Biological molecules

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roles of water
synthesising and breaking down biological molecules in condensation and hydrolysis reactions - it is also a key reactant in photosynthesis
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structure of water
two hydrogen atoms bound to one oxygen atom - bonded through a covalent bond -
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what is water referred to as being and why
this is because the negative electrons are more attracted to the oxygen nucleus as there are more positively charged protons - unequal sharing of the electrons result in oxygen being slightly negative and the hydrogen atoms are slight positive
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what bonding occurs in water and why
hydrogen bonding because of the polar nature of water as opposites attract
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what happens when temperature is increased
particles gain more kinetic energy - forces between them break and they change state
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why does water have a high boiling point
water is polar and has hydrogen bonds between them therefore more energy is required to break the bonds
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why does water being a liquid at room temperature useful
provides habitats for aquatic organisms - provides a medium for chemical reactions - provides a medium for transport
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what are the uses of carbohydrates
as an energy source - structural function -
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what element are carbohydrates made of
carbon, hydrogen and oxygen
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what are the simplest carbohydrates called
monosaccharides
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what are monosaccharides
they are the building blocks for more complex carbohydrates
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what happens when two monosaccharides join what is this reaction called and water molecules does it form
a disaccharide - condensation reaction - water is formed
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what happen when many monosaccharides join together
a polysaccharides
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what are monosaccharides
they are single sugar monomers that are sweet an soluble
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wht is the genral formula of monosaccharides
(CH2O)n
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what type of sugar is glucose
a hexose
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what is the molecular formula of glucose
C6H1206
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importance of ice being less dense than water
it provides habitat creature it also provides an insulating layer against external cold which prevents lakes and rivers from freezing
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why is glucose an important sugar
it is the main source of energy in respiration, building blocks of larger carbohydrates
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what stain is used for starch granules and what colour does it go and can it be used for other cell structures
iodine starch granules dark purple and cell walls yellow
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properties of glucose
small - easily transported, less reactive than other monosaccharides - must be catalysed by enzyme controlled reactions
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what are two isomers of glucose
alpha glucose and beta glucose
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what bonds join two monosaccharides
glycosidic bonds
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what are macronutrients
they are main elements such as NO3- that are needed in large quantities by the body
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what are micronutrients
they are inorganic ions needed in small traces such as iron
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why is calcium needed in the body
helps with muscle contraction - helps to strengthen teeth, bones and exoskeletons - helps with enzyme activity - regulating transmission form neuron to neuron - regulating protein channels - formations of blood clots - development of middle lamellae
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why is sodium needed in the body
helps plant to remain turgid - regulating reabsorption in the kidney - transmission of nervous impulses - maintaining the pH of the body - acitve transport of glucose and amino acis in the intestine
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why is potassium needed in the body
osmotic potential - nervous transmission - assisting active transport - maintenance of pH - for plants to grow healthy leaves and flowers - synthesis of proteins and breakdown of glucose
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why is hydrogen ions needed in the body
photosynthesis and respiration in the production of ATP - determine the pH of bodily fluid
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why is ammonium ions needed in the body
amino acids, which make up proteins - needed to make organic bases - vitamins e.g. vitamin B - nitrogen found in chlorophyll - formed from ammonia by accepting a H+ so regulate pH
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why is nitrate ions needed in the body
source of nitrogen for amino acids - organic bases - vitamins - chlorophyll - important in the nitrogen cycle
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why is hydrogen carbonate ions needed in the body
formed when CO2 dissolves in the blood - important in the transport of CO2 in the blood - regulation of blood pH -
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why is phosphate ions needed in the body
forming nucleotide like DNA and RNA - form ATP can have up to 3 phosphate groups - phospholipids - breakdown of glucose in respiration
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Why is the incompressible nature of water important for organisms?
Provides turgidity to plant cells. Provides hydrostatic skeleton for some small animals e.g. earthworms.
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Why is water an important solvent for organisms?
Polar universal solvent dissolves & transports charged particles involved in intra & extracellular reactions e.g. PO4 3- for DNA synthesis.
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Explain why ice floats on water. Why is this important for organisms?
Ice is less dense than water because H-bonds hold molecules in fixed positions further away from each other. Insulates water in arctic climates so aquatic organisms can survive. Water acts as a habitat.
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Why is the high surface tension of water important for organisms?
Slows water loss due to transpiration in plants. Water rises unusually high in narrow tubes, lowering demand on root pressure. Some insects can ‘skim’ across the surface of water
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State 7 biologically important properties of water.
reaches maximum density at 4℃ - high surface tension - incompressible - metabolite/ solvent for chemical reactions in the body ● high specific heat capacity - high latent heat of vaporisation cohesion between molecules
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How do hydrogen bonds form between water molecules?
Water is polar: O more electronegative than H, so attracts electron density in covalent bond more strongly. Forms O
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Why are the high specific heat capacity and latent of vapourisation of water important for organisms?
Acts as a temperature buffer which enables endotherms to resist fluctuations in core temperature to maintain optimum enzyme activity. Cooling effect when water evaporates from skin surface as sweat/ from mouth when panting
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Describe the properties of
Small & water soluble = easily transported in bloodstream. - Complementary shape to antiport for co-transport for absorption in gut. ● Complementary shape to enzymes for glycolysis = respiratory substrate.
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Name the elements found in carbohydrates, lipids, proteins and nucleic acids.
carbohydrates & lipids: C, H, O proteins: C, H, O, N, S nucleic acids: C, H, O, N, P
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Describe the structure and function of cholesterol.
Steroid structure of 4 hydrocarbon rings. Hydrocarbon tail on one side, hydroxyl group (-OH) on the other side. Adds stability to cell surface phospholipid bilayer by connecting molecules & reducing fluidity.
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Define primary and secondary structure of a protein.
Primary: sequence, number & type of amino acids in the polypeptide, determined by sequence of codons on mRNA. Secondary: hydrogen bonds form between O
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Define ‘quaternary structure’ of a protein
Functional proteins may consist of more than one polypeptide. ● Precise 3D structure held together by the same types of bond as tertiary structure. ● May involve addition of prosthetic groups e.g metal ions or phosphate groups.
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Describe the 2 types of secondary protein structure
α-helix: - All N-H bonds on same side of protein chain. - Spiral shape. ● H-bonds parallel to helical axis. β-pleated sheet: ● N-H & C=O groups alternate from one side to the other.
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Define ‘tertiary structure’ of a protein. Describe the bonds present.
3D structure formed by further folding - Disulfide bridges: strong covalent S-S bonds between molecules of the amino acid cysteine. - Ionic bonds: relatively strong bonds between charged R groups (pH changes cause these bonds to break). - Hydrogen bo
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importance of ice being less dense than water
it provides habitat creature it also provides an insulating layer against external cold which prevents lakes and rivers from freezing
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structure of water

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two hydrogen atoms bound to one oxygen atom - bonded through a covalent bond -

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what is water referred to as being and why

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Card 4

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what bonding occurs in water and why

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what happens when temperature is increased

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