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
Redox Rxns
Occurs when molecules gain or lose electrons
OIL RIG
Oxidation Is Loss: loss of electrons
Reduction Is Gain: gain of electrons
Electron carriers
- Electron carriers: molecules that make up the ETC
- Accept electrons (become reduced) and then donate electrons (become oxidized)
- Some are enzymes - use energy from electrons to accomplish tasks in cell
pattern of affinity for electrons in ETC
each EC in ETC has increasingly more affinity for electrons
ECs and ETCs are critical to photosynthesis and cellular respiration
photosynthesis
efficient energy transfer %
sunlight + CO2 + H2O = glucose (sugar) + O2
30% efficient
Where is the site of photosynthesis?
thylakoid membranes
stroma
chloroplasts
Thylakoid membranes: contain pigments (chlorophylls) that capture light energy
Stroma: where glucose is made
Part 1 of photosynthesis
Light reactions (light dependent rxns): occur at the thylakoid membrane
Requires (input)
* Light as an energy source
* H2O as an electron source
* ADP + Pi (for ATP synthesis)
* NADP+: an electron carrier (oxidized form)
Produces (output)
* ATP: an energy storage molecules
* NADPH: an electron carrier (reduced form)
* O2: a byproduct
Part 2 of photosynthesis
Dark reactions (also called light-independent rxns, the Calvin cycle, and the Calvin-bensen cycle): occur in the stroma
Dark rxns do NOT occur at night
Requires
* CO2 as a carbon source
* ATP (from light reactions) as an energy source
* NADPH (from light reactions) as an electron source
Produces
* Glucose (energy storage molecule)
* ADP+Pi (from ATP hydrolysis)
* NADP+ (from oxidation of NADPH)
