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Biology AQA AS > Biological molecules chapter 1 > Flashcards

Biological molecules chapter 1 Flashcards

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1
Q

What is hydrogen bonding?

A

when electrons within a molecule are not evenly distributed but tend to spend more time at one position. This region is more negatively charged than the rest of the molecule.

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2
Q

What is a polar molecule?

A

A molecule with an uneven distribution of charge.

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3
Q

What are condensation reactions?

A

In polymerisation in organisms, each time a new sub-unit is attached a molecule of water is formed.

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4
Q

What is hydrolysis?

A

The process of polymers being broken down through the addition of water.

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5
Q

What is a molar solution?

A

A molar solution (M) is a solution that contains one mole of solute in each litre of solution. A mole is the molecular mass expressed as grams.

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6
Q

What is the atomic number?

A

The number of protons in an atom.

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7
Q

What is the mass number?

A

The total number of protons and neutrons in an atom.

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8
Q

What are examples of monosaccharides?

A

Glucose Fructose and Galactose

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9
Q

Examples of disaccharides

A

Sucrose
Maltose
Lactose

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10
Q

Examples of Polysaccharides

A

Starch
Cellulose
Glycogen

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11
Q

What is the molecular formula of glucose

A

C6H12O6

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12
Q

What is the difference between the two isomers for glucose?

A

for carbon one for alpha, hydrogen is on top and hydroxide on bottom and for carbon one for beta, hydroxide is on top and hydrogen is on the bottom

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13
Q

What are disaccharides joined together by?

A

A glycosidic bond

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14
Q

Glucose + Glucose

A

maltose + water

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15
Q

glucose + galactose

A

lactose + water

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16
Q

glucose + fructose

A

sucrose + water

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17
Q

Starch function and location?

A

Found in plants and is a store of glucose

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18
Q

Where is cellulose found and what is its function

A

Plants in cell wall and function is for structural strength

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19
Q

Where is glycogen found and what is its function?

A

Found in animals- mainly in liver and muscle cells and is a store of glucose.

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20
Q

What is starch formed from?

A

2 polymers of alpha glucose: amylose and amylopectin

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21
Q

Structure of Starch

A

Formed from two polymers of alpha glucose. Chains may be branched of unbranched. The unbranched chain is wound into tight coil which makes the molecule very compact.

22
Q

Structure of glycogen

A

A highly branched polymer and can be compacted easily

23
Q

What is cellulose formed from?

A

Formed from beta glucose
1-4 glycosidic bonds

24
Q

Structure of cellulose

A

Beta glucose molecules formed by condensation reactions to create long straight chains. These chains line up parallel to each other. They are held in place by many hydrogen bonds. This is called a fibril.

25
Q

How does the structure of starch leads to its function

A

Helix can compact to fit a lot of glucose in a small space
Branched structure increases SA for rapid hydrolysis back to glucose
Insoluble- wont affect water potential.

26
Q

How does the structure of cellulose leads to its function

A

Many hydrogen bonds provide collective strength

27
Q

How does the structure of glycogen leads to its function

A

Branched structure increases surface area for rapid hydrolysis back to glucose. This is useful as glycogen is a storage molecule in animals and animals need to move, which requires energy and glucose is required in respiration to release that energy.
Insoluble- won’t affect water potential.

28
Q

What is the difference between the structure of a triglyceride and a phospholipid?

A

a triglyceride has a glycerol molecule bonded to 3 fatty acids, however a phospholipid only has two chains and the third one is replaced by a phosphate group.

29
Q

How are triglycerides formed?

A

By condensation reactions between one molecule of glycerol and three fatty acids. End up with three waters. Three ester bonds form.

30
Q

What are R groups?

A

Fatty acids which can be saturated or unsaturated.

31
Q

What is the difference between saturated and unsaturated fatty acids?

A

Saturated has only single bonds between carbons and unsaturated consists of atleast one double bonds between carbons.

32
Q

Properties of triglycerides?

A

-Energy storage due to large amount of energy-storing carbon-hydrogen bonds compared to the number of carbon atoms.
-High ratio of hydrogen to oxygen atoms therefore they act as a metabolic water source. Triglycerides release water when oxidised. This is essential in animals of the desert eg camels.
-Don’t affect water water potential and osmosis as they are large and hydrophobic, making them insoluble in water.
-Low in mass. A lot can be stored without increasing the mass and preventing movement.

33
Q

Describe the emulsion test for lipids.

A

Dissolve sample in ethanol
Add distilled water
If white emulsion appears there is a lipid

34
Q

What does the hydrophilic head of a phospholipid do?

A

It can attract water as it is charged

35
Q

What does the hydrophobic tail of a phospholipid mean?

A

It repels water but will mix with fats.

36
Q

What are amino acids made up of?

A

amine group, carboxyl group, R group and a hydrogen.

37
Q

How do amino acids join together to form a dipeptide?

A

By a condensation reaction, water is removed. Peptide bond is formed between OH of carboxyl and H of amine group.

38
Q

What is the primary structure in proteins?

A

The sequence of amino acids in a polypeptide chain.

39
Q

What is the secondary structure of proteins?

A

Sequence of amino acids causes parts of protein molecule to bend into α helix or fold into beta pleated sheets.

40
Q

What holds the secondary structure in place?

A

Hydrogen bonds

41
Q

Where do the hydrogen bonds form in amino acid sequences?

A

Between the C=O of the carboxyl group of one amino acid and the H in the amine group of another amino acid.

42
Q

What is the tertiary structure of a protein?

A

The further folding of secondary structure to form unique 3D shape. Held in place by ionic, hydrogen and disulphide bonds.

43
Q

Where do ionic and disulphide bonds form in proteins?

A

The R groups of different amino acids.

44
Q

What is the quaternary structure of a protein?

A

A protein made up of more than one polypeptide chain.

45
Q

What are the conditions that denature a protein?

A

Too high a temperature
Too high/low a pH

46
Q

Why is the active site specific and unique in shape?

A

Due to the specific folding and bonding in the tertiary structure of a protein.

47
Q

What does the lock and key model suggest about the active site’s shape?

A

That it is a fixed shape.

48
Q

What happens once the enzyme-substrate complex has formed in lock and key model?

A

It will cause the substrate to slightly distort in shape, which lowers the activation energy. The products are then released and enzyme active site is empty ready to be reused again.

49
Q

What happens in the induced fit model?

A

Enzyme active site slightly changes shape to mould around the substrate. This puts strain on the bonds in substrate and weakens them. Therefore less energy is needed for reaction to occur. Product will be removed. Active site goes to its original shape.

50
Q

How does pH affect enzymes?

A

Too high or too low a pH will interfere with the charges in the amino acids in the active site. This can break the bonds holding the tertiary structure in place, therefore active site changes shape.
Therefore enzymes denatures and fewer enzyme-substrate complexes form.

51
Q

What happens if there is insufficient substrates?

A

Reaction will be slower as there will be fewer collisions between the enzyme and substrate.

52
Q

What happens if there is insufficient enzymes?

A

The enzyme active sites will become saturated with substrate and unable to work any faster.

Biology AQA AS (10 decks)

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