Chapter 21: The Generation of Biochemical Energy

Cytosol

Cytosol

________ is the fluid part of the cytoplasm surrounding the organelles within a cell, contains dissolved proteins and nutrients.

Pathway

________ is a series of enzyme- catalysed chemical reactions that are connected by their intermediates, that is, the product of the first reaction is the reactant for the second reaction, and so on.

Citric acid cycle

________ is the series of biochemical reactions that breaks down acetyl groups to produce energy carried by reduced coenzymes and carbon dioxide.

accessible forms

Energy must be stored in readily ________ as glycogen and fat (triacylglycerides)

Catabolism

________ is a metabolic reaction pathways that break down food molecules and release biochemical energy.

Anabolism

________ is a metabolic reactions that build larger biological molecules from smaller pieces.

→ATP generation

________ is accomplished by a series of enzyme complexes in the inner memranes of mitochondria.

Carbohydrates

________ are broken down to glucose and other sugars; proteins are broken down to amino acids; and triacylglycerols, the lipids commonly known as fats and oils, are broken down to glycerol plus long- chain carboxylic acids, termed fatty acids.

Cytoplasm

________ is the region between the cell membrane and the nuclear membrane in a eukaryotic cell.

→Mitochondria

________ contain their own DNA, synthesize some of their own proteins, and multiply using chemicals moved from the cell cytosol into the mitochondrial matrix.

net result of catabolism

The ________ is the oxidation of food molecules to release energy.

chemical reactions

Energy in a form other than heat must be available to drive ________ that are not favourable at body temperatures.

coenzymes

Thus, the reduced ________ are in effect oxidized by atmospheric oxygen, and the energy that they carried is stored in the chemical bonds of ATP molecules.

hydrogen ions

Electrons and ________ enter the first two complexes of the electron- transport chain from succinate (in the citric acid cycle), NADH, and FADH2, where they are transferred to coenzyme Q.

mitochondria

The ________ (singular, ________), often called the cells "power plants, "are the most important of the organelles for energy production and produce about 90 % of the bodys energy- carrying molecule, ATP.

large molecules

STAGE 1: Digestion Enzymes in saliva, the stomach, and the small intestine convert the ________ of carbohydrates, proteins, and lipids to smaller molecules.

Electron transport chain

________ is the series of biochemical reactions that passes electrons from reduced coenzymes to oxygen and is coupled to ATP formation.

citric acid cycle

Within the matrix, the ________ and production of most of the bodys adenosine triphosphate (ATP) take place.

There are two main categories of cells where the energy generating reactions can take place

prokaryotic cells, found in single-celled organisms (e.g., bacteria and blue-green algae), and eukaryotic cells, found in some single-celled organisms, such as yeast, and all plants and animals

STAGE 1

Digestion Enzymes in saliva, the stomach, and the small intestine convert the large molecules of carbohydrates, proteins, and lipids to smaller molecules

STAGE 2

Acetyl-coenzyme A production The small molecules from digestion follow separate pathways that separate their carbon atoms into two-carbon acetyl groups

STAGE 3

Citric acid cycle Within mitochondria, the acetyl-group carbon atoms are oxidized to the carbon dioxide that we exhale

STAGE 4

ATP production Electrons from the reduced coenzymes are passed from molecule to molecule down an electron-transport chain

The most important electron acceptors are of three types

(1) various cytochromes that are proteins that contain heme groups in which the iron cycles between Fe2+ and Fe3+;

endergonic

Reactions in which the products are higher in energy than the reactants can also take place, but such unfavourable reactions cannot occur without the input of energy from an external source