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AQA A Level Biology > 3.1 Biological Molecules > Flashcards

3.1 Biological Molecules Flashcards

(72 cards)

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1
Q

State the different bonding atoms may have undergo to combine?

A

Hydrogen, Covalent, and Ionic Bonding

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2
Q

What are monomers?

A

Small units from which larger molecules are made (from)

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3
Q

What are polymers?

A

Large molecules made up many monomers joined together

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4
Q

Give three examples of monomers?

A

Monosaccharides, amino acids and nucleotides

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5
Q

What is the name of the process of making polymers?

A

Polymerisation

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6
Q

What is a condensation reaction?

A

A reaction where 2 molecules join together to form a chemical bond, eliminating a water molecule in the process.

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7
Q

What is a hydrolysis reaction?

A

Breakdown of a chemical bond between two molecules involving a water molecule

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8
Q

What is metabolism?

A

All the chemical processes that take place in a living organism

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9
Q

What are most biological molecules made up of?

A

Carbon, Hydrogen, Oxygen and Nitrogen

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10
Q

What is a monosaccharide?

A

A monomer which a larger carbohydrate is made from

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11
Q

Give examples of three common monosaccharides?

A

Glucose, Galactose and Fructose

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12
Q

If a pair of monosaccharides combine, then what is the compound called?

A

Disaccharide

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13
Q

What are the characteristics of a monosaccharide?

A

sweet
Soluble
(extra: has formula of CH20n)

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14
Q

What are isomers?

A

Molecules that have the same chemical formula but different arrangement

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15
Q

What are the isomers of monosaccharides?

A

a-glucose and J3-glucose

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16
Q

“All monosaccharides and some disaccharides are reducing sugars” - True or False?

A

True

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17
Q

What is meant by a reducing sugar?

A

A sugar that can donate electrons to reduce another chemical

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18
Q

What is the test for reducing sugars?

A

Benedict’s Test

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19
Q

Describe how to do the benedict’s test?

A

Add 2cm3 of liquid (grinded) food sample
Add equal volume of Benedicts reagent
Heat mixture in water bath for 5 mins
If orange-brown-brick red precipitate then present

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20
Q

What is the name of the disaccharide when:
Glucose and Glucose bond?

A

Maltose

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21
Q

What is the name of the disaccharide when:
Glucose and Fructose bond?

A

Sucrose

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22
Q

What is the name of the disaccharide when:
Glucose and Galactose bond?

A

Lactose

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23
Q

What is the reaction when two monosaccharides join?

A

Condensation Reaction

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24
Q

What is the name of the bond when two monosaccharides join?

A

Glycosidic Bond

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25
Describe the formation of a disaccharide.
The condensation reaction of two monosaccharides forming a glycosidic bond involving the loss of water
26
What is the name of the reaction? “Water added to the disaccharide causes the breakdown of the glycosidic bond between monosaccharides”
Hydrolysis Reaction
27
How do we know if we have a non-reducing sugar in a Benedict's Test?
If the benedict's reagent does not change colour after being heated for 5 minutes
28
What do we have to do in order to detect a non-reducing sugar? (not asking for the method)
Need to hydrolyse into monosaccharide components (HCL will hydrolyse any disaccharide present)
29
Describe the test for non-reducing sugars?
Add 2cm3 of sample in equal volume of HCL Place in water bath for 5 mins Add some sodium hydrogen carbonate solution to neutralise HCL Test with PH paper = alkaline Re-test using the benedicts reagent in water bath for 5 It should now turn orange-brown
30
What are polysaccharides?
Polymers formed by the condensation reaction of many monosaccharides
31
What are the three main polysaccharides?
Starch,Glycogen and Cellulose
32
What features make polysaccharides useful for storage?
Large molecules Insoluble
33
Glycogen and starch are formed by the [...] of [...] glucose
condensation , alpha
34
Cellulose is formed by the [...] of [...] glucose
Condensation, beta
35
Describe the test for starch?
Add 2cm3 of sample in test tue Drop 2 drops of iodine Shake or stir If starch is present, the sample will be blue-black
36
What is the main role of starch
Act as energy storage for plants
37
What structural features benefit starch?
Insoluble → water potential not affected Large → can't leave cell Helical → compact for storage in cell
38
What is starch made up of?
Amylose and Amylopectin
39
Describe the structure of amylose
Unbranched polysaccharide Bonded by 1,4 glycosidic bonds Coiled shape
40
How does the coiled part of amylose help function of starch?
A lot of alpha glucose can be stored in a small area
41
What is the limitation of amylose?
1,4 Glycosidic bonds mean glucose can only be hydrolysed off two end = slower hydrolysis
42
Describe the structure of Amylopectin
Branched polysaccharide Bonded w/ C1,C4 and C1,C6 glycosidic bonds
43
How do the 1,4 and 1,6 glycosidic bonds benefit starch?
There is a greater number of terminal glucose = a FASTER HYDROLYSIS
44
What is glycogen?
The storage for animals
45
Describe structural features in glycogen that benefit role?
Insoluble = no osmosis and no diffusion Compact = a lot of it can be stored in small space Large → can’t leave Very highly branched = more terminal glucose → faster hydrolysis of glucose for respiration
46
Why is having highly branched structure in glycogen good for animals?
Faster hydrolysis of glucose can support animals with high energy release due to their high metabolic rate
47
What is the function of cellulose?
Provides strength and structural support to plant cell walls
48
Describe the structure of cellulose
Straight, unbranched chains Parallel to each other Hydrogen bonds (forming cross-linkages)
49
How are the B-glucose arranged to create straight chains?
Adjacent glucose rotated by 180˚ This means hydroxyl group is able to form a condensation reaction.
50
How does the structure of cellulose help its function?
Hydrogen bonds are strong in high numbers Many H bonds link to form microfibrils Provides strength and structural support to plant cell walls
51
What is the function of cellulose?
Provides rigidity to the plant cell and prevents cell bursting due to osmotic pressure
52
Describe how you would determine glucose concentration?
1. Produce a dilution series of glucose solutions of known concentrations 2. Perform a Benedict’s test on each sample 3. Using a colorimeter, measure the absorbance of each sample and plot a calibration curve 4. Repeat with the unknown sample and use graph to determine glucose concentration
53
What are the main groups of lipids?
Triglycerides and Phospholipids
54
What are the roles of lipids?
Cell membrane Source of energy Waterproof (insoluble) Insulation Protection ( stored around delicate organs)
55
Explain the formation of a triglyceride
Condensation of 1 molecule of glycerol and 3 fatty acids forming three ester bonds
56
Describe the structure of a triglyceride
3 fatty acids and 1 glycerol
57
What does the hydrolysis of a triglyceride produce?
1 glycerol and three fatty acids
58
Describe the properties of triglycerides related to its structure
- High ratio of C-H bonds to C atoms = more energy released - Insoluble in water = no effect on the water potential
59
How do you identify a saturated lipid?
No carbon-carbon double bonds on hydrocarbon chain (fully saturated with hydrogen)
60
How do you identify an unsaturated lipid?
One or more C=C bonds in a hydrocarbon chain
61
If a lipid structure had several double bonds, what may we suggest?
The molecule is caused to bend = not packed together anymore= meaning that it is most likely a liquid
62
Describe the structure of a phospholipid
Glycerol Phosphate (containing group) Two fatty acids
63
What are the two parts that make up the phospholipid?
Hydrophilic phosphate head Hydrophobic Fatty acid tails
64
Describe the formation of a phospholipid
The condensation reaction between 1 glycerol, 1 phosphate group and 2 fatty acids
65
What is formed due to the amphipathic parts in a phospholipid?
Creation of a phospholipid bilayer
66
Describe structure of phospholipid?
- Forms bilayer → allowing diffusion of nonpolar/small molecules - Hydrophilic phosphate heads → orient to aqueous environment - Hydrophobic tails → orient to interior → repels polar/charger molecules
67
Describe the test for lipids
Add sample of food Add ethanol Shake the tube Add water and shake gently If there is a cloudy, white colour then present
68
What are amino acids?
The monomers from which proteins are made
69
What is the general structure of amino acids?
NH2-CHR-COOH
70
Describe the formation of dipeptides?
A condensation reaction between 2 amino acids forms a peptide bond
71
Describe the formation of polypeptides?
Condensation of many amino acids
72
What may a functional protein contain?
One or more polypeptides

AQA A Level Biology (9 decks)

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