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AQA A-Level Biology > Biological Molecules > Flashcards

Biological Molecules Flashcards

1
Q

What are monomers?

A

Smaller units which can join together to form larger molecules

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2
Q

What are polymers?

A

Made from lots of monomers bonded together

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3
Q

Name three polymers of glucose

A

Starch, Cellulose and Glycogen

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4
Q

Name the polymer for amino acids

A

Proteins

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5
Q

Name the polymers for nucleotides

A

DNA and RNA

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6
Q

What are examples of monosaccharides?

A

Glucose, fructose, galactose

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7
Q

What is the difference between monomers and monosaccharides?

A

Monomers are smaller units which can join up to create larger molecules, whereas monosaccharides are specific types of monomers (monomers are more general, whilst monosaccharides are more specific forms of monomers!)

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8
Q

What are some disacccharides and what is the molecular formula?

A

Sucrose, maltose and lactose and it is C12H22O11

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9
Q

What are some polysaccharides?

A

Starch, cellulose and glycogen

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10
Q

What is an isomer?

A

Different structure, same molecular formula

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11
Q

What are disaccharides made from?

A

2 monosaccharides joined together by glycosidic bonds, and these are created during condensation reactions

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12
Q

What is a glycosidic bond?

A

A covalent bond formed between 2 monosaccharides during condensation reactions

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13
Q

What is a condensation reaction?

A

The joining up of molecules through the removal of water

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14
Q

What is a hydrolysis reaction?

A

The splitting up of molecules through the addition of water

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15
Q

What are the two isomers of glucose?

A

Alpha glucose and beta glucose

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16
Q

What is the difference between alpha glucose and beta glucose?

A

The hydroxyl group and hydrogen group is flipped on beta glucose, compared to alpha glucose

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17
Q

What monomer is starch made from?

A

Alpha glucose

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18
Q

What are the 2 polymers of alpha glucose called?

A

Amylose and amylopectin

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19
Q

What type of bond exists in amylose and amylopectin?

A

In amylose, there are 1-4 glycosidic bonds, whilst in amylopectin there are 1-4 glycosidic bonds as well as 1-6 glycosidic bonds

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20
Q

What is the function of starch?

A

As an insoluble store of glucose

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21
Q

Where is starch located?

A

In chloroplasts of plant cells

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22
Q

Where is amylose and amylopectin found in?

A

Starch grains or in amyloplasts

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23
Q

What is the structure of amylose?

A

Unbranched structure
Coiled into a spiral shape held in place by H bonds

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24
Q

What is the structure of amylopectin?

A

Branched structure, due to the 1-6 glycosidic bonds
Forms a spiral shape held in place by H bonds

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25
How does structure lead to function (starch)?
Helix shape - can compact to fit a lot of glucose in a smaller space Branched structure - increases surface area for rapid hydrolysis back into glucose Insoluble - doesn’t affect water potential
26
What is the difference between phospholipids and triglycerides?
Triglycerides contain 3 fatty acid chains, rather than phospholipids which contain 2 fatty acid chains and a phosphate group
27
How are triglycerides formed?
Via the condensation between one molecule of glycerol and three molecules of fatty acids - each of the fatty acids chain will go through a condensation reaction with glycerol
28
What bonds exist within triglycerides?
Ester bonds
29
What is an ester bond?
A covalent bond formed between a glycerol molecule and a fatty acid during a condensation reaction.
30
What are r-groups?
Fatty acids which can be saturated or unsaturated
31
What is a saturated fatty acid?
When the hydrocarbon chain has only single bonds between carbons (MUST SAY BETWEEN CARBONS)
32
What is a unsaturated fatty acid?
When the hydrocarbon chain consists of at least one double bond between carbons (MUST SAY BETWEEN CARBONS)
33
What does energy storage mean for triglycerides?
Due to the large ratio of energy-storing carbon-hydrogen bonds compared to the number of carbon atoms, a lot of energy is stored in the molecule
34
What does a metabolic water source mean for triglycerides?
Due to the high ratio of hydrogen to oxygen atoms, triglycerides can release water if they are oxidised - this is essential of animals in the desert, like camels
35
Why don’t triglycerides affect water potential and osmotic effect?
This is because they are large and hydrophobic, making them insoluble in water
36
What does the fact that lipids have a relatively low mass mean?
A lot of lipids can be stored without increasing the mass and preventing movement
37
What monomer is glycogen made from?
Alpha glucose
38
What bonds exist between monomers in glycogen?
1-4 and 1-6 glycosidic bonds
39
What is the function of glycogen?
As a storage of glucose
40
Where is glycogen found in?
The liver and muscle cells of animals (sometimes bacteria)
41
What is the structure of glycogen?
It is a highly branched molecule which can be compacted
42
How does structure relate to function in glycogen?
Branched structure - increases surface area for rapid hydrolysis back into glucose - can also be compacted Insoluble - so it won’t affect water potential Is a polymer of glucose so it is easily hydrolysed
43
What monomer is cellulose made from?
Beta glucose
44
What bonds exist between monomers in cellulose?
1-4 glycosidic bonds
45
What is the function of cellulose?
To provide structural strength for the cell wall of plants
46
What is the structure like in cellulose?
The polymer forms long, straight chains, and contains covalent cross links
47
What are fibrils?
When cellulose forms chains which are held in place by MANY hydrogen bonds
48
What is the formula for fatty acids?
RCOOH
49
What is the name of the test for lipids?
Emulsion test
50
What are the steps for the test for lipids?
1) Dissolve (shake) the sample in ethanol 2) Then add cold distilled water 3) If a milky white emulsion appears, then a lipid is present
51
What does a precipitate mean?
A solid has been produced
52
What are phospholipids made from?
A glycerol molecule, two fatty acid chains and a phosphate group (attached to the glycerol)
53
How do the fatty acids bond to the glycerol?
Via two condensation reaction, which results in two ester bonds forming
54
What does hydrophilic mean?
It can attract water as it is charged
55
Is the head or tail hydrophilic?
Head
56
What does hydrophobic mean?
It repels water, but will mix with fats (uncharged)
57
Is the head or tail hydrophobic?
Tail
58
Why are phospholipids polar?
Because they have two charged regions (are amphipathic)
59
How are phospholipids arranged in water?
They are positioned so that the heads are exposed to water and the tails are not
60
What membrane structure makes up the plasma membrane around cells?
The phospholipid bilayer
61
What is the general structure of an amino acid?
Carboxyl group on the right, amine group on the left, R group (variable group - 20 options for 20 amino acids) below the middle carbon
62
How are amino acids joined together to form a dipeptide?
Condensation reaction occurs Water is removed A peptide bond is formed between the OH of the carboxyl group and the H of the amine group
63
What are proteins, and what monomer are they made up from?
Proteins are polymers, and they are made up of the monomer amino acids
64
What are the four levels or structure in a protein?
Primary, secondary, tertiary and quarternary
65
What is the primary structure?
The SEQUENCE of amino acids in the polypeptide chain
66
What is the secondary structure?
When the sequence of amino acids causes parts of a protein molecule to bend into an alpha helix shape, or fold into beta pleated sheets
67
What kind of bonds hold the secondary structure of a protein into place?
Hydrogen bonds
68
Where do the hydrogen bonds form within the secondary structure?
The hydrogen bonds form between the C=O groups of the carboxyl group of one amino acid, and the H amine group of another amino acid
69
How is the tertiary structure formed?
1) This includes the further folding of the secondary structure 2) This forms a unique 3D shape 3) Held in place by ionic, hydrogen and disulphide bonds
70

AQA A-Level Biology (4 decks)

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