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Biological molecules Flashcards

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1
Q

What are the 6 main elements that make up the complex molecules found in living things?

A
  1. S: Sulfur
  2. P: Phosphoris
  3. O: Oxygen
  4. N: Nitrogen
  5. C: Carbon
  6. H: Hydrogen
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2
Q

What is a molecule?

A

A group (2 or more) atoms bonded (covalently) together.

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3
Q

Are all molecules compunds? Explain

A

No

O2 is a molecule made from two oxygen molecules bonded together, therefore it is a molecule that is an element not a compund.

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4
Q

What are the 4 main types of maromolecules that make up living things?

A
  1. Carbohydrates
  2. Proteins
  3. Lipids (including fats)
  4. Nucleic acids (DNA and RNA)
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5
Q

What is an organic molecule?

A

A molecule that cotains carbon (and hydrogen).

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6
Q

What are macromolecules?

A

Molecules made from large numbers (hundreds or thousands) of atoms.

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7
Q

What are monomers and polymers are?

A

Monomers: Small molecules that join together to make polymers

Polymers: Long chains of similar molecules (monomers joined together)

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8
Q

Name as many polymers found in living things as you can.

A

Carbohydrate polymers: Starch, cellulose, glycogen.

Nucleic acids: DNA and RNA

Polypeptides: The polymers that form proteins.

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9
Q

What elements are carbohydrates made from?

A

Carbon

Hydrogen

Oxygen

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10
Q

What is the ratio of hydrogen to oxygen atoms in carbohydrates?

A

2:1 (hydrogen:oxygen)

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11
Q

Name three monosaccharides.

A

Glucose

Fructose

Galactose

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12
Q

Name 3 disaccharides

A

Maltose

Sucrose

Lactose

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13
Q

What monosaccharides join to form maltose?

A

2 alpha-glucose molecules

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14
Q

What monosaccharides join to form sucrose?

A

An alpha-glucose and a fructose molecule

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15
Q

What monosaccharides join to form lactose?

A

An alpha-glucose and a galactose molecule

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16
Q

What type of bonds is formed during condensation of two monosaccharides?

A

A glycosidic bond

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17
Q

Alpha glucose, beta glucose and galactose are isomers. What does the term isomer mean?

A

Molecules with the same chemical formula but different arrangements of atoms.

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18
Q

Which two polysaccharides are used for storage of glucose?

A

Glycogen

Starch

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19
Q

Which two polysaccharides are found in plants?

A

Cellulose

Starch

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20
Q

Which polysaccharides are found in animal cells?

A

Glycogen

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21
Q

Which polysaccharides might you find in the digestive system of herbivores (plant eaters)?

A

Starch

Cellulose

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22
Q

Which polysaccharides are made from alpha glucose?

A

Starch

Glycogen

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23
Q

Which polysaccharides is made from beta-glucose?

A

Cellulose

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24
Q

What two molecules is starch made from?

A

Amylose

Amylopectin

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25
Q

Describe the structure of amylose.

A
  • A chain
  • (of) Alpha glucose molecules
  • Bonded by 1,4-glycosidic bonds
  • Coiled into spirals
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26
Q

Describe the structure of amylopectin.

A
  • Branched chains
  • (of) Alpha glucose molecules
  • Bonded by 1,4-and 1,6-glycosidic bonds
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27
Q

Describe the structure of glycogen.

A
  • Branched chains
  • (of) Alpha glucose molecules
  • Bonded by 1,4-and 1,6-glycosidic bonds
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28
Q

In what way do the structure of glycogen and amylopectin differ?

A
  • Glycogen has more branches (more 1,6-glycosidic bonds).
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29
Q

In what ways are glycogen and starch adapted to their function as storage molecules?

A
  1. They are insoluble
  2. They are easy to make
  3. They are easy to break down
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30
Q

Why do storage molecules need to be insoluble?

A
  1. So that they do not alter the water potential of the cell: Cause water to leave or enter the cell.
  2. So that they stay in the desired location. Soluble molecules would diffuse to other parts of the cell organism.
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31
Q

Why do storage molecules need to be easy to break down?

A

So that glucose can be made available quickly for respiration (to release energy)

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32
Q

Where is starch stored in plants?

A

In leaves (overnight storage)

In seeds

In bulbs and tubers (winter storage)

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33
Q

Where is glycogen stored in animals?

A

(Small reserves) In muscle cells

(Large reserves) In the liver

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34
Q

What is the function of cellulose?

A

It is a structural molecule found in plant cell walls.

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35
Q

What monomers is cellulose made from?

A

Beta glucose

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36
Q

What type of bonds hold the beta-glucose molecules together in cellulose?

A

1,4 glycosidic bonds

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37
Q

Cellulose chains are linked together to form microfibrils. What type of bonds hold the cellulose chain/molecules together?

A

Hydrogen bonds

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38
Q

Cellulose is difficult to break down. Explain why.

A

Because:

  • Each cellulose molecule only has two ends (no branches) where digestion can begin.
  • The ends are embeded within microfibrils so are difficult for enzymes to get to.
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39
Q

As well as being difficult to break down, how else is cellulose adapted to its function?

A
  1. It’s insoluble.
  2. Cellulose microfibrils and firers are extremelly strong.
  3. It’s easy to make.
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40
Q

What elements are proteins made from?

A

Carbon, hydrogen, oxygen, nitrogen and sulfur

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41
Q

What monomers are polypeptides made from?

A

Amino acids

42
Q

What type of bond forms between amino acids during condensation?

A

Peptide bonds

43
Q

Amino acids are made from a central carbon atom, bonded to a hydrogen atom and 3 other groups. What are the 3 other groups?

A
  1. Carboxyl group (COOH)
  2. Amino group (NH2)
  3. R-group (variable group)
44
Q

What is meant by the PRIMARY structure of a protein?

A
  • Number
  • Type
  • Order
  • of amino acids
  • In the polypeptide chains
45
Q

What type of bonds are involved in maintaining the primary structure?

A

Peptide bonds

46
Q

What is meant by the SECONDARY structure of a protein?

A

The bending and folding to give an alpha-helix or beta-pleated sheet.

47
Q

What type of bonds maintain the secondary structure in proteins?

A

Hydrogen bonds

48
Q

What is meant by the TERTIARY structure of a protein?

A

The bending and folding of the polypeptide chains

To give them their globular or fibrous structure.

49
Q

What type of bonds maintain the tertiary structure of a protein?

A

Hydrogen bonds

Ionic bonds

Disulfide bonds

50
Q

What is meant by the QUATERNARY structure of a protein?

A

The bonding of two or more polypeptides

And/or other groups

51
Q

What type of bonds maintain the quaternary structure of a protein?

A

Hydrogen bonds

Ionic bonds

Disulfide bonds

52
Q

Triglycerides (fast and oils) are lipids. What other molecules are liids?

A
  • Waxes
  • Steriods
  • Sterols
  • Phospholipids
53
Q

What elements are lipids made from?

A
  • Carbon
  • Hydrogen
  • Oxygen
54
Q

What are lipids used for in living things?

A
  • Energy storage
  • Insulation
  • Protecting vital organs
  • Waterproofing
  • Plasma membranes
55
Q

Why is more energy stred as lipids than as gycerol in animals?

A

Twice as much energy stored per gram in lipids

56
Q

What are lipids made from?

A

Fatty acids

Alcohols

57
Q

What are triglycerides made from?

A

THREE Fatty acids

Glycerol (an alcohol)

58
Q

Through want type of reaction do fatty acids become bonded to glycerol?

A

Condensaton

59
Q

Describe or draw the structure of glycerol.

A

3 carbon atoms (saturated)

Each carbon atoms is bonded to a hydrogen atom and a hydroxyl group (OH)

The end carbon atoms are also bonded to an additional hydrogen atom.

60
Q

Describe the structure of a saturated fatty acid.

A

A carboxyl group (COOH)

Bonded to a hydrocarbon chain

Saturated: All the carbon atoms are bonded to each other by single bonds

61
Q

Describe the structure of a unsaturated fatty acid.

A

A carboxyl group (COOH)

Bonded to a hydrocarbon chain

Unaturated: One or more pairs of carbon atoms are bonded t each other by double bonds.

62
Q
  • What are the two types of nuclei acids?
A

DNA (deoxyribonucleic acids)

RNA (Ribonucleic acids)

63
Q

What monomers are nucleic acids made from?

A

Nucleotides

64
Q

What elements are nucleic acids made from?

A

Carbon

Hydrogen

Oxygen

Nitrogen

Phosphorus

65
Q

What groups are nucleotides made from? How do these differ in DNA and RNA?

A
  1. Pentose sugar (Deoxyribose in DNA and Ribose in RNA)
  2. Phosphate group
  3. Nitrogen containing base (Adenine, Cytosine, Guanine or Thymine in DNA, Thymine replaced by Uracil in RNA)
66
Q

What type of bonds form between nucleotides during condensation reactions?

A

Phosphodiester bonds

67
Q

DNA is made from two polynucleotide chains that are bonded together. What type of bonds hold the chains together?

A

Hydrogen bonds.

68
Q

Hydrogen bonds form between nitogen containing bases. Which bases bond to each other (are complementary)?

A

Adenine bonds to thymine (or Uracil in RNA)

Guanine bonds to cytosine

69
Q

Describe the structure of DNA.

A
  1. Two (antiparallel) polynucleotide chains: Chains of nucleotides bonded by phosphodiester bonds.
  2. Bonded to each other by hydrogen bonds.
  3. Between complementary bases: A to T and C to G.
  4. Twisted into a double helix.
70
Q

What are the three main stages in DNA replication?

A
  1. The polynucleotides strands (unwind and) seperate.
  2. Free DNA nucleotides bond to exposed bases on the template strand.
  3. New nucleotides bond (phosphodiester) together.
71
Q

What is the role of DNA helicase during DNA replication?

A

It breaks the hydrogen bons between the polynucleotide strands, allowing them to unwind and seperate.

72
Q

What is the role of DNA polymerase during DNA replication?

A

It catalyses the formation of condensation reactions between nucleotides to form phosphodiester bonds, creating the sugar phosphate backbone.

73
Q

Why is DNA replication called semi-conservative replication?

A

One original polynucleotide strand remains intact (is conserved) and one new complementary strand is made.

74
Q

What is ATP made from?

A
  1. Ribose
  2. Adenine
  3. Three inorganic phosphate groups
75
Q

Whys is ATP described as a ‘nucleotide derivative’

A

Because it is a modified (two phosphate groups have been added) RNA nucleotide.

76
Q

Whys is ATP described as the immediate energy source.

A

Because ATP is the molecule that directly provides energy to all the enery requiring processes that take place in living things.

77
Q

Give three examples of processes that require energy from ATP.

A
  1. Biosynthesis: Protein synthesis, DNA replication, synthesis of phospholipids.
  2. Muscle contraction
  3. Active transport: Moving particles across plasma membranes against their concentration gradient.
  4. Cytoplasmic transport: Vesicles or organelles can be transported along microtubule tracks using molecular motor proteins.
78
Q

In what ways is ATP adapted to its function?

A

It is small and soluble: so can diffuse rapidly to the areas of the cells where it is needed.

It can release energy through a single hydrolysis reaction: Thererefore making energy available very quickly.

79
Q

Describe how ATP is synthesised.

A
  1. Made from ADP and an inorganic phosphate group.
  2. Condensation reaction (H2O also made).
  3. Catalysed by ATP synthase.
  4. Energy provided by respiration (or photosynthesis).
80
Q

Water is a solvent? Why is this important for living organisms?

A
  1. Most metabolic reactions take place in solution.
  2. Substances are easier to transport in solution.
81
Q

Water molecules are cohesive? Why is this important for living organisms?

A
  1. Helps water transport in plants.
  2. Supports transport in other organisms.
82
Q

Water has a high latent heat of vaporisation? Why is this important for living organisms?

A

It allows organisms to cool down (e.g through sweating, panting and transpiration) without significant water loss.

83
Q

Water has a high specific heat capacity? Why is this important for living organisms?

A
  1. It helps organisms maintain a stable internal temperature.
  2. It provides a stable external temperature for water bourne organisms.
84
Q

Explain why water molecules are polar.

A
  • The shared electrons are pulled towards the oxygen nucleus.
  • Giving the hydrogen atoms a slight positive charge.
  • The unshared negative electrons on the oxygen atom, give it a slight negative charge.
85
Q

Explain why water molecules are cohesive.

A
  1. The negatively charged oxygen atoms of water molecules attract the positively charged hydrogen atoms of other water molecules.
  2. Forming hydrogen bonds.
86
Q

What are ions?

A

Atoms or groups of atoms that have an electric charge.

87
Q

What are positively charged ions called?

A

Cations

88
Q

What are negatively charged ions called?

A

Anions

89
Q

What type of ions are at the centre of each of the polypeptides in haemoglobin?

A

Iron ions

90
Q

What type of ions determine the pH of a region?

A

Hydrogen ions

91
Q

Glucose and amino acids are transported into cells alongisde which type of ions? What is this process called?

A

Sodium ions

Co-transport

92
Q

How do catalysts speed up the rate of reaction?

A

By reducing activation energy.

Increasing the proprtion of collisions that are successful.

93
Q

What is an intracellular enzyme? Give an example?

A

An enzyme that is active within cells. E.g DNA helicase, DNA polymerase, ATP synthase and ATP hydrolase.

94
Q

What is an extracellular enzyme? Give an example?

A

An enzyme that is active outside of cells. E.g All the enzymes in the digestive system: Pepsin, salivary amylase etc.

95
Q

What is activation energy?

A

How much energy you have to put into a system to make a chemical reaction occur.

How much energy reactant /substrate molecules need to react

96
Q

What part of the enzyme bonds to the substrate?

A

The active site

97
Q

The shape of an enzyme and the substrate for the enzyme is catalyses are described as…

A

complementary

98
Q

Describe the lock and key model of enzyme action.

A

The enzyme’s active site and substrate have complimentary shapes.

Like a lock and key.

The substrate binds to the active site forming an enzyme-substrate complex.

99
Q

What are the limitations of the lock and key model?

A
  • It does not take into account the fact that enzymes change shape when the substarte bonds to the active site.
  • It does not explain how enzymes reduce activation energy.
100
Q

Describe the induced-fit model of enzyme action.

A
  • The enzyme’s active site and substrate have complimentary shapes.
  • The substrate binds to the active site forming an enzyme-substrate complex.
  • As the substrate enters the active site the enzyme changes shape slightly.
  • This exerts a force/puts pressure/puts stress on the bonds in the substrate.
  • This brings the substarte molecules closer together overcoming repulsive forces between them.
101
Q

What do we call the pH or temperature at which an enzyme works best.

A

The optimum pH/temperature.

102
Q
A

Biology A-Level (1 decks)

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