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How do 2 DNA nucleotides link together?
- Covalent bond between sugar (of one nucleotide) and phosphate (of the next one)
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What four bases are found in DNA?
- G - guanine
- C - cytosine
- A - adenine
- T - thymine
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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
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What are the most frequently occuring elements in living things?
Carbon (C), Hydrogen (H), Oxygen (O) and Nitrogen (N)
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Apart from C, H, O, N what other things are needed by living organisms?
- Sulphur (S)
- Calcium (Ca)
- Phosphorus (P)
- Iron (Fe)
- Sodium (Na)
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Give a role for sulphur (S)
in some amino acids
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Give 2 roles for Calcium (Ca)
- co-factor in some enzymes
- Component of bones
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Give a role for Phosphorous (P)
phosphate groups in ATP (for energy)
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Give a role for Iron (Fe)
- in cytochromes
- in haemoglobin in red blood cells
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Give a role for Sodium (Na)
- Membrane function
- Sending nervous impulses
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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
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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
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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 an organic molecule?
- Contain the element carbon
- BUT beware...not all elements containing carbon are necessarily organic.
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Give 3 examples of monosaccharides
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Give 3 examples of disaccharides
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Give 3 examples of polysaccharides
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State 1 function of glucose in animals
Used in respiration (for release of energy)
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State 1 function of lactose in animals
Milk sugar
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State 1 function of glycogen in animals
Insoluble storage molecule in animals
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State 1 function of fructose in plants
Fruit sugar
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State 1 function of sucrose in plants
Soluble - transported in phloem sap
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State 1 function of cellulose in plants
Insoluble, structural fibers of plant cell wall
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How does condensation bond two molecules of monosaccharides or between two amino acids, or between two fatty acids.
- Water is removed and the two molecules now bind.
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Condensation of two monosaccharides to make a disaccharide
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State 3 functions of lipids
- Energy Storage
- Thermal insulation
- Buoyancy
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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
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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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How does a DNA double helix form?
- Using complementary base pairing and hydrogen bonds
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What enzyme 'unzips' the double stranded DNA?
Helicase
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What enzyme is involved in adding new nucleotides (base, phosphate and sugar) to the new strand?
DNA polymerase (there are many of these)
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State 5 differences between DNA and RNA.
- DNA and RNABoth contain 5 carbon sugar
- Both have 4 nitrogenous bases
- DNA vs RNA
- 5 carbon sugar is deoxyribose vs ribose in RNACytosine, guanine, adenine and thymine in DNA
- Cytosine, guanine, adenine and uracil in RNA
- Doublestranded moleculein DNA, and single stranded molecule in RNA
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What is transcription?
Synthesis (making) an RNA molecule
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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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