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Flans AS Biology > Biological Molecules > Flashcards

Biological Molecules Flashcards

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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
What are the 4 main characteristics of cellulose?
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)
26
What is the reagent used in the reducing sugar test?
Benedict's solution
27
Describe the method used in the reducing sugar test
-Add Benedict's to solution and heat in water bath at 80 degrees
28
What is the colour change for a positive reducing sugar test?
From blue to a brick red precipitate
29
What are the reagents used in the non-reducing sugar test?
Acid and Benedict's
30
Describe the method for the non-reducing sugar test
- 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
31
What is the colour change for a positive result non-reducing sugar test?
From blue to a brick red precipitate
32
What is the reagent in the starch test?
Iodine
33
Describe the method for the starch test
Add iodine to the solution and shake gently
34
What colour change will there be in a positive starch test?
From orange to inky blue/black
35
Are lipids polymers?
No
36
Name two groups of lipids
Triglycerides and phospholipids
37
What elements do lipids contain?
Carbon, hydrogen, and oxygen
38
What is different about the oxygen in lipids and in carbohydrates
There is a very small proportion of oxygen in lipids compared to carbohydrates
39
What is the covalent bond called in lipids?
Ester bond
40
What are the components to a triglyceride molecule?
A glycerol molecules ester bonded to 3 fatty acid chains
41
What are the 4 functions of a triglyceride?
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
What makes a triglyceride saturated?
The fatty acid chains have no carbon to carbon double bonds
43
What makes a triglyceride mono-unsaturated and polyunsaturate?
- 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
Where are phospholipids found?
In cell membranes
45
What does a phospholipid consist of?
A glycerol molecule and two fatty acids with he third fatty acid group replaced by a phosphate group
46
Which part of the phospholipid is hydrophilic and which part is hydrophobic?
The phosphate head is hydrophilic and the fatty acid tail is hydrophobic
47
What does a phospholipid bilayer look like?
The phosphate heads all point outwards and the hydrophobic tails point inwards
48
What is the reagent used in a lipid test?
Ethanol
49
Describe the method of a lipid test
- Add ethanol - Shake - Add a few drops of water
50
What would the colour change be in a positive lipid test?
From colourless to white emulsion
51
What is the covalent bond in proteins?
Peptide bond
52
What are the 7 functions of proteins?
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
What are the monomer unit of proteins?
Amino acids
54
What elements do amino acids contain?
Carbon, hydrogen, oxygen and nitrogen (sometimes sulfur)
55
How many types of amino acids are naturally occurring?
20
56
What is the general structure of amino acids?
The central carbon atom has one hydrogen, an amine group, a variable region and a carboxyl group attached
57
How are dipeptides and polypeptides formed?
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
What is the primary structure of proteins?
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
What is the secondary structure of proteins?
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
What is the tertiary structure of proteins?
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
What is the quaternary structure of proteins?
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
What are fibrous proteins?
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
What are globular proteins?
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
What is the reagents use in the test for proteins?
Sodium hydroxide and copper sulfate (biuret solution)
65
Describe the method used in testing for proteins
Add NaOH and then about 5 drops of biuret solution
66
What is the colour change for a positive protein test?
From pale blue to lilac
67
Name the 6 ways in which all enzymes are the same
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
What is activation energy?
The extra energy required to enable a reaction to occur
69
What do enzymes do in terms of activation energy?
They lower the activation energy of a reaction to allows it to proceed more quickly at a lower temperature in the body
70
Describe the lock and key model
Enzymes have a specific shaped active site which is complementary to the shape of the substrate molecules being used in the reaction
71
Describe the induced fit model
- 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
Define the term limiting factor
A variable that prevents V max from being achieved. If it is increased, then the rate of the process will increase
73
Define the term V max
The reaction is fastest as all the enzyme active sites are occupied no more enzymes-substrate complexes can form
74
What are the 4 possible limiting factors of enzyme activity?
Temperature, pH, concentration of enzyme, concentration of substrate
75
What are competitive inhibitors?
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
What are non-competitive inhibitors?
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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