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Chapter 4
- 1. Chapter 4 Chemical CompositionIn a Cell
- 2.
- 3. 4.1 Water • 65-95%of the mass of most plants • 80% of human cells consist of water • Adapted to the physical and chemical properties of water
- 4. • H2O • 2hydrogen atoms and 1 oxygen atom • Oxygen attracts electrons stronger than hydrogen causes irregular distribution of electrons • This causes partial charges at both ends of hydrogen and oxygen atoms • Hence, end of hydrogen is attracted to end of oxygen and form a weak hydrogen bond.
- 6. Specific Heat Capacityof Water • High specific heat capacity among all types of liquids. • Caused by the presence of a weak hydrogen bond • If water is heated hydrogen bond will be broken down and water molecules can move freely. • This enables water to absorb a large quantity of heat with a minimum temperature rise
- 7. Cohesive Force ofWater • Water molecules attract to one another. • Causes by hydrogen bond between the water molecules
- 8. Adhesive Force ofWater • Attractive forces between water and the molecules of other subtances. • Parts of the water molecule that are partially positive and negatively charged are attracted respectively to ions and the molecules of other subtances that are negative and positively charged.
- 9. Importance of waterin cells • Maintains the stability of temperature in cells • Water as a solvent • Transportation of water and minerals in cells
- 10. 4.2 Carbohydrates • Formedfrom elements of carbon (C), hydrogen (H) and oxygen (O). • C:H:O 1:2:1 • Main source of energy
- 13. Reducing Sugar • Allmonosaccharides • Maltose, lactose • Benedict solution
- 14. Non-reducing sugar • Allpolysaccharides • Sucrose
- 15. The formation andbreaking down of disaccharides • Condensation ( formation ) • Glucose + Glucose = Maltose + water • Glucose + Fructose = Sucrose + water • Glucose + Galactose = Lactose + water • Hydrolysis (breaking down)
- 16. Polysaccharides • Polymerisation isa condensation process of monosaccharide molecules to form a large molecule of polysaccharide. • In polymerisation, monosaccharide molecules are called monomers • Starch • Glycogen • Cellulose
- 18. 4.3 Protein • Carbon •Hydrogen • Oxygen • Nitrogen • Sulphur • Phosphorus
- 19. • Essential aminoacids cannot be synthesised by vertebrate cells • Non-essential amino acids can b e synthesised.
- 20. • Amino acidare the monomers to polypeptides / protein • Amino acid joined together through condensation process
- 21. Formation and BreakingDown of Dipeptides
- 24.
- 25. • Consists ofC H O, similar to Carbohydrates • Difference: Oxygen level in lipids is lower than in carbs • Rich in energy • Do not dissolve in water but dissolve in other lipids and organic solvent such as ethanol
- 35. Importance of Lipids Energystorage Insulator to reduce heat loss Mechanical protection to the body Lipid storage around organs For aquatic organisms to obtain buoyancy
- 36.
- 37. • Complex macromolecules •Store genetic information in the form of genetic codes • Contains C H O N P • Monomer of nucleic acids are nucleotides
- 38. 2 types ofnucleic acid • Deoxyribonucleic acid DNA foundn in chromosome of the nucleus • Ribonucleic acid RNA found in cytoplasm, ribosome, nucles
- 39. DNA PENTOSE SUGAR (5 CARBON SUGAR) PHOSPHATE GROUP NITROGENOUS BASE (ADENINE (A), THYMINE (T), GUANINE (G), CYTOSINE (C)
- 40. • Phosphate groupof a nucleotide can form a chemical bond with other nucleotide sugar to form a long nucleotide chain, known as nucleic acid molecule / polynucleotides • Complementary base pairs: • AT • GC
- 42. • DNA consistsof 2 polynucleotide chains and form double helix
- 43. RNA • Consists apolynucleotide chain • Shorter than a DNA chain • Consists of Ribose sugar • 4 nitrogeneous base AG, cytosine (S) and Uracil (C) • Phosphate group
- 44. Types of RNA Mrna(messengers) Trna (transfer) Rrna (ribosomal) (involved in protein synthesis)
- 46. Importance of NucleicAcids in a Cell • DNA and RNA carrying genetic information • The production of protein • DNA carries genetic information in the form of genetic codes on a polypeptide chain • Production of protein: • Both types of nucleic acids complement each other to produce proteins • DNA is in the nucleus, but the synthesis of protein occurs in the ribosome in the cell cytoplasm
- 48. Formation of Chromosomesfrom DNA and Proteins • Each chromosome consists of a continuous thread of DNA molecule that spiral closely around histone molecules • Histone is the form of protein molecules functions as a spindle for DNA thread loop, acts to strengthen the structure of chromosomes • Histone does not carry genetic information • DNA spirals around 8 histone molecules • The combination of DNA loop and 8 histones is called nucleosome • Nucleosome spiral again to form solenoid • Solenoid spirals to form chromatin threads • One chromosome consists of 2 chromatids with centromere.