1. Substances in Cells

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2 1. Substances in Cells Students: Investigate cell requirements, including but not limited to: - Suitable forms of energy, including light energy and chemical energy in complex molecules. - Matter, including gases, simple nutrients and ions. Introduction to Biological Macromolecules In the previous lesson, we learnt about how each cell is made up of many organelles which each have their specialised functions. But what if we go one step further what are organelles made up of? Everything in our body is composed of biological macromolecules. What does the term 'macromolecule' means? 1 There are four classes of macromolecules found in cells that you must learn about: carbohydrates, lipids, proteins and nucleic acids. Macromolecules can be considered as long polymers made up of smaller repeating units called monomers. You will be able to see this on the following page. Copyright MATRIX EDUCATION 2018 Page 60 of 208 Our Students Come First!

3 Below is a summary of the macromolecules we will be studying this lesson. Copyright MATRIX EDUCATION 2018 Page 61 of 208 Our Students Come First!

4 2. Carbohydrates Carbohydrates are Composed of C, H and O You may have heard about carbohydrates in the context of foods and diets. Some examples of carbohydrates are sugars and starch. Can you think of some foods that are rich in carbohydrates? 2 Carbohydrates are composed of carbon, hydrogen and oxygen atoms. Carbohydrates can be categorised as monosaccharides, disaccharides and polysaccharides. Copyright MATRIX EDUCATION 2018 Page 62 of 208 Our Students Come First!

5 Monosaccharides Monosaccharides are the most basic units of carbohydrates. Some examples are glucose, fructose and galactose. They can all exist as a ring-like structure as depicted below. By OpenStax College [CC BY 3.0 ( via Wikimedia Commons You may have heard of glucose from Junior Science. What is the name of the process that produces glucose from sunlight? Write the word equation for this process. 3 What is the name of the process that releases energy from glucose in a usable form for cells? Write the word equation for this process. 4 These basic monosaccharides are important in the storage of energy, and as building blocks for more complicated carbohydrates. Copyright MATRIX EDUCATION 2018 Page 63 of 208 Our Students Come First!

6 Disaccharides As the name suggests, disaccharides are made up of two monosaccharide units joined together. By CNX OpenStax [CC BY 4.0 ( via Wikimedia Commons For example, the reaction between a glucose and fructose monomer produces the disaccharide sucrose. What is another common name for sucrose? 5 Here are some other examples of disaccharides. By CNX OpenStax [CC BY 4.0 ( via Wikimedia Commons Where would you expect to find lactose? 6 Maltose is found as a component of malt, in germinating seeds, and as caramelised glucose. Copyright MATRIX EDUCATION 2018 Page 64 of 208 Our Students Come First!

7 Polysaccharides Polysaccharides are made up of thousands of repeating monosaccharide units, most commonly glucose. This is illustrated below. By OpenStax College [CC BY 3.0 ( via Wikimedia Commons Polysaccharides can play a structural role in cells. Cellulose is a sturdy material found in the cell walls of many plant cells. In fact, it is the most abundant plant fibre on Earth! What is the role of the cell wall? 7 Copyright MATRIX EDUCATION 2018 Page 65 of 208 Our Students Come First!

8 Polysaccharides can also be used for short-term energy storage. Two forms of energy storage are shown below. By OpenStax College [CC BY 3.0 ( via Wikimedia Commons In plants, energy is stored as starch. It can exist in two forms, amylose and amylopectin. Why might starch be found in the chloroplasts of some plant cells? 8 In animals, energy is stored in branching structures called glycogen. They are found within mitochondria of liver and muscle cells. Why might glycogen be found in the mitochondria of some animal cells? Hint: what is the role of mitochondria? 9 Copyright MATRIX EDUCATION 2018 Page 66 of 208 Our Students Come First!

9 Testing for Starch Using Iodine Iodine solution can be used to test for the presence of starch. Can you recall which class of macromolecules starch belongs in? 10 Which substances or foods are rich in starch? 11 Iodine is normally a deep orange solution that turns dark purple in the presence of starch. Source: Which of the test tubes above contains starch? 12 Since this test is so simple, it is commonly used to test for the presence of starch in plant experiment, as we will see in Lesson 5! Copyright MATRIX EDUCATION 2018 Page 67 of 208 Our Students Come First!

10 3. Lipids Lipids are Composed of C, H and O Lipids are more commonly known as fats and oils. They are composed of long chains of carbon, hydrogen and oxygen atoms, like carbohydrates. An example of a lipid is shown below. By OpenStax College [CC BY 3.0 ( via Wikimedia Commons Lipids have many important uses. They are essential for the body to function properly, although too much of the wrong kinds of fats are unhealthy. Lipids make up the cell membrane in cells. We will learn more about the cell membrane and its structural role in the next lesson. They are also important in long-term energy storage. Some steroid hormones are synthesised by cholesterol, a type of lipid. Can you recall which organelle was primarily responsible for lipid synthesis in the cell? 13 Waxes are another type of lipid that is important in forming waterproof coatings, for example, the inner surface of your ear canals! Copyright MATRIX EDUCATION 2018 Page 68 of 208 Our Students Come First!

11 4. Proteins Proteins are Composed of C, H, O and N Proteins are by far the most abundant and diverse group of macromolecules found in the human body. Which organelles are required to synthesise proteins? 14 Since proteins are so enormous and complex, there are many different levels of protein organisation, summarised below. By CNX OpenStax [CC BY 4.0 ( via Wikimedia Commons Copyright MATRIX EDUCATION 2018 Page 69 of 208 Our Students Come First!

12 Protein Structure Proteins are long polymers of amino acids, made of carbon, hydrogen, oxygen and nitrogen. The general structure of an amino acid is shown below. By OpenStax College [CC BY 3.0 ( via Wikimedia Commons The 'R' group is actually a side chain that can be replaced by a series of different atoms. This means that amino acids are variable and in fact, there are 20 different amino acids that make up protein. By CNX OpenStax [CC BY 4.0 ( via Wikimedia Commons Copyright MATRIX EDUCATION 2018 Page 70 of 208 Our Students Come First!

13 Amino acids can join together to form longer chains, as seen previously. As more amino acids join on, they form a long polypeptide chain. This sequence of amino acids is called the primary structure of a protein. The chain can fold and form repeating structures, such as helices and sheets. This constitutes the secondary structure of the protein. The polypeptide chain can keep folding to form a large threedimensional structure, known as the tertiary structure of a protein. Finally, two or more polypeptide chains can fold together to form the functional protein. This is known as the quaternary structure. Because there are so many different amino acids which can each join up to form different sequences, there are millions of possible different proteins! Immunoglobulins, or antibodies, are proteins that are involved in immunological defence. They bind to antigens on bacteria, viruses and other foreign organisms. Enzymes are proteins that act as catalysts in the human body. They speed up and facilitate chemical reactions. Haemoglobin is an example of a transport protein. It is found in red blood cells and carries oxygen around to our tissues. In fact, the diagram above is actually of haemoglobin. Keratin is an example of a structural protein which contributes to the structure of hair, fur, claws and hooves. Some hormones, such as the human growth hormone and insulin, are also proteins. Copyright MATRIX EDUCATION 2018 Page 71 of 208 Our Students Come First!