LESSON 1-3: Biomacromolecules

1. LESSON 1-3: Biomacromolecules LEARNING OUTCOMES By the end of these lessons, you should be able to: • Describe the structure and function of lipids. • Describe the structure and function of the nucleic acids; DNA and RNA. • Describe the structure and functional diversity of proteins. • Describe the synthesis of the biomacromolecules: polysaccharides, nucleic acids and proteins.

2. Water – what do you already know? • Each water molecule consists of a single oxygen atom covalently bonded to two hydrogen atoms. • The main component of organisms. • It provides the environment needed for metabolic reactions to take place. • A dipolar molecule – one side is positively charged and the other is negatively charged. • Water molecules are attracted to each other and form hydrogen bonds easily (but these also break easily). • This allows it to have a low viscosity and act as a solvent. 1 2 3 4 5 6 7 8 9 10

3. Carbohydrates • All carbohydrates contain the elements carbon, hydrogen and oxygen in varying ratios. • The basic unit of a carbohydrate is a sugar molecule – a monosaccharide. Glucose and fructose are examples. They have the formula C6H12O6. • A disaccharide contains two monosaccharides. E.g. sucrose and lactose. They have the formula C12H22O11. • A polysaccharide is a complex carbohydrate and contains many sugar units. E.g. starch, cellulose, glycogen. 1 2 3 4 5 6 7 8

4. Lipids • Fats, oils and waxes. • Hydrophobic – no attraction to water; they are insoluble. • Contain C, H and O, but little water. • Contain a lot more energy than any other compound found in plants and animals. • Fats are made of fatty acids and glycerol. • A common fat is a tryglyceride – a single glycerol with three fatty acids attached. NOW TEST EACH OTHER!

5. Phospholipids Phosphate ‘Head’ is HYDROPHILLIC Fatty Acid Tails are HYDROPHOBIC Phospholipids are made from glycerol, two fatty acids, and (in place of the third fatty acid) a phosphate group.

6. Phospholipids Hydrophobic tails (lipid) Hydrophilic heads (phosphate) Water Phospholipids will spread out on water into a single layer (monolayer) because of their hydrophilic heads and hydrophobic ends.

7. In the bilayer of the membrane, the non-polar tails face inwards and the polar heads face outwards.

8. Nucleic Acids • DNA and RNA are examples of molecules in the group called nucleic acids. • DNA is a polymer of nucleotides. • Each nucleotide is made of a sugar (deoxyribose), a phosphate and a nitrogenous base.

9. Nucleotides A phosphate group An organic nitrogenous base, either Thymine, Adenine, Guanine or Cytosine A pentose (5 carbon) sugar called deoxyribose DNA is an example of a group of molecules called nucleic acids. It is made of monomers called mononucleotides.

10. A nucleotide

11. Structure of DNA The sugar and the phosphate join to form ‘a sugar phosphate backbone’. The bases are complementary to each other and are held together by hydrogen bonds. A polynucleotide chain is formed.

12. RNA: Ribonucleic acid • Also a polymer of nucleotides. • Exists as a single chain (rather than double like DNA). • The sugar is ribose instead of deoxyribose in DNA. • The bases are Adenine, Guanine, Cytosine and Uracil(instead of Thymine in DNA). • There are three kinds of RNA, all of which have very specific jobs: • Messenger RNA (mRNA) – involved in protein synthesis. • Transfer RNA (tRNA) – also involved in protein synthesis. • Ribosomal RNA (rRNA) – part of the ribosomes.

13. Now complete Page 14 “Organic Molecules” in your Student Workbook.

14. Proteins Use the plasticine to make what you think a protein molecule might look like.

15. What are Proteins? • Proteins are organic molecules made of carbon, hydrogen, oxygen and nitrogen. They sometimes also contain sulphur and may form complexes with other molecules. • Proteins are made of small units called amino acids. These link together by peptide bonds to form chains of polypeptides. • Musical Proteins

16. Types of Proteins • Antibodies bind to specific foreign particles, such as viruses and bacteria, to help protect the body. • Enzymes carry out almost all of the thousands of chemical reactions that take place in cells. They also assist with the formation of new molecules by reading the genetic information stored in DNA.

17. Messenger proteins, such as some types of hormones, transmit signals to coordinate biological processes between different cells, tissues, and organs. • Structuralproteins provide structure and support for cells. On a larger scale, they also allow the body to move. • Transport proteins bind and carry atoms and small molecules within cells and throughout the body.

18. Amino Acid Structure • There are twenty different amino acids, but they all have the general formula NH2.RCH.COOH The ‘R’ group differs between amino acids. It is always bonded to a C-H They all have an amino group (basic) They all have a carboxyl group (acidic)

19. Identify the amino, carboxyl and ‘R’ groups on the following amino acids:

20. Peptide Bonds: How do amino acids join together? Two amino acids link together to form a dipeptide. When more amino acids are linked together, a polypeptide is formed Try and draw out 2 amino acids linked by a peptide bond. This reaction produces water? What type of reaction is it? animation

21. Condensation Reaction • At least two amino acids join together (with a peptide bond) to form a larger _____________. • A peptide bond forms between the _________ and __________ _____(hydroxyl) groups. • _______ is released. polypeptide hydrogen carboxylic acid Water

22. Hydrolysis Reaction • Breaks the ________bond holding the amino acids together. • _______ is used to split the bond. peptide Water

23. Try and draw the basic structure of an amino acid (from memory!) labelling the different groups.

24. Amino Acid Structure The ‘R’ group differs between amino acids. It is always bonded to a C-H They all have an amino group (basic) They all have a carboxyl group (acidic)

25. Protein Structure Find out: a) what the primary, secondary, tertiary and quaternary structures of proteins are. b) For each of the above, what type of bonding is involved in creating and maintaining the structures.

27. Structures • Primary structure – the long chain of _______ ______. • Secondary structure – a c____ and t______ chain of amino acids. • Tertiary structure – when the protein is _______ up tightly. The 3D shape of the tertiary structure is held together by _________ ______and intermolecular forces. • The 3D shape is important in situations like active sites in enzymes and use in cell membranes. amino acids oiled wisted folded chemical bonds

29. SECONDARY STRUCTURE

30. Alpha Helix • An alpha helix is formed when hydrogen bonds form between the amino and carboxylic acid groups all along the chain. • This makes the chain coil up (like a DNA helix).

31. Beta-pleated Sheets • Parallel folded sections. • They are held in place by hydrogen bonds between the amino and carboxylic acid groups along the parallel chains.

32. TERTIARY STRUCTURE

33. Quaternary Structure • A protein that is made up of more than one folded protein unit joined together have quaternary structure. • ____________ is an example – it has four joined polypeptide chains. Haemoglobin

34. QUATERNARY STRUCTURE

36. The 3D shape depends on the primary structure because the amino acid side groups respond differently to water, altering the shape. • Hydrophobic – water repelling. A hydrophobic side group will turn inwards, away from the water, towards the centre of the protein molecule. • Hydrophilic – water attracting. A hydrophilic side group will turn outwards, forming hydrogen bonds with the surrounding water molecules.

37. KEY WORDS Anagrams ROTINPE RAYMIRP NODYCRASE RABCOXLYIC LAAPHLEIXH TITYREAR TEBA-DEELPAT GOBLINMEAOH NETRAQUYAR DITYEEPPOLP NOGHYEDRNOBD SORDYYISHL NOOTDENCANSI TIEDEPPNOBD NIMAOCAID Protein Primary Secondary Carboxylic Alpha helix Tertiary Beta-pleated Haemoglobin Quaternary Polypeptide Hydrogen bond Hydrolysis Condensation Peptide bond Amino acid

38. Card sort • Now complete the Proteins Key Terms card sort