Lectures 17 & 18

Question 1

All organisms contain which 6 primary atoms which are the building blocks of macromolecules?

Answer 1

Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Sulfur

Question 2

Lipids

Answer 2

C, H, O, P

Question 3

Proteins

Answer 3

C, H, O, N, S

Question 4

Carbohydrates

Answer 4

C, H, O

Question 5

DNA, RNA

Answer 5

C, H, O, P, N

Question 6

Since CHONPS is limited, _____

Answer 6

each element cycles in and out of living systems in different ways

Question 7

primary reservoir (PR) definition

Answer 7

where the element is when it’s not part of an organism

Question 8

3 primary reservoirs

Answer 8

1. atmosphere
2. water
3. sediment

Question 9

water

Answer 9

PR for Oxygen: H2O molecules
PR for Hydrogen: H2O molecules

Question 10

atmosphere

Answer 10

PR for Carbon: CO2 in the atmosphere
PR for Nitrogen: N2 in the atmosphere

Question 11

sediment

Answer 11

PR for Phosphorus: soil and ocean beds
PR for Sulfur: soil and ocean beds

Question 12

cycling pattern for CHONPS

Answer 12

Elements cycle between reservoirs and organisms
* look at pic

Question 13

What connects photosynthesis and cellular respiration

Answer 13

cycling of C, H, and O
* look at pic

Question 14

What 2 things are nitrogen needed for?

Answer 14

proteins and nucleic acids

Question 15

What is the problem with N2?

Answer 15

atmospheric N2 is not usable by most organisms b/c it’s very stable with 3 bonds

Question 15

The atmosphere is 80% __.

Answer 15

N2

Question 16

What is step 1 of the solution to the nitrogen problem?

Answer 16

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

Question 17

What is step 2 of the solution to the nitrogen problem?

Answer 17

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)

Question 18

Nitrogen fixation provides __% of the N needed for living things
Nitrogen recycling provides __% of the N needed for living things

Answer 18

5
95

Question 19

denitrification

Answer 19

NO3- is returned to the air as N2, carried out by bacteria

Question 20

What 3 things are phosphorus important for?

Answer 20

Nucleotides (ex. ATP)
Nucleic acid polymers (RNA/DNA)
Phospholipids (plasma membranes)

Question 21

What is the phosphorus cycle?

Answer 21

• 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

Question 22

Sulfur Cycle

Answer 22

• 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

Question 22

What 2 things are sulfur important for?

Answer 22

• Found in certain amino acids (proteins)
• Methionine and cysteine
• Critical for protein folding

Question 23

Redox Rxns

Answer 23

Occurs when molecules gain or lose electrons

Question 24

OIL RIG

Answer 24

Oxidation Is Loss: loss of electrons
Reduction Is Gain: gain of electrons

Question 25

Electron carriers

Answer 25

• 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

Question 26

pattern of affinity for electrons in ETC

Answer 26

each EC in ETC has increasingly more affinity for electrons
ECs and ETCs are critical to photosynthesis and cellular respiration

Question 27

photosynthesis

efficient energy transfer %

Answer 27

sunlight + CO2 + H2O = glucose (sugar) + O2

30% efficient

Question 28

Where is the site of photosynthesis?

thylakoid membranes
stroma

Answer 28

chloroplasts

Thylakoid membranes: contain pigments (chlorophylls) that capture light energy
Stroma: where glucose is made

Question 29

Part 1 of photosynthesis

Answer 29

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

Question 30

Part 2 of photosynthesis

Answer 30

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)