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.

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

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 C 6 H 12 O 6.  A disaccharide contains two monosaccharides. E.g. sucrose and lactose. They have the formula C 12 H 22 O 11.  A polysaccharide is a complex carbohydrate and contains many sugar units. E.g. starch, cellulose, glycogen

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!

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

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

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

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.

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

A NUCLEOTIDE

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.

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.

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

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

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. together by to form chains of.  Proteins are made of small units called amino acids. These link together by peptide bonds to form chains of polypeptides.  Musical Proteins Musical Proteins

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.

 Messenger proteins, such as some types of hormones, transmit signals to coordinate biological processes between different cells, tissues, and organs.  Structural proteins 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.

Amino Acid Structure  There are twenty different amino acids, but they all have the general formula NH 2.RCH.COOH They all have an amino group (basic) They all have a carboxyl group (acidic) The ‘R’ group differs between amino acids. It is always bonded to a C-H

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

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

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 carboxylicacid Water

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

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

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

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.

LEVEL OF STRUCTURE DESCRIPTION BONDING INVOLVED Primary Specific sequence of amino acids forming a polypeptide chain Peptide bonding Secondary Shape the polypeptide folds into; an alpha helix or beta pleated sheet (non-specific) Hydrogen bonding Tertiary Caused by interactions between R groups which leads to bending and twisting of the polypeptide helix into a compact shape Disulphide (between sulphurs on R groups) Hydrogen and ionic bonds Hydrophillic and hydrophobic interactions Quaternary Combinations of a number of different polypeptide chains and associated non-protein groups As above

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

SECONDARY STRUCTURE

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).

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.

TERTIARY STRUCTURE

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

QUATERNARY STRUCTURE

 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.

KEY WORDS Anagrams 1.ROTINPE 2.RAYMIRP 3.NODYCRASE 4.RABCOXLYIC 5.LAAPH LEIXH 6.TITYREAR 7.TEBA-DEELPAT 8.GOBLINMEAOH 9.NETRAQUYAR 10.DITYEEPPOLP 11.NOGHYEDR NOBD 12.SORDYYISHL 13.NOOTDENCANSI 14.TIEDEPP NOBD 15.NIMAO CAID 1.Protein 2.Primary 3.Secondary 4.Carboxylic 5.Alpha helix 6.Tertiary 7.Beta-pleated 8.Haemoglobin 9.Quaternary 10.Polypeptide 11.Hydrogen bond 12.Hydrolysis 13.Condensation 14.Peptide bond 15.Amino acid

Card sort  Now complete the Proteins Key Terms card sort

Proteins 1. Amino acids join together so that the hydrogen and hydroxyl groups meet. Water is removed in this reaction. Carboxylic acid group 2. The amino acid group consisting of 2 hydrogen atoms and a nitrogen atom. Amino group 3. This type of bond is formed between the two amino acids. Ions 4. Polymers made up of long chains of 20 different amino acids. R group 5. The amino acid group consisting of COOH. Condensation 6. This amino acid group varies from a single hydrogen atom, to a side chain several carbon atoms long, or containing a benzene ring. Peptide bond 7. Amino acids are soluble in water so they form these.

Proteins 4. Polymers made up of long chains of 20 different amino acids. Carboxylic acid group 5. The amino acid group consisting of COOH. Amino group 2. The amino acid group consisting of 2 hydrogen atoms and a nitrogen atom. Ions 7. Amino acids are soluble in water so they form these. R group 6. This amino acid group varies from a single hydrogen atom, to a side chain several carbon atoms long, or containing a benzene ring. Condensation 1. Amino acids join together so that the hydrogen and hydroxyl groups meet. Water is removed in this reaction. Peptide bond 3. This type of bond is formed between the two amino acids.

Dipeptide 1. This structure is formed when the protein folds up tightly. Hydrolysis 2. This structure is formed when proteins are made up of more than one folded protein unit joined together. E.g. haemoglobin. Primary structure 3. This reaction involves water being used to split the bond between amino acids. Secondary structure 4. The name of the product formed between two amino acids. Tertiary structure 5. This structure is a long chain of amino acids. Quaternary structure 6. This structure is formed from interactions between the different side groups of the amino acids, causing the long chain to coil and twist.

Dipeptide 4. The name of the product formed between two amino acids. Hydrolysis 3. This reaction involves water being used to split the bond between amino acids. Primary structure 5. This structure is a long chain of amino acids. Secondary structure 6. This structure is formed from interactions between the different side groups of the amino acids, causing the long chain to coil and twist. Tertiary structure 1. This structure is formed when the protein folds up tightly. Quaternary structure 2. This structure is formed when proteins are made up of more than one folded protein unit joined together. E.g. haemoglobin.