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AQA A-level Biology Year 1 > Chapter 1 Biological Molecules > Flashcards

Chapter 1 Biological Molecules Flashcards

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1
Q

What is a condensation reaction?

A

Breakdown of a chemical bond by the addition of water

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2
Q

What is covalent bonding?

A

A shared pair of electrons in their outer shells

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3
Q

What is an Ionic bonding?

A

The electrostatic attraction between oppositely charged ions

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4
Q

What is Hydrogen Bonding?

A

Formed when the negative and positive region of two polarised molecules attract one another to form a weak electrostatic bond

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5
Q

What is metabolism?

A

The chemical processes that occur within a living organism in order to maintain life.

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6
Q

What is a polymer?

A

long chain of monomers

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7
Q

A molar solution is?

A

a solution that contains one mole of solute in each litre of solution

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8
Q

pair of monosaccharides =

A

Disaccharides

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9
Q

Monosaccharides combined in large numbers =

A

Polysaccharides

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10
Q

Monosaccharide general formula

A

(CH2O)n

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11
Q

Alpha Glucose

A

OH on bottom (DRAW)

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12
Q

Beta Glucose

A

OH on top (DRAW)

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13
Q

Benedict’s test for reducing sugars

A

1) Add 2cm3 of food sample in test tube (If sample not liquid grind in H20)
2) Add equal vol of Benedicts Reagent
3) Heat mixture in gently boiling H20 bath for 5 mins

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14
Q

Benedicts test results

A 
NEGATIVE RESULT
Blue = Non-reducing sugar
POSITIVE RESULT
Green
Yellow
Orange
Brick Red
Reducing sugar -> Increasing amount of reducing sugar
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15
Q

Glucose + Glucose

A

maltose

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16
Q

Glucose + Fructose

A

sucrose

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17
Q

Glucose + Galactose

A

lactose

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18
Q

Test for non-reducing sugars

A

Do Benedict’s test (negative stays blue)
Place test tube in boiling water for 5 mins
Add 2cm3 food sample to 2cm3 of HCl in gently boiling H20, 5 mins to hydrolyse disaccharides -> monosaccharides
Add Sodium hydrogen carbonate solution to neutralise HCl
Test with Ph paper (Alkaline)
Re-Test Solution

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19
Q

Results for non-reducing test

A

Benedicts solution in OG should turn:

ORANGE-BROWN

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20
Q

What is starch made up of?

A

A polysaccharide made up of a-glucose monosaccharides linked by glycosidic bonds formed by condensation reactions.
Chains may be branched or unbranched

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21
Q

What is the role of Starch?

A

Energy storage

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22
Q

What is Glycogen used for?

A

Storage form of glucose

23
Q

What is a polymer?

A

long chain of monomers

24
Q

What is hydrolysis?

A

Breakdown of a chemical bond by the addition of water

25
Q

Describe how the structure of Glycogen suits its function?

A

1) Insoluble - doesn’t all H2O draw by osmosis or diffuse out
2) Compact - lots of storage
3) More highly branched

26
Q

Describe the structure of Cellulose?

A

Straight unbranched chains that run parallel to each other allowing strong H bonds form cross-linkages between adjacent chains (formed from b-glucose)

27
Q

How is the structure of cellulose suited to its function?

A

B-glucose - form long, straight, unbranched chains
Chains parallel + cross-linkage by H bonds - add cohesive strength
Grouped to form microfibrils - Strength

28
Q

What are the characteristics of lipids?

A

Made of C H O (proportion
Insoluble in H2O
Soluble organic substances (Alcohol, acetone)

29
Q

What are the roles of lipids?

A

Energy - when oxidised
Waterproofing - insoluble in H2O
Insulation - Conductor of heat(slow), retain body heat, electrical insulator
Protection - Stored around delicate organs

30
Q

What state are lipids at room temp?

A

Solids

Oils are liquids (10-20 degrees)

31
Q

What are the components of triglycerides?

A

3 fatty acids combined with glycerol

32
Q

How are Triglycerols formed?

A

Fatty acids form ester bond with glycerol in condensation reaction (opposite hydrolysis)

33
Q

What does saturated mean?

A

No double bonds between C atoms

34
Q

What does monosaturated mean?

A

One double bond between C atoms

35
Q

What does polysaturated mean?

A

More than one double bond between C atoms

36
Q

Describe the structure of a phospholipid?

A

Hydrophilic ‘head’ - attracted to H2O, not with fat
Hydrophobic ‘tail’ - Not attracted to H2O, mixes readily with fat
They are polar

37
Q

How are the structures of a phospholipid related to its function?

A

Polar - Forms bilayer in aqueous environment, Hydrophobic barrier formed in + out cell
Hydro phobic/phillic help hold surface of CSM
Phospholipid structure allows forming glycolipids by combining carbohydrates with CSM

38
Q

What is the test for lipids?

A

1) Completely dry + grease free test tube
2) 2cm3 sample, add 5cm3 Ethanol
3) Shake tube thoroughly to dissolve lipid in sample
4) Add 5cm3 H2O + shake gently
5) Cloudy-white colour = Lipid
6) Repeat experiment as a control

39
Q

What is the result of a lipid test?

A

Cloudy-White colour

40
Q

How are proteins formed?

A

Amino acids combined to form polypeptide

Polypeptides combined to form Proteins

41
Q

What are the components of Protein?

A 
Amino group (-NH2
Carboxyl group (-COOH)
Hydrogen atom (-H)
R (side) group
(DRAW)
42
Q

Describe how a peptide bond is formed?

A

Carboxyl (-OH) + (-H) combined -> Peptide bond

43
Q

Describe the primary structure of a protein?

A

Sequences of amino acids - Polypeptide chain

Peptide bonds

44
Q

Describe the secondary structure of a protein?

A

H bonding
3D shape spiral
Primary structure twists + folds into another configuration

45
Q

Describe the tertiary structure of a protein?

A

Bending + twisting polypeptide helix into a compact structure
Folding + twisting of secondary structure into more compact
3 types of bonds:
1) Disulfide - Strong + not easily broken
2) Ionic - Carboxyl + amino group - easily broken Ph change
3) H bond - Numerous, easily broken

46
Q

Describe the quatenary structure of a protein?

A

Number of different polypeptide chains
Non protein prothetic
Large, complex protein molecule
Separate chains held together by hydrophobic interaction ; H bonds + ionic bonds

47
Q

What are enzymes?

A

Biological catalysts that speed up reactions
Are globular proteins
Can be reused but don’t get used in a reaction

48
Q

How do enzymes work in a reaction?

A

Lower activation energy
Allows reaction to take place in lower temp
Enables metabolic processes to happen rapidly (Human body temp)

49
Q

Describe the enzyme structure?

A 
3D shape (primary structure)
Specific region functional - Active site
Active site forms small depression within larger enzyme molecule
50
Q

How does the enzyme act on a substrate?

A

Fits neatly into depression + form ESC

Enzyme held in AS have temporary bonds

51
Q

Describe the induced fit model?

A

Active site forms as enzyme + substrate interact
Enzyme flexible + mould itself around substrate
As it changes shape puts strain on substrate

52
Q

Describe the lock and key theory

A

Shape of substrate (Key) exactly fits in active site (lock)

53
Q

What are the factors affecting enzyme activity?

A

Temperature

Ph

AQA A-level Biology Year 1 (10 decks)

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