Biological Molecules Flashcards
1
Q
Covalent bonds are…
A
- Formed when atoms share electrons
- Strong Bonds
2
Q
Hydrogen bonds are…
A
- A weak interaction that occurs when a negatively charged atom is bonded to a positively charged atom
3
Q
Water makes up… of mammals
A
60-70%
4
Q
Water makes up… of plants
A
90%
5
Q
Where did life originate?
A
In Water
6
Q
Water is a polar molecule because?
A
It is made up of two positively charged hydrogen atoms and one negatively charged oxygen atom
7
Q
What bonds makeup water
A
- Covalent
- Hydrogen
8
Q
Covalent bonds are formed between… in water
A
Between oxygen and hydrogen (O-H) with electrons shared between them
9
Q
Hydrogen bonds are formed between… in water?
A
Between water molecules
10
Q
How many water molecules can form clusters?
A
Up to four
11
Q
Do water molecules form clusters?
A
Yes, they break and reform all the time
12
Q
What are the key features of water?
A
- Good solvent
- High specific heat capacity
- High latent heat of vaporisation
- High cohesion
- Reactive
- Incompressible
13
Q
What is Metabolism
A
The sum/total of all biochemical reactions in the body
14
Q
What is needed to maintain a healthy body?
A
- Carbohydrates
- Lipids
- Proteins
- Nucleic acid
- Vitamins and minerals
- Water
- Fibre
15
Q
What are the most common elements in living organisms?
A
Carbon, Hydrogen, Nitrogen, Oxygen
16
Q
What are macromolecules made up of?
A
Repeating subunits that are joined end to end, they are easy to make
17
Q
What is polymerisation?
A
The making of polymers
18
Q
What does Anabolism do and require?
A
- Builds smaller molecules into complex molecules
- Requires energy
19
Q
What does Catabolism do and releases?
A
- Breakdowns a complex molecule into simple molecules
- Releases energy
20
Q
What happens in a Condensation reaction?
A
- Water molecule is released
- New covalent bond is formed
- Larger molecule is formed by the bonding together of smaller molecules
21
Q
What happens in a Hydrolysis reaction?
A
- Water molecule is used
- Covalent bond is broken
- Smaller molecules are formed by the splitting of a larger molecule
22
Q
What do carbohydrates contain?
A
Carbon, Hydrogen, Oxygen
23
Q
What is the general formula for a carbohydrate?
A
Cx(H2O)y
24
Q
What are the three main groups of carbohydrates?
A
- Monosaccharides
- Disaccharides
- Polysaccharides
25
What are the three main types of monosaccharides?
- Trioses (3C)
- Pentoses (5C)
- Hexoses (6C)
26
What is glucose made up of?
A chain of atoms long enough to close up on itself
27
What do the chain of atoms in glucose make?
A stable ring structure
28
Carbon atom 1 joins to the...
O on Carbon atom 5
29
The six-sided structure from is known as a
Pyranose ring
30
What does a-glucose look like>
First cabon is bonded to O, H, OH, and second carbon
Second carbon is bonded to H, OH, and third carbon
Third carbon is bonded to H, OH, and fourth carbon
Fourth carbon is bonded to OH, H, and fifth carbon
Fifth carbon is bonded to H, O, sixth carbon
Sixth carbon is CH2OH
Oxygen is bonded to both fifth carbon and first carbon
31
Which way round is the H and OH on first carbon in a-glucose?
H on top
| OH on bottom
32
What does b-glucose look like?
First cabon is bonded to O, H, OH, and second carbon
Second carbon is bonded to H, OH, and third carbon
Third carbon is bonded to H, OH, and fourth carbon
Fourth carbon is bonded to OH, H, and fifth carbon
Fifth carbon is bonded to H, O, sixth carbon
Sixth carbon is CH2OH
Oxygen is bonded to both fifth carbon and first carbon
33
Which way round is the H and OH on first cabon in a B-glucose?
OH on top
| H on bottom
34
What is an Isomer?
They posses the same molecular formula but differ in arrangement of atoms.
35
a-glucose and B-glucose are different arrangments of glucose so they are?
Isomers
36
What are Disaccharides?
Two monosaccharides combined
37
How are disaccharides formed?
Condesation reaction occurs, so a water molecule is lost and a 1,4 glycosidic bond is formed between the monosaccharides
38
To break a disaccharide, what is needed?
The addition of water, hydrolysis
39
What are polysaccharides?
Many monosaccharides
40
Polysaccharides are ... because of size?
Insoluble
41
Are polysaccharides sugars?
No
42
Starch, glycogen and cellulose are examples of?
Polysaccharides
43
What is starch made up of?
Mix of Amylose and Amylopectin
44
Starch granules are ... in water?
Insoluble
45
What is starch used for?
Storage in plants
46
Where is strach stored in plants?
Chloroplasts or storage organs
47
What are the chains like in Amylose?
Long, unbranching
48
What is the bond in Amylose?
1,4 glycosidic bond
49
Which reaction forms amylose?
Condesation reaction
50
What structure are the chains in, in amylose?
Helical Structures
51
What are the chains like in Amylopectin?
Shorter than amylose, branches
52
What are the bonds in Amylopectin?
- 1,4 glycosidic bonds
| - 1,6 glycosidic bonds
53
What do the 1,6 glycosidic bonds do in Amylopectin?
Form the branches
54
What is glycogen used for?
Storage in animals
55
Where is glycogen stored in animals?
Liver, Muscles
56
There are more ... containing a ... number of ... molecules than ...
Branches, Smaller, Glucose, Amylopectin
57
What isomer of glucose does glycogen have?
Alpha
58
What isomer of glucose does amylopectin and amylose have?
Alpha
59
What are the bonds in glycogen?
- 1,4 glycosidic bonds
| - 1,6 glycosidic bonds
60
What do the 1,6 glycosidic bonds do in glycogen?
Form the branches
61
Energy ... molecules that take up ... space due to their ... shape. Helps to prevent a too ... concentration of ... in cells.
Storage, Little, Compact, High, Glucose
62
Why is cellulose the most abundant organic molecule on the planet?
Presence in cell walls
63
What is cellulose rate of breakdown?
Slow
64
What isomer of glucose does cellulose have?
B-glucose
65
How many B-glucose molecules does cellulose contain approximately?
10,000
66
What is the chain like in cellulose?
Long, Unbranching
67
Many chains run ... to each other and have ... linkages between the ..., giving increased ...
Parallel, Cross, Chains, Stability
68
What bond is in cellulose
1,4 glycosidic bonds
69
What bond forms the links between chains in cellulose?
Hydrogen
70
What do the hydrogen bonds do in cellulose
Form cross-links between chains which collectively give the structure increased strength
71
B-glucose molecules have to be rotated how many degrees?
180° relative to the other B-glucose molecules
72
Cellulose forms microfibrils because?
It becomes tightly cross-linked with each other
73
True or false: Does cellulose have high contractile strength?
False. Cellulose has a high tensile strength
74
What bond form cellulose fibres?
Hydrogen bonds
75
Which fibres form cellulose fibres?
Microfibrils
76
What can you test for when testing for the presence of a carbohydrate?
- Starch
- Reducing sugar
- Non-reducing sugar
77
Which of the three main groups of carbohydrates are always reducing sugars?
All monosaccharides
78
What group do reducing sugars have?
Aldehyde group (H-C=O)
79
What does the aldehyde group in reducing sugars do
It contributes an electron to the sugar
80
Reducing sugars become?
Oxidised
81
How to test for Starch?
Iodine test
- Add iodine solution to test sample
- If sample turn blue-black then starch is present
82
Why does the test for starch work?
Iodine gets trapped in the amylose helix which stains it
83
How to test for reducing sugar?
Benedicts test
- Add sample to boiling tube
- Add benedicts solution
- Heat in a water bath at 80° for 3 minutes
- If a red-orange precipitate forms then a reducing sugar is present
- If there is no colour change then a reducing sugar is not present
84
Why does the benedicts test work for reducing sugars?
If added to a reducing agent (reducing sugar), Cu^2+ ions are reduced to Cu^+, which gives the red colour of Copper (I) sulphate
85
If lipids are not polymers, then what are they?
Large molecules
86
What are the features of lipids?
- Have few Oxygen atoms
- Have many Carbon and Hydrogen atoms
- It is hydrophobic
- Less dense than water
87
What does hydrophobic mean?
Repels/fails to mix with water
88
What does hydrophilic mean?
Mixes with water
89
What are the two important groups of lipids?
- Triglycerides
| - Phospholipids
90
What are the two sub-groups of triglycerides?
Fats
| Oils
91
What state is fat in at room temperature?
Solid
92
What state is oil in at room temperature?
Liquid
93
What are the functions of lipids?
- Source of energy
- Store of energy
- Biological membranes
- Thermal insulators/Insulation
- Buoyancy
- Protection (Cuticle of a leaf/Internal organs)
- Metabolic source of water
- Hormones
94
What does the structure of glycogen look like?
3 carbon atoms each bonded to one H and one OH
| The two end carbon atoms are bonded to an extra H
95
What does the structure of a fatty acid look like?
```
An acid (Carboxyl) group at one end (COOH), attached to a hydrocarbon tail
Hydrocarbon chain (2-20 carbons long)
Can be either saturated or unsaturated
```
96
What is a saturated fatty acid?
No double bonds between carbon atoms on the carbon skeleton (C-C)
97
What is an unsaturated fatty acid?
One or more double bonds between carbon atoms on the carbon skeleton (C-C or C=C)
98
What is a polyunsaturated fatty acid?
Has more than one double bond
99
What is a monosaturated fatty acid?
Has only one double bond
100
What do animal lipids tend to be and occur as?
Saturated
| Fats
101
What do plant lipids tend to be and occur as?
Unsaturated
| Oils
102
What is the most common form of lipid?
Triglycerides
103
What are triglycerides made up of?
Three fatty acids and one glycerol molecule
104
Glycerol is a type of...?
Alcohol
105
What type of reaction occurs between the three OH groups on a glycerol molecule and the carboxyl groups of a fatty acid?
Condensation
106
What type of bond is formed between glycerol and the fatty acids?
Ester bond
107
Features of Triglycerides
- Insoluble in water
- Soluble in some organic solvents
- Non-polar (not charged)
- Hydrophobic
108
What are the roles of triglycerides?
- Energy reserve
- Insulator against heat loss
- Buoyancy
- Protection (vital organs)
- Metabolic source of water
109
What are phospholipids?
A special type of lipid
110
What is one of the fatty acids replaced by in phospholipids?
A phosphoric acid
111
What is phosphoric acid (in terms of water)?
Hydrophilic, it is the head of the phospholipid
112
What are the hydrophobic tails?
Fatty acids
113
Cholesterol is a ... molecule
Small
114
The ... group is polar
-OH
115
The ... rings and the ... tail are non-polar
4 carbon rings, Hydrocarbon
116
What are the functions of cholesterol?
- Found in biological membranes
- Steroids are made from cholesterol
- Excess cholesterol forms gallstones and causes atherosclerosis in blood vessels
117
How much of the dry mass of cells is protein?
50%
118
What are the important functions of proteins?
- Cell membranes
| - Enzymes
119
What are proteins made of?
Amino acids
120
How many amino acids are there?
20
121
What changes between amino acids?
The residual group (R group)
122
A single chain of amino acids makes a?
Polypeptide
123
What types of bonds are between amino acids in a polypeptide chain?
Peptide bonds
124
Wha is the structure of an amino acid?
Amine group (NH2)
Carboxyl group (COOH)
R group
Hydrogen
These are joined at the same C atom in the middle of the amino acid
125
What reaction forms a peptide bond?
Condensation
126
What is the primary structure?
It is the proteins amino acid sequence
127
What determines the primary structure?
The gene that codes for the polypeptide
128
What is the secondary structure?
Polypeptides become twisted or coiled
129
What structures does the secondary structure occur in?
- Alpha helix (Right-handed)
| - Beta-pleated sheet
130
What holds the coils in place in an alpha helix?
Hydrogen bonds
131
What do the hydrogen bonds give to a protein molecule?
Stability
132
What is a tertiary structure?
The folding of the polypeptide to give a move complex 3-D shape
133
The tertiary structure is ... to the ... of the polypeptide
Specific
| Function
134
What are the three bonds and one interaction that helps to hold the folded protein in its precise shape?
- Hydrogen bonds
- Ionic bonds
- Disulphide bonds
- Hydrophobic interactions
135
Where are the hydrogen bonds in a tertiary structure?
Between polar groups
- Electronegative oxygen atoms of the -CO
- Electropositive hydrogen atoms on -OH/-NH
136
Where are the disulphide bonds in a tertiary structure?
Between sulfur-containing R-groups
137
What type of bond are disulphide bonds?
Covalent
138
How do disulphide bonds make the tertiary protein structure very stable?
By forming strong links
139
How can disulphide bonds be broken?
Reducing agents
140
Where are ionic bonds in a tertiary structure?
Between R groups
141
The ionic bonds in a tertiary ionise to form...
Positively and negatively charged groups that attract each other
142
Where do hydrophobic interactions occur in a tertiary structure?
Between non-polar side chains of a protein molecule
143
Bonds form between ..., ... R groups on amino acids in a tertiary structure
Non-polar
| Hydrophobic
144
What attraction reinforces the interactions when the two hydrophobic molecules are close together?
Van der Waals attractions
145
What do Van der Waal attractions provide to a tertiary structure?
Weak bonds
146
Electrons are... and ...?
Always in motion
| Not evenly distributed around a molecule
147
The constant movement of electrons and the electrons not being evenly distributed around a molecule causes?
Areas of positive and negative charges which are continuously changing
148
What do Van der Waals attractions allow?
Molecules to 'stick' to one another
149
What is a quaternary structure?
The association of different polypeptide chains bonded together to form intricate shapes
150
What do quaternary structures sometimes contain?
Prosthetic groups
151
What are prosthetic groups?
A permanent part of a protein molecule, but not made of amino acids
152
What are globular proteins?
Molecules curl up into a 'ball' shape
153
What are examples of globular proteins?
Haemoglobin, Myoglobin, Insulin
154
What are conjugated proteins?
Globular proteins that contain a prosthetic group
155
What is an example of a conjugated protein?
Haemoglobin
156
What are fibrous proteins?
Structural proteins
157
What are the features of fibrous proteins?
- Long strands
| - Usually insoluble
158
What are examples of fibrous proteins?
- Keratin
- Elasticin
- Collagen
159
What is the function of Haemoglobin?
It is an oxygen-carrying pigment found in red blood cells
160
What is the structure of Haemoglobin?
- Four polypeptides
- 2 Alpha-globin
- 2 Beta-globin
- Each polypeptide has a 3-D structure
- In the middle, each polypeptide has a Haem group
161
What is the 3-D structure stabilized by in Haemoglobin?
Hydrophobic interactions in the centre
162
What type of protein is collagen?
Fibrous protein
163
Collagen is a important...?
Structural protein
164
How many polypeptide chains are in collagen? (Structure)
Three identical polypeptide chains
165
The three polypeptide chains in collagen are would in a ...? (Structure)
Left-handed triple helix
166
How long is each polypeptide in collagen?
About 1000 amino acids long
167
What type of structure does the three polypeptide chains have in collagen?
Primary structure
168
Which amino acid is found every three amino acids in collagen?
Glycine
169
What happens to the sequence in the polypeptide chains in collagen that allows glycine to be found at every position along the triple helix?
The polypeptide chains are staggered
170
What bonds hold the three polypeptide chains together in collagen?
Hydrogen
171
Which type of bond holds together adjacent molecules of collagen?
Covalent bonds
172
Where are the covalent bonds formed in collagen?
Between the carboxyl group of one amino acid and the amine group of another
173
Collagen is a structural protein, what property allows this?
It is a tough, rope-like protein
174
What type of structure does collagen have overall?
Quaternary
175
What do the staggered ends allow the proteins to do, in collagen?
Join end to end
176
What are the fibrils called that collagen produces?
Tropocollagen
177
What do the tropocollagen fibrils do that produce strong fibres in collagen?
They cross-link
178
What two other amino acids, other than glycine, make up a high proportion of collagen?
Proline, hydroxyproline
179
What do the R groups in proline and hydroxyproline do that adds to the stability of collagen?
Repel each other
180
Elastin is made by linking?
Many soluble tropoelastin protein molecules
181
What do the soluble tropoelastin molecules form?
A large, insoluble, and stable, cross-linked structure
182
Tropoelastin molecules are said to act similar to springs, why is this?
They are able to stretch and recoil without breaking
183
What do tropoelastin molecules contain?
Alternate hydrophobic and lysine-rich areas
184
When is elastin formed?
When multiple tropoelastin molecules aggregate via interactions between the hydrophobic areas
185
How is elastin stabilised?
By cross-linking covalent bonds, involving the amino acid lysine
186
Elastin gives the ... to expand when needed
Flexibility
187
What type of protein is elastin?
Fibrous protein
188
Where is elastin found?
In elastic fibres
189
What structure protein is elastin?
Quaternary
190
Keratin has a high proportion of...?
The sulfur-containing amino acid, cysteine
191
What does the cysteine amino acid result in, in keratin?
Many strong disulphide bonds
192
What do the disulfide bonds form, in keratin?
Strong, inflexible, and insoluble materials
193
What does the degree of disulphide bonds determine in Keratin
The flexibility of the molecules
194
What is the biuret test actually looking for, instead of the presence of proteins?
The presence of peptide bonds
195
What makes up biuret A?
Sodium Hydroxide, NaOH
196
What makes up biuret B?
Copper Sulphate, CuSO4
197
How do you perform a biuret test for proteins?
Mix biuret A with biuret B in the sample.
If there is a protein present, then the sample will turn purple
If no protein present, sample will not change colour
198
How do you do a test for lipids?
Emulsion test
- Add ethanol to the solution
- Mix solution
- Add some water
199
Why do you add ethanol to the sample when testing for lipids
Lipids are soluble in alcohols
200
Why do you add water to the sample when testing for lipids?
All of the dissolved lipids will come out of the solution and are dispersed as small droplets throughout the solution of ethanol and water
201
Explain why water can form hydrogen bonds
The positive and negative regions of the water molecule attract each other and form hydrogen bonds because it is polar
202
Hydrogen bonds allow water to act as a solvent
| Why is the ability of water to act as a solvent important for the survival of organisms?
Many of the solutes in organisms can be dissolved in water. Water acts as a medium for chemical reactions and also helps transport dissolved compounds in and out of cells
203
Agarose forms part of a more complex carbohydrate called agar, which is used as a growth medium for bacteria. Bacteria cannot break down the agarose in agar.
Suggest why bacteria cannot break down agarose.
Do not have the necessary enzyme
204
State the name given to the sequence of amino acids in a protein molecule
Primary structure
205
State one function of haemoglobin
Transports oxygen in the blood
206
What does this description describe:
| The type of reaction that occurs when water is added to break a bond in a molecule?
Hydrolysis
207
What does this description describe:
| The phosphate group of a phospholipid that readily attracts water molecules?
Hydrophilic
208
Collagen is found in the ligaments which hold bones together at joints.
State two properties of collagen that make it suitable for this purpose
Strong
| Insoluble
209
Suggest why a student would be unsure if the positive result for lipid was correct for the milk sample
The milk is already white
210
State three roles of lipids in living organisms
- Protection of vital organs
- Buoyancy
- Insulator
