NUTRITION/FEEDING
Nutrition: This is the process by which living organisms obtain and utilize food materials from external environment in order to supply the nutrients required for metabolic activities.
Food: This is any substance which when absorbed into the body cells yields energy and materials for growth, repairs of damaged tissues and regulation of body processes without harming the living organism. Food is the source of nutrients.
Usefulness of food
Living cells or organisms require food for the following reasons:
To provide energy needed for various life activities;
To make essential substances such as hormones and enzymes;
To make new cells for growth and replacement of worn-out tissues;
To supply various substances required for healthy growth and development
Modes/Types of Nutrition
The following are the types of nutrition:
Autotrophic nutrition (self-feeders); and
Heterotrophic nutrition (dependent-feeders)
Autotrophic nutrition: A type of nutrition in which organisms are able to manufacture their own organic food (i.e. glucose) from simple carbon compound and simple inorganic nitrogen . Such organism is referred to as autotroph,
Types of autotrophic nutrition
Photosynthetic (holophytic) e.g. green plants;
Chemosynthetic nutrition i.e. some bacteria e.g. blue-green algae; nostoc, suphur bacteria, Nitrosomonas e.t.c.
2. Heterotrophic nutrition: A type of nutrition carried out by organisms that are not capable of manufacturing their own food from simple inorganic substances. Such organism is called heterotroph
Types of heterotrophic nutrition
Holozoic nutrition: This is a type of nutrition in which food is obtained as a solid organic material, eaten, digested and absorbed into the body. Nearly all animals are holozoic in nutrition.
Saprophytic nutrition: This is a type of nutrition in which non-green plants feed on dead and decaying organic matter.
Note: organisms which feed saprophytically are known as saprophytes. Examples are most fungi (e.g. Mucor, Mushroom, and Yeast) and bacteria.
Symbiotic nutrition: This is a type of nutrition in which two organisms of different species live together to take advantage of each other. Examples are the association between alga and a fungus to form lichens, where the fungus provides moisture (i.e. water), mineral salts and support for the alga which the alga used in manufacturing food by photosynthesis for the fungus and itself; other example is the relationship between herbivorous animals (e.g. goat, sheep) and cellulose-digesting bacteria that live in the caecum and colon of herbivores.
Parasitic nutrition: This is a type of nutrition in which one organism obtains food from another organism and during the feeding process one organism is harmed and does not benefit. The organism causing harm is called parasite, while the one been harmed is called host.
Note: the association between a host and a parasite is called parasitism. Examples of parasites are Plasmodium, Ascaris lumbricoides, ticks, bugs e.t.c.
ROLES OF ENZYMES IN DIGESTION
Enzymes are organic catalysts of protein origin produced by living cells which help to speed up or slow down the rate of chemical reactions but remain unchanged chemically at the end of the reaction.
We shall discuss this in detail next term!
MINERAL SALTS
Mineral salts are contained in important elements. They have to be taken in compound forms, for example sodium chloride (table salt) is a compound of sodium and chlorine.
Why do we have to take mineral elements in compound forms?
Because if they are taken like that i.e. as mineral elements, they could be fatal but when taken in a compound form, they become harmless and useful to the body.
The soil is the main source of mineral salts, while gaseous elements such as oxygen, hydrogen and carbon are mainly derived from the atmosphere.
Classes of elements or plant nutrients
Plant nutrients are grouped into two classes depending on the quantity that is required by plants. The classes are:
Macro-nutrient or major elements: They are required by plants in large quantities for healthy growth and development. Examples are nitrogen, phosphorus, potassium, magnesium, calcium, oxygen, hydrogen, carbon, sulphur and iron.
Micro-nutrients or trace elements: They are required by plants in small quantities for healthy growth and development. Examples are zinc, copper, boron, molybdenum, cobalt, chlorine, and manganese, fluorine and iodine.
METABOLISM
Metabolism is the physical and chemical processes by which simple molecules of food are built up into complex molecules (assimilation, anabolism)and complex molecules are broken down into simple molecules (respiration)with liberation of energy for work by the organism.
Types of metabolism
Anabolism: This is the building up of simple molecules of food into complex molecules by living things, with the use of energy leading to an increase in size and complexity. Anabolism, or constructive metabolism, is the process of synthesis required for the growth of new cells and the maintenance of all tissues.
Examples of anabolic processes are:
formation of glycogen from glucose;
formation of starch from glucose;
formation of proteins from amino acids;
formation of fats and oil from fatty acids and glycerol;
photosynthesis in green plants
growth
Catabolism: This is the breakdown of complex food molecules by living things with liberation of energy for work. It is the production of energy through the conversion of complex molecules into simple ones. Catabolism, or destructive metabolism, is a continuous process concerned with the production of the energy required for all external and internal physical activity.
Examples of catabolic processes are:
Respiration;
Fermentation;
Digestion.
Note:
When anabolism exceeds catabolism, growth or weight gain occurs. When catabolism exceeds anabolism, such as during periods of starvation or disease, weight loss occurs. When the two metabolic processes are balanced, the organism is said to be in a state of dynamic equilibrium.
Usefulness of energy released during metabolism
Energy released during metabolic activities is the ATP, which is used for the following purposes:
Anabolic process: ATP provides the energy necessary to build up macro molecules, e.g. proteins from amino acids;
Active transport: Energy is needed to move materials against a concentration gradient, e.g. by the use of ion pumps;
Movement: Muscle contraction, ciliary movement and contraction of the spindle fibers during cell division all require energy from the hydrolysis of ATP;
Activating reactants: Chemicals often require the addition of phosphate groups from ATP to make them more reactive, e.g. phosphorylation of glucose at the beginning of glycolysis;
Secretion: ATP provides energy for the secretion of cell products.
Uses of glucose
Builds new plant materials;
Used by plant as energy source;
Eaten by animal and used as energy source;
Used in building new animal materials.
Uses of ATP (adenosine triphosphate)
For chemical work (e.g. enzyme synthesis)
For mechanical work (e.g. muscle contraction)
For osmotic work e.g. water regulation
For electrical work e.g. nerve impulse transmission
For cell division i.e. it provides energy required by cells to divide
CELLULAR/INTERNAL/TISSUE RESPIRATION
This is the process of breaking down glucose by a series of chemical reactions controlled by enzymes to release energy. It may also be defined as the oxidation of food substance in the cells (particularly in the mitochondria), to release energy for work. The energy released is stored in adenosine triphosphate (ATP).
Differences between glucose and ATP
Types of cellular respiration
Aerobic respiration: it requires oxygen to break down/oxidize glucose/simple sugar (substrates) in the cell to release carbon (IV) oxide and water.i.e.
C6H12O6 + 6O2 →6CO2 + 6H2O + 38ATP
Anaerobic respiration: it does not require oxygen to break down glucose in the cells to release alcohol, carbon dioxide and 2 ATP as the products. i.e.
C6H12O6 → C2H5OH + 2CO2 + 2ATP
Chemical processes of cellular respiration
The breaking down of glucose in the body passes through several pathways before it can produce energy. These pathways are Glycolysis and Kreb’s cycle
Glycolysis: This is a series of chemical reactions which involves the breaking down of glucose to a 3-carbon molecule called pyruvic acid.
Note: what happens to the pyruvic acid depends on the presence or absence of oxygen. For example in animals, the pyruvic acid is converted to lactic acid. But in plant, the pyruvic acid is converted to alcohol; this is known as alcoholic fermentation.
Examples of organism that undergoes fermentation is yeast
Kreb’s cycle/citric acid cycle/tricarboxylic acid(TAC): This is a series of cyclic reactions which begin with the pyruvic acid formed from glycolysis which combined with acetyl co-enzyme A to form citric acid.
Differences between Glycolysis and Kreb’s cycle
Similarities between aerobic and anaerobic respiration
Both lead to the release of energy
Both occur in plant and animal cells
Both require enzymes to speed up the reactions
Both lead to generation of heat
Both give off carbon dioxide as by-product.
Differences between aerobic and anaerobic respiration
E
Nutrition: This is the process by which living organisms obtain and utilize food materials from external environment in order to supply the nutrients required for metabolic activities.
Food: This is any substance which when absorbed into the body cells yields energy and materials for growth, repairs of damaged tissues and regulation of body processes without harming the living organism. Food is the source of nutrients.
Usefulness of food
Living cells or organisms require food for the following reasons:
To provide energy needed for various life activities;
To make essential substances such as hormones and enzymes;
To make new cells for growth and replacement of worn-out tissues;
To supply various substances required for healthy growth and development
Modes/Types of Nutrition
The following are the types of nutrition:
Autotrophic nutrition (self-feeders); and
Heterotrophic nutrition (dependent-feeders)
Autotrophic nutrition: A type of nutrition in which organisms are able to manufacture their own organic food (i.e. glucose) from simple carbon compound and simple inorganic nitrogen . Such organism is referred to as autotroph,
Types of autotrophic nutrition
Photosynthetic (holophytic) e.g. green plants;
Chemosynthetic nutrition i.e. some bacteria e.g. blue-green algae; nostoc, suphur bacteria, Nitrosomonas e.t.c.
2. Heterotrophic nutrition: A type of nutrition carried out by organisms that are not capable of manufacturing their own food from simple inorganic substances. Such organism is called heterotroph
Types of heterotrophic nutrition
Holozoic nutrition: This is a type of nutrition in which food is obtained as a solid organic material, eaten, digested and absorbed into the body. Nearly all animals are holozoic in nutrition.
Saprophytic nutrition: This is a type of nutrition in which non-green plants feed on dead and decaying organic matter.
Note: organisms which feed saprophytically are known as saprophytes. Examples are most fungi (e.g. Mucor, Mushroom, and Yeast) and bacteria.
Symbiotic nutrition: This is a type of nutrition in which two organisms of different species live together to take advantage of each other. Examples are the association between alga and a fungus to form lichens, where the fungus provides moisture (i.e. water), mineral salts and support for the alga which the alga used in manufacturing food by photosynthesis for the fungus and itself; other example is the relationship between herbivorous animals (e.g. goat, sheep) and cellulose-digesting bacteria that live in the caecum and colon of herbivores.
Parasitic nutrition: This is a type of nutrition in which one organism obtains food from another organism and during the feeding process one organism is harmed and does not benefit. The organism causing harm is called parasite, while the one been harmed is called host.
Note: the association between a host and a parasite is called parasitism. Examples of parasites are Plasmodium, Ascaris lumbricoides, ticks, bugs e.t.c.
ROLES OF ENZYMES IN DIGESTION
Enzymes are organic catalysts of protein origin produced by living cells which help to speed up or slow down the rate of chemical reactions but remain unchanged chemically at the end of the reaction.
We shall discuss this in detail next term!
MINERAL SALTS
Mineral salts are contained in important elements. They have to be taken in compound forms, for example sodium chloride (table salt) is a compound of sodium and chlorine.
Why do we have to take mineral elements in compound forms?
Because if they are taken like that i.e. as mineral elements, they could be fatal but when taken in a compound form, they become harmless and useful to the body.
The soil is the main source of mineral salts, while gaseous elements such as oxygen, hydrogen and carbon are mainly derived from the atmosphere.
Classes of elements or plant nutrients
Plant nutrients are grouped into two classes depending on the quantity that is required by plants. The classes are:
Macro-nutrient or major elements: They are required by plants in large quantities for healthy growth and development. Examples are nitrogen, phosphorus, potassium, magnesium, calcium, oxygen, hydrogen, carbon, sulphur and iron.
Micro-nutrients or trace elements: They are required by plants in small quantities for healthy growth and development. Examples are zinc, copper, boron, molybdenum, cobalt, chlorine, and manganese, fluorine and iodine.
METABOLISM
Metabolism is the physical and chemical processes by which simple molecules of food are built up into complex molecules (assimilation, anabolism)and complex molecules are broken down into simple molecules (respiration)with liberation of energy for work by the organism.
Types of metabolism
Anabolism: This is the building up of simple molecules of food into complex molecules by living things, with the use of energy leading to an increase in size and complexity. Anabolism, or constructive metabolism, is the process of synthesis required for the growth of new cells and the maintenance of all tissues.
Examples of anabolic processes are:
formation of glycogen from glucose;
formation of starch from glucose;
formation of proteins from amino acids;
formation of fats and oil from fatty acids and glycerol;
photosynthesis in green plants
growth
Catabolism: This is the breakdown of complex food molecules by living things with liberation of energy for work. It is the production of energy through the conversion of complex molecules into simple ones. Catabolism, or destructive metabolism, is a continuous process concerned with the production of the energy required for all external and internal physical activity.
Examples of catabolic processes are:
Respiration;
Fermentation;
Digestion.
Note:
When anabolism exceeds catabolism, growth or weight gain occurs. When catabolism exceeds anabolism, such as during periods of starvation or disease, weight loss occurs. When the two metabolic processes are balanced, the organism is said to be in a state of dynamic equilibrium.
Usefulness of energy released during metabolism
Energy released during metabolic activities is the ATP, which is used for the following purposes:
Anabolic process: ATP provides the energy necessary to build up macro molecules, e.g. proteins from amino acids;
Active transport: Energy is needed to move materials against a concentration gradient, e.g. by the use of ion pumps;
Movement: Muscle contraction, ciliary movement and contraction of the spindle fibers during cell division all require energy from the hydrolysis of ATP;
Activating reactants: Chemicals often require the addition of phosphate groups from ATP to make them more reactive, e.g. phosphorylation of glucose at the beginning of glycolysis;
Secretion: ATP provides energy for the secretion of cell products.
Uses of glucose
Builds new plant materials;
Used by plant as energy source;
Eaten by animal and used as energy source;
Used in building new animal materials.
Uses of ATP (adenosine triphosphate)
For chemical work (e.g. enzyme synthesis)
For mechanical work (e.g. muscle contraction)
For osmotic work e.g. water regulation
For electrical work e.g. nerve impulse transmission
For cell division i.e. it provides energy required by cells to divide
CELLULAR/INTERNAL/TISSUE RESPIRATION
This is the process of breaking down glucose by a series of chemical reactions controlled by enzymes to release energy. It may also be defined as the oxidation of food substance in the cells (particularly in the mitochondria), to release energy for work. The energy released is stored in adenosine triphosphate (ATP).
Differences between glucose and ATP
Types of cellular respiration
Aerobic respiration: it requires oxygen to break down/oxidize glucose/simple sugar (substrates) in the cell to release carbon (IV) oxide and water.i.e.
C6H12O6 + 6O2 →6CO2 + 6H2O + 38ATP
Anaerobic respiration: it does not require oxygen to break down glucose in the cells to release alcohol, carbon dioxide and 2 ATP as the products. i.e.
C6H12O6 → C2H5OH + 2CO2 + 2ATP
Chemical processes of cellular respiration
The breaking down of glucose in the body passes through several pathways before it can produce energy. These pathways are Glycolysis and Kreb’s cycle
Glycolysis: This is a series of chemical reactions which involves the breaking down of glucose to a 3-carbon molecule called pyruvic acid.
Note: what happens to the pyruvic acid depends on the presence or absence of oxygen. For example in animals, the pyruvic acid is converted to lactic acid. But in plant, the pyruvic acid is converted to alcohol; this is known as alcoholic fermentation.
Examples of organism that undergoes fermentation is yeast
Kreb’s cycle/citric acid cycle/tricarboxylic acid(TAC): This is a series of cyclic reactions which begin with the pyruvic acid formed from glycolysis which combined with acetyl co-enzyme A to form citric acid.
Differences between Glycolysis and Kreb’s cycle
Similarities between aerobic and anaerobic respiration
Both lead to the release of energy
Both occur in plant and animal cells
Both require enzymes to speed up the reactions
Both lead to generation of heat
Both give off carbon dioxide as by-product.
Differences between aerobic and anaerobic respiration
E
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