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Biology A-level > Biological Molecules > Flashcards

Biological Molecules Flashcards

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1
Q

What is the chemical process that combines several monomers to form polymers?

A

Polymerisation

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2
Q

What is a monomer?

A

A single molecule

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3
Q

What is a polymer?

A

Many molecules bonded together to make a chain

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4
Q

What are disaccharides?

A

Sugars composed of two monosaccharides covalently bonded together by a glyosidic link.

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5
Q

What is maltose formed from?

A

Two glucose molecules

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6
Q

What is lactose formed from?

A

a disaccharide formed when ​the monosaccharides glucose and galactose bond

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7
Q

What is sucrose formed from?

A

Glucose and fructose

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8
Q

What is a polysaccharide?

A

carbohydrate composed of many monosaccharides

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9
Q

What is glycogen made of?

A

Glycogen is the stored form of glucose and is made from many connected glucose molecules

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10
Q

What is starch made from?

A

Starch is a chain of bound glucose molecules, made up of amylose and amylopectin. Its a way of storing energy for plants.

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11
Q

How is glycogens structure related to its function?

A

Insoluble-No osmotic effect
Large molecules-Allows for more storage
Compact-More storage space
(structure is glucose residues in linear chains linked by 1-4 and 1-6 glyosidic bonds)

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12
Q

How is starches structure related to its function?

A

Insoluble-No osomotic effect
Large molecules-Allows more storage space
Amylopectin large SA- More storage room

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13
Q

How is celluloses structure related to its function?

A

Straight chain provides strength.
Large NO of hydrogen bonds give strength
( Made of B-glucose and does not undergo coiling)

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14
Q

What is the activation energy?

A

The minimum amount of energy required to start a reaction.

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15
Q

What is the saturation point?

A

Where there is an excess substrate concentration so all enzymes have been used up

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16
Q

What do competitive inhibitors do?

A

Bind to the active site. Can be out competed by higher substrate concentrations.

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17
Q

What do non-competitive inhibitors do?

A

Bind to allosteric site which alters the shape of the active site therefore can not be affected by concentrations. Substrate can bind to the active site but no reaction will occur.

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18
Q

What is end product inhibition?

A

If there is too much of the final product, the product will inhibit the first reaction so it stops being made.

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19
Q

What is a metabolic pathway?

A

Sequences of chemical reactions each controlled by a specific enzyme.

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20
Q

What is the role of lipids?

A

Storing energy, insulation and protection

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21
Q

What are the two main groups of lipids?

A

Triglycerides and phopholipids

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22
Q

How is the structure of triglycerides related to its function?

A

Non-polar so insoluble in water.
Long carbon chains=insoluble and can store more energy
Fatty acids are hydrophobic so so not cause osmotic uptake

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23
Q

What bond is formed when a fatty acid joins to glycerol?

A

Ester bond

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24
Q

What does having unsaturated r groups do to the fluidity of the triglycerides?

A

Can not make intermolecular hydrogen bonds and become solid.

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25
Q

Difference in structure between phospholipids and triglycerides?

A

Phospholipids have two fatty acids and a phosphate head whilst triglycerides have three fatty acids and no phosphate head

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26
Q

How do triglycerides react to water?

A

Hydrophobic

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27
Q

How do phospholipids react to water?

A

Head is hydrophilic and tail is hydrophobic

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28
Q

What is the primary structure of the protein?

A

The amino acid sequence and the number of acids in the polypeptide.
Determined by the codons on mRNA.

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29
Q

What is the secondary sequence of the protein?

A

The 3D shape such as the alpha helix and beta pleated sheet created by the hydrogen bond between the carboxylic acid and amine group

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30
Q

What is the tertiary structure of the protein?

A

The alpha helix that has been twisted to give a more complex 3D structure. Maintained by many bonds.

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31
Q

What is the quaternary structure of the protein?

A

Allows protein to fulfill more functions. The result of two or more polypeptide chains. May involve a prosthetic group E.G phosphate group or metal ions.

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32
Q

State the bond involved in the secondary structure.

A

Hydrogen bond

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33
Q

State the bonds involved in the tertiary structure.

A

Disulfide
Ionic
Hydrogen

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34
Q

What is the test for proteins?

A

Biuret. Add equal volumes of the sample and Biuret reagent, mix gently, colour changes from blue to purple.

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35
Q

What is the main role of fibrous proteins?

A

Structural support

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36
Q

What is the main role of globular proteins?

A

Metabolic reactions

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37
Q

What is a polysaccharide?

A

A carbohydrate composed of many monosaccharides.

38
Q

What is the structure of glycogen?

A

Linear chains linked by 1,4 and 1,6 glyosidic bonds

39
Q

What are metabolic reactions?

A

The sum of all reactions in the organism

40
Q

What is the induced fit model?

A

Based on the idea the enzyme is slightly complementary to the substrate. While they bind, the enzyme changes its shape slightly to fit around the substrate.

41
Q

What creates the active site?

A

Tertiary structure

42
Q

What factors are involved in the rate of enzyme controlled reactions?

A

Temperature, inhibitors, substrate and enzyme concentrations and ph.

43
Q

How does a competitive inhibitor affect the working of an enzyme?

A

Has a similar shape to the substrate so binds to the active site.

44
Q

Would a competitive inhibitor stop the reaction completely?

A

No as it is not permanently binded. Eventually all substrates will bind.

45
Q

How does a non-competitive inhibitor affect the working of an enzyme?

A

Binds to the allosteric site and alters the shape of the active site.

46
Q

What does ABBA symbolise?

A

Alpha below, beta above.
(The OH group on Carbon 1 of a-glucose is below the ring, on B-glucose it is above)

47
Q

Name the type of bond formed when monosaccharides react

A

Glycosidic bond

48
Q

Why is water a polar molecule?

A

Oxygen is more electronegative than hydrogen, so attracts the electron density in the covalent bond more strongly.

49
Q

State four biologically important properties of water

A
  • Solvent for chemical reactions in the body
  • High specific heat capacity
  • High latent heat of vaporisation
  • Cohesion between molecules
    ( Due to polarity and hydrogen bonds)
50
Q

Explain why water is significant to living organisms

A
  • Solvent for polar molecules during metabolic organisms
  • Enables organisms to avoid fluctuations in core temperature
  • Cohesion-tension of water molecules in the transpiration stream
51
Q

Describe the structure of adenosine triphosphate (ATP)

A

Nucleotide derivative of adenine with three phosphate groups and ribose

52
Q

Explain the role of ATP in cells

A
  • Energy released is coupled to metabolic reactions
  • Phosphate groups phosphorylates compounds to make them more reactive
53
Q

How is ATP re-synthesised in cells?

A
  • ATP synthase catalyses condensation reaction between ADP and Pi
  • During photosynthesis and respiration
54
Q

Explain why ATP is suitable as the energy currency of cells

A
  • Small amounts of energy are released at a time so less energy is wasted as heat and matches the needs of cellular reactions
  • Single-step hydrolysis so energy is available quickly
  • Readily resynthesised
  • Weak, unstable bonds which are broken down easily
  • Phosphorylates other compounds making them more reactive
55
Q

What three groups do nucleotides contain?

A

A nitrogenous base
A phosphate group
A pentose sugar

56
Q

What is the sugar in DNA?

A

Deoxyribose

57
Q

What is the sugar in RNA?

A

Ribose

58
Q

What are the bases included in DNA?

A

Adenine
Cytosine
Thymine
Guanine

59
Q

What are the bases included in RNA?

A

Adenine
Cytosine
Uracil
Guanine

60
Q

What is the 5’ end?

A

Free phosphate group

61
Q

Where is the 3’ end?

A

Free OH group

62
Q

What is the role of RNA?

A

Transfers the genetic information from the DNA in order for the correct ribosomes to produce

63
Q

What is the role of DNA?

A

Contains the genetic information

64
Q

State the mechanism of DNA replication

A

Semi-conservative replication

65
Q

Describe semi-conservative replication

A

DNA helicase causes the two strands of DNA to separate, free nucleotides bind to their complementary bases, and they are joined together by DNA polymerase which makes phosphodiester bonds.

66
Q

Describe the structure of DNA

A
  • Double helix
  • Large molecule
  • Two polynucleotide chains held by hydrogen bonds
67
Q

How is the structure of DNA related to its function?

A
  • Stable structure that can be passed from generation to generation
  • Two separate strands joined by hydrogen bonds allow replication
  • Large molecule so can store more genetic information
  • Genetic information is protected by a sugar-phosphate backbone.
  • Base pairing leads to DNA being able to replicate and transfer information as mRNA.
68
Q

State the number of hydrogen bonds between A and T

A

Two

69
Q

State the number of hydrogen bonds between C and G

A

Three

70
Q

What is the bond between two nucleotides?

A

Phosphodiester bond

71
Q

Describe the structure of RNA

A

Relatively short polynucleotide chain

72
Q

What is the process of DNA replication?

A
  • Unwinding of the double helix.
  • Breakage of hydrogen bonds by DNA helicase
  • Attraction of new DNA nucleotides to exposed bases on template strands (complementary base pairing)
  • DNA Polymerase joins adjacent nucleotides in a condensation reaction.
73
Q

What enzyme is required to make ATP?

A

ATP synthase

74
Q

What enzyme is required to hydrolyze ATP?

A

ATP hydrolase

75
Q

What is formed in ATP hydrolysis?

A

ADP

76
Q

State the roles of ATP

A
  • Muscle contraction
  • Active transport
  • Metabolic reactions
  • Activation molecules
77
Q

What are the reactants needed to make ATP?

A

ADP and inorganic phosphate ion

78
Q

Why is semi-conservative replication important in the genetic continuity between cells?

A

Ensures genetic continuity between generations. Means there will always be a strand of former DNA molecule used as a template. Semi-conservative means half is preserved and half is new.

79
Q

What does DNA polymerase do?

A

Catalyses condensation reaction, creating phosphodiester bonds between nucleotides

80
Q

What are the new strands of DNA formed from?

A

Free nucleotides

81
Q

How do the free nucleotides get into the right order when they form the new strand during DNA replication?

A

Original strand acts as a template
Complementary base pairing attraction

82
Q

Why does ATP need to be constantly made?

A

Can not be stored

83
Q

What is cohesion in terms of water?

A

Where water sticks to itself

84
Q

What is surface tension in terms of water?

A

Where a body of water meets the air and hydrogen bonds occur between the top layer of water molecules to create a sort of film on the body of water allowing certain insects to float.

85
Q

Name five inorganic compounds

A

Hydrogen, phosphate, iron, sodium, and calcium.

86
Q

Why is iron ion important and what is it a key component of?

A

It can bind to oxygen and so is a key component of haemoglobin

87
Q

Why are sodium ions important?

A

Required for the transport of glucose and amino acids across the cell surface membrane by co-transport.

88
Q

Why are phosphate ions important?

A

Attaches to other molecules to form phosphate groups.
Essential in ATP, DNA, and RNA.
Phosphate groups allow DNA and RNA to join up.

89
Q

Why are calcium ions important?

A

Essential in the movement of organisms and stimulates muscle contraction and regulates protein channels.

90
Q

What is the general structure of an amino acid?

A

-COOH (carboxylic group)
-R (Variable group)
-NH2 (Amino group)

91
Q

Describe the structure of globular proteins

A

Spherical and compact
Usually water soluble
Hydrophilic R groups face out and hydrophobic R groups face in

92
Q

Describe the structure of fibrous proteins

A

Can form long chains or fibres
Insoluble in water

Biology A-level (22 decks)

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