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IB Chemistry HL > OPTION B Biochemistry > Flashcards

OPTION B Biochemistry Flashcards

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1
Q

What does the diverse functions of biomolecules depend on?

A

Their structure and shapes

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2
Q

What are metabolic reactions and under which circumstances do they occur?

A

Term for the different chemical reactions of biomolecules.
These reactions occur in highly controlled aqueous environments.

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3
Q

What is catabolism?

A

Reactions of breakdown (of biomolecules)

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4
Q

What is anabolism?

A

Synthesis of biomolecules.

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5
Q

From what reactions are biopolymers formed?

A

Condensation reactions.
(Monomers bond tgthr w covalent bonds and a water molecule produced for each covalent bond. Monomer must have 2 functional groups)

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6
Q

Through what reactions are biopolymers broken down?

A

Hydrolysis reactions.
(Reverse of condensation reaction; water molecule added for each covalent bond broken)

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7
Q

What is the difference between condensation and hydrolysis reactions?

A

Biopolymers are formed by condensation reactions and broken down by hydrolysis reactions. (Is this enough?? In syllabus)

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8
Q

What is photosynthesis (1 sentence)

A

Photosynthesis is the synthesis of energy-rich molecules from carbon dioxide and water using light energy.

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9
Q

What is respiration?

A

Complex set of metabolic processes (breaking down the energy rich molecules formed through photosynthesis) providing energy for cells.

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10
Q

Explain the balancing of oxygen and carbon dioxide in the atmosphere using equations.

A

6CO2 + 6H2O —> C6H12O6 + 6O2
(Photosynthesis^^)

C6H12O6 + 6O2 —> 6CO2 + 6H2O
(Respiration^^)

Photosynthesis synthesizes energy rich molecules — glucose and oxygen — from carbon dioxide and water, and respiration breaks down these molecules to form carbon dioxide and water again, keeping the amount of carbon dioxide and oxygen in the atmosphere constant.

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11
Q

What are proteins? And what bond do they contain?

A

Proteins are polymers/macromolecules of 2-amino acids (alfa-amino acids), joined by amide links/peptide bonds.

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12
Q

What functional groups does a general 2-amino acid consist of?

A

Amino group (-NH2) & carboxyl group (-COOH)

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13
Q

Amino acids are … (in relation to acids and bases) and can exist as (what 3 kinds of ions?)

A

Amino acids are amphoteric
And can exist as zwitterions, cations and anions

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14
Q

What is a zwitterion?

A

Dipolar ion // ion with two different charges
Exists at a unique pH for each amino acid = isoelectric point

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15
Q

What is meant by “isoelectric point”?

A

The pH value at which the amino acids have no net charge (are zwitterions).

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16
Q

What happens to an amino acid in a pH HIGHER THAN its isoelectric point?

A

It has the basic form (the carboxyl group is COO-) and is negatively charged. (The NH2 is still that)

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17
Q

What happens to an amino acid in a pH LOWER THAN its isoelectric point?

A

It has the acidic form (the amino group becomes NH3+) and is positively charged. (The COOH is still that)

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18
Q

What reaction does amino acids react in? And what kinds of bonds are formed between the amino acids?

A

Condensation reactions! (Forms long chains)
(The amino acids are bonded together by) peptide links (that are amides)

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19
Q

With which 4 levels/kinds of structures are proteins described?

A

Primary
Secondary
Tertiary
Quaternary
(Levels/structure)

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20
Q

What does Primary structure of a protein refer to?
OBS WHAT FORCE???

A

The sequence of amino acids

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21
Q

What does Secondary structure of a protein refer to?

A

Describes the two ways that the polypeptide chain fold itself due to intramolecular HYDROGEN BONDING. Alfa-helix; Beta-pleated sheet

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22
Q

What does Tertiary structure of a protein refer to?

A

Describes the overall flooding of the chain by interactions between distant amino acids to give the protein it’s 3-D shape.
The interaction can be due to:
-hydrogen bonds
-London forces between nonpolar R groups
-ionic attractions between polar R groups
-disulphide bridges between Cysteines

23
Q

What does Quaternary structure of a protein refer to?

A

Several polypeptide chains interact to give a complex structure — quaternary structure

24
Q

Proteins are divided into… (which 2 types?)

A

Fibrous
Globular

25
Q

Fibrous proteins (eg keratin — hair nails) are

A
  • Structural components
  • Elongated molecules with dominant secondary structure
  • Insoluble in water
26
Q

Globular proteins (eg hemoglobin) are

A
  • Tools that operate at the molecular level (enzymes, carriers, receptors)
  • Compact spherical molecules with dominant tertiary structure
  • Soluble in water
27
Q

A protein’s 3D shape determines its role in (2 things)

A

Structural components
Metabolic processes

28
Q

How can the 3-D structure and primary structure of proteins be determined?

A

3D: X-ray crystallography (should know this from T. 21 (structure and bond angles))
Primary: chromatography or electrophoresis

29
Q

OBS syllabus applications and skills: “Deduction of the structural formulas of reactants and products in condensation reactions of amino acids, and hydrolysis reactions of peptides.”

A

Condensation: 1 water molecule produced for each covalent bond formed.

Hydrolysis: 1 water molecule added for each covalent bond broken.

30
Q

OBS syllabus applications and skills: “Explanation of the solubilities and melting points of amino acids in terms of zwitterions.”

A
31
Q

Explain paper/thin layer chromatography in amino acid and protein separation and identification.

A
32
Q

Explain gel electrophoresis in amino acid and protein separation and identification.

A
33
Q

What is the equation for Rf (paper chromatography)

A

Rf=(d travelled by sample)/(d travelled by eluent)
(Can think part/whole)

34
Q

What are enzymes?

A

Proteins that can catalyze biological reactions.
Highly specific for particular reaction, dep tertiary and quaternary structure. Substrate binds at active site.

35
Q

How do you graph enzyme activity and substrate concentration?

A

X=[substrate], y=
At first: rate of reaction proportional to [substrate]. Then change in rate lower, reaches max rate, all enzymes occupied.

36
Q

What happens if the tertiary structure of an enzyme changes?

A

It’s effectiveness decreases, if too much denatures
Enzymes activity dep it’s 3D shape

37
Q

Expl effect T on enzyme activity

A

Initially incr T incr rate, highest rate at optimal T (gen 40degC), if T over optimal rate decreases, if too high denatures. (Graph rate highest at optimal T, lower T rate incr, higher T rate decr)

38
Q

Effect pH enzyme activity

A

If pH changes (not the optimal), the side chain of amino acid can become charged or neutral which affects its tertiary structure. Graph: rate highest at optimal pH=7 on either side rate decr and denatures.

39
Q

Effect heavy metal ion enzyme activity

A

Replace the hydrogen atom w heavy metal atom/ion which changes the tertiary structure, denatures

40
Q

Denatures means

A

Tertiary structure breaks down

41
Q

Define Xenobiotics

A

= chemicals found in an organism that are not normally present there, or are present in abnormally high amounts.

42
Q

What is biomagnification?

A

The increase in concentration of a substance in a food chain.

43
Q

What are biodegradable substances? (Definition)

A

Substances that can be degraded by bacteria in the environment and produce non-harmful end products.
Biodegradable/compostable plastics can be consumed or broken down by bacteria or other living organisms.

44
Q

Explain host-guest chemistry

A

Involves the creation of synthetic host molecules that mimic some of the actions performed by enzymes in cells, by selectively binding (non-covalently) to specific guest species (xenobiotics gen) such as toxic materials in the environment. Bind to xenobiotics, form super molecules which can be removed from the environment

45
Q

What are biological pigments?
And why are they colored?

A

Biological pigments are colored compounds produced by metabolism.

The color of the pigments are due to highly conjugated systems with délocalisés electrons, which have intense absorption bands in the visible region.

46
Q

Describe the interactions between amino acids occurring at the primary secondary and tertiary levels within a protein.
THAT IS DESCRIBE THE BONDING!!!

A

Primary: covalent bonding//peptide bond//amide bond

Secondary: hydrogen bonding

Tertiary: hydrogen bonding//disulfide bridges//ionic/electrostatic attraction//interactions between R groups

47
Q

Explain how paper chromatography can SEPARATE and IDENTIFY mixtures of amino acids. (2 marks)

A
  • sample spotted on paper AND solvent moves up the paper.
  • different/dep on attractions to mobile phase AND stationary phase/paper.
    Or separated based on solubilities/affinity to the two phases.
  • become identified with UV light
  • Rf values compared with known samples.
48
Q

Explain the concept of product inhibition in metabolic pathways. (2 marks)

A

Product of reaction is inhibitor of enzyme
OR Product binds to allosteric site of enzyme

Regulates own production
OR Sets up feedback loop to control concentration/production

49
Q

Compare the hydrolysis and oxidative rancidity and contrast where the chemical changes occur. (2 marks)

A

Comp rancidity: both produce DISAGREEABLE TASTE/SMELL/TEXTURE/APPEARANCE

Contrast site: Hydrolytic occurs at the ESTER LINK (COOC link) AND the oxidative occurs at the CARBON-CARBON DOUBLE BOND. (MUST specify that it is the CC double bond)

50
Q

Explain two ways in which lipids and carbohydrates differ as sources of energy.

A

Carbohydrates are already partially oxidized whereas lipids are not and hence lipids provide more energy.

Lipids are less water soluble AND energy is released slower/less available than in carbohydrates.

51
Q

What bond and by-products are formed when monosaccharides combine?

A

Glycosidic link
Water

52
Q

Outline how host guest chemistry mimics enzymes in the removal of xenobiotics. (2M)

A

The host is synthesized to be able to bond the xenobiotic, guest, and bonds non-covalently.

Key points: host molecule bonds w guest xenobiotic
And non-covalent bonding

53
Q

Similarity and difference between the structures of starch and cellulose.

A

Sim: both are POLYMERS OF GLUCOSE

Diff: starch contains alfa glucose AND cellulose beta glucose
OR
Starch may be branched AND cellulose unbranched.

OR
Starch contains Alfa AND cellulose contains beta glycosidic links

IB Chemistry HL (8 decks)

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