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A Level Biology > Biological Molecules > Flashcards

Biological Molecules Flashcards

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1
Q

What are polysaccharides?

A

Very large molecules that contain many monosaccharides

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2
Q

Give three examples of polysaccharides

A

Starch, Glycogen, Cellulose

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3
Q

How are polysaccharides formed?

A

The condensation of many glucose units

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4
Q

What type of glucose is glycogen and starch made up of?

A

Alpha glucose

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5
Q

What type of glucose is cellulose formed by?

A

Beta glucose

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6
Q

What are monomers?

A

Smaller, repeated units that larger molecules are made of.

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7
Q

What are polymers?

A

A large number of monomers joined together

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8
Q

Give three examples of monomers

A

Monosaccharides, amino acids, nucleotides

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9
Q

What are monosaccharides?

A

Single sugar monomers

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10
Q

Give three examples of monosaccharides

A

Glucose, fructose, galactose

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11
Q

How is a disaccharide formed?

A

2 monosaccharides join together via a condensation reaction + form a glycosidic bond

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12
Q

What is the formula for glucose?

A

C6H12O6

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13
Q

What are the two types of glucose?

A

Alpha and beta

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14
Q

Define a structural isomer.

A

Atoms are arranged in different ways.

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15
Q

What is the molecular formula for fructose and galactose?

A

C6H12O6

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16
Q

What does hydrolising a bond mean?

A

Breaking it down

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17
Q

What is a condensation reaction?

A

When one monomer joins to another monomer.

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18
Q

What does a condensation reaction eliminate?

A

A molecule of water.

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19
Q

What does a hydrolysis reaction involve the use of?

A

A water molecule.

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20
Q

What does a condensation reaction between two monosaccharides form?

A

A glycosidic bond

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21
Q

What is maltose?

A

A disaccharide formed by the condensation of 2 glucose molecules

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22
Q

What is sucrose?

A

A disaccharide formed by the condensation of a glucose molecule and a fructose molecule

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23
Q

What is lactose?

A

A disaccharide formed by condensation of a glucose molecule and a galactose molecule

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24
Q

What is the test for starch?

A

Iodine/ potassium iodide

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25
What is the test for both reducing sugars and non-reducing sugars?
Benedict's solution
26
What is glycogen?
A polysaccharide found in animal cells where it acts as an energy store and an energy source
27
What is the structure of alpha glucose?
OH on the bottom
28
What is the structure of beta glucose?
OH on the top
29
What type of glucose is glycogen formed from?
Alpha glucose
30
What type of glucose is starch formed from?
Alpha
31
What is starch?
A polysaccharide found in plant cells where it acts as an energy store and an energy source
32
What polysaccharides is starch constructed from?
Amylose (10-30% starch) and Amylopectin (70-90%)
33
What is the structure of Amylose?
Unbranched helix-shaped chain with 1,4 glycosidic bonds between alpha-glucose molecules
34
What is the structure of amylopectin?
1,4 glycosidic bonds between alpha glucose molecules but also 1,6 glycosidic bonds form between glucose molecules creating a branched molecule
35
What can having a branched structure be useful for?
It can easily be hydrolysed for use during cellular respiration or added to for storage
36
What cells have a high concentration of glycogen and why?
Liver and muscle cells as the cellular respiration rate is high in these cells (due to animals being mobile)
37
Is glycogen more branched than amylopectin?
Yes, makes it more compact which helps animals store more
38
What is the structure of cellulose?
A polymer consisting of long chains of beta glucose joined together by 1,4 glycosidic bonds
39
Why must the beta glucose molecules be rotated to 180° to each other?
In order to form the 1,4 glycosidic bond
40
What gives cellulose the strength it has?
The many hydrogen bonds that are formed between the long chains (due to the inversion of the beta glucose molecules)
41
What is the function of cellulose?
The main structural component of cell walls (has high tensile strength)
42
Is sucrose a reducing sugar?
No
43
Name the five properties of water
Is a metabolite Is an important solvent in which metabolic reactions occur Has a relatively high heat capacity Has a relatively large latent heat of vaporisation Has strong cohesion between water molecules
44
Describe cohesion of water molecules
When water molecules get close together, oppositely charged parts of molecules attract each other, forming hydrogen bonds - called cohesion At an air-water surface, the cohesion between water molecules produces surface tension
45
Describes water's high specific heat capacity
Water acts as a temperature buffer - temp of water in ponds etc does not vary much compared to the air above them Important for enzyme controlled reactions and animals who cannot regulate their own temp
46
Describe water's high latent heat of evaporation
By removing a large amount of heat energy when evaporating, organisms are cooled
47
Describe water as a solvent
Water has polar molecules so water attracted to any substance that is also polar
48
What are hydrophilic substances?
Substances that can become part of water's hydrogen-bonded structure will dissolve in water
49
What are hydrophobic substances?
Substances that cannot become part of water's hydrogen-bonded structure will not dissolve in water
50
Name two hydrophobic substances
Triglycerides Large polymers
51
What are proteins?
Large polymers made up of monomers called amino acids
52
What is the primary structure of a protein?
The sequence of amino acids in a polypeptide chain Each amino acid is held in the polypeptide chain by peptide bonds
53
What is the secondary structure of a protein?
alpha helix beta pleated sheet
54
How is the secondary structure of a protein formed?
Hydrogen bonds form between the carboxyl groups of one amino acid and the amine group of another
54
Describe the tertiary structure of a protein
The further folding of the secondary structure to create a unique 3D structure held in place by hydrogen, ionic and disulfide bonds.
55
When is the quaternary structure of a protein formed?
When there is more than one polypeptide chain
56
Describe the quaternary structure of proteins.
It is still folded into a 3D shape and held by hydrogen, ionic and disulphide bonds
57
How are triglycerides formed?
Formed via the condensation reactions between one molecule of glycerol and three molecules of fatty acid
58
What type of bond is formed in triglycerides?
Ester bonds
59
Describe saturated fatty acids.
The hydrocarbon chain has only single bonds between carbons.
60
Describe unsaturated fatty acids.
The hydrocarbon chain consists of at least one double bond between carbons
61
Name four properties of triglycerides.
1. A lot of energy is stored in the molecule 2. Act as a metabolic water source 3. Do not affect water potentials and osmosis 4. A lot can be stored without increasing the mass and preventing movement
62
Why is a lot of energy stored in triglycerides?
Due to the large ratio of energy-storing carbon-hydrogen bonds compared to the number of carbon atoms
63
Why do triglycerides act as a metabolic water source?
Due to the high ratio of hydrogen to oxygen atoms They can release water if they are oxidised
64
Why do triglycerides not affect water potential or osmosis?
They are large and hydrophobic, making them insoluble in water.
65
Why can lots of triglycerides be stored without increasing the mass?
They have a relatively low mass.
66
What are phospholipids made of?
A glycerol molecule, two fatty acid chains and a phosphate group (attached to the glycerol) Two ester bonds (fatty acids to glycerol)
67
Describe a phospholipid's 'head'
It is hydrophilic and can attract water because it is charged The phosphate is charged so it repels other fats
68
Describe a phospholipid's 'tail'
The fatty acid chain which is non-polar and is hydrophobic Will repel water but mix with fats
69
Are phospholipids polar?
Yes
70
How are phospholipids positioned in water?
The heads are exposed to water and the tails are not Forms a phospholipid bilayer which makes up the plasma membrane around cells.
71

A Level Biology (4 decks)

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