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2.1.2 biological molecules Flashcards

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1
Q

How does hydrogen bonding occur?

A

Each hydrogen share an electron with oxygen and because oxygen has a higher affinity for electrons it pulls the electrons closer to itself.

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2
Q

Why is water a polar molecule?

A

Oxygen has a partially negative charge meaning that hydrogen has a partially positive charge.
Di-polar because it two charged regions.

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3
Q

What are the properties of water?

A

-cohesion/adhesion
-universal solvent
-liquid at room temperature
-specific heat capacity
-latent heat of vaporisation
-latent heat of fusion
-density
-capillarity
-surface tension
-transparency

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4
Q

What is a hydrophilic substance?

A

Substances that can become part of water’s hydrogen-bonded structure and will dissolve in water.

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5
Q

what is a hydrophobic substance?

A

Substances that cannot become part of water’s hydrogen-bonded structure and will not dissolve in water.

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6
Q

What is a polymer?

A

A polymer is a repeat unit of monomers.

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7
Q

What is the general formula for a carbohydrate?

A

Cx(H2O)y

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8
Q

How is alpha-glucose different from beta-glucose?

A

In alpha-glucose the -OH group is below the carbon one as opposed to beta-glucose where it is above.

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9
Q

How is deoxyribose different to ribose?

A

In deoxyribose carbon 2 has two H atoms attached to it as opposed to ribose where there is one H atom and an -OH group.

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10
Q

What are the three glucose equations?

A

glucose + glucose = maltose
glucose + fructose = sucrose
glucose + galactose= lactose

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11
Q

What are the properties of Amylose?

A
  • 1-4 glycosidic bonds
    -unbranched chains
    -helical structure
    -only two points to get glucose from
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12
Q

What are the properties of Amylopectin?

A
  • 1-4 + 1-6 glycosidic bonds
    -highly branched chains
  • multiple points to get glucose from
    -70-80% present in starch
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13
Q

What are the differences between starch and glycogen?

A

Glycogen is less dense than starch and more soluble, it is broken down more rapidly.
Glycogen has points every 12 subunits whereas every 25 subunits for starch.

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14
Q

What are the features of cellulose?

A

-very strong and prevents cells from bursting when taking excess water in.
-long chains of beta glucose molecules joined by beta 1-4 glycosidic bonds.
-rope-like microfibrils, layered.
-hydrogen bonds form between layers providing tensile strength.

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15
Q

Why is it important for animals to store carbohydrates as glycogen rather than starch?

A

Animals have a much higher metabolic demand for energy than plants so it is essential for animals to have glycogen so that they can assess more energy quicker.

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16
Q

What are triglycerides made up of?

A

A glycerol backbone (C3H8O3) and three fatty acid chains (CH3(CH3)nCOOH).

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17
Q

How are the components of a triglyceride bonded?

A

The three fatty acids are bonded to the glycerol backbone through ester bonds with the -OH group on both the backbone and the fatty acids.

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18
Q

What are unsaturated fatty acids?

A

Fatty acids containing one or more double bonds between carbon atoms.
This causes a kink causing them to be weaker.
They cannot pack together and are a liquid at room temperature.

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19
Q

What is the structure of a phospholipid?

A

The hydrophilic head is comprised of glycerol (backbone) with a phosphate group (PO4) attached to the top carbon.
The hydrophobic tail is made up of two fatty acid chains bonded to the second and third carbon of glycerol.

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20
Q

What are the features of triglycerides?

A

-large amounts of chemical energy
-insoluble and doesn’t affect water potential inside cell.

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21
Q

What is the test for lipids?

A

The emulsion test:
-add ethanol and shake.
-add water.
-milky white emulsion will form if results are positive.

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22
Q

What the features of triglycerides?

A

-a key role in membrane formation by separating aqueous environments which allows membrane to act like a barrier.

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23
Q

What are the features of cholesterol?

A

-adds stability to cell-surface membrane
-regulates fluidity of cell-surface membrane also

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24
Q

What are the roles of lipids?

A

-membrane formation
-hormone production
-electrical insulation (impulse transmission)
-waterproofing (feathers and leaves)
-long term energy storage
-thermal insulation
-‘cushioning’ to protect organs
-buoyancy for aquatic animals

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25
Q

What are the roles of proteins?

A

-structural
-catalytic (enzymes)
-signalling (hormones, receptors)
-immunological (antibodies)

26
Q

What bonds are broken during the breakdown of triglycerides?

A

Ester bonds between fatty acids and glycerol.

27
Q

What is the general structure of an amino acid?

A

-Amine group (NH2)
-R group (specific amino acid group)
-Carboxyl group (COOH)

28
Q

What happens during the synthesis of peptides?

A

A peptide bond is formed between the amino acids, the hydroxyl group in carboxylic acid group reacts with a hydrogen in the amine group.

29
Q

What is the primary structure of a protein?

A

Sequence in which the amino acids are joined.

30
Q

What bonds are involved in the primary protein structure?

A

Only peptide bonds.

31
Q

What is the secondary structure of a protein?

A

Oxygen, hydrogen, and nitrogen atoms interact.
Hydrogen bonds may from in the chain, which can cause localised 3D sections: alpha-helix or beta-pleated sheet.

32
Q

How is a beta pleated sheet formed?

A

When polypeptide chains lie parallel to one another joined by hydrogen bonds.

33
Q

What is the tertiary structure of a protein?

A

Folding of a protein into final shape.

34
Q

What interactions are there between R-groups in the tertiary structure of a protein?

A

-Hydrophobic and hydrophilic interactions.
-Hydrogen bonds.
-Ionic bonds.
-Disulphide bonds (only form between R-groups containing sulphur atoms).

35
Q

What is the quaternary structure of a protein?

A

Two or more individual proteins (subunits).
Interactions are between different protein molecules rather than one molecule.

36
Q

What are globular proteins?

A

Compact, water soluble proteins.

37
Q

How do globular proteins form?

A

They form when proteins fold into their tertiary structure in a way in which the hydrophobic R-groups are kept away from the aqueous environment.

38
Q

What is Insulin as an example of a globular protein?

A

A hormone involved in the regulation of blood glucose concentration=>hormones are transported in blood so need to be soluble.

39
Q

What are conjugated proteins?

A

Globular proteins that contain non-protein component, prosthetic group.

40
Q

What is haemoglobin as an example of a conjugated protein?

A

Oxygen carrying pigment found in red blood cells.
Quaternary protein made of four polypeptides, two beta and two alpha.
Each subunit containing a prosthetic haem group-iron 2 ions are able to combine with oxygen molecule.

41
Q

What is catalase as an example of a conjugated protein?

A

An enzyme.
Quaternary protein containing four haem prosthetic groups.
Presence of iron 2 ions in prosthetic groups allow catalase to interact with hydrogen peroxide and speed up its breakdown.

42
Q

What are fibrous proteins formed from?

A

Formed from long, insoluble molecules-due to high proportion of amino acids with hydrophobic R-groups in their primary structure.

43
Q

What is keratin as an example of a fibrous protein?

A

A group of fibrous proteins present in hair, skin, and nails.
Large proportion of sulphur-containing amino acid, cysteine=>strong disulphide bonds forming strong, inflexible, and insoluble materials.

44
Q

What is elastin as an example of a fibrous protein?

A

Fibrous protein found in elastic fibres.
Elastic fibres are present in walls of blood vessels and alveoli=>give structure needed to expand and return to normal size.
Quaternary protein made from stretchy molecules, tropoelastin.

45
Q

What is collagen as an example of a fibrous protein?

A

Connective tissue found in skin, tendons, ligaments, and NS.
Made up of three polypeptides wound together in a long and strong rope-like structure.

46
Q

What are the key inorganic cations involved in biological processes?

A

-Ca^2+ (calcium ions)
-Na^+ (sodium ions)
-K^+ (potassium ions)
-H^+ (hydrogen ions)
-NH4^- (ammonium ions)

47
Q

What are the key inorganic anions involved in biological processes?

A

-NO3^- (nitrate)
-HCO3^- (hydrogencarbonate)
-Cl^- (chloride)
-PO4^3- (phosphate)
-OH^- (hydroxide)

48
Q

What does Benedict’s reagent test for?

A

Non-reducing and reducing sugars.

49
Q

How is a Benedict’s test carried out?

A

1) sample placed in a test tube.
2) add equal volume of Benedict’s reagent.
3) add to a water bath for five minutes.

50
Q

What are the results from a Benedict’s test?

A

Reducing sugars-
Blue -> brick-red
Non-reducing sugars-
Blue-Green-Yellow-Orange-Red
(depends on the concentration of reducing sugars, none to high).

51
Q

What does the Iodine test, test for?

A

Starch.

52
Q

How is an Iodine test carried out?

A

1) add few drops of iodine dissolved in potassium iodine solution to sample.

53
Q

What are the results for the Iodine test?

A

yellow/brown -> purple/black if present.

54
Q

What do reagent strips test for?

A

Reducing sugars (can be compared using a colour chart).

55
Q

What is a colorimeter?

A

Piece of equipment used to quantitatively measure the absorbance, or transmission, of light by a coloured solution.
The more concentrated it is the more light it will absorb.

56
Q

What are biosensors?

A

Biosensors use biological components to determine presence and concentration of molecules.

57
Q

What does the Biuret test, test for?

A

Proteins.

58
Q

How is a Biuret test carried out?

A

1) sample added to test tube with equal amount of sodium hydroxide solution
2) biuret solution added few drops at a time until turned blue
3) left to stand for five minutes

59
Q

What are the results for the Biuret test?

A

Blue -> lilac if present.

60
Q

What is TLC?

A

Thin layer chromatography:
Technique used to separate the individual components of a mixture.

61
Q

How is Rf value calculated?

A

Distance travelled by component DIVIDED BY distance travelled by solvent.

62
Q

What chemical elements make up: lipids, proteins, carbohydrates, and nucleic acids?

A

Lipids: C, H, O
Proteins: C, H, O, N, S
Carbohydrates: C, H, O
Nucleic acids: C, H, O, N, P

Biology (25 decks)

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