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A-levels > Biology UNIT 1-Biological Molecules > Flashcards

Biology UNIT 1-Biological Molecules Flashcards

1
Q

What is a Monomer?

A

The smallest repeating unit.

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2
Q

what is a Polymer?

A

A chain of identical monomers. Eg.(Primary protien is a polymer of amino acids

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3
Q

What does ATP stand for?

A

Adenosine Triphosphate

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4
Q

What are DNA and RNA examples of?

A

Polynucleotides.

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5
Q

What are the 3 main Carbohydrates?

A

Starch
Cellulose
Glycogen

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6
Q

Why are Starch and Glycogen good storage molecules?

A

They are long chains of glucose and are insoluble

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7
Q

How are Disaccharides formed and name the 3 main disaccharides.

A

From a condensation reaction involving 2 monosaccharides.
Maltose=Glucose and Glucose (alpha)
Sucrose=Glucose and Fructose
Lactose=Glucose and Galactose

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8
Q

What is a Hydrolysis reaction

A

Where a water molecule is added to a bond in order to break it

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9
Q

What is a condensation reaction

A

Where a water molecule is removed and a bond forms between 2 molecules.

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10
Q

What is a reducing sugar?

A

A Sugar which is able to give/donate an electron to reduce a solution. (and occasionally donate a hydrogen ion)

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11
Q

Name 3 reducing sugars

A

Glucose, Fructose, Galactose.

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12
Q

Which disaccharide is not a reducing sugar?

A

Sucrose as this cannot donate an electron and will not produce a positive result in the reducing sugars test.

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13
Q

What is an Aldehyde?

A

A reducing sugar is an Aldehyde. Their structural group is R-CHO.

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14
Q

What is the test for a Reducing sugar?

A
  1. Crush/ grind up the sample to be tested.
  2. Add a few cm of distilled water.
  3. Add a few cm of benedicts reagent.
  4. Heat in a water bath at 95 degrees for 5 mins
  5. Positive result = Brick Red/orange precipitate.
    Negative result = No colour change.
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15
Q

What is a Non-reducing sugar?

A

Non-reducing sugars do not reduce solutions as they themselves cannot be oxidised. (eg.Sucrose)
The monosaccharides that make non-reducing sugars have thier Oh and HO groups removed by condensation. To test if a sugar is non reducing the glycosidic bond must be broken by a hydrolysis reaction.

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16
Q

What is the test for a non-reducing sugar?

A
  1. Crush/grind up the sample to be tested.
  2. Add a few cm of HCl and heat in water bath for 3 mins to hydrolyse the sample.
  3. Neutralise the sample by adding sodium carbonate until neutral/ slightly alkaline.
  4. Add benedicts reagent and heat again in water bath for 5 mins.
  5. Positive result = Brick red/ orange precipitate
    Negative result = No colour change.
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17
Q

What are the Disaccharidases?

A

Maltase, Lactase, Sucrase.

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18
Q

Why is starch a good storage molecule?

A

The alpha helix structure of starch makes it compact and the 1-4 glycosidic liking means that a large quantity of glucose can be stored in a small area. The glycosidic bond angle gives a coiled structure allowing more glucose molecules to be stored within coils. Starch is Insoluble.

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19
Q

Why is starch efficient at releasing energy? (ATP)

A

The enzymes that break down the molecule are easily able to catalyse a reaction to break the glycosidic bond so the release of glucose molecules is quick and efficient.

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20
Q

Why is Glycogen a good storage molecule?

A

Glycogens structure has a lot of branching enzymes which create an alpha 1-6 glycosidic link allowing extensive branches to develop. This means that a glycogen molecule can have long polysaccharide chains so more glucose molecules can be stored and individually cut out when required.

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21
Q

Why is Cellulose so strong/ a supportive molecule?

A

Cellulose is made up of 2 polysaccharide chains of beta glucose. The 2 polysaccharide chains are layered on top of each other and are linked horizontally by hydrogen bonds creating micro-fibrils. This gives the unique property of strength as the 2 layers cannon move past each other.

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22
Q

What is the test for starch?

A
  1. Grind/crush the sample to be tested.
  2. Add a few cm of distilled water.
  3. Add 2-3 drops of Iodine.
  4. Positive result = purple/blue/black colouring.
23
Q

What is the monomer of a protein

A

Amino Acids

24
Q

Give some examples of proteins

A 
Enzymes
Hormones
Antibodies
Carrier/Transport Proteins
Keratin
Haemoglobin
25
Q

What is the general formula for an amino acid?

A

CH(R)NH2C00H

26
Q

How are polymers of amino acids formed? and what are they called?

A

Polypeptides formed by a condensation reaction creating a peptide bond. (2 amino acids bonded together is called a dipeptide)

27
Q

How many protein structures are there and what are they?

A

4

  1. Primary Structure
  2. Secondary Structure
  3. Tertiary Structure
  4. Quaternary Structure
28
Q

What is the primary structure of a protein?

A

The number and sequence/order of which the amino acids appear in the sequence. THis determines which protein it will be.

29
Q

What is the secondary structure of a protein?

A

Hydrogen bonds form between the oxygen and hydrogen atoms on different amino acids in the primary structure. This causes the protein to fold into an alpha helix or beta pleated sheet. The polypeptide chains are pulled into a regular shape by the hydrogen bonds.

30
Q

What is the tertiary structure of a protein?

A

Proteins are folded around themselves even more than regular secondary structured proteins. Depending on the type of R group of the amino acids, Disulphide (bridges), Hydrogen or Ionic bonds will form folding the proteins into a specific shape. The function of a protein depends on the bonding and shape of the tertiary structure.

31
Q

What is the Quaternary structure of a protein?

A

One or more polypeptides bonded together via Hydrogen, Disulphide or Ionic bonds.
Examples-Haemoglobin
-Antibodies
-Keratin

32
Q

What are Enzymes?

A

Enzymes are proteins with the function to be a biological catalyst. These catalysts cannot be used up within a reaction.

33
Q

What do Enzymes do?

A

speed up the rate of a reaction by providing an alternative pathway for the reaction to take place with a lower activation energy.
They also lower the transition state energy.

34
Q

What is the induced fit hypothesis?

A

The original active site changes slightly to get a tight fit to the substrate so that the catalysing complex is at full force.

35
Q

Give some comparisons between the induced fit model and lock and key hypothesis.

A

Lock & Key:
Exact fit between the substrate and the enzymes active site. Enzymes are specific
Similarities:
Lowers activation energy. Both have an active site binding to a substrate. Both form an enzyme substrate complex.
Induced Fit:
Active site and substrate both slightly change to ensure a perfect fit. Enzymes are not completely specific.

36
Q

What are competitive inhibitors of an enzyme and what do they do?

A

Competitive Inhibitors can fit into the active site due to the fact they are complimentary in shape.
This blocks the active site from binding to a substrate and therefore preventing the formation of the enzyme substrate complex.
This is not a permanent binding.

37
Q

What are Non-competitive inhibitors and what do they do?

A

Non-competitive inhibitors bind to an enzymes allosteric site.
This changes affects the bonds in the tertiary structure of the enzyme so the active site changes shape and is not longer complimentary to the substrate.
This also prevents the formation of the enzyme substrate complex. The change in the tertiary structure is permanent.

38
Q

What is RUBISCO?

A

An inefficient enzyme which attempts to catalyse the reactions in photosynthesis.

39
Q

How do you calculate rate of reaction from a graph?

A

Calculate the gradient:
(Change in y/ Change in x)
For curved graphs draw a tangent and then calculate the gradient.

40
Q

What are the equations to calculate pH or [H+]

A

pH=-log([H+])

[H+]=10^-pH

41
Q

What does ATP stand for and what are its main components?

A

Adenosine Triphosphate.
Adenine= Nitrogenous organic base
Ribsose= Pentose sugar
Phosphate groups x3

42
Q

What happens during the hydrolysis of ATP?

A

ATP= ADP + Pi

Enzyme to catalyses ATP is ATPsynthase.

43
Q

What does ATP do?

A

Releases smal packets of energy in manageable amounts.
Phosphate released through hydrolysis of ATP can be used to phosphorylate molecules (eg. in respiration/photosynthesis)
Released energy can be used in active transport or building macromolecules.

44
Q

Why is ATP good at releasing energy?

A

Can easily be hydrolised in a one step reaction to form ADP and Pi.
ATP is a soluble molecule.
ATP cannot be stored so must be used up quickly.

45
Q

What are the main properties of a water molecule?

A 
Biological solvent
Forming in or is necessary for metabolic reactions
High specific heat capacity
High latent heat of vapourisation
Adhesion
Cohesion
46
Q

Explain the solvent properties of water.

A

Due to water molecules being Bi-polar, water can act as a powerful solvent to other polar substances,

47
Q

Explain the high specific heat capacity of water.

A

A lot of heat is required to raise the temperature of water due to the energy required to break the hydrogen bonds between water molecules.

48
Q

How is water linked to metabolic reactions?

A

Water is either formed or used in metabolic reactions due to the condensation or hydrolysis reactions that take part. Water is the solvent of the body and regulates all functions.

49
Q

How is water Adhesive?

A

Water is attracted to other substances.
(eg. in a glass of water, the water level is higher on the sides than the centre due to the attraction between the glass and the water molecules.

50
Q

How is water Cohesive?

A

Water molecules are attracted to other water molecules & essentially give water its sticky properties as water will combine to other water molecules.
(eg. formation of water droplets)

51
Q

Explain the density of water.

A

As water freezes it expands (mass per unit volume decreases) so Ice is therefore less dense than water and will float.
In Ice water molecules form a rigid structure so there is more space between molecules.

52
Q

How does water create surface tension?

A

Behaves like an elastic sheet due to the intermolecular forces of attraction between water molecules in the liquid.

53
Q

Explain waters high latent heat of vaporisation property.

A

When changing state a substance absorbs or expels heath without changing temperature.
Water absorbs large amounts of heat energy when vaporising so as water molecules evaporate the molecules kinetic energy leaves with them, therefore the average kinetic energy decreases and the water cools down.

A-levels (23 decks)

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