Topic 3 - Chemicals of Life

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  1. How do 2 DNA nucleotides link together?
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    • Covalent bond between sugar (of one nucleotide) and phosphate (of the next one)
  2. What four bases are found in DNA?
    • G - guanine
    • C - cytosine
    • A - adenine
    • T - thymine
  3. What is a nucleotide?
    3 parts - sugar (deoxyribose), phosphate group and a base
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    What does the blue pentagon represent?
    The pentose sugar - deoxyribose.
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    What does the green circle represent?
    Phosphate - the PO4-3 group
  6. What are the most frequently occuring elements in living things?
    Carbon (C), Hydrogen (H), Oxygen (O) and Nitrogen (N)
  7. Apart from C, H, O, N what other things are needed by living organisms?
    • Sulphur (S)
    • Calcium (Ca)
    • Phosphorus (P)
    • Iron (Fe)
    • Sodium (Na)
  8. Give a role for sulphur (S)
    in some amino acids
  9. Give 2 roles for Calcium (Ca)
    • co-factor in some enzymes
    • Component of bones
  10. Give a role for Phosphorous (P)
    phosphate groups in ATP (for energy)
  11. Give a role for Iron (Fe)
    • in cytochromes
    • in haemoglobin in red blood cells
  12. Give a role for Sodium (Na)
    • Membrane function
    • Sending nervous impulses
  13. Give a thermal property of water
    High specific heat = meaning that it can absorb OR give off a lot of heat without changing temperature greatly
  14. Give a cohesive property of water
    Water molecules are cohesive = attracted to each other. Ah - cute!

    Attraction is due to polar covalent bonding via positive end of one molecule attaching to negative end of another molecule
  15. Give a solvent property of water
    Many things dissolve in it! Water is an excellent solvent for other polar molecules (like carbohydrates, proteins, DNA, RNA)
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    What property of water does the pondskater demonstrate?
    Cohesive property
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    What is this molecule?
  18. What is an organic molecule?
    • Contain the element carbon
    • BUT beware...not all elements containing carbon are necessarily organic.
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    What is this molecule?
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    What is this molecule?
    Amino acid
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    What is this molecule?
    Fatty acid
  22. Give 3 examples of monosaccharides
    • Glucose
    • Fructose
    • Galactose
  23. Give 3 examples of disaccharides
    • Maltose
    • Lactose
    • Sucrose
  24. Give 3 examples of polysaccharides
    • Starch
    • Glycogen
    • Cellulose
  25. State 1 function of glucose in animals
    Used in respiration (for release of energy)
  26. State 1 function of lactose in animals
    Milk sugar
  27. State 1 function of glycogen in animals
    Insoluble storage molecule in animals
  28. State 1 function of fructose in plants
    Fruit sugar
  29. State 1 function of sucrose in plants
    Soluble - transported in phloem sap
  30. State 1 function of cellulose in plants
    Insoluble, structural fibers of plant cell wall
  31. How does condensation bond two molecules of monosaccharides or between two amino acids, or between two fatty acids.
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    • Water is removed and the two molecules now bind.
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    What is this?
    Condensation of two monosaccharides to make a disaccharide
  33. State 3 functions of lipids
    • Energy Storage
    • Thermal insulation
    • Buoyancy
  34. Compare use of carbohydrates and lipids in energy storage
    • Carbohydrates
    • More easily digested - so energy released more easily
    • Soluble in water, and so easy to move to/from the store

    • Lipids
    • More energy per gram than carbohydrates
    • Insoluble in water and so does not cause problems with osmosis
    • Require more oxygen per molecule
  35. What does semi-conservative replication mean?
    • When the DNA unzips and the new bases are added, half of the 'old' DNA is always conserved (saved).
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  36. How does a DNA double helix form?
    • Using complementary base pairing and hydrogen bonds
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  37. What enzyme 'unzips' the double stranded DNA?
  38. What enzyme is involved in adding new nucleotides (base, phosphate and sugar) to the new strand?
    DNA polymerase (there are many of these)
  39. State 5 differences between DNA and RNA.
    • DNA and RNA
    • Both contain 5 carbon sugar
    • Both have 4 nitrogenous bases

    • DNA vs RNA
    • 5 carbon sugar is deoxyribose vs ribose in RNA
    • Cytosine, guanine, adenine and thymine in DNA
    • Cytosine, guanine, adenine and uracil in RNA
    • Doublestranded moleculein DNA, and single stranded molecule in RNA
  40. What is transcription?
    Synthesis (making) an RNA molecule
  41. Outline transcription
    • Only area of DNA that has a 'gene' is unzipped
    • Free nucleotides float in and bind by base pairing (but U of RNA, binds to A in DNA).
    • The presence of Uracil identifies it as RNA.
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Topic 3 - Chemicals of Life
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