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A Level Biology OCR > Chapter 3- Biological Molecules > Flashcards

Chapter 3- Biological Molecules Flashcards

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1
Q

What are the 4 main groups of ‘Macro Molecules’ in Biochemistry?

A
  1. Carbohydrates
  2. Lipids
  3. Proteins
  4. Nucleic Acids (DNA, RNA)
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2
Q

What are the main elements in Carbohydrates?

A

C, H, O.

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3
Q

Name 4 big group molecules that belong to ‘Carbohydrates’:

A
  • Glucose
  • Starch
  • Glycogen
  • Cellulose
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4
Q

What is a single unit, or monomer, of a Carbohydrate called?

A

Monosaccharide.

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5
Q

What do you call many single units, or monomers, of Carbohydrates?

A

-Polysaccharides.

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6
Q

What is the general formula for Carbohydrates?

A

CH2O

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7
Q

What is ‘OH’ called in structural formula?

A

Hydroxyl Group

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8
Q

What is the difference between alpha glucose and beta glucose?

A

In beta glucose, structural formula is different to alpha. The OH (hydroxyl group) on Carbon #1 is switched with H.

Otherwise, they both have the same chemical formula, C6H12O6.

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9
Q

What is it called when two compounds have the same chemical formula but different structural formulas?

A

Isomers.

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10
Q

Describe a property of fructose that differs it from alpha and beta glucose and Galactose.

A

Fructose is the only sugar that appears in pentagon shape.
It is 1/2x sweeter than sucrose, so important for diabetics.
(less sugar for same taste)

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11
Q

What is a condensation reaction?

A

(in exam, always draw diagram!)
When water is created and removed. Reversible Reaction.

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12
Q

What kind of bond does Maltose have?

A

1-4 Glycosidic Bond.

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13
Q

What monosaccharides make the disaccharide Maltose?

A

2x alpha glucose.

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14
Q

What is hydrolysis?

A

When water is added to a compound to separate the components in it.
e.g. water and enzyme can be used to split Maltose into 2x alpha glucose.

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15
Q

What monosaccharides make the disaccharide Lactose?

A

Galactose
beta Glucose

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16
Q

What monosaccharides make the disaccharide Sucrose?

A

Glucose
Fructose

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17
Q

What is the general formula for Lactose and Sucrose (disaccharides)?

A

C12H22O11

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18
Q

What is the general formula for a Polysaccharide?

A

(C6H12O6)n
n= at least 500+

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19
Q

Describe the differences between Polysaccharides and Mono/Disaccharides:

A

Polysacc:

  1. Relatively insoluble in H2O
  2. Powder
  3. Not Sweet.

Mono/Disacc:

  • soluble in H2O
  • Crystalline
  • Sweet
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20
Q

Name 3 major Polysaccharides:

A
  • Starch
  • Glycogen
  • Cellulose
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21
Q

Describe Starch:

A

Polymer of alpha glucose.

Made of 2 sections: Amylose (30%)and Amylopectin (70%)

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22
Q

Describe Amylose:

A

Amylose makes up 30% of starch
Polymer of alpha glucose
1-4 Glycosidic Bond
forms helix
(1 turn every 6 units)

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23
Q

Describe Amylopectin:

A

Amylopectin makes up 70% of starch
Polymer of alpha glucose
1-4 glycosidic bonds
forms helix
BUT! attaches to Amylose using 1-6 glycosidic bond.
no structural difference.

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24
Q

Describe Iodine test for Starch:

A

Iodine used to detect presence of starch.
Few drops of iodine dissolved in potassium iodide mixed with sample
If solution changes colour from yellow/brown to purple/black,
=starch present.
Negative Result- solution remains yellow/brown

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25
Q

Describe the properties of Glycogen:

A

-Similar structure to amylopectin
-Contains many alpha 1-6 glycosidic bonds AND 1-4 glycosidic bonds
-produce branched structure
= BRANCHED STORAGE
-Glycogen stored as small granules
-Glycogen less dense + more soluble than starch.
-broken down more rapidly
-indicates higher metabolic requirements of animals compared with plants.

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26
Q

What kind of reaction is the Benedict’s test for reducing sugars?

A

REDOX reaction

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27
Q

What kind of sugars are reducing sugars?

A

All Monosaccharides and some disaccharides (maltose, lactose).
NOT polysaccharides or sucrose.

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28
Q

What is the chemical name for Benedict’s Reagent?

A

Alkaline solution of copper (II) sulfate.

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29
Q

Describe the Benedict’s test for reducing sugars?

A
  1. Add 2cm3 of sample to test tube. If not already, ensure sample is in liquid form.
  2. Add 2cm3 of Benedict’s Reagent
  3. Heat mixture in gently boiling water bath for 5 mins.
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30
Q

What is the colour of a negative + positive result for Benedict’s test for reducing sugars?

A

Negative- blue

Positive- green (very low), yellow (low), brown (medium), brick-red (high)

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31
Q

Define ‘hydrolyse’:

A

Break down a compound by a chemical reaction with water.

32
Q

Describe the Modified Benedict’s test for non-reducing sugars and the colours for the negative and positive results:

A
33
Q

Name some properties of Celluose:

A
  • Most abundant polymer on Earth
  • Polymer of β glucose
  • held together by hydrogen bonds and β 1-4 glycosidic bonds.
  • chains are linear
  • very strong- used in cell walls.
    *
34
Q

What does Cellulose look like and how is it formed:

A
35
Q

How are cellulose chains held together to form microfibrils?

A
36
Q

Why is cellulose ‘strong’ :

A
  • Cellulose molecules make H-bonds w/ between each chain = microfibrils
  • These microfibrils join together forming macrofibrils = fibres
  • These fibres = strong + insoluble (cell walls)
  • Cellulose is in our diet
  • It is hard to break down into monomers (hard to hydrolyse due to alternate hydroxyl group on β glucose)
37
Q

What are two types of lipids:

A
  1. True Lipids : [fats @ standard temp + pressure (stp)] + [oils @ stp]
  2. Not true lipids: steroids, waxes, cholesterol.
38
Q

What are uses of lipids?

A
  • formation of cell membranes
  • storage (energy)
  • buoyancy
  • insulation
  • protecting organs, e.g. kidneys
39
Q

What are properties of lipids:

A
  • 2 components: glycerol + fatty acid (true lipid only)
  • high in energy
  • less dense than other macromolecules.
  • contain elements C, H, O
  • are non-polar, so un-reactive and not soluble in water
  • called macromolecules
  • two types: saturated + unsaturated
  • part of the molecule is hydrophilic, and part of the molecule is hydrophobic
  • Soluble in organic solvents like alcohol, chloroform, acetone, benzene.
  • Pure fats and oils are colourless, odourless, and tasteless
40
Q

What is the structure of true lipids: (draw it + label)

A

Synthesis of triglyceride from 1x glycerol and 3x fatty acids by formation of 3 ester bonds = 3x H2O molecules.

Hydrolysis= break down triglyceride by adding 3x H2O.

Condensation reac = makes triglyceride, removes 3x H2O, forms 3x ester bonds

41
Q

What is esterification?

A
42
Q

How does presence of double bond (C=C) affect lipids…?

A
43
Q

What are the biological roles of lipids..??

A

Due to non-polar nature..:

  • membrane formation + creation of hydrophobic barriers
  • hormone production (steroids)
  • electrical insulation necessary for impulse transmission (myelin sheath)
  • water proofing (impermeability) on leaves (waxy cuticle) and bird feathers
  • (triglycerides only) role in energy storage, stored under skin + around vital organs
  • provide thermal insulation to reduce heat loss
  • cushioning to protect vital organs
  • buoyancy for aquatic animals.
44
Q

What are properties of sterols/n non-true lipids?

A
45
Q

What are biological roles of cholesterol?

A
  • used in cell membrane to add stability
  • is a sterol
  • two types HDL (good) LDL (bad!!)
  • body manufacturers cholesterol in liver + intestines
  • function- formation of cell membranes
  • how does it add stability?
    • cholesterol positioned between phospholipids with OH group at periphery of membrane
  • cholesterol regulates cell fluidity by keeping membranes fluid at low temps + stopping them becoming too fluid at high temps.
    *
46
Q

What are phospholipids?

A
47
Q

What is the structure of a phospholipid:

A
48
Q

What are the properties of phospholipids?

A
49
Q

Describe the emulsion test for lipids + a problem of this method:

A
50
Q

What elements make up proteins?

A

C, H, O, N, S

51
Q

What are the properties of Amino Acids and the general formula for AA’s:

A
52
Q

What does Amphoteric mean?

A

Amphoteric is a property of AAs. It means they have both acid + alkali/base properties.

This means they can be buffer solutions (solution that can accept/donate both H+ and OH- without changing pH (found in blood!)

53
Q

What is an ‘R’ group in AAs?

A

‘R’ Groups- any group in which a carbon or hydrogen atom is attached to the rest of the molecule.

some R groups are non-polar, therefore have hydrophobic properties.

some R groups are polar, therefore have hydrophilic properties.

54
Q

Draw-/describe the formation of a dipeptide from AAs:

A
55
Q

In proteins, what is the primary (10) structure?

A
56
Q

In proteins, what is secondary (20) structure?

A
57
Q

What are H-bonds in proteins (purpose of them??)

A
58
Q

In proteins, what is the tertiary (30) structure?

A
59
Q

What are the different types of bonds that can form in the 30 of the protein?

A

Ionic

Covalent

Hydrogen (cellulose, proteins, DNA)

Disulphide (strongest proteins only, e.g. ligaments)

60
Q

What are the two different types of protein formations in the 30 of a protein?

A

Globular and Fibrous

61
Q

Describe the structure of a globular protein:

A
62
Q

Describe the structure of a fibrous protein:

A
63
Q

In proteins, what is the quaternary (40) structure?

A
64
Q

What is denaturation and how does it affect a protein?

A
65
Q

What are conjugated proteins?

A
66
Q

Describe the structure/function of Heamoglobin:

A
67
Q

Describe the structure of catalase:

A
68
Q

Describe at least 7x details about collagen (structure, function):

A

peptide bonds , between amino acids / in polypeptide ;

every 3rd amino acids is , same / glycine ;

coil / twist / spiral / helix ;

left-handed (helix) ;

glycine / small R group , allows closeness / twisting (of polypeptide chains) ;

three polypeptide chains ;

hydrogen / H , bonds between (polypeptide) chains ;

no / few, hydrophilic (R) groups on outside (of molecule) ;

(adjacent molecules joined by) crosslinks ;

crosslinks / ends of molecules , being staggered ;

fibril ;

69
Q

Describe 7x details about elastin (structure/function):

A
70
Q

Why is water so important?

A
71
Q

What is the brief structure of water?

A
72
Q

Describe positioning and effect of H-bonds in water molecules:

A
73
Q

What is the density of water like? why is this important for survival?

A
74
Q

How does water behave as a solvent?

A
75
Q

Describe the cohesion of water molecules:

A

A Level Biology OCR (23 decks)

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