7.4 The Citric Acid Cycle Flashcards
the citric acid cycle is the stage in cellular respiration in which:
fuel molecules are completely oxidized
Describe the outcomes of the citric acid cycle:
the acetyl group of acetyl-CoA is completely oxidized to carbon dioxide, the chemical energy is transferred to ATP by substrate-level phosphorylation and to the reduced electron carriers NADH and FADH2
by producing NADH and FADH2, the citric acid cycle is able to supply electrons to the:
electron transport chain, leading to the production of much more energy in the form of ATP
the citric acid cycle takes place in the:
mitochondrial matrix
the citric acid cycle is composed of:
8 reactions
the starting molecule is:
oxaloacetate and is regenerated at the end
in the first reaction, the 2-carbon acetyl group of acetyl-CoA is transferred to:
a 4-carbon molecule of oxaloacetate to form the 6-carbon molecule citric acid
the last reaction in the citric acid cycle regenerates a molecule of:
oxaloacetate, joining to a new acetyl group and allowing the cycle to continue
the citric acid cycle results in the complete oxidation of:
the acetyl group of acetyl-CoA
how many carbons are eliminated during the cycle?
2 carbons that are released as carbon dioxide
which reaction is the source of carbon dioxide released during cellular respiration?
the citric acid cycle
the oxidation reactions that produce carbon dioxide are coupled with:
the reduction of the electron carrier NAD+ to NADH
how many reduced electron carriers does the citric acid cycle produce?
3 NADH, 1 FADH2 per turn of the cycle
one of the reactions in the citric acid cycle uses substrate-level phosphorylation to generate a molecule of:
GTP
GTP can transfer:
its terminal phosphate to transform ADP to form ATP
what is the only substrate-level phosphorylation reaction in the citric acid cycle?
the production of GTP
what are the overall products produced from a single molecule of glucose into two molecules of acetyl-CoA?
2 molecules of ATP, 6 molecules of NADH, 2 molecules of FADH2
some bacteria run the citric acid cycle in reverse? how does this process work then?
carbon dioxide is incorporated into organic molecules, requires energy such as sunlight or chemical reactions
the intermediates generated step by step in the citric acid cycle provide:
the building blocks for synthesizing the cell’s key biomolecules
pyruvate is the starting point for the synthesis of:
sugars and the amino acid alanine
acetate is the starting point for the synthesis of:
lipids
oxaloacetates is modified to form:
different amino acids and pyrimidine bases
what suggests that the citric acid cycle evolved early?
because the centrality of the citric acid cycle to both the synthesis of biomolecules and to meeting the energy requirements of cells suggested it appeared in the first cells to feature metabolism
