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OCR A Biology A-Level > 2.3 Biological Molecules (Spec) > Flashcards

2.3 Biological Molecules (Spec) Flashcards

1
Q

Biochemical molecules

A 
Carbon
Nitrogen
Hydrogen
Oxygen
Sulfur
Sodium 
Potassium
Iron
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2
Q

Ca2+ function

A

Nerve impulse transmission, muscle contraction

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3
Q

Glycosidic bond formation/breakage

A

Monosaccharide -> Disaccharide/Polysaccharide
Condensation reaction
Polysaccharide/Disaccharide -> Monosaccharide
Hydrolysis reaction

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4
Q

Hydrogen bond formation (Water)

A

Affinity to shared pair of electrons in covalent bond
Oxygen > Hydrogen
Partial positive on oxygen, partial negative on hydrogen
Electrostatic attraction between lone pair on O and partial positive on H of different molecules

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5
Q

High boiling point function in water

A

Coolant - Narrow temperature range of enzyme activity

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6
Q

Density function

Ice < Water

A

Insulating layer for lakes/ponds

Creation of semi-aquatic habitat

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7
Q

Na+ function

A

Nerve impulse transmission, kidney function

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8
Q

K+ function

A

Nerve impulse transmission, stomatal opening

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9
Q

H+ function

A

Catalysis, pH determination

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10
Q

NH4+ function

A

Bacterial NO3- production

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11
Q

NO3- function

A

Plant amino acid & protein formation (N)

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12
Q

HCO3- function

A

Blood pH maintenance

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13
Q

Cl- function

A

Cell pH maintenance (Na+/K+)

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14
Q

(PO4)3- function

A

Bone, cell membrane, nucleic acid & ATP formation

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15
Q

OH- function

A

Catalysis, pH determination

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16
Q

Cohesion function in water

A

Transport medium

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17
Q

Adhesion function in water

A

Capillary action

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18
Q

Polarity function in water

A

Universal solvent

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19
Q

Starch structure & function

A

20-30% amylose
70-80% amylopectin
Dense energy storage
Water-insoluble

20
Q

Amylose structure

A

Alpha-glucose polymer
1-4 glycosidic bonds
Straight chain -> helical structure

21
Q

Amylopectin structure

A

Alpha-glucose polymer
1-4 & 1-6 glycosidic bonds
Highly branched structure
Dense energy storage

22
Q

Glycogen (properties, structure, function)

A 
Water-insoluble
Alpha-glucose polymer
1-4 & 1-6 glycosidic bonds
Highly branched structure
Dense energy storage - animals' high metabolic demand
23
Q

Cellulose

A

Water-insoluble
Beta-glucose polymer
Alternate monomers rotated 180 degrees
1-4 glycosidic bonds form on opposite chain sides
High compressive strength
Hydrogen bonds - chains, microfibril, macrofibril

24
Q

Benedict’s test

A 
For reducing sugars
Equal volume of solution and sample
Heat in water bath
CuSO4 & NaOH solution
Blue - Negative test
Green - Low reducing sugar conc
Yellow/Orange - Medium reducing sugar conc
Red - High reducing sugar conc
25
Q

Iodine test

A

For starch
Equal volume of solution and sample
Negative test - orange
Positive test - blue-black

26
Q

Reagent test strips

A

Colour-coded chart - reducing sugar conc

Industrially manufactured

27
Q

Triglyceride structure/formation

A 
3 fatty acid chains 
Glycerol backbone
Ester bonds between fatty acid chain & backbone
Ester bond formed in condensation
Ester bond broken in hydrolysis
28
Q

Triglyceride function

A

Long-term energy storage
Thermal insulation -> reduce heat loss
Cushioning protection of vital organs
Aquatic animals’ buoyancy

29
Q

Phospholipid structure, function, properties

A

Hydrophilic phosphate head (Inorganic phosphate group)
Hydrophobic fatty acid tails (hydrocarbon chain ending in methyl group)
Phospholipid bilayer - plasma membrane
Ester bond between glycerol & fatty acid chain, glycerol & phosphate head

30
Q

Cholesterol function

A

Stability to cell membrane

Regulates membrane fluidity

31
Q

Emulsion test

A 
For lipids
Equal volume of ethanol, sample & distilled water
Shaken, not stirred
Milky emulsion - positive test
Clear solution - negative test
32
Q

Amino acid structure

A

Amine group, R-group, carboxyl group

33
Q

Dipeptide/Polypeptide formation/breakdown

A

Peptide bond (C-N) forms in condensation reaction
Hydroxyl of carboxyl on one amino acid
Hydrogen of amine of another amino acid
Catalysed by peptidyl transferase - present in ribosomes

Hydrolysis reverse reaction
Catalysed by protease enzymes

34
Q

Primary protein structure

A

Peptide bonds

Order of amino acids

35
Q

Secondary protein structure

A

Hydrogen bonds within polypeptide chain

Alpha helix/Beta pleated sheet dependent on primary structure

36
Q

Tertiary protein structure

A 
Ionic bonds
Hydrogen bonds
Disulfide bridges
Hydrophobic/Hydrophilic interactions
Within polypeptide chain, between R-groups
37
Q

Quaternary protein structure

A 
Ionic bonds
Hydrogen bonds
Disulfide bridges
Hydrophobic/Hydrophilic interactions
Between subunits/polypeptide chains
38
Q

Biuret test

A 
For proteins
Equal volume of solution and sample
CuSO4 & KOH solution
Blue solution - negative test
Lilac solution - positive test
39
Q

Nucleotide structure

A 
Pentose sugar
Phosphate group
Nitrogenous base
DNA - Deoxyribose, phosphate & A, T, C or G
RNA - Ribose, phosphate & A, U, C or G
40
Q

Polynucleotide formation

A

Phosphodiester bond formed between 3’ hydroxyl and 5’ phosphate of adjacent nucleotides
Catalysed by DNA/RNA polymerase
Formed in condensation reaction/broken by hydrolysis

41
Q

DNA structure

A

Sugar phosphate backbone (Deoxyribose and phosphate)
Phosphodiester bonds between 3’ hydroxyl and 5’ phosphate
Nitrogenous bases attached to C1 of deoxyribose
Hydrogen bonds between complementary nitrogenous base pairs
Pyrimidines always pair with purines (A-T and C-G)

42
Q

DNA purification

A

Grind cells in pestle and mortar - break cell walls (plant-cellulose, bacterial-peptidoglycan, etc)
Add detergent - break membranes, release cell contents into solution
Add salt - breaks hydrogen bonds -> DNA & water
Add protease-break down histones associated w/ DNA
Add ethanol down test tube side to prevent agitation and allow DNA to precipitate

43
Q

DNA replication

A
  1. DNA helicase breaks hydrogen bonds between bases, unwinds & unzips the DNA double helix
  2. Free DNA nucleotides arrange by complementary base pairing and form hydrogen bonds with exposed bases of existing strands
  3. DNA polymerase catalyses formation of phosphodiester bonds between free DNA nucleotides in condensation (3’ hydroxyl/5’ phosphate)
    Each daughter DNA molecule has one old strand and one new strand
44
Q

Genetic code nature

A

Non-overlapping: Each codon is read individually
Triplet code: Three-base sequence codes for one amino acid
Universal: Same codons code for same amino acids in all organisms
Degenerate: >1 codon codes for each amino acid

45
Q

DNA transcription (protein synthesis)

A

DNA helicase breaks hydrogen bonds between bases in DNA at locus of gene coding for desired protein
Free RNA nucleotides arrange by complementary base pairing to exposed template strand (complementary-template, identical-coding), form hydrogen bonds w/ template strand
RNA polymerase catalyses phosphodiester bond formation between RNA nucleotides
Pre-mRNA matures as introns removed by enzyme (introns: non-coding)
mRNA leaves nucleus by nuclear pore

46
Q

DNA translation (protein synthesis)

A

mRNA moves to ribosome
mRNA passes between ribosomal subunits
tRNA molecules w/ complementary anticodons to mRNA codons enter ribosome and form hydrogen bonds
2 tRNA molecules can enter ribosome at any time
tRNA carries specific amino acid, peptide bond formed between amino acids, catalysed by peptidyl transferase
tRNA w/ complementary anticodons continue to bring amino acids to ribosome until stop codon reached - no amino acid on stop codon - polypeptide released.

47
Q

ATP structure

A

Nucleotide derivative:
Ribose, adenine and phosphate groups
AMP: Adenosine monophosphate (1 phosphate)
ADP: Adenosine diphosphate (2 phosphates)
ATP: Adenosine triphosphate (3 phosphates)
Most energy stored in final phosphate bond in chain
Inorganic phosphates added in condensation/removed in hydrolysis

OCR A Biology A-Level (31 decks)

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