AP Biology Vocabulary & Roots: Ch. 9
1. acetyl CoA (Acetyl coenzyme A)- the entry compound for the citric acid cycle in cellular
respiration, formed from a fragment of pyruvate attached to a coenzyme.
2. aerobic respiration-A catabolic pathway that consumes oxygen (O2) and organic molecules,
producing ATP. This is the most efficient catabolic pathway and is carried out in most eukaryotic
cells and many prokaryotic organisms.
3. alcohol fermentation-Glycolysis followed by the conversion of pyruvate to carbon dioxide and
ethyl alcohol.
4. anabolic pathway-A metabolic pathway that consumes energy to synthesize a complex molecule
from simpler compounds.
5. anaerobic respiration-The use of inorganic molecules other than oxygen to accept electrons at
the “downhill” end of electron transport chains.
6. ATP synthase-A complex of several membrane proteins that provide a port through which
protons diffuse. This complex functions in chemiosmosis with adjacent electron transport chains,
using the energy of a hydrogen ion (proton) concentration gradient to make ATP. ATP synthases
are found in the inner mitochondrial membrane of eukaryotic cells and in the plasma membrane of
prokaryotes.
7. beta oxidation-A metabolic sequence that breaks fatty acids down to two-carbon fragments that
enter the citric acid cycle as acetyl CoA.
8. catabolic pathway-A metabolic pathway that releases energy by breaking down complex
molecules to simpler compounds.
9. cellular respiration-The catabolic pathways of aerobic and anaerobic respiration, which break
down organic molecules for the production of ATP.
10. chemiosmosis-An energy-coupling mechanism that uses energy stored in the form of a
hydrogen ion gradient across a membrane to drive cellular work, such as the synthesis of ATP.
Most ATP synthesis in cells occurs by chemiosmosis.
11. citric acid cycle-A chemical cycle involving eight steps that completes the metabolic
breakdown of glucose molecules begun in glycolysis by oxidizing pyruvate to carbon dioxide;
occurs within the mitochondrion in eukaryotic cells and in the cytosol of prokaryotes; the second
major stage in cellular respiration.
12. cytochrome-An iron-containing protein that is a component of electron transport chains in the
mitochondria and chloroplasts of eukaryotic cells and the plasma membranes of prokaryotic cells.
13. electron transport chain-A sequence of electron carrier molecules (membrane proteins) that
shuttle electrons during the redox reactions that release energy used to make ATP.
14. facultative anaerobe-An organism that makes ATP by aerobic respiration if oxygen is present
but that switches to anaerobic respiration or fermentation if oxygen is not present.
15. fermentation-A catabolic process that makes a limited amount of ATP from glucose without an
electron transport chain and that produces a characteristic end product, such as ethyl alcohol or
lactic acid.
16. glycolysis-The splitting of glucose into pyruvate. Glycolysis occurs in almost all living cells,
serving as the starting point for fermentation or cellular respiration.
17. lactic acid fermentation- Glycolysis followed by the conversion of pyruvate to lactate, with no
release of carbon dioxide.
18. NAD+ (Nicotinamide adenine dinucleotide) - A coenzyme that can accept An electron and acts
as An electron carrier in the electron transport chain.
19. obligate anaerobe-An organism that only carries out fermentation or anaerobic respiration.
Such organisms cannot use oxygen and in fact may be poisoned by it.
20. oxidation-The loss of electrons from a substance involved in a redox reaction.
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21. oxidative phosphorylation-The production of ATP using energy derived from the redox
reactions of an electron transport chain; the third major stage of cellular respiration.
22. oxidizing agent-The electron acceptor in a redox reaction.
23. proton-motive force-The potential energy stored in the form of An electrochemical gradient,
generated by the pumping of hydrogen ions across a biological membrane during chemiosmosis.
24. reducing agent-The electron donor in a redox reaction.
25. reduction-The addition of electrons to a substance involved in a redox reaction.
26. substrate-level phosphorylation-The formation of ATP by an enzyme directly transferring a
phosphate group to ADP from an intermediate substrate in catabolism.
Word Roots
aero- = air (aerobic: chemical reaction using oxygen)
an- = not (anaerobic: chemical reaction not using oxygen)
chemi- = chemical (chemiosmosis: the production of ATP using the energy of hydrogen ion
gradients across membranes to phosphorylate ADP)
glyco- = sweet; -lysis = split (glycolysis: the splitting of glucose into pyruvate)
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