Topic 1.1 - Biological Molecules Flashcards
1
Q
Give 3 examples of monomers and their polymers
A
Amino acids > proteins
Monosaccharides > carbohydrates
Nucleotides > nucleic acids
2
Q
Define monomer
A
- Small, basic molecular units.
- Repeating units form larger molecular units called polymers.
3
Q
Define polymer
A
Large, complex molecules made up of long chains of repeating units (monomers) joined together
4
Q
Define a condensation reaction
A
- A chemical bond formed between monomers.
- A molecule of water is eliminated/ released.
5
Q
Define a hydrolysis reaction
A
Breaks a chemical bond between monomers using a water molecule
6
Q
What are the two sugar types?
A
Monosaccharides and disaccharides
7
Q
What are monosaccharides?
Give 3 examples
A
Monomers of which carbohydrates are made
- Glucose
- Galactose
- Fructose
8
Q
What is glucose?
A
- Hexose sugar (C6H12O6)
- Has two isomers (alpha-glucose and beta-glucose)
9
Q
How are disaccharides formed?
Give three examples and how they are made.
A
Disaccharides are formed from the condensation reaction of two monosaccharides
- Maltose (glucose + glucose)
- Lactose (glucose + galactose)
- Sucrose (glucose + fructose)
10
Q
What does a condensation between two monosaccharides form?
A
A glycosidic bond
11
Q
What are polysaccharides made of and how are they formed?
A
- Made of monosaccharides
- Formed by the condensation reaction of many glucose units
12
Q
What are types of polysaccharides?
A
- Starch > amylose
> amylopectin - Glycogen
- Cellulose
13
Q
Structure and function of starch
A
- Formed by condensation reaction of alpha-glucose
- Plants storage of excess glucose
- Insoluble (no impact on water level)
- Amylose:
Glycosidic bonds make it coiled (helical structure)
Long and unbranched
Compact (good for storage) - Amylopectin:
Long and branched (allows enzymes that break down molecule to get at glycosidic bonds easily > quick and easy release of glucose)
14
Q
Structure and function of glycogen
A
- Formed by condensation reaction of a-glucose
- Animals storage of excess glucose (in liver and muscles)
- Many side branches (hydrolysis releases a-glucose to release energy by respiration for movement)
- Compact (good for storage)
15
Q
Structure and function of cellulose
A
- Formed by condensation reaction of b-glucose
- Straight, unbranched chains (linked together by hydrogen bonds which form strong fibres called microfibrils)
- Provide structural support and prevent lysis
16
Q
What are the two types of lipids?
A
Triglycerides and fatty acids
17
Q
How are triglycerides formed?
What are they made of?
What are their functions?
A
- Formed by condensation reactions between one glycerol molecule and each fatty acid
- Made of 1 glycerol and 3 fatty acids (store lots of chemical energy)
- Functions > Heat insulation
> Electrical insulation
> fat as buoyancy
18
Q
What is the bond formed during the condensation reaction between a glycerol molecule and a fatty acid?
A
Ester bond
19
Q
What are phospholipids made of?
What are their functions?
A
- Made of 1 glycerol, 2 fatty acids and 1 phosphate group
- Functions > Energy storage molecules
> Makes up phospholipid bilayer cell membranes
> Controls what substances move in and out of cell
20
Q
What are amino acids?
A
The monomers of which proteins are made
21
Q
How is a dipeptide formed?
A
Condensation of two amino acids
22
Q
How is a polypeptide formed?
A
Condensation of more than two amino acids
23
Q
What bond does a condensation reaction between amino acids form?
A
Peptide bond (C-N)
24
Q
Describe the structure of a primary protein (include types of bonding)
A
- Sequence of amino acids in a polypeptide chain
- Peptide bonds
25
Describe the structure of a secondary protein (include types of bonding)
- Polypeptide chain coils into alpha-helix or beta pleated sheet
- Hydrogen bonds
26
Describe the structure of a tertiary protein (include types of bonding)
- Alpha - helix or beta pleated sheet folded or coiled further
- 3D structure
- Hydrogen bonds, ionic bonds and disulphide bridges
27
Describe the structure of a quaternary protein (include types of bonding)
- Several polypeptide chains
- 3D structure
- Hydrogen bonds
28
How are proteins specialised?
They have a specific shape which makes them specialised to carry out different jobs
29
What are four examples of proteins?
- Enzymes
- Antibodies
- Transport proteins
- Structural proteins
30
Name of food test to test for sugars?
Benedict’s solution
31
What are the two classifications of sugars (examples of each) ?
- Reducing sugars (all monosaccharides and some disaccharides (e.g. maltose and lactose))
- Non-reducing sugars
32
How do you test for a reducing sugar?
Give results
Heat sample with Benedict’s reagent
(Blue > brick red)
33
What piece of equipment can you use to measure concentration of substance in sample?
Colorimeter measure absorbance.
Higher absorbance reading means a higher concentration of substance in sample.
34
How do you test for a non-reducing sugar?
Give results
- Heat sample
- Add dilute Hydrochloric acid (turn to monosaccharide)
- Add Benedict’s reagent
Add sodium hydrogen carbonate (to neutralise)
(Blue > brick red)
35
What is the food test to test for starch?
Iodine / potassium iodide
36
How do you test for presence of starch?
Give results
Iodine dissolved in potassium iodide solution
(Brown > blue black)
37
What is the food test to test for lipids?
Emulsion test
38
How do you test for lipids in a sample?
Give results
Shake test substance with ethanol. THEN add water
(Colourless > milky white)
39
What is the food test to test for proteins?
Biuret test
40
How to test for the presence of proteins in a sample?
Give results
- Add few drops of sodium hydroxide solution (turn to alkaline)
- Add some copper sulphate solution
(blue > lilac/purple)
41
What are enzymes?
Biological catalysts
42
Describe the structure of an enzyme
- Specific 3D (tertiary) structure
- Active site has a specific shape which is complementary to the substrate
- Only catalyse specific reactions (usually one reaction)
- Specific due to their tertiary structure
43
How might the tertiary structure of an enzyme be altered?
- Changes in pH
- Changes in temperature
44
How might a mutation affect primary / tertiary structure of an enzyme?
Primary structure of an enzyme is determined by a gene. If a mutation occurs in that gene, it could change the tertiary structure of the enzyme produced
45
Describe the induced fit model
- Before substrate binds to enzymes active site, they are not precisely complementary in shape
- After substrate binds, active site changes shape and moulds closely round the substrate, which forms and enzyme-substrate complex
- Once products are released, active site returns to its original shape by stressing/distorting bonds
46
Why do enzymes lower the activation energy?
They create an alternative pathways for reactants that requires a lower activation energy
47
What does an enzyme form when it binds to its substrate?
Enzyme - substrate complex
48
What factors affect enzyme activity (four)?
- Temperature
- pH
- Substrate concentration
- Enzyme concentration
49
How does temperature affect enzyme activity?
- Increase in temperature
- Increase in kinetic energy
- Higher frequency of successful collisions between substrate molecule and enzyme’s active site
TOO HIGH, enzymes denature as:
- Enzymes vibrate more
- Bonds break
- Active site permanently changes shape
- Substrate no longer fits
- Enzyme-substrate complexes are not formed
50
How does pH affect enzyme activity?
H+ and OH- ions
- Disrupt ionic bonds and hydrogen bonds
- Interrupting tertiary structure
- Enzyme becomes denatured
51
How does substrate concentration affect enzyme activity?
- Higher enzyme concentration
- Increase in likelihood of collisions to form enzyme- substrate complexes
SATURATION POINT:
- Rate plateaus
- Limited substrates
- Adding more enzymes will have no affect
52
How does enzyme concentration affect enzyme activity?
Higher enzyme concentration
Increase in likelihood of collisions to form enzyme- substrate complexes
SATURATION POINT:
Rate plateaus
Limited substrates
Adding more enzymes will have no affect on
53
What can prevent enzyme activity?
Enzyme inhibitors which bind to the enzyme’s active site
54
What are the two types of enzyme inhibitors?
- Competitive inhibitors
- Non-competitive inhibitors
55
What are competitive inhibitors?
How do they work?
- Molecules have similar shape to the substrate
- Compete to bind with active site
- Block active site
- No enzyme - substrate complexes
- Decreased rate of reaction
56
What are non-competitive inhibitors?
How do they work?
- Molecules bind to the enzyme’s active site away from the active site
- Active site changes shape
- Active site and substrate are no longer complementary
57
Equations for rate of reaction
Change in concentration or mass of products or reactants / time
