KNOWLEDGE AREA: Life at Molecular, Cellular and Tissue Level

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KNOWLEDGE AREA: Life at Molecular, Cellular and Tissue Level TOPIC 1.1: The Chemistry of Life Organic Compounds

Organic compounds Carbohydrates, proteins and lipids
Summary of Presentation Carbohydrates, proteins and lipids Enzymes Nucleic Acids Vitamins

Organic substances contain the element carbon together with hydrogen.
Organic compounds Organic substances contain the element carbon together with hydrogen. They may also contain oxygen. Some organic compounds may have other elements than the ones mentioned above. Such as nitrogen and phosphorus.

terminology TERM: DEFINITION: USE IN SENTENCE: Organic substances
contain the element carbon together with hydrogen USE IN SENTENCE: Proteins are an example of an organic substance

Organic compounds We shall look at the following organic substances:
Carbohydrates Lipids Proteins Nucleic acids Vitamins

Carbohydrates Carbohydrates are made up of the elements carbon, hydrogen and oxygen. There are usually double the number of hydrogen atoms than oxygen atoms in any carbohydrate molecule. There are three types of carbohydrates. These are: Monosaccharide Disaccharides polysaccharides

monosaccharide These are simple sugars.
They all have a single ring, six sided structure as shown in the picture alongside- this picture is called a structural formula. Glucose and fructose are examples of monosaccharide's. Structural Formula of Glucose

monosaccharide A monosaccharide is the simplest form of carbohydrates.
In other words they are the smallest units that more complex carbohydrates are made up of. The smallest or simplest unit of any substance is called its building block. Another word for building block is monomer. The monomer of a carbohydrate is the monosaccharide.

Terminology: TERM: DEFINITION: USE IN SENTENCE: Monosaccharides
Monosaccharides are simple sugars and are monomers of carbohydrates. USE IN SENTENCE: Glucose is the monosaccharide of a carbohydrate

Can you define the term monomer?
monosaccharide Can you define the term monomer?

Solution: A monomer is a building block or simplest unit of a more complex substance.

Disaccharides are made up of two monosaccharides.
Therefore they have a double-ring structure as shown by the structural formula below. Examples of disaccharides are maltose, fructose and lactose. Structural formula of Maltose

Terminology: TERM: DEFINITION: USE IN SENTENCE: Disaccharides
are carbohydrates that are made up of two monosaccharides USE IN SENTENCE: Sucrose is an example of a disaccharide.

polysaccharides These are carbohydrates that are made up of more than two monosaccharides Examples of polysaccharides are cellulose and starch. Structural formulae of a polysaccharide

Terminology: TERM: DEFINITION: USE IN SENTENCE: Polysaccharides
are carbohydrates that are made up of more than two monosaccharides USE IN SENTENCE: Cellulose is an example of a polysaccharide.

Carbohydrates-functions
Carbohydrates have three main functions. These are: Energy. They are an important source of energy. During cellular respiration glucose is broken down to release energy.

Storage. They serve as storage substances for energy. For example in the human body extra glucose (energy source) is converted into glycogen and stored in the liver.

Building materials. For example they supply cellulose for the production of plant cell walls.

lipids Lipids include fats and oils.
They are made up of the elements carbon, hydrogen and oxygen. They can contain other elements such as phosphorus. The ratio of hydrogen to oxygen in lipids is greater than 2:1 The building blocks or monomers of lipids are fatty acids and glycerol.

lipids One glycerol molecule combines with three fatty acids to form one lipid molecule. During this process water is released as shown in the diagram alongside. Structural formula of glycerol

Terminology: TERM: DEFINITION: USE IN SENTENCE:
Fatty acids and glycerol DEFINITION: are the building blocks or monomers of lipids USE IN SENTENCE: Each lipid molecule is made up of 3 fatty acids and 1 glycerol

Lipids-saturated fats
Some fatty acids cannot take any more hydrogen atoms. Such fatty acids are said to be saturated or are called saturated fatty acids. Fats that are formed from such fatty acids are called saturated fats. Saturated fats are solid at room temperature. Some examples of saturated fats are lard, beeswax, butter and animal fat.

Terminology: TERM: Saturated fatty acids DEFINITION:
are fatty acids that cannot take any more hydrogen atoms. USE IN SENTENCE: When the fatty acid can not take anymore hydrogen atoms it is called a saturated fatty acid.

Lipids-unsaturated fats
Of course there are unsaturated fatty acids. Fats formed from these fatty acids are called unsaturated fats. Unsaturated fats are called oils. They are liquid at room temperature. Examples include olive oil, cod-liver oil.

Something for you to do:
Tabulate 2 differences between saturated and unsaturated fats. (NB.: remember your table rules)

solution Saturated fats Unsaturated fats
Difference between saturated and unsaturated fats. Saturated fats Unsaturated fats Made from saturated fatty acids Made from unsaturated fatty acids Solid at room temperature Liquid at room temperature

Lipids-functions They are able to store large amounts of energy.
They act as packing tissue between organs. All major organs are surrounded by a layer of fat like the kidneys. The fat acts as a shock absorber. They acts as insulation. Fat is found as a layer below the skin, its function is to reduce heat loss. The cell membranes of all living organisms are made up of a lipid called phospholipids.

Heart disease, saturated fats and cholesterol
One of the causes of heart disease is a diet rich in saturated fats and high in cholesterol. Remember that there are many other causes of heart disease. Can you name some of these causes? The fatty acids are deposited on the inside of the arteries. This narrows the diameter of the arteries. This slows down the flow of blood. If this happens to the coronary artery then the person suffers from atherosclerosis. What is the coronary artery?

solution Other causes of heart disease are:
Heredity, age, gender, smoking, lack of exercise and high blood pressure. The coronary artery is a blood vessel that supplies the heart muscle with food and oxygen.

proteins Proteins are made up of the elements carbon, hydrogen, oxygen and nitrogen. They may also contain other elements such as sulphur, phosphorus and iron. The building blocks or monomers of proteins are called amino acids. Changes in the pH and temperature can change the structure of the protein. When this happens we say that the protein is denatured. If a protein is denatured it cannot function.

Terminology: TERM: DEFINITION: USE IN SENTENCE: Amino acids
Amino acids are the building blocks or monomers of proteins. USE IN SENTENCE: A chain of 3 or more amino acids is called a polypeptide chain.

Enzymes and hormones are protein in nature.
Proteins-functions Proteins store energy. They form cell components. This means that they make up parts of the cell like the cell membrane. Enzymes and hormones are protein in nature.

Something for you to do:
The list below shows some characteristics of organic compounds. Contain nitrogen Contain H, C and O Energy source Ratio of H:O is 2:1 Denatured by excessive heat Choose letters from the above list that correspond to:- Two characteristics of lipid Three characteristics of carbohydrates Three characteristics of proteins

solution B, D B, C, D A, B, E

ENZYMES Enzymes are organic catalyst.
A catalyst is a substance that speeds up a chemical reaction without being used up in the reaction. An organic catalyst is one that contains the element carbon and is usually protein in nature.

Enzymes-functions Enzymes function as catalysts.
As catalysts they have 2 functions. These are:- They speed up the chemical reactions without being used up during the chemical reaction. They control and regulate all chemical reactions so that they occur at the best possible or optimum rate.

Optimum rate Optimum rate is the rate at which the most product is formed in the shortest space of time.

Lock and key theory Lock and Key Theory The substance on which the
enzyme works is called a substrate 3. This is part of the enzyme to which the substrate becomes attached. 1. Each enzyme has a particular shape. Lock and Key Theory

Lock and key theory A. the substrate fits into the active site of the enzyme forming…

Lock and key theory B- an enzyme- substrate complex

Lock and key theory C- a chemical reaction occurs and the substrate changes shape

Lock and key theory D- the enzyme and substrate separate and the enzyme can now react with more of the substrate

Lock and key theory Most enzymes need the help of a partner.
This partner is organic and non-protein in nature The partner is called a co-enzyme The co-enzyme is loosely bound to the enzyme

effect on temperature on enzyme activity
According to the graph as the temperature increases, the rate of reaction also increase, until the temperature is about 37⁰C then enzyme activity is at it maximum. This temperature is called the optimum temperature. Graph showing the Effect of Temperature on the Rate of Reaction

Then as the temperature increases further then enzyme activity starts to decrease because the temperature is too high and the enzymes become denatured. Graph showing the Effect of Temperature on the Rate of Reaction

Terminology: TERM: DEFINITION: USE IN SENTENCE: Denatured
occurs when the shape of the enzyme changes and it can no longer function. USE IN SENTENCE: If the temperature is too high the enzymes will become denatured.

When the enzyme becomes denatured the shape of the enzyme changes. This means that the substrate can no longer fit into the enzyme. This cause the chemical reaction to either slow down or stop.

Effect of ph on enzyme activity
The graph shows that the enzyme activity peaks at a certain pH. This pH is called the optimum pH. If the pH is lower or higher than this optimum pH, then enzyme activity decreases, because the enzyme becomes denatured. Effect of pH on the Rate of Enzyme Activity

Effect of ph on enzyme activity
The shape of the enzyme changes and enzyme activity slows down or stops. This tell us that enzymes are very specific, that is a certain enzyme will only work in a certain pH. Salivary amylase only works in an alkaline medium.

Use of enzymes in Industry
There are many uses of enzymes in industry. They are used as meat tenderizer They remove hair form skins They are used in the making of beer, wine and vinegar They are also used to make chocolate and syrups. They also used to make washing powders.

Most washing powders only contain one type of enzyme while some have more than one. This is done to keep costs down. Most washing powders contain protease. Protease is an enzyme that breaks down protein. Therefore these washing powders can be used to remove stains caused by blood, egg and gravy. Other washing powders contain amylase. Amylase remove greasy stains.

Enzymes can be used over and over again. They do not need high temperatures to work. Therefore they are cheap to use in industry.

Something for you to do 3. What is the enzyme activity at 20⁰ C?
4. At what temperature does enzyme activity start to decrease. Explain your answer. 5. What is the optimum temperature for this enzyme? 6. Use the graph to describe the relationship between enzyme activity and temperature. Provide a suitable heading for the graph. Name the dependent and independent variables

Solution The effect of temperature (⁰ C) on the rate of reaction.
Independent- temperature; dependent-rate of reaction 1 About 41⁰C. The temperature is too high the enzyme becomes denatured and its shape changes and it can no longer function. 40⁰C As the temperature increases so does the rate of reaction. The rate of reaction is at its max. at 40⁰C, this is the optimum temperature. As the temperature continues to increase the rate of reaction slows down and eventually stops because the temperature is too high and the enzymes has become denatured.

Nucleic acids Nucleic acids are organic compounds found in the cells.
There are two types of nucleic acids. They are:- Deoxyribonucleic acid Ribonucleic acid

Deoxyribonucleic acid
DNA is found in the nucleus of the cell. It forms a part of the chromosome. The chromosome is found in the nucleus.

Structure of DNA The structure of DNA is based on a model put forward by two scientist, James Watson and Francis Crick, in 1953 According to their model the DNA is a ladder like structure with a double helix shape. Model of DNA

Structure of DNA DNA is made up of building block or monomers.
These building blocks or monomers are called nucleotides. A specific length of DNA is called a gene.

Structure of DNA Each gene has the following functions:
Genes carries the code for the formation of proteins. Since proteins are necessary for the formation of cells we can say that the genes controls the structure of organisms.

Structure of DNA Genes also determine the enzymes that are formed.
Enzymes control all chemical reactions in a cell. Therefore we can say that genes control the functioning of the organism.

Structure of DNA Genes are responsible for the transfer of characteristics from parent to offspring.

Structure of Rna RNA occurs in the cells.
There many different types of RNA. Some occur in the nucleus and some occur in the cytoplasm. They are single stranded. They are involved in protein synthesis. RNA

vitamins Vitamins are organic compounds.
They are found in very small quantities in natural food. They are required for the maintenance of the metabolism in the body. They are absorbed from the small intestine.

vitamins Vitamin Function Sources
Deficiency disease and their symptoms Vitamin A Essential for the correct functioning of the eye. Liver, milk, milk products, fruit and vegetables Night blindness: difficulty in seeing in dim light Vitamin B Acts as a co-enzyme in cellular respiration Whole grains of cereals, nuts, meat and yeast. Beri-beri: stunted growth and heart disorders

Deficiency disease and their symptoms Vitamin C Maintains intercellular substance in cartilage, bone & dentine. May acts as a catalyst in cell respiration Citrus fruit, guavas, tomatoes, potatoes. Scurvy: bleeding gums, under the skin especially at the joints. Poor healing of wounds.

Deficiency disease and their symptoms Vitamin D Increases absorption of calcium & phosphate salts. Diary products, egg yolk Rickets in children: abnormal bone formation. Osteomalacia in adults: compressed vertebrae, bow-shaped legs, swollen joints.

Deficiency disease and their symptoms Vitamin E Prevents oxidation of unsaturated fatty acids Leafy green vegetables Excessive bleeding-known as haemorrhage

Terminology: Organic substances contain the element carbon together with hydrogen. Monosaccharides are simple sugars and are monomers of carbohydrates. Monomer is another word for building block. Disaccharides are carbohydrates that are made up of two monosaccharides. Polysaccharides are carbohydrates that are made up of more than two monosaccharides. Fatty acids and glycerol are the building blocks or monomers of lipids.

terminology Saturated fatty acids are fatty acids that cannot take any more hydrogen atoms. Amino acids are the building blocks or monomers of proteins. Denatured occurs when the shape of the enzyme changes and it can no longer function. Enzymes are organic catalyst. A catalyst is a substance that speeds up a chemical reaction without being used up in the reaction.

Terminology An organic catalyst is one that contains the element carbon and is usually protein in nature. Optimum rate is the rate at which the most product is formed in the shortest space of time. Co-enzyme is the non protein organic partner of enzymes Double helix shape is the twisted shape of the DNA molecule. Nucleotides are the building block or monomers of nucleic acids.

QUESTION 1 Organic compound made up of H, C, and O whose monomer is monosaccharide is… A. Carbohydrate B. Protein C. Lipids D. Vitamins

QUESTION 2 A disaccharide is made up of … A. Nucleotides B. Enzymes
C. Amino acids D. Monosaccharides

QUESTION 3 An organic compound who is a source of energy and serves as a substance in which energy is stored is … A. Carbohydrate B. Protein C. Lipids D. Vitamins

QUESTION 4 The organic compound in which the ratio or H:O is greater than 2:1 A. Carbohydrate B. Protein C. Lipids D. Vitamins

QUESTION 5 The monomer of lipids are A. Nucleotides B. Enzymes
C. Amino acids D. Fatty acids and glycerol

QUESTION 6 The monomer of proteins are… A. Nucleotides B. Enzymes
C. Amino acids D. Monosaccharides

QUESTION 7 The organic compound that may contain other element such as Fe in addition to H, O and C. A. Lipid B. Carbohydrate C. Protein D. Vitamin

QUESTION 8 The organic compound that forms many parts of the cell.
A. Lipid B. Carbohydrate C. Protein D. Vitamin

QUESTION 9 Enzymes are ______ in nature. A. Lipid B. Carbohydrate
C. Protein D. Vitamin

QUESTION 10 Organic catalysts are called… A. Amino acids B. Enzymes
C. Nucleotides D. Lipids

QUESTION 11 Proteases are… A. Co enzymes B. Nucleotides C. Lipids
D. Enzymes

QUESTION 12 The enzyme that can remove oily stains are… A. Proteases
B. Amylase C. Both A and B D. None of the above

QUESTION 13 DNA and RNA are examples of … A. Co enzymes B. Nucleotides
C. Lipids D. Enzymes

QUESTION 14 The nucleotide that has a double helix shape is… A. DNA
B. RNA C. Both A and B. D. None of the above

QUESTION 15 The vitamin that prevents scurvy is… A. Vitamin A
B. Vitamin B C. Vitamin C D. Vitamin D

QUESTION 16 The vitamin that increases the absorption of calcium…
A. Vitamin A B. Vitamin B C. Vitamin C D. Vitamin D

QUESTION 17 This vitamin prevents night blindness. A. Vitamin A

QUESTION 18 The vitamin that prevents rickets. A. Vitamin A

QUESTION 19 In order to prevent osteomalacia one should have a diet that contains… A. Leafy green vegetables B. Dairy products C. Nuts D. Liver

QUESTION 20 The vitamin maintains the intercellular substance in cartilage is… A. Vitamin A B. Vitamin B C. Vitamin C D. Vitamin D

solution A D C B D B A C

KNOWLEDGE AREA: Life at Molecular, Cellular and Tissue Level

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