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Biological Molecules Flashcards

1
Q

Describe the strength of hydrogen bonds

A

-Individually weak
-Collectively strong

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2
Q

Describe the formation of hydrogen bonds between two molecules of water & explain why water can form these bonds

A

-Form between electropositive H & electronegative O
-Can form bc water is polar

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3
Q

Define the term polar

A

Uneven distribution of charge across a bond

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4
Q

State 6 properties of water

A

-Higher density than ice
-Acts as solvent
-Acts as reagant
-Cohesive + adhesive
-↑ specific heat capacity
-↑ latent heat of vaporisation

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5
Q

State 5 roles of water

A

-Solvent (dissolves polar substances, hard to dissolve non-polar)
-Medium for chemical reactions -> being dissolved in water allows molecules to react
-Transport medium
-Coolant (e.g. sweat evaporates -> heat loss)
-Habitat (aquatic organisms)

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6
Q

State 3 examples of water acting as a transport medium in animals and plants

A

-Animals: Blood (plasma)
-Plants: Xylem (transports water & MI), Phloem (transports dissolved sugars)

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7
Q

Describe the importance of the density of ice and water on living organisms

A

-Ice = ↓ dense than water
-Floats on surface
-Forms insulating layer

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8
Q

Describe why ice is less dense than water

A

Bc of how H bonds arranged in ice -> molecules arranged spaced apart

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9
Q

a) What property of water allows it to act as a solvent?
b) Describe how this works

A

a) -Polar molecule -> solvent for other polar molecules + ions
b) -Surrounds molecules/ions -> dissolves them
-So acts as transport medium

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10
Q

Define the term cohesion in reference to water molecules

A

Water molecules = polar -> form H bonds -> stick together

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11
Q

Define the term adhesion in reference to water molecules

A

Force/H bonds between water molecule & surface it is attached to

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12
Q

What does capillary action of water lead to on the surface of a body of water?

A

Surface tension

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13
Q

What is the result of cohesion and adhesion in a narrow tube

A

-Capillary action
-Water can travel up narrow tube against gravity

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14
Q

Define the term specific heat capacity

A

E required to heat 1kg of material by 1°C

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15
Q

Explain why water has a high specific heat capacity and why this is a good thing

A

-H bonds reduce movement of molecules
-Helps maintain stable temp in aquatic & cellular environ

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16
Q

Define the term latent heat of vaporisation

A

E required to change state from liquid to gas

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17
Q

Why does water remain liquid over a large range of temperatures?

A

Has ↑ latent heat of vaporisation

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18
Q

a) These 2 monosaccharides join to form which disaccharide?
α glucose + α glucose ->
b) Which type of cells is this found in?

A

a) Maltose
b) Animals & plants

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19
Q

a) These 2 monosaccharides join to form which disaccharide?
α glucose + fructose ->
b) Which type of cells is this found in?

A

a) Sucrose
b) Plants

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20
Q

a) These 2 monosaccharides join to form which disaccharide?
β glucose + galactose ->
b) Which type of cells is this found in?

A

a) Lactose
b) Animals

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21
Q

a) These 2 monosaccharides join to form which disaccharide?
β glucose + β glucose ->
b) Which type of cells is this found in?

A

a) Cellobiose
b) Plants

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22
Q

α glucose, β glucose, fructose and galactose are all examples of what? What does this mean?

A

Monosccharides that are structural isomers (have same molecular formula)

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23
Q

State the molecular formula for
a) α glucose
b) β glucose

A

Both: C6H12O6

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24
Q

Draw an α glucose and β glucose molecule

A

https://www.ecosia.org/images?q=alpha+and+beta+glucose&addon=opensearch#id=C64A4BB8AE302BB1A814555CFA2D5E719AA2C233

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25
State the molecular formula for a) Ribose b) Deoxyribose
a) C5H10O5 b) C5H10O4
26
Give 2 examples of pentose monosaccharides and state what makes them pentose
-Ribose -Deoxyribose -Have 5 C atoms
27
Give 4 examples of hexose monosaccharides and state what makes them hexose
-α glucose -β glucose -Galactose -Fructose -Have 6 C atoms
28
What is the structural difference between α glucose and β glucose molecules
-Orientation of hydroxyl group (-OH) on first C atom -α: OH group is below plane of ring structure, β: above
29
What is the difference between reducing and non-reducing sugars
-Reducing sugars donate e^- (carbonyl group oxidised) -Non-reducing don't
30
Give 3 examples of reducing sugars
-Glucose -Galactose -Fructose (have same molecular formula but diff structural formula which gives them diff properties)
31
State the role of glucose in organisms
-E source -Main substrate used in resp -> releases E for production of ATP
32
Why is glucose referred to as an isomer?
Exists in 2 structurally diff forms
33
Is glucose soluble?
Yes, so can be transported in water
34
Which isomer of glucose forms each of these polysaccharides? a) Starch b) Glycogen c) Cellulose
a) α b) α c) β
35
Where is ribose and deoxyribose found?
Nucleotides that make up RNA and DNA
36
What is hydrolysis?
-Reaction -Breaking compound down w/ water
37
What is condensation?
-Reaction -2 or more molecules combine to form larger molecule & release water as by-product
38
a) What type of molecules are all carbohydrates? b) What does this allow for?
a) Polar b) Formation of H bonds w/ other polar molecules
39
What bonds form between monosaccharides when forming disaccharides and polysaccharides
Glycosidic bonds
40
Do you find these in animals or plants: a) Amylose b) Amylopectin c) Glycogen
a) Plants b) Plants c) Animals
41
Where in its organism are the following stored: a) Amylose b) Amylopectin c) Glycogen
a) Roots b) Roots c) Liver/muscles
42
Are the following a form of starch: a) Amylose b) Amylopectin c) Glycogen
a) Yes b) Yes c) No
43
What is the monomer in the following: a) Amylose b) Amylopectin c) Glycogen
a) α glucose b) α glucose c) α glucose
44
Are these branched: a) Amylose b) Amylopectin c) Glycogen
a) No b) Yes c) Yes
45
Are these soluble (how do you know): a) Amylose b) Amylopectin c) Glycogen
a) No b) No c) No -Too big -Don't have enough -OH groups
46
Which form of glycosidic bond do the following have: a) Amylose b) Amylopectin c) Glycogen
a) 1-4 b) 1-4 & 1-6 c) 1-4 & 1-6
47
Are the following spiralled: a) Amylose b) Amylopectin c) Glycogen
a) Yes b) To some extent c) To little extent
48
Do the following have hydrogen bonds within the molecule: a) Amylose b) Amylopectin c) Glycogen
a) Yes b) Yes c) No
49
State the difference between a 1-4 and 1-6 glycosidic bond
-1-4 forms between OH groups of C1 & C4 of diff subunits -1-6 forms between OH groups of C1 & C6
50
Amylose, amylopectin and glycogen can all be described as compact molecules. Suggest why this is a useful property to an energy storage molecule
-Larger no. α glucose molecules stored in smaller area -> larger store of E -Allows space in cell for other structures
51
Rank these molecules from most compact to least: Amylose Glycogen Amylopectin
Glycogen Amylopectin Amylose
52
Why do animals require more compact energy providing molecules than plants
-Animals have greatER metabolic rate -> requre greatER supply of E from ATP -Can store ↑ glucose in ↓ space
53
Explain the biological significance of glycogen being very branched
↑ free ends -> ↑ glucose molecules added/removed -> speeds process of storing/releasing at any time
54
Describe the arrangement of β glucose in a cellulose chain
-Each alternating β glucose molecule = upside down -1-4 glycosidic bond between OH groups -Form straight chain
55
Describe and explain the arrangement of α glucose molecules in starch/glycogen
-All molecules same way up -Bc condensation reaction between monosaccharides require 2 OH groups positioned next to each other
56
Does cellulose have hydrogen bonding? If so, where?
-Yes -Within & between cellulose molecules -Between cellulose chains
57
Is cellulose soluble in water?
No (but does have polar OH groups capable of forming H bonds w/ other polar regions within same molecule -> helps create straight chain)
58
Name 3 parts that make up cellulose fibres
Cellulose fibres have macrofibrils, which have microfibrils, which have chains of cellulose molecules
59
Why do cell walls not prevent the movement of water/molecules/ions in and out of plant cells?
Criss cross arrangement of cellulose **microfibrils** means there are large gaps
60
Define the term tensile strength
Resistance to being stretched
61
Describe the arrangement of cellulose in cell walls
-Bundle of cellulose molecules (joined by H bonds) -> microfibrils -Microfibrils bundle -> macrofibrils -Run in all directions -> criss-cross structure surrounding cell
62
Describe the structure of phospholipids. State the bonds involved
-1 phosphate group (hydrophilic head) ----Phosphodiester bond? -1 glycerol ----Ester bond -2 fatty acids (1 saturated & 1 unsaturated (hydrophobic tails)
63
State where phospholipids are found
Plasma membranes
64
Describe the structure of triglycerides. State the bonds involved
-1 glycerol ----Ester bonds -3 fatty acids
65
What process forms ester bonds
Esterification
66
State the general molecular formula of: a) Saturated fatty acids b) Unsaturated fatty acids c) Monosaccharides
a) CnH2nO2 b) CnH2n-2O2 c) CnH2nOn
67
Are lipids polar? Hence are they soluble in water?
No -> insoluble
68
Describe 5 functions of triglycerides
-E source Used in aerobic resp (1st ester bonds broken down. then glycerol & fatty acids) -Good E store Compact, insoluble in water -Insulation Provide thermal & electric insulation (electric in nerve cells) -Buoyancy (ability to float) Less dense than water -> help aquatic mammals float -Protection Soften impact (shock absorber)
69
When something is both polar and non-polar it is called...
Amphipathic
70
Describe the structure of cholesterol
-Has 4 C-based rings -> hydrophobic -Has 1 hydroxyl group (-OH) -> hydrophilic
71
What forms can proteins come in
-Enzymes -Antibodies -Hormones -Transport proteins
72
a) Define the term macromolecule b) Name the 4 main ones c) Name 2 smaller ones
a) Large molecule made of monomers b) -Carbs -Lipids -Proteins -Nucleic acids c) -Phospholipids -Triglycerides
73
Name the elements present in these macromolecules: a) Carbohydrates b) Lipids c) Proteins d) Nucleic acid
a) C,H,O b) C,H,O c) C,H,O,N,S d) C,H,O,N,P
74
What distinguishes amino acids from each other?
The R group
75
What are the 4 types of amino acids?
-Non-polar -Polar -Non-charged -Charged
76
Name 2 amino acids
-Glycine -Cysteine
77
Which group of proteins do all enzymes belong to?
Globular
78
Are globular proteins water soluble? Why?
-Yes -Polar, hydrophilic R groups orientated outwards -> water molecules can surround them
79
a) Define the term conjugated protein b) What is the opposite of a conjugated protein?
a) Protein with non-protein group permanently attached b) Simple protein
80
Give an example of a simple globular protein
Insulin
81
What are insulin and glucagon an example of?
Antagonistic pair
82
Where is haemoglobin found?
Erythrocytes
83
State the function of catalase
Converts hydrogen peroxide (harmul by-product of metabolic reactions) -> water & oxygen (not harmful)
84
Describe the structure of haemoglobin
-Quaternary structure -4 polypeptide chains: 2 α chains & 2 β chains -Each chain has prosthetic haem group which has Fe2+ atom
85
a) State the function of haemoglobin b) Why is this useful for oxygen
a) Pigment that binds to O -> transports around body b) O = not very water soluble -> can't easily dissolve in blood -> only small amount will be transported w/o haeomoglobin
86
a) What is a prosthetic group? b) What is a prosthetic haem group
a) Inorganic component found in protein, helps w/ function b) Contains iron -> forms bonds w/ O molecules
87
How many polypeptide chains are found in catalase?
4
88
How many polypeptide chains are found in insulin?
2
89
State the function of insulin
-Controls blood glucose conc -Stimulates uptake of glucose
90
What are enzymes and insulin an example of?
Globular proteins
91
What are globular proteins?
-Compact, spherical shape -Water soluble -Hydrophilic aa on outside -Hydrophobic aa on inside
92
What is it called when oxygen is bound to... a) Haemoglobin b) Hydrogen c) Carbon
a) Oxyhaemoglobin b) Haemoglobinic acid c) Carbaminohaemoglobin
93
Explain why globular proteins form a spherical shape when folding into a tertiary structure
-Non-polar, hydrophobic R groups orientated towards centre -Polar, hydrophilic R groups orientated outwards.
94
Haemoglobin has a quaternary structure. What does this mean?
Has more than 1 polypeptide chain
95
What makes up the primary structure of a protein?
Chains of aa
96
What are fibrous proteins?
-Long strands of polypeptide chains w/ cross linkages due to H bonds -Insoluble in water -Provide strength/support -Little/no tertiary structure
97
Are fibrous proteins water soluble? Why?
-No -Large no. hydrophobic R groups
98
What makes fibrous proteins suitable for structural roles?
-Insoluble -Organised structures (Limited no. amino acids -> highly repetitive sequence)
99
State 3 examples of fibrous proteins and where they are found
-Keratin Hair, nails -Collagen Connective tissue found in skin, tendons, ligaments -Elastin In connective tissues, skin, bones, tendons
100
Describe the structure of collagen
3 polypeptide chains held by H & covalent bonds -> triple helix
101
State the function of collagen
Structural (connective tissue e.g. tendons, skin)
102
Describe 4 properties of collagen
-Flexible but does not stretch -Long -↑ tensile strength (many H bonds) -Strong (staggered ends within fibrils)
103
What are 2 sources humans get cholesterol from?
-Absorbed from food -Synthesised by liver cells
104
a) What type of chains do 1,4-glycosidic bonds form? b) What type of chains do 1,6-glycosidic bonds form?
a) Straight b) Branched
105
Why is amylopectin branched?
Has 1,6-glycosidic bonds
106
How does glycogen release glucose molecules from it's branched ends?
The **reaction** of hydrolysis
107
If a substance's name ends in 'ol' it is an...
Alcohol
108
Draw the structural formula of a glycerol molecule
https://www.ecosia.org/images?q=glycerol+molecule&addon=opensearch#id=1AD37047EB3F8B137C916BCB44F644112BFA1B2D
109
What are triglycerides broken down into and by what?
Glycerol & fatty acids by lipase
110
If I mix oil and pH indicator together, why would I observe a drop in pH after mixing in lipase?
-Triglyceride broken down by lipase into fatty acids & glycerol -Fatty acids make mixture acidic
111
Draw the structural formula of an amino acid
https://www.ecosia.org/images?q=molecular+formula+of+protein&addon=opensearch#id=6F045697D7A7B4803ACC9AD6DFAC35162EA9FDFA -NH2 is the amine group -R group varies with each type of amino acid -COOH is the carboxyl group
112
How many different types of amino acids are there?
20
113
Describe the chemical test for starch
-Iodine SOLUTION -Present: Yellow/orange -> Blue/black
114
Describe the chemical test for reducing sugars
-Mix sample w/ Benedict's reagent -Heat in water bath -Present: Blue, green, yellow, brick red PRECIPITATE
115
Give an example of a non-reducing sugar
Sucrose
116
Describe the test for non-reducing sugars
-Boil w/ HCl -HYDROLYSES sucrose into glucose & fructose (non-reducing sugar -> reducing sugar) -Benedict's reagent, HEAT SAMPLE, blue->green->yellow->brick red precipitate
117
MAKE MORE SPECIFIC Describe the test for lipids
-Emulsion test -Dissolve lipid in ethanol -Mix with water -Present: white emulsion layer
118
Describe the test for protein
-Biuret's test -Mix Biuret's solution w/ sample -Present: Blue -> Purple
119
Why are Biuret's and Benedict's solution initially blue?
They're alkaline solutions of copper sulfate
120
Name a beta glucose polysaccharide
Cellulose
121
Name the strongest bond found in the tertiary and quaternary structure
Disulphide bridges
122
Name 10 key inorganic ions
-Calcium Ca^2+ -Sodium Na^+ -Potassium K^+ -Hydrogen H^+ -Ammonium NH₄^+ -Nitrate NO₃^- -Hydrogencarbonate HCO₃^- -Chloride Cl^- -Phosphate PO₄^3- -Hydroxide OH^-
123
CHECKWhat is a function of maltose?
Respiration
124
Suggest 2 differences between lipids from animals and those from plants
In animals: -Saturated -Solid at room temp
125
List 3 examples of where hydrogen bonds are found in biological molecules
-Between bases in DNA -Between chains of cellulose -Protein secondary/tertiary structure
126

BIO A-level (13 decks)

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