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Flans AS Biology > Biological Molecules > Flashcards

Biological Molecules Flashcards

1
Q

What are the 4 key biomolecules?

A

Carbohydrates, proteins, lipids and nucleic acids

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2
Q

What are the main chemical elements found in biological molecules?

A

Carbon, hydrogen, oxygen and nitrogen (some contain sulfur and phosphorous)

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3
Q

Define monomer

A

Single small molecules

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4
Q

Define polymer

A

A large molecule made up of many similar monomers covalently bonded together

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5
Q

What is the name given to the reaction where a large molecule is formed and a water molecule is released?

A

Condensation reaction

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6
Q

What is the name given to the reaction where a large molecule is broken into smaller molecule is used?

A

Hydrolysis reaction

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7
Q

Name all 9 properties of water

A 
1 - Metabolic role
2 - High latent heat vaporization
3 - Liquid with relatively high boiling point
4 - Low density of ice
5 - High specific heat capacity (thermostability) 
6 - Cohesion/Adhesion 
7 - Solvent
8 - Transport medium
9 - Transparency
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8
Q

What elements do carbohydrates consist of?

A

Carbon, hydrogen and oxygen

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9
Q

What is a monosaccharide?

A

A simple sugar

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10
Q

Give an example of a monosaccharide

A

Glucose, fructose, ribose

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11
Q

What are the 3 similar properties of monosaccharides?

A

1 - Water soluble
2 - Sweet tasting
3 - Form crystals

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12
Q

What is the general formula of monosaccharides?

A

(CH20)n

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13
Q

What defines a glucose molecule as alpha glucose?

A

The OH group on carbon 1 is at the bottom

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14
Q

What defines a glucose molecule as beta glucose

A

The OH group on carbon 1 is at the top

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15
Q

What are alpha and beta glucose?

A

They are isomers of each other

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16
Q

Define isomer

A

Molecules with the same chemical formula but a different structure

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17
Q

What is a disaccharide?

A

Two monosaccharide sugars joined together by a condensation reaction

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18
Q

What is the covalent bond known as in carbohydrates?

A

Glycosidic bond

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19
Q

Describe the reaction forming maltose

A

Glucose + glucose —> maltose

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20
Q

Describe the reaction forming sucrose

A

Glucose + fructose —> sucrose

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21
Q

Describe the reaction forming lactose

A

Glucose + galactose —> lactose

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22
Q

What is a polysaccharide?

A

A molecule of many monosaccharides joined by glycosidic bonds

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23
Q

What are the 6 main characteristics of starch?

A

1 - Large polysaccharide
2 - Insoluble in water (does not affect water potential)
3 - Coiled and compact
4 - The glycosidic bonds can be hydrolysed to form alpha glucose monomers which can easily be transported and used in respiration
5 - Amylose alpha glucose monomers are joined by 1,4 glycosidic bonds
6 - Amylopectin is a branched polymer with 1,4 and 1,6 glycosidic bonds

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24
Q

What are the 4 main characteristics of glycogen?

A

1 - Large polysaccharide with 1,4 and 1,6 glycosidic bonds
2 - Insoluble ( does not affect water potential)
3 - Compact
4 - Highly branched so glycosidic bonds can be RAPIDLY hydrolysed

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25
Q

What are the 4 main characteristics of cellulose?

A

1 - Made of beta glucose monomers with 1,4 glycosidic bonds
2 - Each monomer is rotated 180 degrees relative to the next resulting in alternate glycosidic bonds
3 - Many parallel chains of cellulose forms bundles of hydrogen bonds called microfibrils which are very strong
4 - Cellulose cannot be digested by mammels becuase they do not have the appropriate enzyme (cellulase)

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26
Q

What is the reagent used in the reducing sugar test?

A

Benedict’s solution

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27
Q

Describe the method used in the reducing sugar test

A

-Add Benedict’s to solution and heat in water bath at 80 degrees

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28
Q

What is the colour change for a positive reducing sugar test?

A

From blue to a brick red precipitate

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29
Q

What are the reagents used in the non-reducing sugar test?

A

Acid and Benedict’s

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30
Q

Describe the method for the non-reducing sugar test

A
  • Add HCl to the solution
  • Heat at 80 degrees in water bath for 3 mins
  • Neutralise with NaOH
  • Add Benedict’s solution
  • Heat in water bath at 80 degrees for 5 mins
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31
Q

What is the colour change for a positive result non-reducing sugar test?

A

From blue to a brick red precipitate

32
Q

What is the reagent in the starch test?

A

Iodine

33
Q

Describe the method for the starch test

A

Add iodine to the solution and shake gently

34
Q

What colour change will there be in a positive starch test?

A

From orange to inky blue/black

35
Q

Are lipids polymers?

A

No

36
Q

Name two groups of lipids

A

Triglycerides and phospholipids

37
Q

What elements do lipids contain?

A

Carbon, hydrogen, and oxygen

38
Q

What is different about the oxygen in lipids and in carbohydrates

A

There is a very small proportion of oxygen in lipids compared to carbohydrates

39
Q

What is the covalent bond called in lipids?

A

Ester bond

40
Q

What are the components to a triglyceride molecule?

A

A glycerol molecules ester bonded to 3 fatty acid chains

41
Q

What are the 4 functions of a triglyceride?

A

1 - Source of energy
2 - Act as insulators
3 - Useful for waterproofing as they are large non polar molecules which are insoluble in water
4 - Protection fat around delicate organs

42
Q

What makes a triglyceride saturated?

A

The fatty acid chains have no carbon to carbon double bonds

43
Q

What makes a triglyceride mono-unsaturated and polyunsaturate?

A
  • Mono-unsaturated triglycerides have one carbon to carbon double bond in the fatty acid chain
  • Polyunsaturated have more than one carbon to carbon double bond in the fatty acid chain
44
Q

Where are phospholipids found?

A

In cell membranes

45
Q

What does a phospholipid consist of?

A

A glycerol molecule and two fatty acids with he third fatty acid group replaced by a phosphate group

46
Q

Which part of the phospholipid is hydrophilic and which part is hydrophobic?

A

The phosphate head is hydrophilic and the fatty acid tail is hydrophobic

47
Q

What does a phospholipid bilayer look like?

A

The phosphate heads all point outwards and the hydrophobic tails point inwards

48
Q

What is the reagent used in a lipid test?

A

Ethanol

49
Q

Describe the method of a lipid test

A
  • Add ethanol
  • Shake
  • Add a few drops of water
50
Q

What would the colour change be in a positive lipid test?

A

From colourless to white emulsion

51
Q

What is the covalent bond in proteins?

A

Peptide bond

52
Q

What are the 7 functions of proteins?

A

1 - Structural function e.g. myosin in muscles
2 - Enzymes
3 - Hormones e.g. insulin
4 - Antibodies
5 - Protein receptors e.g. insulin receptor
6 - Transport proteins e.g. carrier/channel proteins
7 - Antigens e.g. cell recognition

53
Q

What are the monomer unit of proteins?

A

Amino acids

54
Q

What elements do amino acids contain?

A

Carbon, hydrogen, oxygen and nitrogen (sometimes sulfur)

55
Q

How many types of amino acids are naturally occurring?

A

20

56
Q

What is the general structure of amino acids?

A

The central carbon atom has one hydrogen, an amine group, a variable region and a carboxyl group attached

57
Q

How are dipeptides and polypeptides formed?

A

A condensation reaction between the carboxyl group of one amino acid and the amine group of another amino acid - a peptide bond is formed between the two molecules. A water molecule is released from the elements of the two molecules (H from amine group and OH from carboxyl group)

58
Q

What is the primary structure of proteins?

A

The sequence and number of amino acids held together by peptide bonds. The primary structure determines the shape of the secondary and tertiary structure of the protein

59
Q

What is the secondary structure of proteins?

A

This is the folding of the primary structure into either an alpha helix or beta pleated sheet. Both secondary structures are held together by lots of weak hydrogen bonds

60
Q

What is the tertiary structure of proteins?

A

This is the further folding of the polypeptide chain to give a more complex 3D shape. The tertiary shape is stabilised by:
Hydrogen bonds between R-groups
Ionic bonds between positively and negatively charged R groups
Disulfide bonds (strong) between sulfurs in the R-groups
Hydrophobic interactions between non-polar R-groups

61
Q

What is the quaternary structure of proteins?

A

These are proteins made up of more than one polypeptide chain e.g. haemoglobin. Haemoglobin consists of 2 alpha and 2 beta chains. Each chain has a haem group which contains an Iron(II) ion which has a high affinity to oxygen

62
Q

What are fibrous proteins?

A

Fibrous proteins form long fibres. They have a regular repeating sequence of amino acids and are usually insoluble in water. They tend to have structura; roles in living organisms e.g. keratin in hair, myosin in muscles

63
Q

What are globular proteins?

A

These fold up into a compact ball like shape. Hydrophobic R-groups tend to be turned inwards towards the centre of the proteins and hydrophilic R-groups tend to be turned outwards. This means they are more water soluble than fibrous proteins. They tend to have a metabolic role in living organisms e.g. enzymes, plasma proteins, antibodiesm, haemoglobin. Globular proteins have a wide range of amino acids in their structure

64
Q

What is the reagents use in the test for proteins?

A

Sodium hydroxide and copper sulfate (biuret solution)

65
Q

Describe the method used in testing for proteins

A

Add NaOH and then about 5 drops of biuret solution

66
Q

What is the colour change for a positive protein test?

A

From pale blue to lilac

67
Q

Name the 6 ways in which all enzymes are the same

A

1 - They are all tertiary proteins with globular structure (and all have active sites)
2 - They all act as biological catalysts - speed up metabolic reactions without being used up
3 - They are all specific - they only catalyse one shape of substrate
4 - The specific substrate has a complementary shape to the active site
5 - Their activity i affected by temperature and pH
6 - They are very important for digestion as they hydrolyse polymers into monomers

68
Q

What is activation energy?

A

The extra energy required to enable a reaction to occur

69
Q

What do enzymes do in terms of activation energy?

A

They lower the activation energy of a reaction to allows it to proceed more quickly at a lower temperature in the body

70
Q

Describe the lock and key model

A

Enzymes have a specific shaped active site which is complementary to the shape of the substrate molecules being used in the reaction

71
Q

Describe the induced fit model

A
  • Substrate collides and binds with the active site of the enzyme
  • The active site changes shape to fit more closely around the substrate molecule and is held in position by oppositely charged R-groups
  • An enzyme-substrate complex is formed
  • A change in the enzyme shape places strain on the bonds in the substrate allowing the reaction to occur more easily. This strain lowers the activation energy needed for the reaction to occur
  • An enzyme-product complex now forms
  • The product no longer fits in the active site
  • Product is released
72
Q

Define the term limiting factor

A

A variable that prevents V max from being achieved. If it is increased, then the rate of the process will increase

73
Q

Define the term V max

A

The reaction is fastest as all the enzyme active sites are occupied no more enzymes-substrate complexes can form

74
Q

What are the 4 possible limiting factors of enzyme activity?

A

Temperature, pH, concentration of enzyme, concentration of substrate

75
Q

What are competitive inhibitors?

A

Have a similar shape to the substrate and must have a complementary shape to the active site of the enzyme. They bind to the active site of the enzyme blocking and actual substrates from binding to the active site. This decreases the rate of reaction

76
Q

What are non-competitive inhibitors?

A

Do not compete with substrate molecules for the active site. Instead they bind to the allosteric site of the enzyme which changes the shaoe of the active site and therefore tertiary structure of the enzyme. The substrate no longer fits into the active site of the enzyme so enzyme-substrate complexes can no longer form. This slows down the rate of reaction

Flans AS Biology (6 decks)

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