1. MOLECULES TO METABOLISM
Living organisms control their composition by a complex web of chemical reactions.
Topic 2.1
IB Biology
Miss Werba

2. TOPIC 2 – MOLECULAR BIOLOGY
2.1
MOLECULES TO METABOLISM
2.2
WATER
2.3
CARBOHYDRATES & LIPIDS
2.4
PROTEINS
2.5
ENZYMES
2.6 STRUCTURE OF DNA & RNA
2.7 DNA REPLICATION, TRANSCRIPTION & TRANSLATION
2.8 CELL RESPIRATION
2.9 PHOTOSYNTHESIS
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3. THINGS TO COVER Statement Guidance U.1 U.2 U.3 U.4 U.5 U.6 A.1
Molecular biology explains living processes in terms of the chemical substances involved.
U.2
Carbon atoms can form four covalent bonds allowing a diversity of stable compounds to exist.
U.3
Life is based on carbon compounds including carbohydrates, lipids, proteins and nucleic acids.
U.4
Metabolism is the web of all the enzyme-catalysed reactions in a cell or organism.
U.5
Anabolism is the synthesis of complex molecules from simpler molecules including the formation of macromolecules from monomers by condensation reactions.
U.6
Catabolism is the breakdown of complex molecules into simpler molecules including the hydrolysis of macromolecules into monomers.
A.1
Urea as an example of a compound that is produced by living organisms but can also be artificially synthesized
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4. THINGS TO COVER Statement Guidance S.1 S.2
Drawing molecular diagrams of glucose, ribose, a saturated fatty acid and a generalized amino acid.
Only the ring forms of D-ribose, alpha–D-glucose and beta-D-glucose are expected.
Sugars include monosaccharides and disaccharides.
Only one saturated fat is expected and its specific name is not necessary.
The variable radical of amino acids can be shown as R. Don’t need to memorise the structure of individual R-groups.
S.2
Identification of biochemicals such as sugars, lipids or amino acids from molecular diagrams.
Should be able to recognize that triglycerides, phospholipids and steroids are lipids from molecular diagrams. Drawings of steroids are not expected.
Proteins or parts of polypeptides should be recognized from molecular diagrams showing amino acids linked by peptide bonds.
NOS 1.9
Falsification of theories
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5. MOLECULAR BIOLOGY
U.1
Molecular biology explains living processes in terms of the chemical substances involved.
Molecular biologists would identify the steps in a metabolic pathway and break down each step into its components.
This has allowed us to better understand the processes of cellular respiration and photosynthesis.
But there is still a lot that we don’t understand about organic molecules and how they act in the body.
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6. CARBON ATOMS
U.2
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7. CARBON ATOMS Carbon is the backbone of every organic molecule.
Carbon atoms can form four covalent bonds allowing a diversity of stable compounds to exist.
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8. CARBON ATOMS Covalent bonds are very strong.
U.2
Covalent bonds are very strong.
This allows large, stable molecules to be formed.
eg. Titin protein (contains 539,000 atoms) found within contractile unit of muscle fibres
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9. CARBON COMPOUNDS Life is based on carbon compounds. These include:
carbohydrates
lipids
proteins and
nucleic acids
Glucose = carbohydrate
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10. CARBON COMPOUNDS
U.3
S.2
S.3
You need to be able to draw molecular diagrams these compounds:
inc. glucose, ribose, a saturated fatty acid and a generalized amino acid
You need to be able to identify biochemicals such as sugars, lipids or amino acids from molecular diagrams.
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11. CARBOHYDRATES Identify: monosaccharides and disaccharides
U.3
S.2
S.3
Identify: monosaccharides and disaccharides
Monosaccharides: Glucose, galactose, fructose
Disaccharides: Lactose, maltose, sucrose
Polysaccharides: Cellulose, glycogen, starch
glycosidic bond
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12. CARBOHYDRATES Identify: monosaccharides and disaccharides
U.3
S.2
S.3
Identify: monosaccharides and disaccharides
Disaccharides: sucrose
glycosidic bond
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13. CARBOHYDRATES hexose sugars
Draw: the ring forms of D-ribose, alpha–D-glucose and beta-D-glucose
alpha-D-glucose beta-D-glucose
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14. CARBOHYDRATES pentose sugar
Draw: the ring forms of D-ribose, alpha–D-glucose and beta-D-glucose
D-ribose
used in RNA
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15. LIPIDS Draw: a saturated fatty acid Identify: lipids
Saturated fatty acid: no double bonds
eg. stearic acid
Unsaturated fatty acid: double bonds
eg. linoleic acid
Generalised fatty acid:
carboxyl group
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16. LIPIDS Identify: lipids
U.3
S.2
S.3
Identify: lipids
Triglycerides : fats, oils, phospholipids and steroids
ester bond
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17. LIPIDS Identify: lipids
U.3
S.2
S.3
Identify: lipids
Triglycerides : fats, oils, phospholipids and steroids
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18. LIPIDS Identify: lipids
U.3
S.2
S.3
Identify: lipids
Triglycerides : fats, oils, phospholipids and steroids
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19. PROTEINS Draw: a generalised amino acid a central carbon atom
U.3
S.2
S.3
Draw: a generalised amino acid
a central carbon atom
4 side groups:
the amine group (-NH2)
the carboxylic acid group (-COOH)
an H group
the R group – R standing for “the rest”
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20. PROTEINS
U.3
S.2
S.3
Identify: proteins or parts of polypeptides, linked with a peptide bond
Amino acid:
Dipeptide:
Polypeptide:
peptide bond
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21. PROTEINS
U.3
S.2
S.3
Identify: proteins or parts of polypeptides, linked with a peptide bond
Dipeptide:
peptide bond
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22. CONDENSATION & HYDROLYSIS
U.5
U.6
Condensation reaction:
Removing water from two monomers to form a dimer
Makes bonds
Also known as ANABOLIC reactions
Also known as DEHYDRATION reactions
Require enzymes and energy
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23. CONDENSATION & HYDROLYSIS
U.5
U.6
Hydrolysis reaction:
Adding water can break polymers and dimers back into monomers
Breaks bonds
Also known as CATABOLIC reactions
Require enzymes but releases energy
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24. CONDENSATION & HYDROLYSIS
U.5
U.6
i.Biology
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25. CONDENSATION & HYDROLYSIS: Carbohydrates
U.5
U.6
disaccharide
monosaccharide
maltose + maltose
starch + water
disaccharide
polysaccharide
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26. CONDENSATION & HYDROLYSIS: Lipids
U.5
U.6
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27. CONDENSATION & HYDROLYSIS: Proteins
U.5
U.6
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28. METABOLISM
U.4
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29. METABOLISM
U.4
Metabolism is the web of all the enzyme-catalysed reactions in a cell or organism.
Most cells use most pathways.
Each step in each pathway is controlled by a specific enzyme.
Metabolism is the sum of all of the pathways used in a particular cell.
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30. UREA
A.1
Urea as an example of a compound that is produced by living organisms but can also be artificially synthesized
Urea is an organic chemical compound.
It is essentially the waste produced by the body after metabolizing protein.
Naturally, the compound is produced when the liver breaks down protein or amino acids, and ammonia.
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31. UREA
A.1
Urea as an example of a compound that is produced by living organisms but can also be artificially synthesized
The average person excretes ~30g of urea per day, mostly through urine, but a small amount in sweat.
Synthetic versions of urea can be created in liquid or solid form, and is often an ingredient found in fertilizers, animal feed, and diuretics.
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32. Falsification of theories with one theory being superseded by another.
UREA
NOS 1.9
Falsification of theories with one theory being superseded by another.
The artificial synthesis of urea helped falsify vitalism.
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33. SYNTHETIC UREA FALSIFIES VITALSIM
Vitalism is the theory that living organisms are fundamentally different from non-living entities because they contain some non-physical element or are governed by different principles than are inanimate things.
Vitalists would theorise that only organisms could synthesise organic compounds.
The synthesis of urea by Friedrich Wöhler in therefore falsified this statement.
Vitalism is no longer a generally accepted idea.
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34. MOLECULES TO METABOLISM
Q1. State the number of covalent bonds formed by a carbon atom. Q2. Define anabolism. Q3. What is meant by the term ‘dimer’?
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35. MOLECULES TO METABOLISM
Q4. Which describes these molecules correctly? A I = ribose; II = amino acid B I = glucose; II = amino acid C I = ribose; II = fatty acid B I = glucose; II = fatty acid
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36. MOLECULES TO METABOLISM
Q5.
A Glucose and galactose are examples of monosaccharides. State one other example of a monosaccharide. (1)
B The equation below shows the production of glucose and galactose from lactose.
There are several different types of carbohydrate. State which type of carbohydrate lactose is. (1)
State the type of chemical reaction that occurs when lactose is digested into glucose and galactose. (1)
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