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Biology > 2.1.2 Biological molecules > Flashcards

2.1.2 Biological molecules Flashcards

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1
Q

What elements make up living things?

A

-Carbon, hydrogen, oxygen, and nitrogen. Some contain phosphorus and sulfur.

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2
Q

Calcium ions function

A

-Nerve impulse transmission, miscle contraction.

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3
Q

Sodium ions function

A

Nerve impulse transmission, kidney function.

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4
Q

Potassium ions function

A

-Nerve impulses transmission, stomatal opening.

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5
Q

Hydrogen ions function

A

-Catalysis of reactions, pH determination.

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6
Q

Ammonium ions function

A

-Production of nitrate ions by bacteria.

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7
Q

Nitrate ions function

A

-Nitrogen supply to plants for amino acid and protein formation.

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8
Q

Hydrogen carbonate ions function

A

-Maintenance of blood pH.

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9
Q

Chloride ions function

A

-Balance and charge of sodium and potassium ions in cells.

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10
Q

Phosphate ions function

A

-Cell membrane, nucleic acid, ATP and bone formation.

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11
Q

Hydroxide ions function

A

-Catalysisnof reactions, pH determination.

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12
Q

Polar molecules

A

-Molecules that contain areas of both negative and positive charge.

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13
Q

Why does water have a high specific heat capacity?

A

-Due to many hydrogen bonds that form within water, which takes a lot of energy to break.
-Allows for a thermostable environment for organisms to live in.

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14
Q

Why does water have a high latent heat of evaporation/vaporisation?

A

-Due to many hydrogen bonds that form between water, which takes a lot of energy to overcome to make water gaseous.
-Allows for a stable environment for organisms and acts as a coolent for living things, e.g, sweat.

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15
Q

Why is water very cohesive?

A

-Water is very cohesive due to the polarity of water molecules, which causes them to become attracted to each other and therefore move as one unit.
-Gives water a surface tension that organisms can inhabit.
-Allows for plants to draw water up their roots.

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16
Q

Why is water less dense when solid?

A

-When water freezes, the hydrogen bonds fix the polar molecules slightly further apart than they are in a liquid, creating a large, open, rigid structure.
-Allows for ice to float so when lakes freeze, it provides an insulating layer so the organisms below can still swim and catch food.

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17
Q

Why is water a good solvent?

A

-Water polarity allows for its negative and positive ends of the molecule to attract oppositly charged ions.
-The ions are then entirely surrounded and dissolved.
-The cytosol of prokaryotes and eukaryotes is mainly water.
-Water acts as a medium for chemical reactions and also helps transport dissolved compounds in and out of cells.

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18
Q

What elements are carbohydrates made of?

A

-Carbon, hydrogen and oxygen.

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19
Q

Carbohydrate functions?

A

-Starch and glycogen= enery storage
-Cellulose= strucural carbohydrate used in cell walls.

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20
Q

Amylose properties

A

-Formed by alpha molecules joined together by only 1-4 glycosidic bonds.
-The angle of the bond causes it to form a helix, which is further stabilised through hydrogen bonds within the molecule.
-Makes it compact and much less soluable than the glucose molecules that make it.
-1-6 glycosidic bonds form between amylose and amylopectin to form starch.

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21
Q

Amylopectin properties

A

-Formed of alpha glucose molecules joined together
-Amylopectin has branched structure with 1-6 glycosidic bonds occouring every 25 glucose subunits.
-Key properties of amylose and amylopectin are compact, insoluable, and have many ends that can be added and removed from.

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22
Q

Glycogen properties

A

-Formed of amylose and amylopectin bonded by 1-6 glycosidic bonds.
-Functionally equivalent energy storage molecule to starch in animals.
-Forms more branches than amylopectin, so is more compact, which is important as animals move, unlike plants.
-Many ends for the addition or removal of glucose molecules.
-Compact so ideal for storage.

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23
Q

Cellulose properties

A

-Polymer of beta glucose bonded by 1-4 beta glycosidic bonds.
-Every 2nd beta glucose is flipped 180 degrees.
Long unbranched chains that form hydrogen bonds with adjoining cellulose molecules forming fibrils.
-Fibrils form larger bundles called fibres.
-Form cellulose cells walls in plants and provide structural support for plants.
-Difficult to digest as not many animald contain the enzymes required to break down 1-4 glycosidic bonds.

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24
Q

Ribose properties

A

-Monosaccharide
-CH2OH side chain
-Pentose sugar
-5 membered ring

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25
Q

Fructose properties

A

-Monosaccharide
-2 CH2OH side chains
-Hexose sugar
-5 membered ring

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26
Q

Glucose+glucose disaccharide

A

-Maltose

27
Q

Glucose+fructose disaccharide

A

-Sucrose

28
Q

Glucose+galactose disaccharide

A

-Lactose

29
Q

Lipids functions

A

-Boyancy=triglycerides
-Energy=triglycerides
-Energy storage=triglycerides
(are)
-Waterproof=waxes/esters
-Insulation=triglycerides/phospholipids
-Membrane formation=phospholipids/cholesterol
-Protection=triglycerides
-Steroid hormones=cholesterol
-

30
Q

Triglyceride formation

A

-Made up of one glycerol molecule and 3 fatty acids
-Condensation reaction known as esterification takes place to create ester bonds between the fatty acids and glycerol molecule.
The carboxylic acid group on the fatty acid reacts with the hydrogen group on the glycerol molecule.

31
Q

Saturated fatty acid properties

A

-Saturated fats have no double bonds present, so carbons have a maximum number of bonds with hydrogen atoms.
-Often solids (fats)

32
Q

Unsaturated fatty acid properties

A

-There are double bonds present between carbon atoms.
-Causes the chain to bend and kink, making it difficult to be compact and solid (oils)

33
Q

Triglycerides structure linking to function

A

-Triglycerides are not soluable and are non-polar, so they can be stored for long periods of time.
-Used for hormone production, insulation, energy storage, and boyancy.

34
Q

Phospholipid formation

A

-Made of one glycerol molecule, 2 fatty acids, and 1 phosphate ion.
-2 esterification reactions take place between the fatty acids and glycerol molecules producing 2 ester bonds.

35
Q

Phospholipids structure linking to function

A

-The dual hydrophillic and hydrophobic characteristics allow for a bilayer to form as the charged heads sit on the edge, protecting the fatty acid tails which point inwards.
-Used as surfactants as they form a layer on the water with their charged heads in the water and fatty acid tails sticking up.

36
Q

Cholesterol formation

A

-Complex alchohol molecules based
on four carbon ring structure with a hydroxyl group at one end, giving them dual hydrophillic/hydrophobic characteristics.

37
Q

Cholesterols structures linking to function

A

-Sits between the phospholipids with the hydroxyl group at the periphery of the membrane.
-Provides stability and regulates fluidity.
-The rigid rings of the cholesterol molecule interact with the hydrophobic tails of the phospholipids, which stabilise them and make them less permeable to small molecules.
-Cholesterol acts like a buffer and extends temperature range, so membrane stay fluid.

38
Q

What are amino acids made of?

A

-An amine group, a carboxylic acid and a variable R-group.

39
Q

Different properties of R-groups

A

-Charged, negative or positive
-Polar, hydrophillic
-Non polar, hydrophobic
-Sizes, small=glycine big=tryptophan

40
Q

4 layers of protein structure

A

-Primary structure, secondary structure, tertiary structure and quaternary structure.

41
Q

Primary structure

A

-Many amino acid monomers are joined together by peptide bonds to form polypeptide chains.
-The sequence of amino acids deternimes the overall structure and function of the final protein.

42
Q

Secondary structure

A

-As a polypeptide chain is formed it coils and folds due to the NH and C=O groups of the monomers in the chains are polar.
-Hydrogen bonds can form between the delta positive H atoms on the NH group of one monomer and the delta negative O on the C=O group of another monomer.
-The two types are an alpha helix and a beta pleated sheet.

43
Q

Tertiary structure

A

-Final 3-dimensionsal shape of the polypeptide chain.
-Due to folding amino acids that were far away from each other are now close enough to form bonds.
-Interactions between R-groups also form tertiary structure.

44
Q

Tertiary structure (disulphide bonds/bridges)

A

-A covelent bond formed between 2 sulfur atoms in the R-groups of cysteine.
-The strong covelent bond stabilises the structure so organisms that live at high temperatures have more cysteine in their proteins in order to form more disulphide bonds.

45
Q

Tertiary structure (ionic bonds)

A

-If one negative R-group and a positive R-group come close enough, they will form an ionic bond.

46
Q

Teritary structure (hydrogen bonds)

A

-Delta negative and delta positve R-groups will form hydrogen bonds when in close proximity.
-Between H atoms and electronegative O or N atoms within the R-groups.

47
Q

Tertiary structure (hydrophobic and hydrophillic interactions)

A

-Hydrophobic= hydrophobic R-groups are found on the inside of folded protein molecules away from the external aqueous environment.
-Hydrophillic= hydrophillic R-groups are found on the outside of folded proteins in contact with the aqueous environment. Also found insidr channrl proteins allowing water soluable substances across the membrane.

48
Q

Disrupting tertiary structure

A

-Increase temperature=causes molecules to vibrate and breaks the weak (non-covelent) bonds in a proteins tertiary structure chaning the proteins 3D structure (denaturing)
-Denatured proteins will not reform when cooled
-Changing pH=distrupts hydrogen bonds and ionic bonds, causing denaturation.

49
Q

Quaternary structure

A

-2 or more proteins joined together by the same bonds present in tertiary structure
-e.g ionic bonds, hydrogen bonds, disulphide bonds, hydrophillic/hydrophobic bonds.

50
Q

Globular proteins

A

-Globular proteins are compact, water soluable, and roughly spherical in shape
-Formed when proteins fold into their tertiary structures in such a way to kepp the hydrophobic R-groups away from the aqueous environment.
-Their solubility is important for regulating processes necessary for life, e.g, chemical reactions.
-Insulin

51
Q

Insulin

A

-Globular protein and a hormone involved in the regulation of blood glucose concentration by promoting conversion of glucose to glycogen.
-Insulin is soluable and has a specific shape in order to be transported in blood and fit the specific receptors on plasma membranes.
-Consists of 2 polypeptide chains held together by 3 disulphide bonds.
-2 subunits - A chain (21 aas long) and B chain (30 aas long)

52
Q

Conjugated proteins

A

-Globular proteins that contain a non-protein component called a prosthetic group, proteins without a prosthetic group are called simple proteins.
-Prosthetic groups like carbohydrates or lipids combine with proteins to form lipoproteins or glycoproteins.
-Haem groups are also prosthetic groups and contain iron II ions.

53
Q

Haemoglobin

A

-Red oxygen carrying pigment found in red blood cells (erythrocytes)
-It has a quaternary structure made from 4 polypeptide chains, two alpha, and two beta subunits.
-Each subunit contains a haem group, and the iron ions present are able to combine reversibly with an oxygen molecule enabling haemoglobin to move oxygen around the body.
-Transports oxygen to respiring cells.

54
Q

Catalase

A

-Catalase is an enzyme that catalyses reactions by increasing reaction rates.
-Quaternary structure contains four haem prosthetic groups (each subunit over 5 aas)
-The iron II ions in the prosthetic groups allow catalase to interact with hydrogen peroxide to speed up breakdown.
-Hydrogen peroxide is a byproduct of metabolism and is toxic if left to accumulate, which catalase prevents.
-Extensive reactions between 4 subunits make it unusually stable.
-Highest known turnover enzymes.

55
Q

Fibrous proteins

A

-Fibrous proteins are formed from long, insoluable molecule due to the hugh proportion of amino acids with hydrophobic R-groups in their primary structure.
-They contain a limited number of amino acids, usually with the small R-groups, and the amino acid sequence is usually quite repetitive.
-Not folded like globular proteins.

56
Q

Keratin

A

-Fibrous proteins present in hair, skin, and nails.
-High proportion of the suphur containing amino acid cysteine, allowing it to form many strong disulphide bonds forming strong, inflexible, and insoluable materials.
-The degree of disulphide bonds determines its felxability.
-The unpleasant smell produced when skin and hair burned is due to the sulphur.
-Dimer of 2 subunits, each of which form an alpha helix.

57
Q

Elastin

A

-Fibrous proteins found in elastic fibres (along with small protein fibres)
-Present in the walls of blood vessels and the alveoli in the lungs, they give these structures the felxability to expand and recoil.
-Quaternary structure made from many stretchy molecules called tropoelastin.
-Many short coiled elastin molecules form cross links with each other.

58
Q

Collagen

A

-Fibrous protein that is a connective tissue found in skin, tendons, ligaments, and the nervous system (25% of all protein)
-All made up of three polypeptides wound together in a long and strong rope like structure.
-Trimer of 3 helical subunits forming a triple ‘superhelix’ each subunit is 1400 aas long.
-Repeating as a sequence of glycine, proline, and hydroxyproline.
-Glycine allows helix to coil tightly because of its small size.
Subunits held together by H bonds and join in parallels to form fibrils, which go on to create fibres.

59
Q

Test for starch

A
  1. Add 3 drops of solution to a well on a spotting tile.
  2. Add 3 drops of iodine.
  3. Look for colour change from brown/orange to blue black.
60
Q

Test for protein

A
  1. Add 3 drops of solution to a well on a spotting tile.
  2. Add 3 drops of biuret reagent.
  3. Look for colour change from blue to lilac.
61
Q

Test for reducing sugar

A
  1. Add 2cm of solution to test tube.
  2. Add 15 drops of benedicts reagent.
  3. Heat for 5 min at 80°C in a water bath.
  4. Look for green/orange/brick red precipitate.
62
Q

Test for non-reducing sugar

A
  1. Add 2 cm of solution to test tube.
  2. Add 15 drops of benedicts reagent.
  3. Heat for 5 mins at 80°C- observe no change from blue.
  4. Add 2 cm of solution to a new test tube.
  5. Add 4 drops 2M HCL
  6. Heat for 5 mins at 80°C in a water bath.
  7. Cool, then add 20 drops 0.4M NaOH.
  8. Add 15 drops of benedicts reagent.
  9. Heat for 5 mins at 80°C in a water bath.
  10. Look for green/orange/brick red precipitate.
63
Q

Test for glucose

A
  1. Dip reagent test strip into solution, and remove.
  2. Wait 10 seconds.
  3. Look for colour change from pink to purple/dark blue.
64
Q

Test for lipids

A
  1. Add 1cm liquid to a test tube.
  2. Add an equal amount of ethanol.
  3. Prepare 2nd test tube half full with water.
  4. Shake 1st tube vigorously with thumb on the top of the tube.
  5. Pour liquid into 2nd tube.
  6. Look for milky white emulsion.

Biology (4 decks)

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