Recommended
More Related Content
What's hot
What's hot (20)
Similar to Chapter 1 the chemical nature of cells
Similar to Chapter 1 the chemical nature of cells (20)
Recently uploaded
Recently uploaded (20)
Chapter 1 the chemical nature of cells
- 1. The Chemical Nature of Cells CHAPTER 1
- 2. Study Design the nature and importance of biomacromolecules in the chemistry of the cell: – synthesis of biomacromolecules through the condensation reaction – lipids and their sub-units; the role of lipids in the plasma membrane – examples of polysaccharides and their glucose monomer – structure and function of DNA and RNA, their monomers, and complementary base pairing – the nature of the proteome; the functional diversity of proteins; the structure of proteins in terms of primary, secondary, tertiary and quaternary levels of organisation
- 3. Internal Environment • Inside a cell is a chemical world. • Energy is constantly being used or produced in chemical reactions • Molecules are constantly being created or broken down.
- 4. Biochemical Processes Anabolic Reactions • Building materials • Requires energy • Eg. Photosynthesis Catabolic Reactions • Breaking down materials • Releases energy • Eg. Cellular respiration
- 5. Metabolism The sum total of all chemical reactions occurring in the body. • Takes into account all catabolic and anabolic reactions
- 6. Chemicals in a Cell Who are the key players in the chemistry of a cell ? • Water • Carbohydrates • Proteins • Lipids • Nucleic Acids
- 7. Water H2O • Oxygen and Hydrogen joined by a strong covalent bond • Oxygen has a slightly negative charge while hydrogen has a slightly positive charge. • Water molecules are attracted to each other – highly cohesive (Remember transpiration)
- 8. Definition Hydrogen bond A weak bond between two molecules or parts of the same molecule; the hydrogen atom is slightly positive and is attracted weakly towards an atom of N, O or F Hydrogen Bonds
- 9. Water H2O • Water molecules tend to stick together by H bonds • Exists in 3 states • Solid - as temperature drops, molecular movement drops. Below 4°C movement not sufficient to break H bonds, making a lattice structure which is less dense than water as molecules are further apart than when a liquid • Liquid – H bonds between water molecules constantly breaking and reforming, but the time apart is so brief, it maintains it cohesive nature • Gas – movement of molecules increases to a point that H bonds no longer hold them together
- 11. Water H2O - Universal Solvent • Hydrophilic or Polar substances • dissolve easily in water • eg salt • Hydrophobic or Non-Polar substances • will not dissolve easily in water • eg fats
- 12. Water H2O - Universal Solvent Dissolving • H2O + NaCl H2O + Na+ + Cl- • Attraction between Na+ and oxygen and Cl- and hydrogen splits the NaCl molecule
- 13. pH A measure of hydrogen H+ ions in a solution. Below 7 – increasing H+ ions pH 7 Equal H+ & OH- ions Above 7 – increasing OH- ions Cells must regulate their pH
- 14. pH • pH of body fluids is kept relatively constant because H+ ions are continually being used and produced in cells • Cells contain buffer substances that combine with or release H+ ions in a cell to prevent severe shifts in pH of a cell or fluid Some fluids – eg urine, blood – have a range for their pH, as the kidneys assist in maintaining the pH of the blood and body tissues by excreting more or less of a particular ion
- 15. Terms • Monomer – a molecule or compound that can join together to form a dimer(2), trimer(3) or polymer (many) • Polymer – a large molecule made of many repeated units (monomers) Monomer Polymer Glucose Polysaccharide Amino Acid Protein Fatty Acid Lipids Nucleotides Nucleic acids
- 16. Condensation Reaction • the joining of monomers involves the release of water molecules 2 Hydrogen molecules and 1 Oxygen molecule are released, joining together to make H2O
- 17. Hydrolysis Reaction • Occurs when a polymer is broken down and a water molecule is used • The opposite of a condensation reaction.
- 18. Definition Biomacromolecule • A naturally occurring substance of large molecular weight http://maxeybio.blogspot.com.au/2013/10/the-building-blocks-of-life.html 5/11/14
- 19. Carbohydrates • Energy rich molecules • Consist of C (5 or 6 C ring), H and O in a 1:2:1 ratio (C:H:O). • The basic unit is a sugar molecule • Can be simple or complex carbohydrates http://jennifer.nutritiontransition.co.uk/carbohydrates.htm 5/11/14
- 20. Simple Carbohydrates • Monosaccharides • one subunit (saccharide) • Examples • Glucose C6H12O6 • Fructose C6H12O6 Glucose and Fructose are structural isomers http://www.nutriology.com/carbfunctions.php 5/11/14
- 21. Simple Carbohydrates Glucose C6H12O6 Galactose C6H12O6 Fructose C6H12O6
- 22. Simple Carbohydrates Disaccharides • two subunits (saccharides) • Examples • Sucrose, Lactose, Maltose …… all C12H22O11 Glucose + Fructose Sucrose + water C6H12O6 +C6H12O6 C12H22O11 + H2O Condensation reaction – water released
- 23. Simple Carbohydrates • Lactose (C12H22O11) Glucose + Galactose • Maltose (C12H22O11) Glucose + Glucose • Cellobiose (C12H22O11) Glucose + Glucose
- 24. Trivia Glucose Glucosamine (Building block for chitin) Galactose Galactosamine (Building block for cartilage)
- 25. Complex Carbohydrates Polysaccharides • Eg. Starch, cellulose, glycogen • All made with glucose monomers (saccharides) • Glycogen • Used for energy in animals • Stored in liver and muscles • Starch • Storage of excess glucose in plants • Insoluble, no effect on diffusion • Cellulose (C6H10O5) n • Structural polysaccharide in plants
- 26. Proteins • All have C,H,O,N • Some have S and P • Makes up 18% of cell contents • Monomer • Amino acids (RCH(NH2)COOH) • R group varies - different A/A • 20 naturally occurring A/A • We can make 11 A/A, • Other 9 from our food
- 27. Amino Acids http://en.wikipedia.org/wiki/Prot ein_structure 5/11/14
- 28. Bonding together • peptide bond forms between the amino group of one amino acid and the carboxyl group of another • Water molecule is released – condensation reaction • A number of amino acids joined together – polypeptide • Polypeptide chains fold different ways depending on their function http://www.ib.bioninja.com.au/higher-level/topic- 7-nucleic-acids-and/75-proteins.html 5/11/14
- 29. Proteins - Structure Four steps to structure Primary Structure • Linear sequence of amino acids Secondary Structure • Folding of chain into • Alpha Helix (coil) • Beta Sheet (Pleated) • Random coil (not alpha or beta) • Held by hydrogen bonds
- 30. Secondary Structure Some examples: • The major protein of wool is alpha-keratin, a spiral molecule. If the fibre is stretched and the H bonds are broken the fibre becomes extended. If the fibre is then ‘let go’, the H bonds reform and the fibre returns to its original length. Alpha Helix • The major protein of silk is fibroin that is fully extended and lacks the coiling found in the structure of wool. The silk molecules from a beta-pleated sheet. The polypeptide chains of silk are already extended and cannot be extended further. • Any major protein or portion is called random coiling if it does not fit into alpha- or beta-coiling. The O2 binding protein of muscle, myoglobin, has random sharp turns in its coil. The place of the random coil is often the most active site of a molecule. Beta pleated Random Coil http://en.wikipedia.org/wiki/Pancreatic_lip ase 5/11/14
- 31. Proteins - Structure Tertiary Structure • Complex shape • Irregular folding held in place by ionic or hydrogen bonds • The 3-D shape of a protein is critical for its function – if changed, esp. at its active site, the protein can no longer function Quaternary Structure • Two or more tertiary structures join to form a protein http://biology.tutorvista.com /biomolecules/proteins.html 5/11/14
- 32. Proteins – Quaternary structure Fibrous Proteins • Stringy and physically tough • Actin, Collagen, Elastin, Fibronectin, Keratin, Myosin, Tropomyosin, Tubulin, Globular Proteins • Generally spherical or globular • most hormones, enzymes, antibodies • Albumins, Alpha globulin, Beta globulin, Cadherin, Fibrin, Gamma globulin, Haemoglobin, Immunoglobins, Myoglobin, Selectin, Serum albumin, Thrombin http://www.differencebetween.net/scienc e/health/difference-between-globular-protein- and-fibrous-proteins/ 5/11/14
- 33. Conjugated Proteins These are proteins which are joined to other molecules Examples • Glycoproteins Protein + sugar • Nucleoproteins protein + nucleic acid • Haemoglobin Tertiary structure + heme group http://www.rottentomatoes.com/q uiz/higher-biology-quiz 5/11/14
- 34. Types of Proteins • Structural – Collagen, Keratin • Enzyme – Amylase, ATP synthase • Contractile – Actin, Myosin • Immunoglobulin – Antibodies • Hormone – Insulin • Receptor – Insulin receptors • Transport - Haemoglobin
- 35. Activating Proteins • Not all enzymes are made ready to work • They must be activated. Why? Example • Pepsinogen Pepsin • Pepsinogen is inactive • Pepsinogen + HCl Pepsin • Pepsin breaks down polypeptides
- 36. What is the Proteome ? Proteome • The complete array of proteins produced by a cell or organism in a particular environment Proteomics • The study of the proteome http://pharmaceuticalintelligence.com/tag/clinical-omics/ 5/11/14
- 37. Lipids • These are : Fats, Oils, Waxes • All contain Carbon, Hydrogen, Oxygen • They have little H2O so they carry more energy per molecule than other compounds • Animals store excess glucose as fat
- 38. Lipids - Fats Insoluble in water (hydrophobic) • Each molecule comprises • Fatty acid(s) and • Glycerol C3H5(OH)3 • Minimum of one fatty acid and one glycerol (mono, di & tri) Eg Triglycerides - Solid Vs Liquid Fats Triglyceride Note the lack of oxygen in the triglyceride molecule
- 39. Saturated Vs Unsaturated Fats • Saturated Fats: • All single bonds between C, so it is saturated with H. • Can be packed close together – solid at room temperature. • Unsaturated Fats: • Not all C have a H attached due to double bond, so are unsaturated (more than one C double bond = polyunsaturated), creating kinks in the tail. • Due to the kinks they are not so tightly packed – liquid at room temperature.
- 40. Lipids - Phospholipids Phospholipid molecules have: • Two fatty acids • Glycerol molecule and • Phosphate group • Includes a variable group which makes each molecule different - Phospholipids are a major component of cell membranes
- 41. Cholesterol • A steroid / lipid molecule • Maintains the fluidity of a membrane
- 42. Fats and Energy • Fats are energy rich molecules • Per gram, fats store twice the energy as polysaccharides • Animals store energy as fat • Plants store energy as polysaccharides Why the difference? Hint:
- 43. Nucleotides There are two types 1. Deoxyribonucleic Acid – DNA 2. Ribonucleic Acid – RNA
- 44. DNA • A molecule made of nucleotides • Each nucleotide is made of three things • Sugar • Phosphate group • Nitrogen base These are the same for all nucleotides http://scienceaid.co.uk/biology/gene tics/images/nucleotide.jpg 5/11/14
- 45. DNA There are four different nitrogen bases which create four nucleotides • Adenine • Thymine • Cytosine • Guanine
- 46. DNA • Nucleotides are joined into chains
- 47. Complementary Bases • Adenine bonds with Thymine • Guanine bonds with Cytosine • This creates a double stranded molecule
- 48. To summarise…
- 49. How much DNA ? • The average length of a chromosome is around 5cm. • That is about 2m of DNA per cell. • How do you fit it all into such a small space?
- 50. Histone Proteins The DNA strand is wrapped around special proteins called histones to make chromosomes
- 51. Why have DNA ? • DNA controls the functioning of cells by controlling the proteins a cell makes. • DNA carries the information required to create polypeptide chains. • Sets of three nucleotides act as a code for one amino acids http://www.chemicalconnection.org.uk/chemistry /topics/view.php?topic=5&headingno=13 5/11/14
- 52. RNA – Ribonucleic Acid Like DNA it: • Is a polymer of nucleotides • Has the nucleotides G, C, A ,U (Uracil) Unlike DNA • RNA is a single strand of nucleotides • Ribose replaces deoxyribose as the sugar in the nucleotide • Thymine is replaced with Uracil • Uracil bonds with Adenine
- 53. RNA Three main types of RNA • Messenger RNA (mRNA) • Carries genetic messages to the ribosome for protein synthesis • Ribosomal RNA (rRNA) • A structural unit of the ribosome • Transfer RNA (tRNA) • Carries amino acids to the ribosome for assembly into a polypeptide