Ch.12.2 Flashcards
What are the six main types of food substances? Put them into two main categories and explain the differences between the food substances in these two categories.
Primary food substances — carbohydrates, lipids, proteins — are essential for supporting life.
Protective food substances — vitamins, minerals, dietary fibre — are important for keeping the body healthy.
Carbohydrates are ____________________________. They are made up of ________________________________________ atoms, in which the __________ ratio is ________. Name an example and of carbohydrates and its chemical formula.
organic substances, carbon, hydrogen and oxygen, H:O, 2:1; glucose, C6H12O6.
Hydrolysis is a _______________ reaction. It involves ______________________________, which is done so by ______________________________________.
Catabolic, breaking down molecules, adding a water molecule.
Condensation is an _______________ reaction. It involves ______________________________, which is done so by ______________________________. In carbohydrates, ____________________________ are formed when condensation is carried out.
anabolic, combining molecules, taking away a water molecule, glycosidic bonds
The processes of hydrolysis and condensation are carried out, or ________________, by _____________________.
catalysed, specific enzymes
What are the three types of carbohydrates?
Monosaccharides, disaccharides, and polysaccharides.
Name the features of monosaccharides and give three examples of this type of carbohydrate along with the food sources in which they can be found.
Monosaccharides are the simplest form of carbohydrates. They taste sweet and are soluble in water.
Glucose and fructose can be found in fruits and honey, while galactose can be found in milk and dairy products.
Name the features of disaccharides.
They are formed by the condensation of two monosaccharide molecules. They can be broken down into monosaccharides by enzymes during hydrolysis. They taste sweet and are soluble in water.
Give three examples of disaccharides, name the monosaccharides that they are formed by and the food sources in which these disaccharides can be found in.
Maltose is formed by the condensation of two glucose molecules. They can be found in germinating barley.
Sucrose is formed by the condensation of a glucose and fructose molecule. They can be found in sugar cane and sugar beet.
Lactose is formed by the condensation of a glucose and galactose molecule. They can be found in milk and dairy products.
Name the features of polysaccharides.
They are long chains of monosaccharides joined by condensation. They do not taste sweet and are insoluble in water.
Give three examples of polysaccharides, describe the functions of these polysaccharides, and name the food sources in which these polysaccharides can be found in (except for no. 2)
Starch acts as the storage form and energy reserves of carbohydrates in plants. They can be found in potatoes and cereal products.
Glycogen acts as the storage form and energy reserves of carbohydrates in animals.
Cellulose is an important source of dietary fibre and can be found in plant products.
What are the 5 functions of carbohydrates?
It acts as the main energy source in our bodies.
Glucose is directly broken down in respiration to release energy.
Starch is the storage form of carbohydrates in plants.
Glycogen is stored in the liver or muscles as energy reserves.
Cellulose is a source of dietary fibre.
Lipids are _______________________ made up of _______________________ atoms, but the _________ ratio is ____________________ 2:1.
organic substances, hydrogen, carbon and oxygen, H:O, much greater than
Lipids are insoluble in _____________ but _________________________________ such as _____________ and _____________.
water, soluble in organic solvents, alcohol, acetone
What are the most common type of lipids? What are they formed from?
Triglycerides. Three fatty acid chains and one glycerol molecule.
Name the chemical formula of the hydrolysis of maltose.
Maltose + water — maltase —> glucose
Name the chemical formula of the hydrolysis of sucrose.
Sucrose + water — sucrase —> glucose + fructose
Name the chemical formula of the hydrolysis lactose.
Lactose + water — lactase —> glucose + galactose
Name the formula of the condensation of triglycerides.
Glycerol + fatty acid — enzyme —> triglyceride + water
What are the two main types of fatty acids?
Saturated fatty acids and unsaturated fatty acids.
What can triglycerides be classified into? What are the features of the triglycerides in these groups?
Fats, which are solids at room temperature, come mainly from animals and are mostly made up of saturated fatty acids; and
Oils, which are liquids at room temperature, come mainly from plants and are mostly made up of unsaturated fatty acids.
How are the fatty acids that fats are made up of related to its physical state at room temperature?
They are mostly made up of saturated fatty acid chains, which contain no double bonds. Hence, the straight chains of fatty acids can be packed closely together as a solid.
How are the fatty acids that oils are made up of related to its physical state at room temperature?
Oils are mostly made up of unsaturated fatty acids chains, which contain some double bonds. Hence, their tails are not straight and they are not closely packed together as a liquid.
Name four examples of foods that are rich in fat.
Meat, lard, butter and cheese.
Name three examples of oils.
Peanut oil, corn oil, canola oil.
Name the three main functions of lipids.
—They are stored in adipose tissues under the skin as subcutaneous fat or as visceral fat around internal organs, which act as energy reserves (second to carbohydrates), an insulator to reduce heat loss, and a shock absorber to protect the internal organs.
—They are involved in transporting and storing lipid-soluble vitamins such as vitamins A and D.
—They are involved in making cell membranes (eg phospholipids), which are thin flexible layers that surround and enclose cells and can control what goes in and out of them, and some hormones (eg sex hormones), which regulate our emotions and metabolic activities by stopping or triggering them.
When is trans fat produced? Give two examples of trans fat.
It is produced when vegetable oils are processed to make semi-solid or solid fat. Margarine and shortening.
Where are trans fat commonly found?
In deep fried foods, bakery products and salad dressings.
Trans fat can raise the level of ____________________________ (________________________) — ______________________, and lower the level of ____________________________ (________________________) — ______________________ in the _____________.
LDL cholesterol (low-density lipoprotein), “bad” cholesterol; HDL cholesterol (high-density lipoprotein), “good” cholesterol, blood
What may the excessive intake of trans fats lead to?
Trans fats raise the level of LDL cholesterol, increasing the risk of cardiovascular diseases such as heart attacks, strokes or even death by causing the accumulation of trans fats in blood vessels.
Proteins are _______________________ made up of ______________________________ atoms. Some proteins also contain _______________.
organic substances, hydrogen, oxygen, carbon, nitrogen; sulphur
Amino acids are ________________________________________. They can be joined together in _________________________ to make __________________________________.
the basic building blocks of proteins, different sequences, proteins of different sizes
Describe the basic structure of an amino acid.
H H O
\ | //
N — C — C
/ | \
H R OH
Left: amino group; Top: hydrogen; Right: carboxylic acid group; Bottom: variable size chain
A __________(a)__________ is formed from condensation of ______________________________. A bond is formed between the ______________________ and _______________________. It can be broken down into amino acids by ____________________, in which ________________ must be added. The combination of a (a) with other amino acids forms a ____________________.
dipeptide, two amino acids; amino group, carboxylic acid group; hydrolysis, water; polypeptide
A protein may consist of ______________________________. Describe and give an example, and name the deficiency disease caused by the lack of this protein.
One or more polypeptides; haemoglobin, a red protein that is responsible for transporting oxygen in red blood cells; anaemia.
The _______________________ of proteins are related to their purpose. When they are destroyed in ways such as ________________, their functions are lost.
specific, unique structures; heating
Our body needs ______ types of amino acids to _______________________________. The amino acids can be classified into _______________________, which _______________________, and _______________________, which _______________________.
20, build up various proteins; non-essential amino acids, can be produced by our body; essential amino acids, have to be obtained from out diet
Name the three functions of proteins.
—They are used for the growth and repair of body tissues such as muscles, bones, skin, hair and blood
—They are used to form enzymes and antibodies; some hormones are protein in nature
—Amino acids are broken down to release energy if the carbohydrates and lipids stored in the body are used up
What happens when excess protein is taken in?
The excess amino acids are broken down in the liver by deamination to form carbohydrates and ammonia (which are combined with CO2 to form urea or uric acid as they are too toxic to the human system on their own; however this is not part of deamination), during which the nitrogen-containing amino group is removed from the amino acid. The waste products are passed out of the body in urea.
What may a deficiency in protein lead to? What are the symptoms of this deficiency disease? Where is this disease most commonly found?
Kwashiorkor. Patients have weak muscles and a swollen abdomen due toe accumulation of tissue fluid. They are usually found in developing countries where milk, meat and eggs are limited in diets.
What are some foods that are rich in protein?
Fish, meat, eggs, milk, cheese, nuts and beans.
Vitamins have no _____________________, but are essential for _____________________________________________________________. Only ________________ amounts of vitamins are needed.
energy value, maintaining the normal functions of cells and organs in our bodies, small
Vitamins help __________________________________, __________________________________ and ___________________________________.
growth and development, regulate metabolism, strengthen immunity
