Nutrition

Those organisms that synthesize food with the help of the light energy of the sun, carbon dioxide and water are called photoautotrophs. The process of synthesis of food in this manner, is called photosynthesis.

Photosynthesis is a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and sulphur bacteria, but not in archaea. Photosynthetic organisms are called autotrophs, since they can create their own food.

It is a protuberance, from the surface of the amoeba, into which the cytoplasm flows. In this way,  the amoeba moves about over the mud at the bottom of the pond. It also helps amoeba in feeding.

Aphids are small, soft-bodied insects with long, slender mouthparts,  with which they pierce stems, leaves, and other tender plant parts,  to suck out plant fluids. Almost every plant,  has one or more aphid species,  which occasionally feed on it.

Nitrobacter is genus of mostly rod-shaped, gram-negative, and chemoautotrophic bacteria. Nitrobacter plays an important role,  in nitrogen cycle by oxidizing nitrite,  into nitrate in soil.

Cuscuta is a genus of about 100-170 species of yellow, orange or red (rarely green) parasitic plants.

Sublingual glands are salivary glands.They secrete a saliva that is predominantly mucous in character.

Amylase is an enzyme,  that breaks starch down into sugar. Amylase is present in human saliva, where it begins the chemical process of digestion.

These glands are located in and around the mouth and throat. The major salivary glands are called the parotid, submandibular and sublingual glands. They all secrete saliva into the mouth: the parotid through ducts near the upper teeth, submandibular into the front portion under the tongue, and the sublingual through multiple ducts, in the floor of the mouth.

These cells are also called parietal cells. These cells are situated mainly towards, the neck of the gastric glands. They secrete hydrochloric acid and intrinsic factor.

The basis for different glands secreting saliva of differing composition, can be seen by examining salivary glands histologically. Two basic types of acinar epithelial cells exist:serous cells, which secrete a watery fluid, essentially devoid of mucus and mucous cells, which produce a very mucus-rich secretion.

It is highly acidic in nature with a pH of 0.9 to1.5. The important constituent of gastric juice include HCl, pepsinogen, intrinsic factor, gastric mucin and gastric lipase. HCl is present in gastric juice in high amount and converts pepsinogen into pepsin and stimulates secretion of various hormones from small intestine.

This class of enzymes is responsible for the catalysis, of biochemical reactions, during which the ions other than hydrogen, are transferred between the reactants. A good example of this type of enzyme, is the class known as the transamidases, that transfer amide ions across reactants; many medical diagnostic techniques employ these enzymes.

The term bolus applies to this mixture of food and solutions, until they are passed into the stomach. The food that has been chewed and mixed in the mouth with saliva, is known as bolus. Chewing helps to reduce food particles to a size readily swallowed and saliva adds digestive enzymes, water and mucus, that help chemically to reduce food particles, hydrate them for taste and lubricate them, for easy swallowing.

These are the enzymes, that actively catalyze the formation of a chemical bond, between two unrelated molecules. They add molecular groups to a substrate.

This class of enzymes is responsible for catalyzing reactions, that result in the rearrangement of the molecular structures, within the reactants. This action results in the chemical conversion of a molecule into another related molecule, called an isomer of the original molecule - the process is called isomerization. The chemical conversion of a D-form of a sugar to an L-form of a sugar, would be a good example of an isomerization reaction, catalyzed by such enzymes.

The pyloric sphincter, or valve, is a strong ring of smooth muscle, at the end of the pyloric canal, and lets food pass from the stomach, to the duodenum. It receives sympathetic innervation from celiac ganglion.

Coprophagia is the consumption of feces. Many animal species practice coprophagia .Coprophagy refers to many kind of feces eating including eating feces, of other species, other individuals, or its own, those once deposited or taken directly, from the anus.

Mastication or chewing is the process, by which food is crushed and ground, by the teeth. It is the first step of digestion, and it increases the surface area of foods, to allow more efficient break down, by enzymes. During the mastication process, the food is positioned between the teeth for grinding, by the cheek and tongue.

Pepsin, the important gastric enzyme, is most active at a pH of 2.0 to 3.0 and is inactive at a pH above about 5.0. Consequently, for this enzyme to cause digestive action on protein, the stomach juices must be acidic. Pepsin initiates the process of protein digestion, usually providing only 10 to 20 per cent of the total protein digestion to convert the protein to, proteoses, peptones, and a few polypeptides. This splitting of proteins occurs as a result of hydrolysis, at the peptide linkages between amino acids.

Mastication or chewing is the process by which, food is crushed and ground by teeth. It is the first step of digestion and it increases the surface area of foods, to allow more efficient break down, by enzymes. During the mastication process, the food is positioned between the teeth for grinding, by the cheek and tongue.

These are enzymes that catalyze only isomerization reactions. These enzymes are responsible for the chemical interconversion of aldose to ketose sugars, as an example.

This class of enzymes, are involved in the catalysis of chemical reactions, in which the chemical bonds are broken off through the addition, of a molecule of water. More properly, it can be understood as the addition of hydrogen [H] to a fragment of the molecule, while a hydroxide [OH] ion is fixed to the other molecule fragment. This important class of enzymes includes the familiar proteolytic protein digesting enzymes, the lipolytic fat digesting enzymes and the amylolytic carbohydrate digesting enzymes.

This class of enzymes is responsible for the catalysis, of biochemical reactions, during which the ions other than hydrogen are transferred, between the reactants. A good example of this type of enzyme, is the class known as the transamidases, that transfer amide ions across reactants; many medical diagnostic techniques employ these enzymes.