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Biology Unit 1 ☁️ > 1.1 Biological Compounds > Flashcards

1.1 Biological Compounds Flashcards

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1
Q

What key elements are present as inorganic ions (minerals) in living organisms? (M PINC)

A

magnesium ions (Mg²⁺)
iron ions (Fe²⁺)
calcium ions (Ca²⁺)
phosphate ions (PO₄³⁻)

nitrate ions are also present

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2
Q

where do inorganic ions occur? and what is an inorganic ion?

A

in the cytoplasm and body fluids of organisms for growth and development.

inorganic - a molecule or ion that has no more than one carbon atom.

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3
Q

What is the role of magnesium ions (Mg²⁺) in plants?

A

constituent of chlorophyll and therefore essential for photosynthesis

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4
Q

what are phosphate ions (PO₄³⁻) required to make? and what is its biological role?

A

used for making nucleotides, including ATP, DNA and RNA.

A constituent of phospholipids found in biological membranes and it hardens bones.

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5
Q

What is the role of iron ions (Fe²⁺) in animals?

A

They are a component of haemoglobin (transports oxygen carrying molecule to red blood cells)

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6
Q

what are nitrate ions required for?

A

to make nucleotides, including ATP, DNA and RNA.
It’s needed for amino acid formation

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7
Q

What is the biological role of calcium ions (Ca²⁻)?

A

hardens bones and teeth (not strengthen) in animals and is a component of plant cell walls.

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8
Q

how is water a polar molecule?

A

due to its uneven distribution of charge within the molecule.

(oxygen atoms attracts stronger electrons than hydrogen atoms. The unequal sharing of electrons means a negative charge is given to water when it’s near oxygen but positive when near hydrogen)

when two water molecules are in close contact the opposing charges attract each other forming a hydrogen bond. Individually hydrogen bonds are weak, but many hydrogen bonds form a lattice like structure which is much stronger.

This attraction between water molecules is called cohesion

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9
Q

What is a metabolite?

A

molecule formed or used in metabolic reactions

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10
Q

describe the role of water as a metabolite.

A

water is a reactant in photosynthesis and hydrolysis reactions.
water is a product in aerobic respiration and condensation reactions.

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11
Q

Why is water’s high specific heat capacity important for organisms?

A

water acts as a temperature buffer, enabling endothermic to resist fluctuations in temperature to maintain optimum enzyme activity.

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12
Q

Why is water’s high latent heat of vaporisation important for organisms?

A

when water evaporates it has a cooling effect so there’s little water loss.
it’s important for homeostasis as organisms can lose heat through sweating or panting.

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13
Q

Why is water an important solvent for organisms?

A

it’s polar universal solvent (ability to dissolve in variety of substances) which enables chemical reactions to take place within cells, transport materials in plasma and removal of metabolic waste.

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14
Q

Why does water have a high surface tension?

A

due to the ordered arrangement and cohesion of molecules at the surface of the water.
In a pond, the cohesion between water molecules supports organisms such as pond skaters, allowing them to walk on water.

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15
Q

Why is high surface tension of water important for organisms?

A

enables transport of water and nutrients through plant stems and small blood vessels in the body.

It allows small insects to ‘walk on water’ due to the supporting cohesion of the column of water

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16
Q

what is a monosaccharide and its general formula?

A

a monosaccharide is a simple sugar
general formula is Cn(H₂O)n

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17
Q

give some examples of monosaccharides.

A

Glyceraldehyde
Ribose
Deoxyribose
Fructose
Galactose

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18
Q

What is the name of the bond formed when two monosaccharides react?

A

Glycosidic bond

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19
Q

What is a disaccharide and its general formula?

A

molecule formed by the condensation of two monosaccharides, forming a glycosidic bond.
formulated C₁₂H₂₂O₁₁

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20
Q

Give some examples of disaccharides and their monosaccharide components.

A

Sucrose ( glucose and fructose)
Maltose (alpha glucose and alpha glucose)
Lactose (glucose and galactose)

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21
Q

What is a polysaccharide?

A

a polymer of monosaccharides, formed by many condensation reactions.

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22
Q

give 4 examples of polysaccharides.

A

starch
glycogen
cellulose
chitin

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23
Q

What is the function of starch?

A

energy storage in plants

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24
Q

Describe the structure of starch.

A

polymer of alpha glucose monomers
two forms: amylose and amylopectin
Amylose: unbranched chain joined by 1,4 glycosidic bonds
Amylopectin: branched chain joined by 1,4 and 1,6 glycosidic bonds

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25
Q

What is the function of glycogen?

A

energy storage in animals

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26
Q

How does the structure of glycogen relate to its function?

A

it’s highly branched enabling rapid hydrolysis of glucose molecules.

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27
Q

Describe the structure of cellulose.

A

Alternate glucose molecules rotated 180 degrees allowing hydrogen bonds between parallel chains, forming myofibrils.

consists of many beta glucose molecules joined by 1 beta and 4 glycosidic bonds.

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28
Q

Describe the function of cellulose.

A

linear polysaccharide that is the main component of the cell wall in plants so it provides structural support

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29
Q

Describe the structure of Chitin.

A

consists of many beta glucose molecules ( with amino acid side chains) joined by 1 beta and 4 glycosidic bonds.

Alternate glucose molecules are rotated 180 degrees allowing hydrogen bonds between parallel chains, forming myofibrils.

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30
Q

Describe the function of chitin.

A

linear polysaccharide found in the exoskeletons of insects as well as fungal cell walls. This is due to it being lightweight but strong.

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31
Q

Explain how triglyceride is formed.

A

one molecule of glycerol forms ester bonds with 3 fatty acids via condensation reactions.

32
Q

Relate the structure of triglycerides to their functions.

A

high energy to mass ratio - energy storage in plant and animal cells
insoluble hydrocarbon chain - no effect on water potential of cells, used for waterproofing
slow conductor of heat - thermal insulation
less dense than water - buoyancy of aquatic animals

33
Q

What is a phospholipid?

A

a type of lipid formed by the condensation of one molecule of glycerol, two molecules of fatty acid and a phosphate group.

34
Q

relate the structure of phospholipids to their functions.

A

Glycerol backbone attached to 2 hydrophobic fatty acid tails and 1 hydrophilic polar phosphate head.

forms phospholipid bilayer in water - component of cell membranes

tails splay outwards - waterproofing for example, the skin.

35
Q

what is the difference between saturated and unsaturated fats?

A

saturated fats have no c = c bonds, and are solid at room temperature due to strong intermolecular forces

unsaturated fats have one or more c=c bonds, and are liquid at room temperature due to weak intermolecular forces.

36
Q

what are the implications of saturated and unsaturated fat on human health?

A

saturated lipids don’t contain C=C bonds. Too much saturated fats can increase the cholesterol level in blood thus increasing the risk of coronary heart disease.

unsaturated lipids contain C=C bonds, melting at lower temperature than saturated. Unsaturated fats are healthy as they provide essential fatty acids.

37
Q

what is the difference between monounsaturated and polyunsaturated fatty acids?

A

Monounsaturated fatty acids contain one c=c bond

polyunsaturated fatty acids contain more than one c=c bond

38
Q

what is meant by a low density lipoprotein? (LDL)

A

combination of triglycerides from saturated fats and protein.

blocks receptor sites, reducing cholesterol absorption.

known as a ‘bad’ lipoprotein.

39
Q

how does low density lipoprotein (LDL) contribute to the risk of cardiovascular disease?

A

The high blood cholesterol level caused by low density lipoproteins leads to formation of atherosclerosis plaques.

40
Q

describe the general structure of an amino acid.

A

amine group (NH₂)
variable side chain (R)
carboxyl group (COOH)
H atom

41
Q

how are polypeptides formed?

A

many amino acid monomers join together in condensation reactions forming peptide bonds (CONH)

42
Q

what is a dipeptide?

A

contains two amino acids

43
Q

how is a dipeptide different to a polypeptide?

A

polypeptides contain three or more amino acids unlike dipeptides which contain two.

44
Q

what is the primary structure of a protein?

A

The individual sequence of amino acids in a protein.

45
Q

describe the secondary structure of a protein.

A

The local interactions of the amino acids in the polypeptide chain resulting in alpha helix or beta pleated sheets. The shape is determined by the type of bonding presence such as hydrogen bonds, ionic bonds and disulphide bridges.

46
Q

describe the tertiary structure of a protein.

A

The folding of a protein to make a three dimensional structure. Held in place by various interactions and bonds such as disulphide bonds, ionic bonds, hydrogen bonds and hydrophobic interactions.

47
Q

Describe the quarternary structure of a protein.

A

interactions of more than one polypeptide chain.

may involve addition of prosthetic groups e.g. metal ions or phosphate groups

48
Q

Describe how the structure of a fibrous protein relates to their function.

A

long peptide chains (hydrogen and covalent bonds) folded in parallel.

little tertiary/quaternary structure aside from cross linkages for strength

makes them insoluble and good for structural roles. (E.g. collagen forms structure of bones, cartilage and connective tissue and is a main component of tendons which connects muscles to bones)

49
Q

describe how the structure of globular protein relates to their function.

A

Spherical, compact, highly folded with complex tertiary/quaternary structures.
Hydrophilic R groups face outwards and hydrophobic R groups face inwards so it’s water soluble.
Metabolic roles e.g. enzymes

50
Q

what type of protein is haemoglobin?

A

water soluble globular protein

51
Q

what does haemoglobin consist of structurally?

A

two beta polypeptide chains and a haem group

52
Q

what is the function of haemoglobin?

A

it carries oxygen in the blood as oxygen can bind to haem (iron) group and oxygen is released when required.

53
Q

what is the difference between a reducing and non-reducing sugar?

A

reducing sugar has a free aldehyde or ketone functional group so can act as a reducing agent.

A non-reducing sugar does not have a free aldehyde or ketone functional group so it cannot act as a reducing agent.

54
Q

describe the Benedict test for reducing sugars.

A

add an equal volume of the sample being tested and Benedict reagent

Heat the mixture in an electrical water bath at 100°C for five minutes

observe the colour of the precipitate formed

55
Q

describe the positive result for reducing sugars

A

colour change from
green to
yellow to
orange to
brown to
brick red
depending on the quantity of reducing sugar present.

56
Q

describe the Benedict test for non-reducing sugars.

A

it must have a negative test for reducing sugar
Hydrolyse non-reducing sugars with an equal volume of dilute HCL
Heat in a boiling water bath for 5 min
Add sodium bicarbonate (NAHCO3) to neutralise the acid.
Re-test the resulting solution with Benedict’s reagent
observe the colour of the precipitate formed.

57
Q

describe the positive result for non-reducing sugars.

A

colour change from
green to
yellow to
orange to
brown to
brick red
depending on the quantity of non-reducing sugar present.

58
Q

name the food test used to identify proteins.

A

Biuret test

59
Q

Describe the biuret test.

A

add an equal volume of the sample to be tested and sodium hydroxide (NaOH)
A few drops of dilute copper (II) sulphate
Mix gently and record any observations

60
Q

describe the positive result of a biuret test

A

colour change from pale blue to purple

61
Q

describe the iodine potassium iodide test for starch and the positive result of this.

A

add iodine potassium iodide solution

colour change from orange to blue black in the presence of starch

62
Q

describe the emulsion test for fats and oils.

A

Add ethanol to sample and shake
Allow mixture to settle
Add an equal volume of water
Record any observations

63
Q

describe the positive result of an emulsion test.

A

White, cloudy emulsion forms.

64
Q

What is Biuret’s test for?

A

Protein.

65
Q

Outline the procedure to a Biuret test.

A
  1. Add sodium hydroxide solution.
  2. Add copper (Il) sulphate solution.
  3. If the colour changes from blue to purple, protein is present.
66
Q

What does iodine test for?

A

Starch

67
Q

What is the colour change for a positive iodine test?

A

Brown to blue-black.

68
Q

Outline the procedure to the emulsion test.

A
  1. Add ethanol to a test tube, add sample and shake to dissolve any lipids.
  2. Add water and shake gently.
  3. A white emulsion forms if lipid is present.
69
Q

What does Benedict’s reagent test for?

A

Reducing sugars.

70
Q

Outline the test for reducing sugars.

A
  1. Add an equal volume or excess
    Benedict’s reagent to a sample and boil.
  2. If positive, colour changes from blue to red, with a brick-red precipitate.
71
Q

Outline the test procedure for non-reducing sugars.

A
  1. Add dilute HCl and boil.
  2. Neutralise with sodium hydrogen carbonate.
  3. Add Benedict’s reagent and boil.
  4. If positive, colour changes from blue to red, with brick-red precipitate.
72
Q

What is a method to test for glucose specifically?

A

Dip the pad of a glucose test strip into the sample. Colour change will occur if glucose is present.

Concentration can be found by comparing colour to a colour standard chart.

73
Q

What is the difference between a micronutrient and a macronutrient?

A

micronutrient - minerals needed in a minute trace concentrations e.g. copper and zinc.

Macronutrient - are needed in small concentrations e.g. magnesium and iron

74
Q

what is an organic molecule?

A

high proportion of carbon and hydrogen atoms

75
Q

what is a dipole?

A

a polar molecule which has a positive and negative charge, separated by a very small distance.

76
Q

what is a hydrogen bond?

A

weak attractive force

between a hydrogen atom with a partial positive charge and

an atom with a partial negative charge usually oxygen or nitrogen

Biology Unit 1 ☁️ (7 decks)

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