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Biology Hope > Biological Molecules > Flashcards

Biological Molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a covalent Bond ?

A

2 atoms share a pair of electrons

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2
Q

what is an ionic bond ?

A

1 atoms in the pair donates an electron and the other receives it

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3
Q

What is a cation ?

A

atoms loses electrons and has a positive charge

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4
Q

what are the roles of cations ?

A

calcium - nerve impulse transmission, muscle contraction

potassium + sodium - nerve impulse transmission

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5
Q

What is an anion ?

A

atoms gain electrons and have a negative charge

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6
Q

what is the structure of water

A
  • 2 atoms of hydrogen covalently bonded to one atom of oxygen
  • polar molecule
  • weakly negative charge on oxygen atom
  • weakly positive charge on hydrogen atom
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7
Q

what are hydrogen bonds

A
  • form between water molecules
  • weak bonds
  • very few bonds
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8
Q

high latent heat of evaporation of water

A
  • very high boiling point
  • takes a lot of energy to increase the temperature and break hydrogen bonds to become a gas and evaporate
  • only need to evaporate little water to lose heat
  • provides cooling effect for living organisms
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9
Q

water is less dense when it is a solid

A
  • hydrogen bonds hold water molecules further apart than in liquid
  • giant rigid open structure
  • solid that is less dense than liquid - ice floats
  • forms insulating layer so water below doesn’t freeze
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10
Q

high specific heat capacity of water

A
  • the amount of thermal energy needed to raise the temperature of 1kg of a substance by 1oc
  • lots of thermal energy can break and build hydrogen bonds
  • provides suitable habitats - maintains constant temperatures
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11
Q

water is a good solvent

A
  • positive water molecule is attached to a negative ion
  • negative water molecule is attached to a positive ion
  • ions are surrounded by water molecules and will dissolve
  • ions can dissolve in the water in the blood and then transported around the body
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12
Q

what is cohesion

A
  • moves as one mass as molecules are attached to each other
  • transpiration
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13
Q

what is adhesion

A
  • water molecule are attracted to other properties
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14
Q

what is a monomer

A
  • many small molecules from which larger molecules are made
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15
Q

what are polymers

A

molecules made from a large number of monomers joined together in a chain

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16
Q

what is a condensation reaction

A
  • monomers are joined together by covalent bonds to form polymers/macromolecules and water is removed
  • dehydration synthesis
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17
Q

what is a hydrolysis reaction

A

covalent bonds are broken when water is added

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18
Q

what are monosaccharides

A
  • single sugar unit
  • glucose, fructose, ribose
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19
Q

what are disaccharides

A
  • two monosaccharides linked together
  • lactose, sucrose
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20
Q

what are polysaccharides

A
  • many monosaccharides linked together
  • glycogen, cellulose, starch
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21
Q

what is the structure of glucose

A
  • hexose monosaccharide - 6 carbons
  • isomer - alpha and beta glucose
  • alpha glucose - OH below the ring
  • beta glucose - OH above the ring
22
Q

what are pentose monosaccharides

A
  • sugars that contain 5 carbon atoms
  • deoxyribose and ribose
23
Q

how is the glycosidic bond formed

A
  • condensation reaction and removal of 1 water molecule
  • catalysed by enzymes specific to which OH groups are interacting
  • maltose has alpha 1-4 glycosidic bonds
  • sucrose has alpha 1-6 glycosidic bonds
24
Q

how is the glycosidic bond broke

A
  • water is added in a hydrolysis reaction
  • catalysed by enzymes
25
Q

what makes up starch

A
  • amylase
  • amylopectin
26
Q

what is the structure of amylase

A
  • 10-30% of starch
  • unbranched helix
  • 1-4 glycosidic bonds between alpha glucose molecules
  • more compact and more resistant to digestion
27
Q

what is the structure of amylopectin

A
  • 70-90% of starch
  • 1-4 glycosidic bonds between alpha glucose molecules
  • 1-6 glycosidic bonds
  • branched molecule
28
Q

what is the structure of glycogen

A
  • made of alpha glucose
  • 1-4 and 1-6 glycosidic bonds
  • more branched - releases glucose quicker
29
Q

what is the structure of cellulose

A
  • polysaccharide found in plants
  • long chains of beta glucose molecules joined by 1-4 glycosidic bonds
  • to form 1-4 bonds consecutive beta glucose molecules must be rotated 180oC to each other
  • several hydrogen bonds = high tensile strength
30
Q

what is the function of starch

A
  • insoluble
  • compact
  • storage polysaccharide in plants
31
Q

what is the function of glycogen

A
  • storage polysaccharide of animals/fungi
  • compact
  • highly branched
  • branching enables more free ends where glucose molecules can be added or removed for faster condensation and hydrolysis
32
Q

what is the function of cellulose

A
  • main structural component of cell walls
  • several hydrogen bonds between microfibrils
  • high tensile strength - cell walls withstand pressure
  • lignin for strengthened cell walls
33
Q

how do you test for reducing and non - reducing sugars

A
  • place sample in boiling water
  • add equal volume of benedict’s reagent
  • heat mixture gently in a water bath for 5 minutes

Red = high concentration of reducing sugar
Yellow/orange = medium concentration of reducing sugar
Green = low concentration of reducing sugar

Non-reducing sugars = don’t react with benedict’s reagent and final colour is blue

34
Q

how do you test for the presence of starch

A
  • iodine test
  • add a few drops of iodine mixed in potassium iodide solution to a sample

Purple/Black = starch is present
Yellow/Brown = no starch present

35
Q

what are lipids

A
  • contain carbon, hydrogen, oxygen
  • non-polar molecules
  • not soluble
36
Q

what are triglycerides

A
  • combines 1 glycerol molecule and 3 fatty acids
  • both molecules contain hydroxyl groups - formation of 3 water molecules and bonds between fatty acids and glycerol
  • non polar-hydrophobic molecules
37
Q

what is a saturated fatty acid

A
  • no double bonds between carbon atoms
  • all carbon atoms form the maximum number of bonds with hydrogen atoms
38
Q

what is an unsaturated fatty acid

A
  • double bonds between some of the carbon atoms
  • one double bond = monosaturated
  • two or more double bonds = polysaturated
  • double bonds cause the molecule to kink
39
Q

what are phospholipids

A
  • contain phosphorus, carbon, hydrogen, oxygen
  • soluble in water due to the presence of inorganic phosphate ions
  • one fatty acid chain replaced with a phosphate group
    -fatty acid tails
  • phosphate heads
  • form a phospholipid bilayer
40
Q

what is the role of lipids

A
  • membrane formation
  • hydrophobic barriers
  • electrical insulation for impulse transmission
  • waterproofing (plant leaves)
  • thermal insulation to reduce heat loss
  • cushion to protect organs (heart, kidneys)
  • Buoyancy for aquatic animals - float
41
Q

how do you test for lipids

A
  • emulsion test
  • add ethanol to sample to be tested
  • shake to mix
  • add mixture to a test tube of water

Clear solution = no lipids present
Milky solution = lipids present

42
Q

what are proteins

A
  • polypeptides made up of monomers : amino acids
  • important for cell growth, cell repair , structure
43
Q

how are peptides synthesised

A
  • amino acids join when amine and carboxylic acid groups connect to the central group and react
  • hydroxyl in carboxyl group of one amino acid reacts with hydrogen in the amine group
  • peptide bond formed between amino acids produces water
44
Q

what is the primary sequence of a protein

A
  • amino acids are joined
  • amino acids influence how the polypeptide will fold
  • determines function
  • peptide bonds
45
Q

What is the secondary sequence of a protein

A
  • oxygen, hydrogen and nitrogen of the structure react
  • form alpha helix or beta pleated sheets by hydrogen bonds
46
Q

what is the tertiary sequence of a protein

A
  • folding of protein into its final shape
  • coils or folds further

-hydrophobic and hydrophilic interactions
- hydrogen bonds
- ionic bonds
- disulphide bonds

47
Q

what is the quaternary structure of a protein

A

proteins that have more than one polypeptide chain

48
Q

what are globular proteins

A
  • compact
  • water soluble
  • spherical
  • fold
  • essential for metabolic reactions
49
Q

what is a conjugated protein

A
  • contains a prosthetic groups

Haemoglobin ]- 4 polypeptides
- haem group containing iron that can combined reversibly with oxygen

50
Q

what are fibrous proteins

A
  • long polypeptide chains
  • little or no tertiary structure
  • highly repetitive amino acid sequence = very organised strong insoluble properties

Keratin - in skin and nails
Elastin - blood vessels and alveoli

51
Q

how do you test for proteins

A
  • biuret test
  • add sodium hydroxide to food sample to make alkaline
  • add a few drops of copper sulphate solution
  • repeat the first steps using a control solution
  • Blue to Lilac = protein
  • no change = no protein

Biology Hope (26 decks)

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