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BIOLOGY A-LEVEL UNIT 1 > 1.1 Chemical elements are joined together to form biological compounds > Flashcards

1.1 Chemical elements are joined together to form biological compounds Flashcards

1
Q

What are the properties of a polar compound?

A
  • attract oppositely charged particles
  • play important roles in molecule structure
  • dissolve in water
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2
Q

What are the properties of a non-polar compound?

A
  • do not dissolve in water
  • dissolve in lipids
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3
Q

What 6 elements account for 99% of the human body?

A

Oxygen, Carbon, Hydrogen, Nitrogen, Phosphorus and Calcium

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4
Q

What is the function of OXYGEN, CARBON and HYDROGEN?

A

Carbon, hydrogen and oxygen are the main components of all organic molecules. Found in amino acids/nucleic acids.

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5
Q

What is the function of CALCIUM?

A

Strengthens teeth, bones and nerves in animals, and cell walls in plants.

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6
Q

What is the function of PHOSPHORUS?

A

Present in cell membranes/ATP/nucleic acids.

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7
Q

What 10 elements account for 1% of the human body?

A

Potassium, Sulfur, Chlorine, Sodium, Magnesium, Iron, Copper, Manganese, Zinc and Iodine

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8
Q

What is the function of IRON?

A

Oxygen transport and Enzyme function

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9
Q

What is the function of MAGNESIUM?

A

Enzyme function (and chlorophyll function in plants)

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10
Q

Water is a polar molecule, what does this mean?

A

it has no overall charge, but the hydrogen atoms have a partial positive charge and the oxygen atoms have a partial negative charge.

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11
Q

What is water often referred to as? and why?

A

Universal solvent as a large number of substances can dissolve in water.

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12
Q

What is the significance of ICE IS LESS DENSE THAN WATER?

A

This forms an insulating layer over the surface of aquatic habitats; ponds and other aquatic habitats do not freeze solid so animals can still move/swim.

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13
Q

What is the significance of WATER IS LIQUID AT MOST TEMPERATURES ON EARTH?

A

It can be used as a transport medium e.g., in blood in mammals, water transports dissolved ions up the xylem in plants.

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14
Q

What is the significance of WATER IS TRANSPARENT?

A

Aquatic plants utilize light to photosynthesise by passing through the cytoplasm of plant cells, which then reaches the chloroplasts.

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15
Q

What is the significance of WATER HAS HIGH SURFACE TENSION?

A

The surface of water can support the mass of many organisms and becomes a habitat for them e.g., pond skaters.

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16
Q

What is the significance of WATER HAS A HIGH SPECIFIC HEAT CAPACITY?

A

Cell and aquatic habitats maintain thermal stability, preventing rapid temperature changes, which is beneficial for cells as the cytoplasm temperature remains stable, preventing enzymes denaturting.

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17
Q

What is the significance of WATER HAS A HIGH LATENT HEAT OF VAPOURISATION?

A

Evaporation of water requires a lot of energy, causing organisms to cool down through sweating and preventing aquatic habitats from disappearing easily. Transpiration in plants also cools leaves.

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18
Q

What is the significance of WATER HAS STRONG COHESIVE AND ADHESIVE PROPERTIES?

A

Hydrogen bonds cause water molecules to stick together and adhere to non-polar or charged substances, allowing them to be pulled through plants during transpiration.

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19
Q

What are monosaccharides?

A

monomers – single sugars named according to the number of carbon atoms in the molecule.

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20
Q

What is the general name for a monosaccharide with 3 carbons?

A

Triose

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21
Q

What is the general name for a monosaccharide with 5 carbons?

A

Pentose

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22
Q

What is the general name for a monosaccharide with 6 carbons?

A

Hexose

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23
Q

What is the general formula of a monosaccharide?

A

CnH2nOn

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24
Q

What are the three structural isomers of Hexose?

A

Glucose, Galactose and Fructose

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25
Q

What are structural isomers?

A

Molecules with the same molecular formula but different arrangements of their atoms

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26
Q

What is the difference between alpha and beta isomers? and how do you remember this difference?

A

The position of the OH.
ABBA - Alpha Below, Beta Above

27
Q

What are disaccharides?

A

Sugars made from two monosaccharide units

28
Q

How are disaccharides formed and what is the name of this bond?

A

Condensation reaction forming a glycosidic bond

29
Q

How can a disaccharide bond be reversed?

A

Hydrolysis reaction

30
Q

Where does the bond form on a disaccharide?

A

Between the 1st and 4th carbon. It is called a 1-4 glycosidic bond

31
Q

What disaccharide is formed from two glucose?

A

Maltose

32
Q

What disaccharide is formed from glucose and galactose?

A

Lactose

33
Q

What disaccharide is formed from glucose and fructose?

A

Sucrose

34
Q

What are polysaccharides?

A

complex carbohydrates - large molecules, or polymers, consisting of chains of monosaccharides linked together by glycosidic bonds.

35
Q

What are starch and glycogen examples of and what is their function?

A

carbohydrates that are involved in the metabolism of an organism. They are both storage polysaccharides that can store and release glucose as necessary.

36
Q

What is starch a mixture of?

A

two different polysaccharides, amylose (which forms coiled molecules) and amylopectin (a branched molecule).

37
Q

What is the structure of glycogen?

A

similar to amylopectin but is even more branched due to glycosidic bonds forming between OH groups on C1 and C4 but also C1 and C6. Glycogen can form granules in cells and act as a carbohydrate/energy store

38
Q

What is cellulose structure?

A

a complex carbohydrate made of a polymer of β-glucose molecules. The β-1,4 glycosidic linkages result in the CH2 XOH groups being on opposite sides of the chain of adjacent glucose molecules rotated 180 degrees relative to each other.

39
Q

What do the hydrogen bonds do in cellulose?

A

Hydrogen bonds form between glucose molecules in different chains, these are called cross linkages which fold chains together.

40
Q

What is cellulose called and what does this mean?

A

A structural polysaccharide. It is hard to digest and has high tensile strength.

41
Q

Where is chitin found?

A

In the cell walls of fungi and the exoskeletons of insects

42
Q

What is the structure of Chitin?

A

It is not a true polysaccharide as it contains nitrogen. It is known as heteropolysaccharide.

43
Q

What are triglycerides?

A

molecules that form fats or oils depending on the size of the molecule. The more carbon atoms, the higher the melting point because the intermolecular forces are stronger and more energy is required to overcome them.

44
Q

What are triglycerides made of?

A

Glycerol combined with three fatty acids

45
Q

How are triglycerides formed and what is the bond called?

A

Condensation reaction forming ester bonds

46
Q

What can the fatty acids be represented by and what does this mean?

A

The letter R - a variable group containing between 4 and 24 carbon atoms

47
Q

What are the functions of triglycerides?

A
  • energy storage
  • thermal insulators
  • mechanical protection
  • waterproofing (fats are hydrophobic)
48
Q

What is a saturated fatty acid?

A

Only single bonds between carbon atoms. They contain the maximum number of hydrogen atoms.

49
Q

What is an unsaturated fatty acid?

A

One or more double bonds between carbon atoms. They do not contain the maximum number of hydrogen atoms.

50
Q

What do phospholipids contain?

A

Hydrophilic phosphorus head and two hydrophobic fatty acid tails

51
Q

What is the function of phospholipids?

A

They form the bilayer of cell membranes.

52
Q

What is the impact of POLYUNSATURATED FAT on human health?

A

An essential fat that we must get from food because our bodies cannot produce it. It lowers LDL (bad cholesterol).

53
Q

What is the impact of MONOUNSATURATED FAT on human health?

A

Considered a healthy fat: it lowers LDL (bad cholesterol) and maintains HDL (good cholesterol).

54
Q

What is the impact of SATURATED FAT on human health?

A

Increases total cholesterol and LDL (bad cholesterol). Best to consume in moderation.

55
Q

What is the impact of TRANS FAT on human health?

A

A by-product of processing healthier fats to give them a longer shelf life. Raises your LDL (bad cholesterol) and lowers your HDL (good cholesterol). Intake should be limited

56
Q

What are proteins?

A

polymers made up of about 20 naturally occurring subunits called amino acids.

57
Q

What does each amino acid have?

A

a central carbon atom with four different functional groups attached:
- the amino/-NH2 group, which has basic properties and can gain a H+ in acidic conditions to form an -NH3+group
- the carboxylic acid/-COOH group, which has acidic properties and can lose a H+ in alkaline conditions to form a -COO- group
- an atom of hydrogen, H
- a variable group, R.

58
Q

What does the R group do in amino acids?

A

Gives different chemical properties to each amino acid

59
Q

How do amino acids Polymerise and what bond do they form?

A

Condensation reaction forming peptide bonds between the carboxyl group of one amino acid and the amino group of another

60
Q

What does polymerisation form?

A

Dipeptides and polypeptides

61
Q

What is the first level of protein structure?

A

Primary structure, based on:
- what amino acids are present
- number of each type of amino acid
- the sequence of amino acids in the polypeptide chain

62
Q

What is the second level of protein structure?

A

Secondary structure:
- contains many polar groups (amino group and carboxylic acid group)
- hydrogen bonds form making the chain fold and twist to form new shape (e.g. alpha helix and beta pleated sheet)

63
Q

What is the third level of protein structure?

A

Tertiary structure:
- depends on properties of R groups
- further twisted and folded
- forms a globular 3D structure
an example of this is enzymes where the bonds form the active site

64
Q

What is the fourth level of protein structure?

A

Quaternary structure:
- combination of two or more polypeptide chains in tertiary form
- form large complex molecules such as haemoglobin
- Four genes are needed to code for haemoglobin

BIOLOGY A-LEVEL UNIT 1 (6 decks)

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