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A-Level Biology - Two > 3.1-7 Biological molecules > Flashcards

3.1-7 Biological molecules Flashcards

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1
Q

How is water a polar molecule?

A
  • due to it’s uneven distribution of charge within the molecule
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2
Q

What is the structure of water in terms of charges?

A
  • the hydrogen atoms are more positive than the oxygen atoms causing one end of the molecule to be more positive than the other
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3
Q

How is water a metabolite?

A
  • involved in the metabolic reactions such as condensation and hydrolysis which are used in the forming and breaking of chemical bonds
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4
Q

What does water being a solvent assist?

A
  • metabolic reactions occur
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5
Q

How is water having a high heat specific capacity?

A
  • minimises temperature fluctuations due to there being a lot of energy required to warm up water
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6
Q

How is a high heat specific capacity used in real-life applications?

A
  • in living things
  • acts as a buffer
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7
Q

What is the use of water having a relatively large latent heat of vaporisation?

A
  • meaning evaporation of water provides a cooling effect with little water loss
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8
Q

What does water having strong cohesion enable?

A
  • effective transport of water in tube-like transport cells as the strong cohesion supports columns of water
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9
Q

What is the result of water having strong cohesion?

A
  • the surface tension at the water-air boundary is high
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10
Q

What temperature does the water have to be for maximum density of water?

A
  • 4 degrees
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11
Q

Water is compressible, why is this beneficial?

A
  • provides good support
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12
Q

What does a low temperature for maximum density of water help?

A
  • this means that ice is less dense than water and floats on top of it creating an insulating layer
  • increases the chance of survival for organisms in large bodies of water as it prevents them from freezing
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13
Q

What are monomers?

A
  • small units which are the components of larger molecules
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14
Q

Examples of monomers are …

A
  • monosaccharides (such as glucose)
  • amino acids
  • nucleotides
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15
Q

What are polymers?

A
  • molecules made from monomers joined together
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16
Q

What is a condensation reaction?

A
  • a reaction which joins monomers by chemical bonds and it involves the elimination of a water molecules
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17
Q

What is a hydrolysis reaction?

A
  • the reverse reaction of a condensation reaction
  • it’s when water is added to break a chemical bond between the two molecules
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18
Q

What are the 8 properties of water?

A
  • polar molecule
  • metabolite
  • solvent
  • high heat specific capacity
  • relatively large latent heat of vaporisation
  • strong cohesion
  • maximum density of water is 4 degrees
  • incompressible
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19
Q

What is a carbohydrate?

A
  • molecules which consist only of carbon, hydrogen and oxygen and they are long chains of sugar units called saccharides
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20
Q

What are the three types of saccharides?

A
  • monosaccharides
  • disaccharides
  • polysaccharides
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21
Q

What do monosaccharides do?

A
  • can join together to form disaccharides and polysaccharides by glycosidic bonds which are formed in a condensation reaction
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22
Q

Example of a monosaccharide.

A
  • glucose is a monosaccharide containing six carbon atoms in each molecule
  • it is the main substrate for respiration (therefore it is of great importance)
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23
Q

The monosaccharide glucose, has how many isomers?

A
  • two isomers
  • alpha and beta glucose
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24
Q

Examples of disaccharides.

A
  • maltose = two glucose molecules
  • sucrose = glucose + fructose
  • galactose = lactose + glucose
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25
Q

How are the elements that make up disaccharides bonded together by?

A
  • condensation reactions
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26
Q

What are polysaccharides formed from?

A
  • from many glucose units joined together
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27
Q

Examples of polysaccharides.

A
  • glycogen and starch which are both formed by the condensation of alpha glucose
  • cellulose formed by the condensation of beta glucose
28
Q

What is glycogen?

A
  • the main energy storage molecule in animals and it’s formed from many molecules of alpha glucose joined together by 1,4 and 1,6 glycosidic bonds
29
Q

What are the features of glycogen?

A
  • has a large number of side branches meaning that glucose & energy can be released quickly
  • it is a relatively large but compact molecule which maximises the amount of energy it can store
30
Q

What does starch do?

A
  • stores energy in plants and it is a mixture of two polysaccharides called amylose and amylopectin
31
Q

What is amylose?

A
  • is an unbranched chain of glucose molecules joined by 1,4 glycosidic bonds
  • as a result of that amylose is coiled and therefore it is a very compact molecules meaning it can store a lot of energy
32
Q

What is amylopectin?

A
  • is branched and is made up of glucose molecules joined by 1,4 and 1,6 glycosidic bonds
  • due to the presence of many side branches it is rapidly digested by enzymes therefore energy
33
Q

What is cellulose?

A
  • a component of cells wells in plants
  • it is composed of long, unbranched chains of beta glucose which are joined by glycosidic bonds
34
Q

What are microfibrils?

A
  • strong threads which are made of long cellulose chains joined together by hydrogen bonds
  • they provide structural support in plant cells
35
Q

What are lipids?

A
  • biological molecules which are only soluble in organic solvents such as alcohols
36
Q

What are the two types of lipid?

A
  • unsaturated
  • saturated
37
Q

What are saturated lipids and where are they found?

A
  • in animal fats
  • saturated lipids don’t contain any carbon-carbon double bonds
38
Q

What are unsaturated lipids and where are they found?

A
  • in plants
  • unsaturated lipids contain carbon-carbon double bonds and melt at lower temperatures than saturated fats
39
Q

What happens if there is a greater number of unsaturated bonds?

A
  • weaker intermolecular bonds resulting in a lower melting point
40
Q

What is the result in saturated/unsaturated fats due to weaker intermolecular bonds?

A
  • saturated lipids which don’t contain any double bonds are solid at liquid temperature
  • unsaturated lipids are liquid at room temperature
41
Q

What are triglycerides?

A
  • are lipids made of one molecule of glycerol and three fatty acids joined by ester bonds formed in condensation reactions
42
Q

How do different types of fatty acid differentiate from one another?

A
  • chain length
  • presence and number of double bonds
  • some contain a mixture of fatty acids
43
Q

When are triglycerides used?

A
  • as energy reserves in plant and animal cells
44
Q

What is contained within a phospholipid?

A
  • one of the fatty acids of a triglyceride is substituted by a phosphate containing group
45
Q

What is the structures of a phospholipidin terms of solubility?

A
  • the phosphate head is hydrophilic and the tail is hydrophobic
  • as a result phospholipids form micelles when they are in contact with water as heads are on the outside as they are attracted to water and tails are on the inside as they move away from water
46
Q

When do inorganic ions occur?

A
  • in solution in the cytoplasm and body fluid of organisms, some in high concentrations and other in very low concentrations
47
Q

What are the four essential ions?

A
  • hydrogen ions
  • iron ions
  • sodium ions
  • phosphate ions
48
Q

What do hydrogen ions do as inorganic ions?

A
  • determines the pH of substances such as the blood
  • the higher the concentration of hydrogen ions the lower the pH
49
Q

What do iron ions do as inorganic ions?

A
  • a component of haemoglobin which is an oxygen carrying molecule in red blood cells
50
Q

What do sodium ions do as inorganic ions?

A
  • involved in the co-transport of glucose and amino acids
51
Q

What do phosphate ions do as inorganic ions?

A
  • are a component of ATP and DNA
52
Q

What are amino acids in terms of proteins?

A
  • amino acids are the monomers from which proteins are made
53
Q

What do amino acids contain?

A
  • NH2
  • carboxylic acid group
  • a variable R group which is a carbon-containing chain
54
Q

How many different types of amino acid are there?

A
  • there are 20 different amino acids with different R groups
55
Q

How are amino acids joined together?

A
  • peptide bonds
56
Q

How many amino acids does a dipeptide contain?

A
  • two
57
Q

How many amino acids does a polypeptide contain?

A
  • three or more
58
Q

How is the structure of proteins determined?

A
  • by the order and number of amino acids in a protein
59
Q

What is the secondary structure of proteins?

A
  • is the shape that the chain of amino acids takes
  • either alpha helix or beta pleated shape sheet
  • shape is determined by the hydrogen bonding
60
Q

What is the tertiary structure of proteins?

A
  • it is the 3D shape of a protein
  • it can be globular or fibrous
61
Q

What are globular proteins?

A
  • have a spherical shape often caused by the tightly folded polypeptide chains
  • such as enzymes are compact
62
Q

What are fibrous proteins?

A
  • such as keratin are long and therefore can be used to form long fibres
63
Q

What is an example of a fibrous protein?

A
  • collagen that has great strength due to the presence of both hydrogen and covalent bonds in the structure
  • collagen fibres wrap around each other and form fibrils which form strong collagen fibres
64
Q

What does collagen form?

A
  • bones
  • cartilage
  • connective tissue
  • is the main component of tendons which connect muscle to bone
65
Q

What is haemoglobin an example of of?

A
  • is a water soluble globular protein which consists of two alpha and two beta polypeptide chains each containing a haem group
  • it carries oxygen in the blood as oxygen can bind to the haem (Fe 2+) group and oxygen is then released when required

A-Level Biology - Two (14 decks)

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