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Biology Paper 1 > Biological Molecules > Flashcards

Biological Molecules Flashcards

1
Q

What is a Monomer?

A

Small units from which larger molecules are made.

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2
Q

What is a Polymer?

A

Molecules made from a large number of similar monomers joined together.

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3
Q

Give 3 exapmles of momomers.

A

Monosaccharides
Amino acids
Nucleotides

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4
Q

What is a condensation reaction?

A

Reaction that joins two molecules together which eliminates a water molecule.

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5
Q

What is a Hydrolysis reaction?

A

A reaction that breaks a chemical bond and involves the usage of a water molecule.

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6
Q

What elements are in a carbohydrate?

A

Carbon
Hydrogen
Oxygen

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7
Q

What is a monosaccharide?

A

Monomer of carbohydrates

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8
Q

What are glucose isomers?

A

Alpha glucose
Beta glucose

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9
Q

What is a disaccharide?

A

Formed when two monosaccharides are joined together by a glycosidic formed by a condensation reaction.

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10
Q

What is the equation for Maltose

A

Glucose + Glucose > Maltose + Water

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11
Q

What is the equation for Sucrose?

A

Glucose + Fructose > Sucrose + Water

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12
Q

What is the equation for Lactose?

A

Glucose + Galactose > Lactose + Water

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13
Q

What is Hydrolysis of a disaccharide.

A

Breaks down disaccharide into monosaccharide with the addition of water

Maltose + Water > Glucose + Glucose

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14
Q

What does the benedicts test test for?

A

Reducing sugars

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15
Q

Describe the Qualitative Benedicts test.

A

• Add sample in tube with benedict’s solution
• heat to 95° in water bath
• If it turns brick red/orange the test is +ve
• If it remains blue then its -ve

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16
Q

What is a Semi-Quantitative Benedicts test?

A

Test where the colour intensity depends on the concentration of reducing sugar in the solution.
It is SUBJECTIVE

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17
Q

What do the colours mean in a Semi-Quantitative Benedict’s test?

A

Brick red - high conc of reducing sugar
Orange - medium conc
Yellow/Green - low conc
Blue - no reducing sugar

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18
Q

What is a Quantitative Benedict’s test?

A

Test carried out to obtain numerical data to compare reducing sugar concentrations in different samples.
Its OBJECTIVE

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19
Q

Describe a Quantitative Benedicts test.

A

• Do Benedict’s test on reducing sugars of know concentrations
• Variables must be controlled ( same volume of Benedicts solution, heat for same time)
• Use a colorimeter to measure the absorbance of each solution
• ploy a graph (conc on x-axis absorbance on y-axis)

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20
Q

Describe the test for a non-reducing sugar?

A

• perform benedict’s test to confirm -ve result
• Hydrolyse another sample of reducing sugar in water bath with dilute acid
• when cooled neutralise with alkali
• add same conc of benedicts solution and heat
• if brick red = positive result

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21
Q

Name three polysaccharides.

A

Cellulose
Glycogen
Starch

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22
Q

Describe the properties of polysaccharides.

A
  • relatively insoluble in water
  • non-reducing
  • either storage or structural molecules
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23
Q

Describe Starch Molecule

A

• long chains of alpha glucose
• linked by glycosidic binfs
• large (cant cross cell surface membrane)
• insoluble (osmotically inactive)
• helical shape, compact store
• branched so glucose is easily released for respiration

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24
Q

What is the function of starch?

A

Storage carb found in plants
- Stored in starch grains in the cytoplasm

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25
How can you test for Starch?
Iodine test • add 2-3 drops of iodine to sample • positive result = blue/ black colour • negative result = orange/yellow
26
Describe Glycogen.
• found in cytoplasm of animal cells • similar to starch but more branched (can release glucose more rapidly) • insoluble (osmotically inactive) • formed by condensation of alpha glucose
27
Where is Glycogen stored?
Liver and Muscle tissues
28
What is the function of Glycogen?
Storage compound
29
Describe Cellulose
• polymer of beta glucose • long straight chains • in cell wall if plants
30
What is the function of Cellulose
Provides rigidity and shape to cell
31
How is the structure of Cellulose formed?
* beta glucose form hydrogen bonds * hydroxyl groups form microfibrils which provide strength
32
What is in a Triglyceride molecule
3 fatty acids 1 glycerol joined in 3 condensation reactions
33
What is the general formula for a fatty acid?
R-COOH
34
What is a Saturated fatty acid?
No double binds between carbon atoms
35
What is an unsaturated fatty acid?
One or more double bonds between carbon atoms
36
How can you hydrolyse a Lipid?
• heat with acid or alkali • use enzyme lipase at its optimum temperature and pH
37
What are some of the properties of a Triglyceride?
• high amount of C-H bonds so release 2x energy as Carbs during respiration • high ratio of hydrogen to oxygen atoms releasing water when respired ( important for organisms in dry habitats) • Non-polar, insoluble, osmotically inactive (ideal storage compounds) • in the waxy cuticle of an insect and plant leaves to help reduce water loss
38
What is in a Phospholipid?
1 phosphates group 1 glycerol 2 fatty acids
39
Describe the Phospholipid head and tail?
• Polar hydrophilic head ( phosphate group) attract water • Non-polar hydrophobic tail (fatty acids) repel water
40
Describe the Phospholipid layer?
•Head and tail form a bilayer, two layers of phospholipids due to the tails being repelled by water • the tails face eachother
41
Outline the emulsion test for lipids.
* add sample to tube with ethanol * shake so fat dissolves * add water and mix * white emulsion of fat = lipid present
42
What properties do Triglycerides and Phospholipids share?
both: - insoluble in water - contain glycerol - contain ester bonds
43
What is an amino acid?
monomers that form proteins
44
How are amino acids joined together.
By peptide bonds (CONH) formed by condensation reactions
45
What is the primary protein structure?
The sequence of amino acids in the polypeptide chain. Determines shap of protein
46
What is the Secondary Protein Structure
• Folding of the polypeptide chain • Due to hydrogen bonding between amino acids
47
What is the Tertiary Protein Structure?
• further folding of the polypeptide chain • due to ionic, hydrogen and disulphide bonds • determined by location and interactions if R groups in amino acids
48
What is a Quaternary Protein Structure?
• Protein’s consist of more that 1 polypeptide chain • Held together by ionic, hydrogen and sometimes disulfide bonds
49
Describe a Globular Protein.
• **soluble and highly folded** polypeptide chain • produces a **compact tertiary structure** • include enzymes and antibodies
50
What is Denaturation of a protein?
Alteration in the tertiary structure of a protein
51
What can cause denaturation of a Protein?
• high temperature • breaking of hydrogen/ionic bonds • extreme changes in pH • heavy metals
52
Describe the Biuret test for Proteins?
• add biuret reagent • purple/lilac colour = protein present • remains blue = negative
53
How does water act as a Metabolite?
metabolite in metabolic reactions * in hydrolysis and condensation * needed for photosynthesis * metabolic product of respiration which is important for organisms in dry habitats
54
How is water used as a Solvent?
• transports nutrients e.g glucose in blood • removes excretory products (urea) • a medium where metabolic reactions occur
55
How does water regulate temperature ?
• has high heat capacity • has large latent heat of vapourisation
56
How does water having high heat capacity regulate temperature?
• means it can absorb large amount of heat energy before rising in temp • this is bc energy is being absorbed by hydrogen bonds - this minimises increase in temperature in cells - prevents fluctuations of temperature in aquatic habitats
57
How does water having latent heat of vaporisation regulate temperature?
• lots of energy is required to break hydrogen bonds and evaporate water • provides cooling effect due to little loss of water thru evaporation - helps animals maintain constant body temp
58
How does water act as an Internal support?
• cohesive forces (due to hydrogen bonds) support water columns in tube like transport cells • this allows transport from roots to leaves • water isn’t easily compressed and provides support in non woody plants via turgor pressure
59
How does water act as an External support?
Strong cohesive forces (due to hydrogen bonds) produce surface tension where water meets air • allows insects to walk on water or be suspended at the surface • provides buoyancy for aquatic organisms
60
What role does the inorganic ion Sodium have?
co transport of glucose and amino acids across cell membranes
61
Role of inorganic ion Iron
Component of haemoglobin which transports oxygen
62
Role of inorganic ion Hydrogen
important in determining pH thus effecting protein structure and enzyme activity
63
Role of inorganic ion Phosphate
Important as a structural component of DNA RNA and ATP
64
How do enzymes work
lower activation energy
65
Describe the induced fit model
active site is flexible and can change shape ans moulds around correct substrate
66
How does substrate concentration affect enzymes?
increases collisions between substrate and enzyme then levels out as active site becomes taken up rate of reaction can be increased again by adding more enzymes
67
how does enzyme concentration affect enzyme reaction?
(substrate must me in excess) when theres more enzymes there’s more active sites available increasing collisions
68
how does temperature affect enzyme reaction
gives molecules more kinetic energy meaning more collisions after optimum temperature tertiary structures denatures as hydrogen bonds are broken active site changes shape
69
how does ph affect enzyme reaction
enzymes have an optimum pH different pH from the optimum can cause denaturariom
70
what is a competitive inhibitor
has similar structure to substrate and competes for attachment to active site rate of reaction reduced as substrates cant bind can be reduced by adding more substrate
71
What is a non competitive inhibitor
binds to enzymes anywhere other than active site which alters tertiary structure adding substrate wont reduce this
72
What is ATP used for?
immediate energy source in biological processes
73
What is in ATP
adenine ribose three phosphates
74
How does ATP release energy
it is continuously hydrolysed
75
What is the equation for the hydrolysis of ATP
ATP + (atp hydrolase) > ADP + inorganic phosphate
76
What is the equation for the syntheses of ATP
ADP + Pi + ( energy from respiration) > ATP

Biology Paper 1 (8 decks)

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