membranes)
What is the phosphorus cycle?
- Plants incorporate P from sediment
- Consumers eat plants, consumers eat each other
- Plant/consumers die and decomposers return P to the sediment
- Plants incorporate it again and the cycle begins again
Sulfur Cycle
- Plants incorporate S from sediment
- Consumers eat plants, consumers eat each other
- Plant/consumers die and decomposers return S to the sediment
- Plants incorporate it again and the cycle begins again
What 2 things are sulfur important for?
- Found in certain amino acids (proteins)
- Methionine and cysteine
- Critical for protein folding
