chapter 7: how cells harvest energy

Question 1

respiration
organisms can be classified based on how they obtain energy:
_____
- able to produce their own organic molecules through photosynthesis
_____
- live on organic compounds produced by other organisms
all organisms use ____ respiration to extract energy from organic molecules

Answer 1

autotrophs, heterotrophs, cellular

Question 2

cellular respiration
is a series of ____
___ - loss of electrons
___ - gain of electron
____ - lost electrons are accompanied by protons
- a hydrogen atom is lost (1 electron, 1 proton)

Answer 2

reactions, oxidized, reduced, dehydrogenation

Question 3

redox reactions
during redox reactions, ___ carry energy from one molecule to another
Nicotinamide adenosine dinucleotide (___)
- an electron carrier and _____ cofactor
- NAD+ accepts _ electrons and _ proton to become ___
- reaction is reversible

Answer 3

electrons, NAD+, enzymatic, two, one, NADH

Question 4

Energy harvest and redox reactions
in overall cellular energy harvest
- ___ of redox reactions take place
- number of ____ acceptors including ___
in the end, high-energy electrons from initial chemical bonds have ___ much of their energy
transferred to a ___ electron acceptor

Answer 4

dozens, electron, NAD+, lost, final

Question 5

electron acceptors
aerobic respiration
- final electron is _____
anaerobic respiration
- final electron acceptor is an ____ molecule (not O2)
fermentation
- final electron acceptor is an ___ molecule

Answer 5

oxygen, inorganic, organic

Question 6

“Burning” carbohydrates
C6H12O6 + 6CO2 –> ___ + ___ + energy
___ energy = -686 kcal/mol of glucose
free energy can be even ___ than this in a cell
- this large amount of energy must be ___ in small steps rather than all at once

Answer 6

6CO2, 6H2O, free, higher, released

Question 7

electron carriers
many types of carriers used
- ____, membrane-bound, move within membrane
all carriers can be reversibly ___ and reduced
some carry just electrons, some electrons and protons NAD+ acquires ___ electrons and __ proton to become __

Answer 7

soluble, oxidized, two, one, NADH

Question 8

ATP
cells use ATP to drive ____ reactions
- change G (___ energy) of hydrolyzing terminal ____ = -7.3 kcal/mol
two mechanisms for synthesis
1. ____-____ phosphorylation
- transfer ____ group directly to ADP
- during ____
2. ____ phosphorylation
- ATP synthase uses energy from a proton gradient

Answer 8

endergonic, free, phosphate, substrate level, phosphate, glycolysis, oxidative

Question 9

oxidation of glucose
the complete oxidation of glucose proceeds in stages
1. _____
2. _____ ____
3. _____ ____ _____
4. _____ ____ _____ & _____

Answer 9

glycolysis, pyruvate oxidation, citric acid cycle, electron transport chain, chemiosmosis

Question 10

glycolysis
- converts __ glucose (__ carbons) to __ pyruvate (__ carbons)
- 10 step biochemical pathway
- Net production of __ ATP molecules by substrate-level phosphorylation
- __ NADH produced by the ____ of NAD+

Answer 10

one, six, two, three, two, two, reduction

Question 11

NAD+ must be regenerated
for glycolysis to continue, ___ must be recycled to NAD+ by either:
1. ____ respiration
- oxygen is available as the final electron acceptor
- produces significant amount of ___
2. _____
- occurs when oxygen is not available
- _____ molecule is the final electron acceptor

Answer 11

NADH, aerobic, ATP, fermentation, organic